CURRENT SENSOR WITH INTEGRATED CURRENT CONDUCTOR

专利摘要:
The invention relates to a current sensor device (200) for measuring a current of at least 30 A, comprising a lead frame with an electrical conductor (203) having a center line (C); a substrate (210) mounted adjacent to the electrical conductor and comprising a first and a second magnetic sensor (211, 212) configured to provide a first and a second value (v1, v2); and a processing circuit (610; 710) for determining the current based on a difference or weighted difference between the first and the second value (v1, v2). The first and second magnetic sensors are arranged asymmetrically with respect to the center line (C). Figure for the abstract FIG. 2 (a)
公开号:FR3090120A1
申请号:FR1914043
申请日:2019-12-10
公开日:2020-06-19
发明作者:Javier Bilbao De Mendizabal；Simon HOUIS
申请人:Melexis Technologies SA；
IPC主号:

专利说明:

Description
Title of the invention: CURRENT SENSOR WITH INTEGRATED CURRENT CONDUCTOR
Field of the invention
The present invention relates generally to the field of current sensors, and more particularly current sensors capable of measuring a relatively strong current (for example of at least 30 A).
Background of the invention
There are current sensors based on magnetic sensors to measure relatively strong currents (for example at least 25 A). They normally measure a current flowing in an external conductor. One problem with such a current sensor system is that the accuracy of the measurement greatly depends on the mounting tolerances of the sensor device with respect to the electrical conductor. Although it is possible to increase accuracy by performing a calibration test at the system level (for example after mounting the sensor circuit on a printed circuit board), this is very impractical, subject to error. human, time consuming and expensive.
There is always room for improvement or other solutions.
Summary of the invention
An object of the embodiments of the present invention is to provide a current sensor capable of measuring a relatively strong current (for example a current of at least 30 amps).
An object of the embodiments of the present invention is also to provide an "integrated current sensor device" (that is to say comprising an electrical conductor incorporated inside the device), and capable of measuring a relatively strong current (for example a current of at least 30 amps).
An object of the embodiments of the present invention is also to provide such a current sensor which is very compact.
An object of the embodiments of the present invention is also to provide such a current sensor which is very insensitive to an external disturbance field (also called "parasitic field").
An object of the embodiments of the present invention is also to provide a current sensor which is very precise without the need for a calibration test at the CCI level (for example by an equipment manufacturer d (OEM)).
An object of the embodiments of the present invention is also to provide a current sensor which is easy to produce.
An object of the embodiments of the present invention is also to provide a current sensor which can be mounted on a PCB with reduced mounting tolerances without sacrificing precision.
An object of the embodiments of the present invention is also to provide a current sensor comprising a semiconductor die, and capable of measuring a relatively strong current (for example a current of at least 30 amps), without (significantly) increasing the size of the chip, and without (significantly) decreasing the accuracy.
An object of the embodiments of the present invention is to provide a current sensor comprising an integrated electrical conductor, and a semiconductor die of a size less than 7 mm ² , and capable of measuring a current d '' at least 40 amps.
An object of the embodiments of the present invention is also to provide such a current sensor having a longer service life, in particular because it is less sensitive to cracks or microcracks.
These and other objects are made by a current sensor device according to the embodiments of the present invention.
In a first aspect, the present invention provides a current sensor device for measuring a current, comprising: a connection grid comprising a first part (for example a high power part) comprising first pins (for example first input pins and first output pins) connected or shaped so as to form an electrical conductor adapted to carry the current to be measured, and a second part, (for example a low power part) comprising a plurality of second pins; a substrate comprising or connected to at least a first magnetic sensor and comprising or connected to a second magnetic sensor, the first and second magnetic sensor forming a first pair of magnetic sensors; wherein the first magnetic sensor has a first axis of maximum sensitivity, and the second magnetic sensor has a second axis of maximum sensitivity parallel to the first axis; wherein the first magnetic sensor is located at a first location and is configured to provide a first indicator value of a first magnetic field component at said first location; wherein the second magnetic sensor is located at a second location and is configured to provide a second indicator value of a second magnetic field component at said second location; in which a magnetic field, induced by the current to be measured, when the latter flows in the electrical conductor, defines a first magnetic field vector at the location of the first sensor, and defines a second magnetic field vector at the location of the second sensor, the first magnetic field vector and the second magnetic field vector defining intersecting or intersecting lines; a processing circuit connected to the first and to the second magnetic sensor, and adapted to determine the current to be measured at least on the basis of a difference or a weighted difference between the first value and the second value obtained from the first pair of sensors; and wherein the electrical conductor has a center line, and a first distance between the center line and the location of the first sensor is different from a second distance between the center line and the location of the second sensor; and wherein the locations of the first and second sensors are located such that one or more of the following conditions is / are met: i) a projection of the location of the first sensor perpendicular to a plane parallel to the electrical conductor (or in other words parallel to a plane containing the electrical conductor), is located outside the electrical conductor, and a projection of the location of the second sensor perpendicular to said plane is located inside the electrical conductor; ii) an angle defined by the first magnetic field vector at the location of the first sensor and the second magnetic field vector at the location of the second sensor is an angle in the range of 70 ° to 110 °; iii) an angle between a first virtual plane containing the center line and the location of the first sensor, and a second virtual plane containing the center line and the location of the second sensor is an angle in the range of 30 ° to 110 °, or from 40 ° to 110 °, or from 50 ° to 110 °, or from 60 ° to 110 °, or from 70 ° to 110 °, or from 80 ° to 100 °, or from 50 ° to 88 °, or 60 ° to 88 °, or from 30 ° to 80 °, or from 30 ° to 88 °.
It is advantageous to calculate the current on the basis of a difference between two sensors having parallel axes of maximum sensitivity, because this makes it possible to determine the current in a way which is substantially immune to a parasitic field. It is advantageous to calculate the current on the basis of a weighted difference, since this also makes it possible to compensate for a disparity in sensitivities.
The integration of the electrical conductor is a major advantage, as it allows very precise positioning of the substrate (and therefore magnetic sensors) relative to the electrical conductor, unlike a system comprising a current sensor device which is mounted on the vicinity of an external electrical conductor, for example on a PCB (printed circuit board). The positioning tolerances of an integrated current sensor are normally an order of magnitude more precise than the positioning tolerances of a chip on a CCI, or on an electrical conductor. In addition, the distance between the sensor location and an integrated current conductor is also characteristically shorter by at least a factor of 2 than the distance between the sensor location and an external current conductor, and if the 'it is taken into account that the magnetic field intensity normally decreases with 1 / r and that the magnitude of a magnetic field gradient normally decreases with l / (r * r), characteristically the SNR is improved by at least a factor of 4 compared to solutions using an external current conductor. Both the lower tolerances and the shorter distance have the effect that a current sensor with an integrated or incorporated electrical conductor has much greater accuracy than a current sensor mounted adjacent to an external electrical conductor.
The placement of the first and second sensors, as described as their projected position, or as their distances from the center line of the electrical conductor, which in simple terms could be interpreted as: located on the opposite sides of a conductor edge, rather than on or near opposite sides of the electrical conductor, is a major advantage because it decouples the relationship between the width of the substrate and the width of the conductor, or in other words, it allows the substrate size (or die size) to be chosen as being smaller than the width of the conductor, which is not possible in solutions in which the sensors are placed near the opposite edges of the current conductor. This advantage should not be underestimated, because the cost of a substrate (for example semiconductor) represents a significant part of the total cost of the current sensor, while (for a given material, and a given thickness of the conductor electric and for a given maximum current to be measured), the width of the electric conductor determines the electric resistance of the conductor, and therefore the heat dissipation (dissipation by Joule effect), and therefore the maximum current which can be measured with the integrated current.
An advantage of this current sensor device is that it is able to measure said current on the basis of the measurement of a magnetic field gradient (for example ΔΒχ / Δχ).
It is advantageous to calculate the current (to be measured) on the basis of a difference between values supplied by two sensors before axes of parallel maximum sensitivity, since this makes it possible to determine the current in a way which is substantially immune to a parasitic field.
The integration of the electrical conductor is a major advantage, cat it allows a very precise positioning of the substrate relative to the electrical conductor, unlike a system comprising a current sensor device which is mounted in the vicinity of an external electrical conductor , for example on a CCI (printed circuit board). The positioning tolerances of an integrated current sensor are normally an order of magnitude more precise than the positioning tolerances of a chip on a CCI, or on an electrical conductor. All other aspects remaining the same, this means that a current sensor with an incorporated electrical conductor has much greater accuracy than a current sensor mounted adjacent to an external electrical conductor, unless additional arrangements are made, such as than a calibration test by the end user in the application.
The placement of the second sensor "above or below" the electrical conductor (or stated as: "so that its projection in a direction perpendicular to the plane of the conductor, is a placement" on "the electrical conductor ”), And the first sensor is“ outside ”of the electrical conductor (so that its perpendicular projection is“ not placed on ”the electrical conductor) is a major advantage, because it decouples the relationship between the width of the substrate and the width of the conductor, or in other words, it allows to choose the size of the substrate (or the size of the die) as being smaller than the width of the conductor, which is not possible in the solutions in which the sensors are placed near the opposite edges of the electrical conductor. This advantage should not be underestimated, because the cost of the substrate represents a significant part of the total cost of the current sensor, while (for a given material, and a given thickness of the electrical conductor and for a given maximum current to be measured ), the width of the electrical conductor determines the electrical resistance of the conductor, and therefore the heat dissipation (dissipation by Joule effect).
The present invention is partly based on the intuitive concept that it is possible to increase the width of the electrical conductor (and therefore reduce the electrical resistance, or increase the maximum permissible current) without significantly reducing the accuracy current measurement, and without significantly increasing the size of the chip, nor therefore the cost.
In one embodiment, the current to be determined is based on a weighted difference of the first value (vl) and the second value (v2), and the respective weighting factors (A, B) are chosen such so that a uniform external magnetic field is suppressed. The weighting factors can for example be determined during a calibration test and stored in non-volatile memory, and retrieved from non-volatile memory during actual use.
The current sensor device can be produced for example by the steps of: a) providing the connection grid comprising the electrical conductor; b) possibly placing an insulating material on the electrical conductor; c) mounting a substrate on the electrical conductor or on the insulating material; d) electrically connect the second pins and the substrate (for example by applying connecting wires); e) overmolding the connection grid and the substrate.
The first pins may include one or more first input pins (primary current) and one or more first output pins (primary current). The plurality of second pins can also be referred to as "low voltage pins" or "signal pins".
By "the first and second vectors defining intersecting or intersecting lines" is meant that the first vector is located on a first virtual line and the second vector is located on a second virtual line, and the first line and the second line is not parallel. Preferably the first and second vectors define in angle in the range of 5 ° to 175 ° or in the range of 185 ° to 355 °, or in the range of 70 ° to 110 °.
The first sensor and the second sensor can be incorporated into the substrate, or can be mounted adjacent to or mounted on, or deposited on said substrate. Alternatively, only the first sensor is incorporated into the substrate, and the second sensor is incorporated into a second substrate, connected to the first substrate, for example by means of connecting wires.
The “electrical conductor” is the part of the lead frame which is galvanically connected to the first pins, including the first pins, and the electrical resistance of the electrical conductor is defined as the electrical resistance which would be measured between the first pins d input and the first output pins.
The first input pins and the first output pins can be located on opposite sides of the device housing, or on adjacent sides of the device housing (for example by forming an L shape).
Such a current sensor device can be produced by the steps consisting in: a) providing the connection grid comprising the electrical conductor; b) possibly placing an insulating material on the electrical conductor; c) mounting a substrate on the electrical conductor or on the insulating material; d) electrically connecting the second pins and the substrate; e) overmolding the connection grid and the substrate.
The electrical conductor may have a beam-like part, but this is not absolutely required.
The embodiments in which the conductor is substantially planar (for example in the form of a beam), and in which the first and second sensors are suitable for measuring a magnetic field component substantially parallel to the plane defined by the conductor (by example field Bx) instead of the field component being substantially perpendicular to the substantially plane field, are advantageous, since the size of the component Bx is substantially independent of the width of the conductor, unlike Bz which strongly depends on the width of the conductor (for Bz means the field component substantially perpendicular to said plane).
The first and second magnetic sensors are arranged asymmetrically with respect to the center line.
Preferably, the electrical conductor has an electrical resistance of less than 0.80 mOhm, or less than 0.60 mOhm, or less than 0.50 mOhm, or less than 0.40 mOhm, or less than 0.30 mOhm, or less than 0.28 mOhm, or less than 0.26 mOhm.
It is advantageous that the electrical resistance is less than, for example
0.30 mOhm, as this allows the current sensor device to carry a current of at least 30 amperes in the electrical conductor (integrated) with maximum current intensities of up to 100 A or even 120 A).
In one embodiment, each of the first and second magnetic sensors comprises at most one or at least one or at least two element (s) with horizontal Hall effect (rate) and at least one or two magnetic concentrator (s) (s) integrated (s) (BMI).
It is advantageous to use a BMI because it transforms the magnetic field components in the plane (frequently designated by Bx or By) into an out-of-plane magnetic field component (frequently designated by Bz), because this the latter can be measured by a horizontal Hall effect element. It is also advantageous to use a BMI because it provides passive signal amplification (typically by a factor of about 5 or 6). The thickness of BMI is normally in the range of about 20 to 25 micrometers, for example, about 23 micrometers.
In one embodiment, the first and second magnetic sensors each comprise at least one vertical Hall effect element. The vertical Hall effect elements can be arranged to measure a magnetic field component (Bx), the magnetic field component Bx being oriented substantially parallel to the plane of the electrical conductor (if the electrical conductor is substantially planar), and in a perpendicular direction at the midline.
In one embodiment, the first and second magnetic sensors each comprise at least one magnetoresistance element. The magnetoresistance element can comprise at least one of indium antimonide (InSb), a giant magnetoresistance element (GMR), an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance element (TMR) or a magnetic tunnel junction element (MTJ).
Said at least one magnetoresistance element can be arranged in a bridge circuit. The magnetic sensor may further include a compensation coil, and a closed loop current sensor system. An advantage of such a closed loop current sensor system is that it can reduce or substantially eliminate nonlinearities.
In one embodiment, the connection grid is a copper connection grid having a thickness in the range of 100 to 600 micrometers, or 200 to 500 micrometers, for example substantially equal to 200 micrometers, or substantially equal at 250 micrometers.
It is not without interest to build a current sensor device capable of measuring a current of at least 30 A or at least 40 A or at least 50 A using an internal conductor formed as part of the lead frame having a thickness in the range of 100 to 400 micrometers, or equal to about 200 or about 250 micrometers, in particular because the conventional way of reducing the electrical conductance of a conductor integrated in devices current sensors consists in increasing the thickness of the conductor (for example up to a value greater than 1 mm) while keeping the width of the conductor unchanged, because otherwise, if the width is increased and the thickness remains the same, the substrate size must be increased (and therefore also the cost).
In one embodiment, a first distance between an edge of the electrical conductor and the projection of the location of the first sensor is greater than 10% of a width of the electrical conductor; and / or a second distance between the center line of the electrical conductor and the projection of the location of the second sensor being less than 10% of a width of the electrical conductor.
It is advantageous to place the first sensor relatively far from the edge of the electrical conductor, since this gives a relatively low first value of the magnetic field component, and therefore a relatively large difference (or a relatively high gradient) between the first and second values.
It is advantageous to place the second sensor relatively close to the center line, for example substantially in the middle of the conductor, for example from 40% to 60% in a transverse direction of the electrical conductor, since this gives a second relatively high value of the magnetic field component, and therefore a relatively large difference (or a relatively high gradient) between the first and second values.
If the electrical conductor is in the form of a beam, the length is substantially parallel to the direction of the current flow, or in other words, is the direction of the first input pins to the first output pins (or vice versa). The width of a beam-like conductor is perpendicular to it. And the height of the beam-like conductor is less than the length and less than the width.
If the electrical conductor is not in the form of a beam, "the width of the conductor" is defined as the largest of a first line segment measured on a virtual line passing through the position of the first sensor and perpendicular to the center line, and a second line segment measured on a virtual line passing through the position of the second sensor and perpendicular to the center line.
In one embodiment, a distance between the location of the first sensor and the location of the second sensor is less than a width of the electrical conductor.
In one embodiment, a width Ws of the substrate is less than a width Wc of the electrical conductor.
In one embodiment, a distance between the location of the first sensor and the location of the second sensor is less than 80% of a width Wc of the electrical conductor, or less than 60% of Wc.
In one embodiment, a distance Δχ between the location of the first sensor and the location of the second sensor is a value in the range of 1.0 mm to 3.0 mm, or in the range of 1, 0 mm to 2.5 mm.
In one embodiment, the electrical conductor has a width Wc in the range of 1.0 mm to 7.0 mm; and / or the substrate has an area in the range of 1 to 5 mm ² .
In one embodiment, the electrical conductor has a width of approximately 4.0 (+ or -) 0.5 mm, and the substrate has a size of 2 (+ or -) 0.5 mm x 0, 5 mm.
Preferably the electrical conductor has a conductor portion having a constant cross section (in a plane perpendicular to the center line) in close proximity to the first and second magnetic sensors.
In one embodiment, the substrate has a first surface containing the first and second magnetic sensors, and the first surface faces the electrical conductor; and the current sensor device further comprises an electrical insulating material disposed between the first surface of the substrate and the electrical conductor. The electrical insulating material may be a layer of polyamide as part of the semiconductor die (eg CMOS device), or may be an electrical insulating tape applied between the lead grid and the semiconductor die.
An advantage of this embodiment is that the distance between the magnetic sensors and the electrical conductor is relatively small, and that the signal measured by at least one or only one of the sensors is relatively strong (for example stronger than in the case where the second surface faced the electrical conductor). This improves the signal-to-noise ratio.
In this embodiment, the substrate is preferably mechanically supported at a first region or first end by the electrical conductor and the insulation material. The substrate may further be mechanically supported at an opposite region or opposite end, or may be left floating at the other end, with a space between them, which space may be filled with air, or by a molding composition, or by an insulating tape or other electrical insulating material (for example a suitable polymer).
In one embodiment, the substrate has a first surface containing the first and second magnetic sensors, and the first surface faces the electrical conductor. The distance between the first surface and the electrical conductor can be a value in the range of 150 to 250 µm, or in the range of 170 to 210 µm, for example, equal to about 190 micrometers.
In one embodiment, the electrical insulating material is adapted to withstand a voltage of about 1000 volts.
In one embodiment, the substrate has a first surface containing the first and second magnetic sensors, and the first surface is diverted from the electrical conductor. In this embodiment, an electrical insulating material is not absolutely required between the electrical conductor and the substrate, but an electrical insulating material may possibly be present. In embodiments without electrical insulating material, the substrate can be positioned directly on the electrical conductor without additional electrical insulating material therebetween. This is easier to produce (requires less material and less handling), and therefore production is faster and less expensive. The distance between the first surface of the substrate and the electrical conductor can be a value in the range of 300 to 400 µm, or in the range of 320 to 380 µm, for example, equal to about 350 micrometers.
In the embodiments in which the substrate is separated from the electrical conductor by means of an electrical insulating tape, the distance between the substrate and the electrical conductor can be a value in the range of approximately 10 to 100 μm, or from 15 to 100 pm, or from 20 to 100 pm, or from 30 to 100 pm, or from 30 to 80 pm, or from 30 to 50 pm, for example equal to about 40 pm.
In one embodiment, the substrate further comprises a plurality of contact pads placed on a part of the substrate covering the electrical conductor; and the current sensor device further comprises a plurality of connecting wires interconnecting one or more of the plurality of second pins and one or more of the plurality of contact pads.
In one embodiment, the contact pads are arranged only in a region of the substrate corresponding to a part of the substrate which is mechanically supported below (that is to say is not left floating).
In one embodiment, the substrate further comprises a plurality of solder bumps connected to at least some of the second pins, but galvanically separated from the electrical conductor and the first pins.
Galvanic separation can be achieved by a space filled with air, or a space filled with a molding composition or a space filled with an insulating material, for example an insulating tape, or the like.
In one embodiment, the electrical circuit comprises a differential amplifier configured to determine and amplify said difference between the first value and the second value.
In one embodiment, the electrical circuit comprises an amplifier configured to selectively amplify the first value and the second value, for example by means of a switch in front of the amplifier, and the two amplified signals can be temporarily stored ( for example on one or more sampling and holding circuits) and then subtracted.
In one embodiment, the signal from the first sensor can be amplified by a first amplifier, and the signal from the second sensor can be amplified by a second amplifier, and the two amplified values can be subtracted from one of the other.
The sensor device may further comprise an analog / digital ADC converter configured to digitize the amplified difference signal (vl-v2), or to selectively digitize the first amplified signal and the second amplified signal. The ADC can be part of a digital processor, for example a programmable micro-controller.
The current to be measured can be supplied in the form of an analog output signal proportional to the current, or can be supplied in the form of a digital signal, which can for example be transmitted via a serial binary train.
In one embodiment, the current sensor device further comprises a digital processor comprising or connected to a non-volatile memory storing at least one constant value (for example a conversion factor), and the digital processor is suitable for determining the current to be measured on the basis of a difference or weighted difference between the first value and the second value and on the basis of said constant value.
The digital processor can include an input connected to an output of the differential amplifier, in which case the digital processor can be adapted to digitize the difference signal, and to multiply the digitized value by said constant value K, for example according to the formula: I = K. (AV), where AV is the digitized difference signal.
Or, the subtraction can be performed in the digital domain. The digital processor may have an input connected to an output of the amplifier, and the digital processor may be adapted to selectively digitize each of the first amplified signal and the second amplified signal, to perform subtraction in the digital domain, and to multiply the result by said constant value K, for obtaining a result which is indicative of the current to be measured, for example according to the formula: I = K. (V1-V2), where VI is a digitized value of the first signal (possibly amplified), and V2 is a digitized value of the second signal (possibly amplified).
In a variant, the digital processor can be adapted to calculate the current using the formula: I = (A.V1) - (B.V2), where "A" is a first amplification factor (analog or digital) and "B" is a second amplification factor (analog or digital). This embodiment offers the advantage of being able to correct a disparity of sensitivities. The values of A and B can be stored in non-volatile memory, and can be determined during calibration or in any other suitable way.
In one embodiment, the substrate also comprises at least one temperature sensor configured to measure at least one temperature in relation to a temperature of the first magnetic sensor and / or of the second magnetic sensor, said at least one sensor of temperature being connected to the digital processor; and the digital processor is adapted to calculate the current to be measured on the basis of a difference or weighted difference between the first value and the second value, and taking account of said at least one measured temperature.
An advantage of this current sensor is that it includes a temperature compensation mechanism. In this way, the accuracy of the current measurement can be further improved.
In one embodiment, the substrate further comprises a first temperature sensor and a second temperature sensor, the first temperature sensor being configured to measure a first temperature T1 of the first magnetic sensor, and the second temperature sensor being configured to measure a second temperature T2 of the second magnetic sensor, the first temperature sensor and the second temperature sensor being connected to the digital processor; and the digital processor is adapted to calculate the current to be measured on the basis of a difference or weighted difference between the first value vl and the second value v2, and taking into account the first temperature and the second temperature.
The fact that the temperature of each magnetic sensor is measured separately is a major advantage of this embodiment, since the temperature of the first magnetic sensor and that of the second magnetic sensor can be significantly different, in particular if a relatively strong current (for example more than 30 A) is measured, since a current of such intensity normally causes significant heating of the electrical conductor, causing a relatively high temperature gradient on the substrate. By measuring and taking into account the two temperatures, the accuracy of current measurement can be further improved. In addition, it is also possible to use the temperature sensor (s) to detect if the device is operating within its specified operational range. Otherwise, the sensor device may report an error, which can be used for security purposes.
In one embodiment, the first magnetic sensor comprises at least a first horizontal Hall effect element, and the first temperature sensor essentially surrounds the first horizontal Hall effect element, and the second magnetic sensor comprises at least a second horizontal Hall effect element, and the second temperature sensor essentially surrounds the second horizontal Hall effect element.
The temperature sensor can be arranged around the horizontal Hall effect elements in a manner similar to that described in patent document EP3109658A1, with or without a strain sensor.
In one embodiment, the substrate also comprises at least one stress sensor configured to measure at least one stress value linked to a mechanical stress undergone by the first magnetic sensor, said at least one stress sensor being connected (for example in a communicating manner) to the digital processor; and the digital processor is adapted to calculate the current to be measured on the basis of a difference or weighted difference between the first value and the second value, and taking account of said at least one measured stress value.
The strain sensor can be arranged around the horizontal Hall effect element in a similar manner to that described in patent document EP3109658A1, but without a temperature sensor.
An advantage of this current sensor is that it includes a stress compensation mechanism. In this way, the accuracy of the current measurement can be further improved.
In one embodiment, the substrate further comprises a first stress sensor and a second stress sensor, the first stress sensor being configured to measure a first stress at the location of the first sensor, and the second sensor being configured to measure a second strain at the location of the second sensor, the first strain sensor and the second strain sensor being connected to the digital processor, and the digital processor is adapted to calculate the current to be measured based on 'a difference or weighted difference between the first value v1 and the second value v2, and taking into account the first constraint and the second constraint.
A major advantage of this embodiment is that the (mechanical) stress of each magnetic sensor is measured separately, since the stress exerted on the first magnetic sensor and that exerted on the second magnetic sensor can be significantly different, in particular if a relatively strong current (for example more than 30 A) is measured, because a current of such intensity normally causes significant heating of the electrical conductor, causing a relatively high temperature gradient, causing mechanical stress (related to the different coefficients of thermal expansion of different materials). In this way, the accuracy of the current measurement can be further improved.
In one embodiment, the substrate further comprises a first temperature sensor and a first stress sensor surrounding the first magnetic sensor, and a second temperature sensor and a second stress sensor surrounding the second magnetic sensor, the first temperature sensor and the first strain sensor and the second temperature sensor and the second strain sensor being connected (for example in a communicating manner) to the digital processor; and in which the digital processor is adapted to calculate the current to be measured on the basis of a difference between the first value (possibly amplified with or multiplied by a first factor A) and the second value (possibly amplified with or multiplied by a second factor B), and taking into account the first and second temperatures and the first and second constraints, where factors A and B can be chosen to compensate for a disparity in sensitivities.
The temperature sensor and the strain sensor can be arranged around the first and second magnetic sensors in a similar manner to that described in patent document EP3109658A1. In this way, the accuracy of the current measurement can be further improved.
In one embodiment, the value of the current determined by the processing circuit on the basis of the first and of the second magnetic sensor is considered as a first current value; and the substrate further comprises a third magnetic sensor arranged in a manner similar to that of the first magnetic sensor and configured to measure a third value, and further comprises a fourth magnetic sensor arranged in a manner similar to that of the second magnetic sensor and configured to measure a fourth value; and the processing circuit is further connected to the third magnetic sensor for obtaining the third value, and to the fourth magnetic sensor for obtaining the fourth value, and is further adapted to determine a second current value on the basis of a difference or a weighted difference between the third value and the fourth value; and is further adapted to compare the second current value and the first current value, and if a difference or a ratio between the first current value and the second satisfies a preset condition (e.g. falls within a preset range or becomes lies beyond such a range), to provide an average of the first current value and the second current value, as the value of the current to be measured. Alternatively, either the first current value or the second current value can be supplied as "the" current value.
The third and fourth magnetic sensors can include a third and a fourth horizontal Hall effect element, forming a second pair of magnetic sensors. The sensor elements of the second pair can be placed at approximately the same distance from the center line as the sensor elements of the first pair, but this is not absolutely required.
This embodiment can use four magnetic sensors for redundancy purposes and / or for "functional safety" purposes. In the case where the first and second current values are substantially the same, the average of these currents is provided, which further improves the accuracy.
In the case where the first and second values deviate too much (by more than a predefined value or by more than a predefined percentage), the current sensor device can provide an error signal, for example a analog error signal via one of the second pins, or a digital error value in a serial information flow via one of the second pins.
In a particular embodiment, the connection grid is a copper connection grid having a thickness in the range of 100 to 600 micrometers; and the first pins include first input pins placed on one side of the device; and first output pins placed on another side of the device opposite the first side; and the electrical conductor comprises a substantially planar and substantially beam-shaped interconnecting portion having a length substantially covering the total distance between the first input pins and the first output pins; and the electrical conductor has an electrical resistance of less than 0.80 mOhm; and the beam-shaped interconnecting part has a width in the range of 1.0 mm to 7.0 mm; and the semiconductor substrate comprises said first magnetic sensor and said second magnetic sensor and said processing circuit integrated or incorporated in said substrate; and the width (Ws) of the substrate is less than the width (Wc) of the beam-shaped interconnection part; and the projection of the location of the first sensor perpendicular to the plane (XY) defined by the direction of the length and the direction of the width of the beam-shaped interconnection part is situated outside the part of beam-shaped interconnection, and the projection of the location of the second sensor perpendicular to said plane is located on the beam-shaped interconnection portion; and the current sensor device is overmolded to form an encapsulated current sensor device.
In this embodiment, the beam-shaped interconnection part constitutes a major part of the electrical conductor. This embodiment has the combination of the advantages mentioned above (for example high precision, insensitivity to external parasitic field, good RSB, ability to measure strong currents, low electrical resistance, low heat production, etc.). In addition, this current device is very compact, has great robustness or mechanical rigidity, and has a relatively low cost of material (in particular thanks to the small size of the semiconductor substrate).
A major advantage of this device is that it has a longer lifespan due to a reduced tendency to cracks or microcracks caused by temperature variations due to heating by Joule effect, unlike the devices of the technique which have a curved conductor part.
According to a second aspect, the present invention also provides a method of manufacturing a current sensor device for measuring a current, the method comprising the steps consisting in: a) providing a connection grid comprising a first part (by example a high power part) comprising first pins (for example first input pins and first output pins) connected or shaped so as to form an electrical conductor suitable for transporting the current to be measured, and a second part ( for example a low power part) comprising a plurality of second pins; b) providing a substrate comprising or connected to at least a first magnetic sensor and comprising or connected to a second magnetic sensor, the first magnetic sensor having a first axis of maximum sensitivity, and the second magnetic sensor having a second axis of parallel maximum sensitivity at the first axis; the first magnetic sensor located at a first location and configured to provide a first value indicative of a first magnetic field component at said first location; the second magnetic sensor located at a second location and configured to provide a second value indicative of a second magnetic field component at said second location; in which a magnetic field, induced by the current to be measured when the latter flows in the electrical conductor, defines a first magnetic field vector at the location of the first sensor, and defines a second magnetic field vector at the location of the second sensor, the first magnetic field vector and the second magnetic field vector defining intersecting or intersecting lines; c) mounting the substrate with respect to the connection grid so that a first distance between the center line and the location of the first sensor is different from a second distance between the center line and the location of the second sensor; and such that the locations of the first and second sensors are located such that one or more of the following conditions is / are satisfied: i) a projection of the location of the first sensor perpendicular to a plane parallel to the electrical conductor (or in other words parallel to a plane containing the electrical conductor), is located outside the electrical conductor, and a projection of the location of the second sensor perpendicular to said plane is located inside the conductor electric; ii) an angle defined by the first magnetic field vector at the location of the first sensor and the second magnetic field vector at the location of the second sensor is an angle in the range of 70 ° to 110 °; iii) an angle between a first virtual plane containing the center line and the location of the first sensor, and a second virtual plane containing the center line and the location of the second sensor is an angle in the range of 70 ° to 110 °, or from 80 ° to 100 °, or from 50 ° to 88 °, or from 60 ° to 88 °; d) providing a processing circuit connected to the first and second magnetic sensors, and adapted to determine the current to be measured at least on the basis of a difference or a weighted difference between the first value and the second value obtained from the first pair of sensors; wherein the electrical conductor has a center line.
The processing circuit can be incorporated on the same substrate as the first magnetic sensor and / or the second magnetic sensor, in which case step d) can be included in step b).
According to a third aspect, the present invention also provides a current sensor device for measuring a current, comprising: a connection grid comprising a first part (for example a high power part) comprising first pins (for example first input pins and first output pins) connected or shaped so as to form an electrical conductor suitable for carrying the current to be measured; a substrate comprising or connected to at least a first magnetic sensor and comprising or connected to a second magnetic sensor; the first and second magnetic sensors forming a first pair of magnetic sensors; wherein the first magnetic sensor has a first axis of maximum sensitivity, and the second magnetic sensor has a second axis of maximum sensitivity parallel to the first axis; wherein the first magnetic sensor is located at a first location and is configured to provide a first value indicative of a first magnetic field component of a magnetic field induced by said current at said first location; wherein the second magnetic sensor is located at a second location and is configured to supply a second indicator value of a second magnetic field component of said magnetic field at said second location, a processing circuit connected to the first and to the second magnetic sensor, and adapted to determine a magnetic field gradient of said magnetic field at least on the basis of a weighted difference between said first value and a said second value, where the respective weighting factors are chosen such that a uniform external magnetic field is deleted.
Specific and preferred aspects of the invention are set out in the independent claims and dependent claims attached hereto. Features of the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not only as set out explicitly in the claims.
These and other aspects of the invention will appear and will be explained with reference to the embodiment (s) described below.
Brief description of the drawings
The and the
[Fig.1 (b)] represent a block diagram by way of example of a current sensor device according to a first embodiment of the present invention, in top view and in cross section respectively.
The shows an enlarged view of FIG. 1 (b).
The and the
[Fig. 2 (b)] represent a block diagram by way of example of a current sensor device according to a second embodiment of the present invention, in top view and in cross section, respectively.
The and the
[Fig. 3 (b)] represent a block diagram by way of example of a current sensor device according to a third embodiment of the present invention, in top view and in cross section, respectively.
The and the
[Fig. 4 (b)] show a block diagram by way of example of a current sensor device according to a fourth embodiment of the present invention, in top view and in cross section, respectively.
The and the
[Fig.5 (b)] show a block diagram by way of example of a current sensor device according to a fifth embodiment of the present invention, in top view and in cross section, respectively.
[Fig. 6] shows an electrical block diagram of an electrical circuit which can be used in embodiments of the present invention.
[Fig. 7] shows an electrical block diagram of an electrical circuit which can be used in embodiments of the present invention.
The and the
[Fig. 8 (b)] show a block diagram by way of example of a current sensor device according to another embodiment of the present invention, in top view and in cross section, respectively.
[Fig. 9] represents a sequential diagram of a process by way of example of production of a current sensor according to embodiments of the present invention.
The drawings are only schematic and are not limiting. In the drawings, the size of some of the items may be exaggerated and not to scale, for illustration purposes. Any symbols in the claims are not to be construed as limiting the scope. In the various drawings, the same symbols refer to the same or similar elements.
Detailed description of illustrative embodiments
The present invention will be described with reference to particular embodiments and with reference to certain drawings, but the invention is not limited thereto but is only limited by the claims. The drawings described are only schematic and are not limiting. In the drawings, the size of some of the items may be exaggerated and not to scale, for illustration purposes. The dimensions and the relative dimensions do not correspond to real reductions for the implementation of the invention.
In addition, the terms first (era), second and similar in the description and in the claims are used to distinguish between similar elements and not necessarily to describe a sequence, of either temporal or spatial order, classification or any other order. It should be understood that the terms thus used are interchangeable under appropriate circumstances and that the embodiments of the invention described here can be implemented in sequences other than those described or illustrated here.
In addition, the terms high, low and the like in the description and the claims are used for description purposes and not necessarily for describing relative positions. It should be understood that the terms thus used are interchangeable under appropriate circumstances and that the embodiments of the invention described here can be implemented in other orientations than those described or illustrated here.
It should be noted that the term "comprising", used in the claims, should not be interpreted as limited to the means set out after; it does not exclude other elements or other steps. It must therefore be interpreted as specifying the presence of the particularities, numbers, steps or components stated as designated, but does not exclude the presence or addition of a ) or of several other particularity (s), number (s), stage (s) or component (s), or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that, as far as the present invention is concerned, the only components relevant are A and B.
In all of this description, the reference to "an embodiment" means that a particular feature, structure or characteristic described in relation to the embodiment is included in at least one embodiment of the present invention. The occurrences of the phrase "in one embodiment" in various places throughout this description therefore do not necessarily all refer to the same embodiment, but may. In addition, the particular features, structures or features can be combined in any suitable manner, as will be apparent to the skilled person in the art from this disclosure, in one or more embodiments.
Similarly, it should be noted that in the description of embodiments by way of examples of the invention, various features of the invention are sometimes grouped together in a single embodiment , figure or description thereof in order to purify the disclosure and to facilitate the understanding of one or more of the various inventive aspects. This method of disclosure should not, however, be interpreted as reflecting an intention that the claimed invention requires more specific features than those expressly stated in each claim. The inventive aspects rather reside, as reflected in the claims which follow, in less than the totality of the particularities of a single embodiment previously described. The claims following the detailed description are therefore expressly incorporated in the present detailed description, each claim being autonomous as a separate embodiment of the present invention.
In addition, although certain embodiments described here include some but not other features included in other embodiments, combinations of features of different embodiments are understood to fall within the scope of invention, and form different embodiments, as will be understood by those skilled in the art. For example, in the claims which follow, any of the claimed embodiments can be used in any combination.
In the description provided here, many specific details are set out. However, it is understood that embodiments of the invention can be practiced without these particular details. In other cases, well-known methods, structures and techniques have not been shown in detail so as not to obscure an understanding of the present description.
In this document, the terms “center line” and “core line” are used as being synonymous.
As used here, the expression “magnetic sensor” can designate one or more sensor elements capable of measuring one or more magnetic effects, such as the Hall effect, or magnetoresistance (MR) effects. Non-limiting examples of magnetoresistance effects include GMR (giant magnetoresistance), CMR (colossal magnetoresistance), AMR (anisotropic magnetoresistance) or TMR (tunnel magnetoresistance). Depending on the context, the expression “magnetic sensor” can denote an individual magnetic sensitive element (for example a horizontal Hall effect element or a vertical Hall effect element), or a group of magnetic elements (for example arranged in a bridge of Wheatstone, or a group of at least two Hall effect sensor elements connected in parallel), or a sub-circuit further comprising one or more of: a bias circuit, a read circuit, an amplifier, an analog converter / digital, etc.
As used here, the expression “integrated current sensor” designates an integrated circuit (chip or IC) comprising an electrical conductor capable of carrying the total current to be measured. The electrical conductor is normally at least partially surrounded by a molding composition (for example in a manner in which at most one surface is exposed). Such an overmolded device is also designated here by an “encapsulated device”.
When reference is made to the "width of the electrical conductor", this means (in general) "the local transverse dimension of the electrical conductor at each point of the center line in a plane perpendicular to the center line and parallel to the plan defined by the grid "unless it is clear from the context that it is something else. For the special case of a beam-shaped electrical conductor, the length simply means the dimension between the first and second pins (in which the current will flow during normal use), and the width simply means the dimension of the conductor transverse to this direction.
When reference is made to a "weighted difference", this means a difference between two values after multiplying one or both of the values by a respective factor. In the context of the present invention, what is meant by "weighted difference of the value VI and the value V2" is a value V calculated as A * V1-B * V2, where A and B are predefined constants, VI is the first value, and V2 is the second value.
The present invention relates to current sensors based on magnetic sensors, also designated by “magnetic current sensors”, more particularly for use in applications for motor vehicles (for example for measuring a current in electric or hybrid vehicles). The current sensor must be capable of measuring currents of at least 30 amps DC with peaks of up to 100 amps or up to 120 amps.
The present invention provides a current sensor device for measuring a current. The device includes a connection grid. The connection grid comprises a first part (for example a high power part) comprising first pins (for example first input pins and first output pins) connected or shaped so as to form an electrical conductor suitable for transporting the current to be measured, and a second part (for example a low power part) comprising a plurality of second pins. The device further comprises at least one substrate (for example a single semiconductor die, or two semiconductor dice, or a multi-die). The substrate can be mounted in a predefined position relative to the electrical conductor. The substrate comprises or is connected to at least a first magnetic sensor, and comprises or is connected to a second magnetic sensor. Each magnetic sensor can include one or more sensor elements, and / or an excitation circuit, and / or a read circuit. The first magnetic sensor has a first axis of maximum sensitivity, and the second magnetic sensor has a second axis of maximum sensitivity. The first and second magnetic sensors are arranged such that the first axis of maximum sensitivity is parallel to the second axis of maximum sensitivity. The first magnetic sensor is located at a first location and is configured to provide a first value indicative of a first magnetic field component (for example a field component in plan in the plane of the substrate, or in a direction orthogonal to the surface from said substrate) to said first location. The second magnetic sensor is located in a second location. The second location can be distant from said first location. The second magnetic sensor is configured to provide a second indicator value of a second magnetic field component (for example a field field component in the plane of the substrate or in a virtual plane orthogonal to the plane of the substrate) at said second location. The magnetic field induced by the current to be measured, when the latter flows through the electrical conductor, defines a first magnetic field vector at the location of the first sensor, and defines a second magnetic field vector at the location of the second sensor. The first magnetic field vector and the second magnetic field vector are not parallel, or in other words, define intersecting or intersecting lines. The current sensor device further includes a processing circuit. The processing circuit can be integrated on the substrate comprising the first magnetic sensor and / or the second magnetic sensor, or on another substrate. The processing circuit is connected to the first magnetic sensor to obtain the first value, and is connected to the second magnetic sensor to obtain the second value, and is adapted or configured to determine the current to be measured on the basis of 'a difference or weighted difference between the first value and the second value. The electrical conductor has a center line. The electrical conductor can have a relatively short beam-shaped part or a relatively long beam-shaped part, or even an infinitesimally small beam-shaped conductor part. In such embodiments, the current to be measured flows in a direction substantially parallel to said center line and substantially perpendicular to a cross section of said lead grid, or in other words parallel to a plane containing the electrical conductor. The current to be measured, when flowing in the electrical conductor, flows in a direction substantially parallel to said center line. The locations of the first sensor and the second sensor are located asymmetrically with respect to the center line. More particularly, the locations of the first and second sensors can be located such that one or more of the following conditions is / are satisfied: i) a projection of the location of the first sensor perpendicular to a plane parallel to the conductor electrical is located outside the electrical conductor, and a projection of the location of the second sensor perpendicular to said plane is located within the electrical conductor; ii) an angle γΐ defined by the first magnetic field vector B1 at the location of the first sensor and the second magnetic field vector B2 at the location of the second sensor is an angle in the range of 70 ° to 110 °; iii) an angle γ2 between a first virtual plane containing the center line and the location of the first sensor, and a second virtual plane containing the center line and the location of the second sensor is an angle in the range of 70 ° to 110 ° .
An advantage of this current sensor device is that it is capable of measuring said current on the basis of the measurement of a magnetic field gradient (for example ΔΒχ / Δχ).
It is advantageous to calculate the current in this way, since this makes it possible to determine the current in a way which is substantially immune to a parasitic field.
The integration of the electrical conductor is a major advantage, because it allows very precise positioning of the substrate relative to the electrical conductor, unlike a system comprising a current sensor mounted in the vicinity of an external electrical conductor, for example on a CCI (printed circuit board). The positioning tolerances of an integrated current sensor are normally an order of magnitude more precise than the positioning tolerances of a chip on a CCI, or on an electrical conductor. All other aspects remaining the same, this means that a current sensor with an incorporated electrical conductor has much greater accuracy than a current sensor mounted adjacent to an external electrical conductor, unless additional arrangements are made, such as than a calibration test by the end user in the application.
The placement of the first sensor above or below the electrical conductor, and of the second sensor outside of the electrical conductor, is a major advantage, since it decouples the relationship between the width of the substrate and the width of the conductor, or in other words, it makes it possible to choose the size of the substrate (or the size of the chip) as being smaller than the width of the conductor W, which is not possible in the solutions in which the sensors are placed near the opposite edges of the current conductor. This advantage should not be underestimated, because the cost of the substrate represents a significant part of the total cost of the current sensor, while (for a given material, and a given thickness of the electrical conductor and for a given maximum current to be measured ), the width of the electrical conductor determines the electrical resistance of the conductor, and therefore the heat dissipation (dissipation by Joule effect).
The electrical conductor may have an electrical resistance less than
0.50 mOhm, or less than 0.40 mOhm, or less than 0.30 mOhm, or less than 0.28 mOhm, or less than 0.26 mOhm, or less than 0.24 mOhm, or less than 0, 22 mOhm, or less than 0.20 mOhm, to allow the electrical conductor to carry a current of at least 30 A.
The present invention is partly based on the recognition that it is possible to increase the width of the electrical conductor (and therefore to decrease the electrical resistance, or to increase the maximum permissible current) without appreciably affecting accuracy of the current measurement, and without increasing the size of the chip, nor therefore the cost, by this particular arrangement of the first and second current sensors. Other optional improvements are explained below.
We will now refer to the figures.
[0134] FIG. 1 (a) and FIG. 1 (b) show a block diagram by way of example of a current sensor device 100 according to a first embodiment of the present invention, in top view and in cross section respectively.
The current sensor device 100 comprises a connection grid 103 comprising a first part (for example a high power part) comprising first pins 101 connected or shaped so as to form an electrical conductor suitable for transporting the current to be measured . In the example shown, a plurality of first input pins 101a and a plurality of first output pins 101b are interconnected by an electrical conductor 103 having a width Wc measured in a local transverse direction relative to a center line of the electrical conductor . The electrical conductor may have a beam-like part, but this is not absolutely required. The beam-shaped part can extend over the entire distance between the first input pins 101a and the first output pins 101b. The connection grid further comprises a second part (for example a low power part) comprising a plurality of second pins 102.
The current sensor device 100 further comprises a substrate 110 (for example a semiconductor substrate) mounted in a predefined position relative to the electrical conductor, more particularly to the electrical conductor 103. The substrate 110 comprises at least a first magnetic sensor 111 and a second magnetic sensor 112. In the example of FIG. 1, each sensor comprises two horizontal Hall effect elements and two structures of integrated magnetic concentrators (IMC). In the example of FIG. 1, BMI structures have an octagonal shape, but this is not absolutely required for the operation of the invention. This arrangement makes it possible to measure a magnetic field component (designated by Bx) parallel to the plane of the substrate using horizontal Hall effect elements. Other embodiments may use other in-plane sensor technologies, such as XMR or vertical Hall effect plates. In other embodiments, horizontal Hall effect plates can also be used to capture out-of-plane magnetic fields (frequently referred to as Bz field).
The first magnetic sensor 111 has a first axis of maximum sensitivity and the second magnetic sensor 112 has a second axis of maximum sensitivity parallel to the first axis. This allows the signals to be combined (for example subtracted) in a way that is substantially immune to stray fields.
The first magnetic sensor 111 is located at a first location and is configured to provide a first value vl indicative of a first magnetic field component at said first location (for example Blx which is a projection of the magnetic field vector B1 on the X axis).
The second magnetic sensor 112 is located at a second location located at a distance Δχ from the first location and is configured to provide a second value v2 indicative of a second magnetic field component at said second location (for example B2x which is a projection of the magnetic field vector B2 on the X axis).
When a current to be measured flows in the electrical conductor, more particularly the electrical conductor 103, a magnetic field is generated, which is measured by the first and the second magnetic sensor 111, 112. This magnetic field defines a first vector magnetic field B1 at the location of the first sensor, and defines a second magnetic field vector B2 at the location of the second sensor. The first magnetic field vector B1 and the second magnetic field vector B2 are not parallel, but define lines that intersect or intersect in a plan view perpendicular to said center line. Said lines intersecting in a plan view perpendicular to said center line define an intersection angle which is in the range of 50 ° to 110 ° or 75 ° to 105 °.
The sensor circuit 100 further comprises a circuit, for example an electrical processing circuit (see for example EIG. 6 or FIG. 7) integrated on the substrate, and connected to the first magnetic sensor for obtaining the first value v1, and connected to the second magnetic sensor to obtain the second value v2, and adapted to determine the current to be measured on the basis of a difference or weighted difference between the first value v1 and the second value v2.
According to an important aspect of the present invention, the electrical conductor has an electrical resistance of less than 0.80 mOhm, or less than 0.50 mOhm, or less than 0.40 mOhm, or less than 0.30 mOhm, or less than 0.28 mOhm, or less than 0.26 mOhm, including the electrical resistance of the first input pins 101a and the first output pins 101b. This can be obtained by choosing an appropriate lead material (copper for example) and a length Le and a width Wc and a suitable lead thickness. With this low resistance value, the energy dissipation caused by a current flowing in the electrical conductor can be limited, so the temperature rise can be limited.
The electrical conductor has a center line C. The locations of the first and second sensors are located such that one or more of the following conditions is / are satisfied: i) a projection of the location of the first sensor perpendicular to a plane p3 parallel to the electrical conductor 103 is located outside the electrical conductor, and a projection of the location of the second sensor perpendicular to said plane p3 is located inside the electrical conductor 103; ii) an angle γΐ defined by the first magnetic field vector BI at the location of the first sensor and the second magnetic field vector B2 at the location of the second sensor is an angle in the range of 70 ° to 110 °; iii) an angle γ2 between a first virtual plane pl containing the center line C and the location of the first sensor, and a second virtual plane p2 containing the center line C and the location of the second sensor is an angle in the range of 70 ° to 110 °.
The placement of the sensors in these particular locations makes it possible to use a relatively small substrate, for example a substrate having a width Ws less than the width Wc of the electrical conductor, or a ratio such as the width of the substrate Ws and the width Wc of the electrical conductor Ws / Wc is a value less than 90% or even less than 80% or less than 70% or less than 60%, or less than 40%.
One of the intuitive concepts of the present invention is that the width of the substrate does not entirely depend on the width of the conductor, but that it is possible to use a smaller width. This has a direct effect on the price of the chip, which is very important in a highly competitive market, such as that of integrated industrial and motor vehicle current sensors.
In particular embodiments, the electrical conductor may have a width Wc in the range of 1.0 to 8.0 mm, or in the range of 2.0 to 6.0 mm, and the substrate may have a size of approximately 2 (+ or -) 0.5 mm x 3 (+ or -) 0.5 mm.
Those skilled in the art having the benefit of this disclosure will understand that at least in some embodiments, the closer the second sensor 112 is to the center line (the smaller the offset d2), the smaller the second signal v2 is strong, and the farther the first sensor 111 is from the edge of the electrical conductor (the greater the offset dl), the weaker the first signal vl, or vice versa; and therefore the stronger the difference signal vl-v2. This means that a skilled person with the benefit of this disclosure can compromise between accuracy and cost (related to the size of the substrate).
In some embodiments, in order to resolve such a compromise, the first and / or the second sensor can / can be on separate substrates in order to increase the distance between the sensors while maintaining the overall silicon budget. In such embodiments, the first and / or the second sensor can be connected to the processing unit via wired connection.
In particular embodiments, a distance between the center line C of the electrical conductor 103 and the projection of the location of the second sensor is less than 10% or 20% of a width Wc of the electrical conductor 103, and a distance dl between an edge of the electrical conductor 103 and the projection of the location of the first sensor is greater than 10% or 20% of the width Wc of the electrical conductor. It is advantageous to place the second sensor 112 near the middle (for example from 40% to 60%) in the transverse direction X of the electrical conductor 103, since this gives a second relatively high value v2 of the magnetic field component Bx2. It is advantageous to place the first sensor 111 relatively far from the electrical conductor 103, because this gives a relatively low first value v1 of the magnetic field component Bxl, and therefore a relatively high difference (or gradient) between the first and second values vl, v2.
The connection grid can be a copper connection grid (for example made of C151 copper) and / or having a thickness in the range of 100 to 600 micrometers or from 200 to 500 micrometers, for example substantially equal to 200 microns, or roughly equal to 250 microns. It is not without interest to build a current sensor device capable of measuring a current of at least 30 A or at least 40 A or at least 50 A using a connection grid having a thickness in the range of 100 to 600 micrometers, or equal to about 200 to about 250 micrometers, particularly since the conventional way of reducing the electrical conductance of a conductor integrated in current sensing devices is to increase the thickness of the conductor while keeping the width of the conductor unchanged, because otherwise, if the width is increased and the thickness remains the same, the size of the substrate must be increased (and therefore also the cost of the substrate).
[0151] In the example of FIG. 1, the electrical conductor is connected to three input pins 101a and three output pins 101b, but the present invention is not limited thereto, and the number of first input pins 101a and first output pins 101b can be greater than three or less than three.
[0152] In the example of FIG. 1, the first pins 101a, 101b have the same shape and size as the second pins 102, but the present invention is not limited thereto, and the first three input pins 101a can be replaced by a single strip d relatively wide input (not shown) and the first three output pins 101b can be replaced by a single relatively wide output strip (not shown). In this way, the electrical resistance can be further reduced, and the thermal conductance (for example to a CCI) can be improved.
The current sensor device 100 of FIG. 1 contains four horizontal Hall effect elements and four integrated octagonal magnetic concentrators, but the present invention is not limited to it, and other magnetic sensors can also be used.
[0154] For example, in FIG. 2 (a) and FIG. 2 (b) the first and second magnetic sensors are also based on horizontal Hall effect elements with IMC, but the shape of the two external magnetic concentrators 221, 222 is changed, and the two internal magnetic concentrators are combined so as to form a common magnetic concentrator 223.
[0155] For example, in FIG. 3 (a) and FIG. 3 (b) the first and second magnetic sensors are also based on horizontal Hall effect elements with IMC, but the shape of the four magnetic concentrators 321, 322 is different from that of FIG. 1. From these examples, it will be clear that horizontal Hall Effect elements with IMC having other shapes can also be used.
It is advantageous to use horizontal Hall effect elements with IMC because IMC provides passive signal amplification (normally by a factor of about 5 or 6). The thickness of BMI is normally in the range of about 20 to 25 micrometers, for example, about 23 micrometers.
[0157] For example, in FIG. 4 (a) and FIG. 4 (b) the first magnetic sensor comprises a vertical Hall effect element 431, and the second magnetic sensor comprises a vertical Hall effect element 432.
Although not explicitly shown, it is also possible to use other magnetic sensor elements, such as for example magnetoresistance elements, for example GMR elements arranged in a Wheatstone bridge. Other types of magnetoresistance sensors can also be used, for example comprising at least one of indium antimonide (InSb), a giant magnetoresistance element (GMR), an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance element (TMR) or a magnetic tunnel junction element (MTJ).
[0159] Although not explicitly shown, the sensors can also include a bias or excitation circuit and a read circuit. For example, in the case of Hall effect elements, it is possible to use a rotating current in order to reduce eccentricity errors. For example in the case of magnetoresistance elements, it is possible to use a closed loop circuit to reduce nonlinearities, by generating a local magnetic field at the locations of the sensors, etc. Appropriate magnetic sensors and bias or excitation circuits and appropriate read circuits are known in the art and therefore need not be explained in more detail here.
[0160] Although this is not explicitly shown in FIG. 1, the substrate can also include an electrical processing circuit. Examples of processing circuits will be shown in FIG. 6 and FIG. 7, but the invention is not limited to these examples, and other processing circuits can also be used.
We will again refer to FIG. 1. The substrate 110 has a first surface, also designated by the active surface containing the sensor elements and the processing circuit, and a second surface.
[0162] In the example of FIG. 1, the substrate 110 is placed above or on the electrical conductor, and the active surface of the substrate is diverted from the electrical conductor 103.
The substrate 110 can be placed directly on the electrical conductor without an additional insulating material between them.
In other embodiments, the substrate 110 can comprise an insulating layer, for example an oxide layer or a nitride layer on the second surface, which can be in contact with the electrical conductor 103.
In yet other embodiments, an insulating layer, for example an insulating polymer or an insulating tape, is applied between the substrate 110 and the electrical conductor 103.
[0166] In other embodiments (known by the designation “inverted chip” arrangement), the substrate 110 has a first surface containing the first and second sensor elements, and the first surface faces the electrical conductor. In this case, the substrate is spaced from the electrical conductor, and the chip preferably further comprises an electrical insulating material placed between the first surface of the substrate and the electrical conductor.
The distance between the first surface of the substrate and the electrical conductor can be a value in the range of 150 to 250 µm, or in the range of 170 to 210 µm, for example equal to about 190 micrometers. The electrical insulating material can be adapted to withstand a voltage of at least 1000 volts.
In the embodiments in which the substrate is separated from the electrical conductor by means of an electrical insulating tape, the distance between the substrate and the electrical conductor can be a value in the range of approximately 10 to 100 μm, or about 30 to 80 pm, or 30 to 50 pm, for example equal to about 40 pm.
An advantage of this embodiment is that the distance between the sensors and the electrical conductor 103 is relatively small, and that the signal measured by the sensors is relatively strong (stronger than in the case where the second surface faced to the electrical conductor). This improves the signal-to-noise ratio, and therefore the accuracy of the measurement.
In this embodiment, the substrate is mechanically supported in a first region or at a first end by the electrical conductor and the insulating material.
The substrate can be mechanically supported at one end, and left floating at the other end, with a space below, and with a space between the substrate and the first pins, as shown for example on the EIG.l at the LIG. 4. The space may be partially or fully filled with air, or with a molding composition, or with electrical tape or other electrical insulating material (eg, a suitable polymer). The substrate 110 can be electrically connected with one or more second pins 102 by means of wire connections 105 interconnecting the contact pads 104 on the substrate 110 with the second pins 102. The contact pads are located in a region of the substrate (half right of the substrate 110 shown in the LIG. 1) which is mechanically supported by the electrical conductor 103 and / or supported by the pin (s) of said connection grid. No connection wire is applied to the floating region (left half of the substrate shown in LIG. 1).
Or, the substrate 110 can be supported at opposite ends, for example as illustrated in the LIG. 5, where some of the second pins 502 are connected to or shaped to form a mechanical support. In the LIG example. 5, two opposite pins 502 are interconnected to form a suspension on which the substrate 510 can rest. In this case, the contact pads 504 connected to the second pins 502 via connecting wires 505 can be provided anywhere on the substrate, not only in a "region resting on the electrical conductor" (right part in FIG. 5), but also in a “region located outside the electrical conductor” but for example supported by second pins 502s (left part in FIG. 5). In the example of FIG. 5 two opposite pins 502s are interconnected, but this is not absolutely required, and it may also be possible to provide two separate supports (for example a first support in the upper left corner of FIG. 5 connected to said one (s) ( one or more) upper pin (s) 502s, and a second support in the lower left corner of FIG. 5 connected to said one (or more) (one or more) lower pin (s) 502s).
In some embodiments, the substrate 110 is supported by a part of the connection grid which is connected to ground, also called here "ground plane".
The substrate 110 may also include a plurality of solder bumps (not shown), for example placed on the second surface. The weld bumps can be electrically connected to elements or tracks or components on the first surface by means of "through vias". The solder bumps can rest on and be connected to second pins 102, but the solder bumps are galvanically separated from the electrical conductor 103 and the first pins 101a, 101b. The galvanic separation can be achieved by a space filled with air, or a space filled with a molding composition or a space filled with an insulating material, for example an insulating tape, or in any suitable manner.
FIG. 1 (c) shows an enlarged view of FIG. 1 (b).
In a first variant, the first magnetic sensor 111 comprises only a single horizontal Hall effect element 131a with two BMI 121a, 121b above, and the second magnetic sensor 112 comprises a single horizontal Hall effect element 131c with two IMC 122a, 122b above. In this embodiment, the horizontal Hall effect elements 131b and 13 Id are therefore omitted. The elements 131a and 131c form an asymmetric pair of sensors. Element 131a can measure vl ~ -Bx + Bz-Kl.current (or ~ means "proportional to"), and element 131c can measure v2 ~ -Bx + Bz-K2.current. Current I can then be calculated based on a difference of these signals, for example as vl-v2, or as a weighted difference of these signals, for example as A.vl-B. v2, where A and B are constants, which can be determined during calibration. At least one of these constants can be other than 1.00. This can be used to compensate for a disparity in sensitivities.
It is also possible to use only the sensor elements 131b and 13Id, and to omit the sensor elements 131a and 131c.
In another variant, four horizontal Hall effect elements 131a to 13 Id are present, the elements 131a and 131c forming a first asymmetric pair, and the elements 131b and 13Id forming a second asymmetric pair. Element 131b can measure vlb ~ + Bx + Bz + Kl. Current, and element 13Id can measure v2b ~ + Bx + Bz + K2. Current. In this embodiment a first value of the current (II) can be calculated on the basis of the values obtained from the first asymmetric pair 131a, 131c, and a second value of the current (12) can be calculated on the basis of the values obtained from the second asymmetric pair 131b, 13 Id. If the first value of the current (II) and the second value of the current (12) satisfy a predefined criterion, for example have a difference less than a predefined value, or have with a ratio falling within a predefined range (eg 95% to 105%), the circuit can provide an average of the two current values as "the" current value. If the value of the first current (II) and the value of the second current (12) are significantly different, for example have a difference greater than said predefined value, or have a ratio lying beyond said predefined range, a signal d error or alarm may be produced. This embodiment provides redundancy which can be used for functional security purposes.
FIG. 2 (a) and FIG. 2 (b) show a block diagram by way of example of a current sensor device 200, seen from above and in cross section respectively. The current sensor device 200 is a variant of the current sensor 100 of FIG. 1. The main difference between the current sensor 200 of FIG. 2 and the current sensor 100 of FIG. 1 is that the integrated magnetic concentrators (IMC) are different. More particularly, FIG. 2 represents a current sensor 200 comprising four horizontal Hall effect elements and three IMC elements, namely two external trapezoidal IMCs 221, 222 and an intermediate orthogonal stretched IMC which is common for the two sensors. Everything else described above for the current sensor 100 of FIG. 1 and its variants is also applicable here, for example, as mentioned above, only two of the horizontal Hall effect elements are required, the other two can be used for redundancy or for improved accuracy or increased sensitivity or the of them.
FIG. 3 (a) and FIG. 3 (b) show a block diagram by way of example of a current sensor device 300, in top view and in cross section respectively. The current sensor device 300 is a variant of the current sensor device 100 of FIG. 1. The main difference between the current sensor device 300 of FIG. 3 and the current sensor device 100 of FIG. 1 is that the integrated magnetic concentrators (IMC) are different. More specifically, the
FIG. 3 represents a current sensor comprising four horizontal Hall effect elements and four trapezoidal IMC components, namely two IMC components 321 for the first magnetic sensor 311, and two IMC components 322 for the second magnetic sensor 312. All the rest described above for the current sensor device 100 of FIG. 1 and its variants is also applicable here.
[0181] FIG. 4 (a) and FIG. 4 (b) show a block diagram by way of example of a current sensor device 400, in top view and in cross section respectively. The current sensor device 400 is a variant of the current sensor device 100 of FIG. 1. The main difference between the current sensor device 400 of FIG. 4 and the current sensor device 100 of FIG. 1 is that the first magnetic sensor comprises a first vertical Hall effect element 431 and the second magnetic sensor comprises a second vertical Hall effect element 432, each configured to measure a magnetic field component Bx oriented in a direction parallel to the plane XY defined by the length and width of the current conductor 403, in the transverse direction X. No BMI is present. The vertical Hall effect elements have an axis of maximum sensitivity in the X direction, or in other words, the first magnetic sensor is adapted to measure a first magnetic field component Blx, and the second magnetic sensor is adapted to measure a second component of magnetic field B2x.
Everything else described above for the current sensor device 100 of FIG. 1 and its variants is also applicable here. In particular, the first sensor is preferably placed relatively far from the electrical conductor 403, so that Bxl is relatively small, while the second sensor is preferably placed relatively close to the middle of the electrical conductor, so that Bx2 is relatively high.
The two vertical Hall effect elements 431, 432 shown in FIG. 4 form a first asymmetric pair. It is possible to add two more vertical Hall effect elements for redundancy or functional safety, in a similar way to that described in FIG. 1 (c), but without BMI. More particularly, a third vertical Hall effect element can be placed near the, for example adjacent to the first Hall effect element 431, and a fourth vertical Hall effect element can be placed near the, for example adjacent to the second Hall effect element 432. The third and fourth vertical Hall effect elements would form a second asymmetric pair. A first value (H) of the current to be measured can be calculated based on the signals from the first asymmetric pair, and a second value (12) of the current to be measured can be calculated based on the signals from the second asymmetric pair . The first current (H) can be calculated on the basis of a difference between the first and the second signal, for example according to the formula K * (vl-v2), where K is a predefined constant, and vl, v2 are the signals supplied by the first and second sensors, respectively, or on the basis of a weighted average of these signals, for example according to the formula K * (A.vl-B.v2), where A and B are predefined constants, which can be determined during a calibration test. Likewise, a second value (12) for the current to be measured can be calculated. If the first current value (II) and the second current value (12) are more or less the same, according to a predefined criterion, an average of the first current value and the second current value can be given in as long as "the" current value, otherwise an error signal can be produced. Due to subtraction, the effect of an external disturbance field (if present) is reduced or eliminated.
In another variant (not shown), three Hall effect elements are provided on the substrate (for example a third vertical Hall effect element is added which is substantially located halfway between the Hall effect elements represented on the FIG 4, which would produce a third signal v3 It is then possible to calculate a first current value (il) using the left Hall effect element and the middle Hall effect element, for example using the formula Il = Kl. (vl-v3) or using the formula Il = Kl. (A.vl - B.v3); and calculate a second current value (12) using the Hall effect element of right and the Hall effect element in the middle, for example using the formula I2 = K2. (v2-v3) or using the formula I2 = K2. (C.v2 B.v3), where A, B and C are constants which can be used to correct a disparity in sensitivities of the different sensor elements. As above, each of the first and second values of the current s have virtually insensitive to an external disturbance field. An advantage of this embodiment is that it requires only three Hall effect elements instead of four.
In another variant of FIG. 4 (not shown), the vertical Hall effect elements 431, 432 are replaced by horizontal Hall effect elements, but no BMI is present. The horizontal Hall effect elements have an axis of maximum sensitivity in the Z direction, or in other words, the first magnetic sensor is adapted to measure a first magnetic field component Blz, and the second magnetic sensor is adapted to measure a second component of magnetic field B2z. Everything else described above for the current sensor device 100 of FIG. 1 and its variants is also applicable here.
In a particular example, the first magnetic sensor 431 is preferably located at a distance of less than 30% of the width Wc of the conductor from the edge of the electrical conductor 403, so that Bxl is relatively strong, while the second sensor 432 is preferably located relatively close to the middle of the electrical conductor, for example at a distance less than 10% of the width Wc of the conductor 403, so that Bx2 is relatively small.
In a particular example, a projection of the second sensor 432 is located substantially in the middle of the electrical conductor, substantially above or below the midline C. In this embodiment the value of B2z induced by the current is substantially zero, therefore, the second sensor 432 would measure only a stray field component. This embodiment allows the stray field component to be measured directly without solving a series of equations. The stray field value can be amplified and provided as an analog signal, and / or can be digitized and provided as a digital output value. To the inventors' knowledge, there are no current sensors which deliberately position one of the sensor elements in this location where no signal from the current conductor 403 can be measured. However, by doing so, the dimensions of the substrate can be reduced by a factor of about two, while at the same time the effect of an external disturbance field can be reduced. This notion is not known in the prior art. On the contrary, in current sensors of the prior art, the sensor elements are characteristically placed at an equal distance from the center line, perhaps because it is wrongly admitted that the sensor elements should not be placed above or below the electrical conductor to measure the disturbance field.
[0188] FIG. 5 (a) and FIG. 5 (b) show a block diagram by way of example of a current sensor device 500, in top view and in cross section respectively. The current sensor device 500 is a variant of the current sensor device 100 of FIG. 1. The main difference between the current sensor device 500 of FIG. 5 and the current sensor device 100 of FIG. 1 is that the substrate 510 is not only supported at one end (right side of FIG. 5), for example by an electrical conductor 503 (directly, or indirectly via an insulating material), but is also supported on one side or opposite edge of the substrate (left side in FIG. 5) by one or more second pins 502s and / or an extension thereof and / or an interconnection thereof. The substrate 510 can include contact pads 504 which are placed anywhere on the substrate 510, not only on the part of the substrate which is supported by the electrical conductor 503. These contact pads can be connected to the second pins 502 via connecting wires 505. This allows more efficient use of the surface of the substrate. Everything else described above for the current sensor device 100 of FIG. 1 and its variants is also applicable here, making the necessary changes.
It will be clear that the feature of "supporting the substrate at its two ends" also works for other magnetic sensors, or in other words, that this feature can also be added to the current sensors of FIG. 2 in FIG. 4. The skilled person can find or design a new housing with a sufficient number of pins.
[0190] FIG. 6 shows an electrical block diagram of a circuit 610 which can be used in a current sensor device, for example as shown in FIG. 1 in FIG. 5, in the absence of one or more temperature sensor (s) and one or more stress sensor (s), or at least ignoring the values provided by them. It will be noted that the current conductor is omitted from this drawing, since it is galvanically separated from this circuit, although the electrical conductor is physically located in the vicinity of the first and second magnetic sensors 611, 621.
The processing unit 630 is adapted to determine in any known manner the current to be measured, for example by calculating the current according to the formula: I = K. (vl-v2), where K is a predefined constant (for example determined during the design or during an evaluation phase), v1 is the value provided by the first magnetic sensor 611, and v2 is the value provided by the second magnetic sensor 621. The unit of processing 630 may include a digital processor comprising or connected to a non-volatile memory 631 storing at least one constant value K.
Although this is not explicitly shown, the processing circuit 610 may include a differential amplifier configured to determine and amplify a difference between the first value v1 and the second value v2, and to amplify this difference. Alternatively, the processing circuit 610 may include an amplifier configured to selectively amplify the first value v1 and the second value v2. The sensor device may further include an analog / digital ADC converter configured to digitize this amplified difference signal. CAN can be part of a digital processing circuit. The current to be measured can be supplied as an analog output signal proportional to the current, or can be supplied as a digital signal indicating the current to be measured. The second pins (shown in FIG. 1 to FIG. 5 and FIG. 8) can be used to supply a supply voltage and a ground signal to the processing circuit 610, and / or to provide a data, for example a serial data bus (for example using the I2C protocol, or using the RS232 protocol, or any other suitable protocol), and / or other input signals or output signals, as the desire.
FIG. 7 shows an electrical block diagram of a processing circuit 710 which can be seen as a variant of the processing circuit 610 of FIG. 6, further comprising first and second temperature sensors 712, 722, connected in a communicating manner to the processing unit 730. The processing unit 730 is adapted to determine the current to be measured on the basis of the values v1 and v2 , but taking into account one of the temperature signals tl, t2 or both. The measured temperature (s) can / can be taken into account to compensate for the variations in temperature of the values v1, v2 of the measurements, for example to compensate for the variations in sensitivity of the sensor elements. Such compensation techniques are known per se in the art, and therefore need not be explained in more detail here. In a particular embodiment, temperature compensation is performed in a similar manner to that described in EP3109658A1, which is incorporated herein by reference in its entirety.
An advantage of this current sensor is that it includes a temperature compensation mechanism. In this way, the accuracy of the current measurement can be further improved.
[0195] The processing unit 630 of the LIG. 6 and the processing unit 730 of the LIG. 7 may contain a digital processor, for example a programmable micro-controller. Although not explicitly shown, circuit 610 and circuit 710 can also contain at least one analog / digital converter, which can be part of magnetic sensors, or can be part of the processing unit, or can be implemented in the form of '' a separate circuit (for example between an output of the sensor circuit and an input of the processing unit). The synoptic diagram of the LIG. 6 and that of the LIG. 7 do not show this level of detail, for the same reasons as they do not show a bias circuit, a read circuit, an optional amplifier, a power supply, etc., which are all well known in the art, and therefore do not need to be described in more detail here.
It will be noted in this connection that if the signals vl, v2, tl and t2 are analog signals, the processing unit 730 can contain at least one ADC to convert these analog signals into digital signals, while in the case where the signals v1, v2, tl and t2 are digital signals, the processing unit 730 does not need to include a CAN.
The embodiments with two temperature sensors, one for each magnetic sensor, offer an advantage, because the temperatures of the first and second magnetic sensors can be significantly different, in particular if a relatively strong current (for example more than 30 A) is measured, because such a normally strong current causes a marked heating of the electrical conductor, causing a relatively high temperature gradient on the substrate. In this way the accuracy of the current measurement can be further improved.
In a variant (not shown) of the LIG. 7, the circuit comprises a single temperature sensor, which can be arranged to measure the temperature of the first magnetic sensor, or to measure the temperature of the second magnetic sensor. The temperature of the other magnetic sensor can then be estimated on the basis of the estimated energy dissipation (in turn based on vl and v2) and on the basis of a predefined assumption of the ambient temperature, instead of actually measure the other temperature. It goes without saying that an embodiment with two temperature sensors is more precise.
In a variant (not shown) of FIG. 7, the circuit comprises one or two stress sensors instead of one or two temperature sensors, and the processing unit 730 is adapted to determine the current on the basis of the values obtained from the magnetic sensors, taking account of the stress value (s) obtained from one or both of the stress sensors.
In another variant (not shown) of FIG. 7, the circuit further comprises one or two stress sensors in addition to one or two temperature sensors, and the processing unit 730 is adapted to determine the current on the basis of the values obtained from the magnetic sensors and one or more temperature sensors and one or more strain sensors.
The processor can also be adapted to calculate a first current and a second current, as described above, for example in relation to FIG. 1 (c), where the third magnetic element 131c can be arranged as an emergency element for the first magnetic element 131a, and the fourth magnetic element 13 Id can be arranged as an emergency element for the second magnetic element 131b. The third and fourth elements 131c and 13 Id can be arranged at a distance similar to that of the first and second elements 131a, 131b respectively, but this is not absolutely required. In fact, it may even be desirable to use other differences such as distances or type of sensor, to provide what is called "non-heterogeneous redundancy". The processing circuit can be adapted to calculate a first current value II based on the first and second values v1, v2, and can be further adapted to calculate a second current value 12 based on the third and fourth values v3, v4. Both measures are immune to a stray field. The first current II and the second current 12 should ideally be the same, unless the current sensor malfunctions.
During use, the circuit can calculate the first and the second current, and calculate a difference 11-12 or a ratio 11/12, and if the difference is smaller than a predefined threshold, or if the ratio falls within predefined limits, the circuit can conclude that the measurements are correct, and if the calculated difference or the calculated ratio is outside of said limits, the circuit can conclude that the measurements are incorrect. If the circuit is designed so that the predefined value of R is approximately equal to 1, the circuit can then provide the average of II and 12 in the case where the measurement is correct. In this way the RSB can be further improved. Embodiments with three or four magnetic sensors can be used for redundancy and / or functional safety.
[0203] FIG. 8 (a) and FIG. 8 (b) show a block diagram by way of example of a current sensor device 800, in top view and in cross section respectively. The current sensor device 800 is a variant of the current sensor device 100 of FIG. 1. The main difference between the current sensor device 800 of FIG. 8 and the current sensor device 100 of FIG. 1 is that the electrical conductor 803 is not straight but U-shaped. In the vicinity of the first and second magnetic sensors 811, 812, the electrical conductor 803 has an infinitesimally small beam-shaped conductor part or a beam-shaped conductor part having an infinitesimally small length. The midline or core line C is shown in dotted lines, and also has a curved shape, for example a U shape or a V shape or a C shape. In this embodiment, the current to be measured flows (locally) in a direction substantially parallel to said center line C and substantially perpendicular to a cross section of said lead grid, or in other words, parallel to a plane containing the electrical conductor 803. Everything else described above for the current sensor device 100 of FIG. 1 and its variants is also applicable here, making the necessary changes.
[0204] FIG. 9 shows a process diagram of a process 900 by way of example of production of a current sensor as described above. The process includes the following steps:
A) providing 901 a connection grid comprising an electrical conductor 103;
B) providing 902 a substrate comprising or connected to at least one first magnetic sensor and comprising or connected to a second magnetic sensor, the first magnetic sensor having a first axis of maximum sensitivity and being configured to provide a first value v1, and the second magnetic sensor having a second axis of maximum sensitivity substantially parallel, for example parallel to the first axis of maximum sensitivity, and being configured to supply a second value v2;
C) mounting 903 the substrate with respect to the connection grid so that one or more satisfied one or more predefined conditions in relation to the distances between the sensors and a median line of the electrical conductor, or with the angles between the locations of said sensors and the center line, or with the angles formed by the magnetic field vectors at the locations of said sensors;
D) supplying 904 a processing circuit connected to the first and second magnetic sensors, and suitable for determining the current I to be measured at least on the basis of the first value v1 and the second value v2.
One can also provide for step e) consisting of: at least partially overmolding the connection grid and the substrate so as to form an encapsulated current sensor device.
In one embodiment, the substrate comprises the first magnetic sensor and the second magnetic sensor and the processing circuit, and step d) is included in step b).
In one embodiment, step b) comprises providing a substrate further comprising an insulating layer (for example an oxide layer or a nitride layer); and step c) includes mounting the substrate directly on the electrical conductor.
In one embodiment, step c) includes providing an insulating tape on the electrical conductor and mounting the substrate on the insulating tape.
Although individual features are explained in different drawings and in different embodiments of the present invention, it is contemplated that features of different embodiments can be combined, as would be apparent to those skilled in the art, on reading this document. REFERENCES
[0214] 100, 200, 300, 400, 500, 800 current sensor device
101, 201, 501, 801 first pins (for example first input pins and first output pins)
102, 202, 502, 802 second pins
103, 203, 303, 403, 503, 803 electrical conductor
104, 504, 804 contact pads
105, 505, 805 connections per wire
110, 210, 310, 410, 510, 810 substrate
111,211,311,511,811 first magnetic sensor
112, 212, 312, 512, 812 second magnetic sensor
121, 221, 321 integrated magnetic concentrator (s) of the first magnetic sensor
122, 222, 322 integrated magnetic concentrator (s) of the second magnetic sensor
131 horizontal Hall effect element
140 molding composition
223 common integrated magnetic concentrator of the 1 ^st and 2 ^nd magnetic sensors
431, 432 first / second vertical Hall effect element
850 part in the form of a beam of the electrical conductor
Pl, p2 plane across the center line of the electrical conductor and the locations of the 1 ^st , 2 ^nd sensors
P3 plane parallel to (at the upper or lower surface of) the electrical conductor across the center line
Dl 1 ^st offset (distance between the location of the 1 ^st sensor and the edge of the electrical conductor)
D2 2 ^nd eccentricity (distance between the location of the 2 ^nd sensor and the center line)
Δχ distance between the locations of the 1 ^st and 2 ^nd sensors
B1, B2 first / second magnetic field vector
[0236] Le, Wc Length / Width of the electrical conductor
[0237] Ls, Ws Length / width of the substrate (semiconductor)
C 02 midline or core line of the electrical conductor

权利要求:
Claims (1)
[1" id="c-fr-0001]
[Claim 1]
Claims
Current sensor device (100; 200; 300; 400; 500; 800) for measuring a current (I), comprising:
- a connection grid comprising a first part comprising first pins (101, 201, 301, 401, 501; 810) connected or shaped so as to form an electrical conductor suitable for transporting the current to be measured, and a second part comprising a plurality of second pins (102, 202, 302, 402, 502; 802);
- a substrate (110; 210; 310; 410; 510; 810) comprising or connected to at least one first magnetic sensor (111,211,311,411,511;
811) and comprising or connected to a second magnetic sensor (112, 212, 312, 412, 512; 812) the first and second magnetic sensors forming a first pair of magnetic sensors;
- wherein the first magnetic sensor has a first axis of maximum sensitivity, and the second magnetic sensor has a second axis of maximum sensitivity parallel to the first axis;
- in which the first magnetic sensor is located at a first location and is configured to supply a first value (vl) indicative of a first magnetic field component (Blx, Blz) at said first location;
- in which the second magnetic sensor is located in a second location and is configured to provide a second value (v2) indicative of a second magnetic field component (B2x, B2z) at said second location;
- in which a magnetic field induced by the current (I) to be measured, when the latter circulates in the electrical conductor, defines a first magnetic field vector (Bl) at the location of the first sensor, and defines a second field vector magnetic vector (B2) at the location of the second sensor, the first magnetic field vector (B1) and the second magnetic field vector (B2) defining intersecting or intersecting lines;
- a processing circuit (610; 710) connected to the first and second magnetic sensors, and adapted to determine the current (I) to be measured at least on the basis of a difference or weighted difference between the first value (vl) and the second value (v2) obtained from the first pair of sensors;
- and in which the electrical conductor has a center line (C),
and a first distance (el) between the center line (C) and the location of the first sensor is different from a second distance (e2) between the center line (C) and the location of the second sensor;- and in which the locations of the first and second sensors are located in such a way that one or more of the following conditions is / are satisfied:i) a projection of the location of the first sensor perpendicular to a plane (p3) parallel to the electrical conductor (103; 203; 303; 403; 503; 803) is located outside the electrical conductor, and a projection of l the location of the second sensor perpendicular to said plane (p3) is located inside the electrical conductor (103; 203; 303; 403; 503; 803);ii) an angle (γΐ) defined by the first magnetic field vector (Bl) at the location of the first sensor and the second magnetic field vector (B2) at the location of the second sensor is an angle in the range of 70 ° to 110 °;iii) an angle (γ2) between a first planar virtual plane (pl) containing the center line (C) and the location of the first sensor, and a second virtual plane (p2) containing the center line (C) and the location of the second sensor is an angle in the range of 30 ° to 110 °. [Claim 2] Current sensor device (100; 200; 300; 400; 500; 800) according to claim 1, wherein each of the first and second magnetic sensors comprises at most one or at least one or at least two Hall effect element (s) horizontal (131) and at least one or two integrated magnetic concentrator (s) (121, 122; 221, 222, 223; 321, 322). [Claim 3] A current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, wherein the lead grid is a copper lead grid having a thickness in the range of 100 to 600 micrometers . [Claim 4] Current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, in which a first distance (dl) between an edge of the electrical conductor (103; 203; 303; 403; 503 ; 803) and the projection of the location of the first sensor is greater than 10% of a width (Wc) of the electrical conductor; and orin which a second distance (d2) between the center line (C) of the
electrical conductor (103; 203; 303; 403; 503; 803) and the replacement projection of the second sensor is less than 10% of a width (Wp) of the electrical conductor. [Claim 5] Current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, in which a distance (Δχ) between the location of the first sensor and the location of the second sensor is less than a width (Wc) of the electrical conductor (103; 203; 303; 403; 503; 803);or wherein a width (Ws) of the substrate (110; 210; 310; 410;510; 810) is less than a width (Wc) of the electrical conductor (103; 203; 303; 403; 503; 803). [Claim 6] Current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, in which the electrical conductor (103; 203; 303; 403; 503; 803) has a width (Wc) in the range of 1.0 mm to 7.0 mm; and / or wherein the substrate (110; 210; 310; 410; 510; 810) has an area in the range of 1 to 5 mm ² . [Claim 7] A current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, wherein the substrate (110; 210; 310; 410; 510; 810) has a first surface containing the first and second magnetic sensors, and wherein the first surface faces the electrical conductor (103; 203; 303; 403; 503; 803);and wherein the current sensing device further comprises an electrical insulating material placed between the first surface of the substrate and the electrical conductor (103; 203; 303; 403; 503; 803). [Claim 8] Current sensor device (100; 200; 300; 400; 500; 800) according to any of claims 1 to 6, wherein the substrate (110; 210; 310; 410; 510; 810) has a first surface containing the first and second magnetic sensors, and in which the first surface is diverted from the electrical conductor (103; 203; 303; 403; 503; 803). [Claim 9] A current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, wherein the substrate (110; 210; 310; 410; 510; 810) further comprises a plurality of pads contact (104; 204; 304; 404; 504; 804) located on a part of the substrate covering the electrical conductor;
and wherein the current sensor device further comprises a plurality of wires (105; 205; 305; 405; 505; 805) interconnecting one or more of the plurality of second pins (102;202; 302; 402; 502) and one or more of the plurality of contact pads (104; 204; 304; 404; 504; 804). [Claim 10] A current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, wherein the substrate (110; 210; 310; 410; 510; 810) further comprises a plurality of bumps solder connected to at least some of the second pins (102; 202; 302; 402; 502; 802), but galvanically separated from the electrical conductor and the first pins (101; 201; 301; 401; 501; 801). [Claim 11] Current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, in which the electrical circuit (610; 710) comprises a differential amplifier configured to determine and amplify said difference or weighted difference between the first value (vl) and the second value (v2);or wherein the electrical circuit (610; 710) includes an amplifier configured to selectively amplify the first value (vl) and the second value (v2). [Claim 12] Current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, further comprising a digital processor (630; 730) comprising or connected to a non-volatile memory (631; 731) storing at least one constant value (K, A, B), and in which the digital processor is adapted to determine the current to be measured on the basis of a difference between the first value (vl) and the second value (v2) and based on said constant value (K, A, B). [Claim 13] A current sensor device (100; 200; 300; 400; 500; 800) according to claim 12, wherein the substrate (110; 210; 310; 410; 510; 810) further comprises at least one temperature sensor (712 , 722) configured to measure at least one temperature in relation to a temperature of the first magnetic sensor (711) and / or the second magnetic sensor (721), said at least one temperature sensor (712, 722) being connected to the digital processor (730);and wherein the digital processor (730) is adapted to calculate the
current to be measured on the basis of a difference or weighted difference between the first value (vl) and the second value (v2), and taking account of said at least one measured temperature (tl, t2). [Claim 14] Current sensor device (100; 200; 300; 400; 500; 800) according to claim 12 or 13, wherein the substrate (110; 210; 310; 410; 510; 810) further comprises at least one stress sensor configured to measure at least one stress value related to mechanical stress experienced by the first magnetic sensor, said at least one stress sensor being connected to the digital processor (730); and in which the digital processor is adapted to calculate the current to be measured on the basis of a difference or weighted difference between the first magnetic value (vl) and the second magnetic value (v2), and taking account of said at least one measured stress value. [Claim 15] Current sensor device (100; 200; 300; 400; 500; 800) according to any one of the preceding claims, in which the current value determined by the processing circuit on the basis of the first and second magnetic sensors is considered to be a first current value (II);- And in which the substrate (110; 210; 310; 410; 510; 810) further comprises a third magnetic sensor arranged in a manner similar to that of the first magnetic sensor and configured to measure a third value (v3), and further comprises a fourth magnetic sensor arranged in a similar manner to that of the second magnetic sensor and configured to measure a fourth value (v4);- and in which the processing circuit (630; 730) is also connected to the third magnetic sensor for obtaining the third value (v3), and to the fourth magnetic sensor for obtaining the fourth value (v4),and is further adapted to determine a second current value (12) based on a difference or weighted difference between the third value (v3) and the fourth value (v4);and is further adapted to compare the second current value and the first current value, and if a difference or a ratio between the first and the second current value satisfies a predetermined condition, to provide an average of the first value of current and the second current value as the current value.
[Claim 16] A current sensor device (100; 200; 300; 400; 500) according to any one of the preceding claims, wherein the lead grid is a copper lead grid having a thickness in the range of 100 to 600 micrometers;and wherein the first pins include first input pins located on one side of the device, and first output pins located on another side of the device, opposite the first side; and wherein the electrical conductor comprises a substantially planar and substantially beam-shaped interconnection having a length covering substantially the entire distance between the first input pins and the first output pins;and wherein the electrical conductor has an electrical resistance of less than 0.80 mOhm;and wherein the beam-shaped interconnecting portion has a width in the range of 1.0 mm to 7.0 mm;and wherein the semiconductor substrate comprises said first magnetic sensor and said second magnetic sensor and said processing circuit integrated or incorporated in said substrate;and in which the width (Ws) of the substrate is less than the width (Wc) of the beam-shaped interconnection part;and in which the projection of the location of the first sensor perpendicular to the plane (XY) defined by the direction of the length and the direction of the width of the beam-shaped interconnection part is located outside the part a beam-shaped interconnection, and in which the projection of the location of the second sensor perpendicular to said plane is located on the beam-shaped interconnection part;and wherein the current sensor device is overmolded to form an encapsulated current sensor device. [Claim 17] Method (900) of producing a current sensor (100; 200; 300;400; 500; 800), including the steps:a) providing (901) a connection grid comprising an electrical conductor (103);b) providing (902) a substrate comprising or connected to at least a first magnetic sensor and comprising or connected to a second magnetic sensor, the first magnetic sensor having a first axis of maximum sensitivity and being configured to provide a first value (vl) , and the second magnetic sensor having a second axis
maximum sensitivity substantially parallel to the first axis of maximum sensitivity, and being configured to provide a second value (v2);c) mounting (903) the substrate with respect to the connection grid so that one or more predefined conditions are satisfied in relation to the distances between the sensors and a median line of the electrical conductor, or with the angles between the locations of said sensors and the center line, or with the angles formed by the magnetic field vectors at the locations of said sensors;d) providing (904) a processing circuit connected to the first and second magnetic sensors, and adapted to determine the current (I) to be measured at least on the basis of the first value (vl) and the second value (v2). [Claim 18] The method of claim 17, further comprising step e) of: at least partially overmolding the lead frame and the substrate so as to form an encapsulated current sensor device. [Claim 19] The method of claim 17, wherein step a) comprises: providing said lead grid in the form of a copper lead grid having a thickness in the range of 100 to 600 micrometers; the connection grid comprising first input pins located on one side of the connection grid and first output pins located on another side of the connection grid, opposite to the first side; the electrical conductor comprising a substantially planar and substantially beam-shaped interconnecting portion having a length covering substantially the entire distance between the first input pins and the first output pins; the electrical conductor having an electrical resistance of less than 0.80 mOhm; the beam-shaped interconnecting part having a width in the range of 1.0 mm to 7.0 mm;and / or wherein step b) and step d) comprise: providing said semiconductor substrate with said first magnetic sensor and said second magnetic sensor and said processing circuit integrated or incorporated in said substrate;and / or in which the width (Ws) of the substrate is less than 90% or less than 80% or less than 70% or less than 60% or less than 50% or less than 40% of the width (Wc) of the part
beam-shaped interconnection;and / or in which step c) comprises mounting the substrate with respect to the lead grid so that one end of the substrate is supported by the electrical conductor, and an opposite end of the substrate is supported by a mechanical support formed by an interconnection of second pins electrically isolated from the electrical conductor. [Claim 20] The method of claim 19, wherein the projection of the location of the first sensor perpendicular to the plane defined by the direction of the length and the direction of the width of the beam-shaped interconnection portion is located outside of the beam-shaped interconnection part, and in which the projection of the location of the second sensor perpendicular to said plane is located on the beam-shaped interconnection part. [Claim 21] The method of claim 17, wherein step c) further comprises: providing insulating tape over the electrical conductor and mounting the substrate on the insulating tape.
1/9

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法律状态:
2020-11-20| PLFP| Fee payment|Year of fee payment: 2 |

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2021-11-17| PLFP| Fee payment|Year of fee payment: 3 |

优先权:

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申请号 | 申请日 | 专利标题

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EP18212127|2018-12-12|

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EP18212127.7|2018-12-12|

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EP19165398|2019-03-27|

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EP19165398.9|2019-03-27|

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