• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a series interlaced double chopper (100) comprising two single choppers each comprising a diode (D1; D2), an input inductor (L1, L2), a switch (T1, T2) connected to the anode of the diode (D1; D2) and a filtering capacitor (C1, C2) connected to the cathode of the diode (D1; D2), the two switches (T1, T2) and the two filtering capacitors (C1, C2) being connected at a midpoint, the double interlaced chopper series (100) further comprising a control circuit (9) switches (T1 and T2) adapted to control: in a first step, the opening of a first switch, the other remaining closed, the two switches (T1, T2) being initially closed; in a second step, the opening of the second switch remained closed; and in a third step, the closing of the two switches (T1, T2).
    公开号:FR3015805A1
    申请号:FR1363270
    申请日:2013-12-20
    公开日:2015-06-26
    发明作者:Philippe Ernest；Yannick Louvrier
    申请人:General Electric Co；
    IPC主号:
    专利说明:

    [0001] Description: [0001] The present invention relates to Boost converters also known as step choppers. The present invention is particularly suitable for the field of X-ray radiography, powered by battery or other energy storage device.
    [0002] STATE OF THE ART Referring to FIGS. 1 and 2, a single Boost converter 200 comprises a voltage source 21 comprising a first and a second terminal (here a + terminal and ground), an inductor 23 whose first terminal is connected to the + terminal of the voltage source 21, a diode 24 whose anode is connected to the second terminal of the inductor 23, a current switch 26 such as a MOSFET field effect transistor connected between the second terminal of the inductance 23 and the mass. The operation of the single Boost converter 200 can be divided into two distinct phases according to the state of the switch 26: an energy accumulation phase (FIG. 1) and an energy transfer phase (FIG. 2). During the energy accumulation phase (FIG. 1), the switch 26 is closed (on state), this causes the increase of the current in the inductor 23 and therefore the storage of a quantity of energy under form of magnetic energy. The diode 24 is then blocked and the load 27 is disconnected from the power supply. During the energy transfer phase (FIG. 2), the switch 26 is open, the inductor 23 is then in series with the generator and its electromotive force is added to that of the generator (booster effect). The current flowing through the inductor then passes through the diode 24 and the load 27. This results in a transfer of the energy accumulated in the inductor 23 to the load 27.
    [0003] With reference to FIG. 3, in order to improve the performance of the single Boost converter with respect to the design voltage, a structure named BOOST double interleaved converter 300 has been proposed (or interleaved double boost in English). It is the combination of two simple Boost circuits having the midpoints of the switches 26 and filter capacitors 25 connected on the one hand to each other and on the other hand to the terminals of the load 27 (FIG. 3), the commands of the switches being shifted by half a period (see Figure 4 in which are represented, at the top the state of the first switch, in the middle the state of the second switch and below the inductive current).
    [0004] A disadvantage of this type of converter is to have a yield that decreases when the operating frequency rises, while, contradictory, it is preferable to choose high operating frequencies, of the order of 100 kHz to 1 MHz, to reduce the size and size of the converter. It is well known that the reduction of the efficiency with the increase of the operating frequency is notably caused by energy losses in the switches 24 and the diodes 26 during the switching periods, these commutations then being commonly called hard commutations ( or hard switching in English).
    [0005] To overcome this drawback, it has been proposed to add so-called switching assistance capabilities (or snubber capacitor in English) in parallel with the switches, which makes it possible to soften the switching (soft switching in English). The introduction of these so-called switching assistance capabilities makes it possible to solve the problem of switching losses when the switches are opened but does not make it possible to solve the problem of switching losses when the switches are closed. Indeed, switching assistance capabilities having been loaded when opening the switch, they are discharged during closing, accentuating the switching losses when closing the switches.
    [0006] These switches cause a loss of energy more sensitive than the frequency is high. In addition, the voltage front during the closing of the switches results in an emission of parasitic electromagnetic radiation. DISCLOSURE OF THE INVENTION The invention overcomes at least one of the aforementioned drawbacks by proposing a series interlaced double chopper comprising two simple choppers each comprising a diode, an input inductor, a switch connected to the anode of the diode and a filtering capacitor connected to the cathode of the diode, the two switches and the two filtering capacitors being connected at a mid-point, the series interleaved double chopper being characterized in that it further comprises a suitable switch control circuit to control: - in a first step, the opening of a first switch, the other remaining closed, the two switches being initially closed; - in a second step, the opening of the second switch remained closed; - and in a third time, the closing of the two switches. The invention is advantageously complemented by the following characteristics, taken individually or in any of their technically possible combinations: the series-interleaved double chopper furthermore comprises a switching aid capacitor placed in parallel with each of the switches; the series interleaved double chopper furthermore comprises a current sensor measuring the inductive current and supplying the measured values to the control circuit; the control circuit consists of a circuit for regulating the voltage across the load and a control circuit incorporating a state machine, based on the voltage state variables at the terminals of the load, and inductive current; - The control circuit is adapted to trigger the opening of the first switch when the current / 1, inductive passes above a first threshold value set by the voltage control circuit across the load; - The control circuit is adapted to trigger the opening of the second switch when the current / 1, inductive goes below a second threshold value; the cathodes of the diodes are connected to a load, the second threshold value being furthermore fixed as a function of the value of the load; the closing of the two switches is simultaneous; the control circuit controls the simultaneous closing of the two switches when the current / 1, inductive goes below a third negative threshold value; the second and / or third threshold value is chosen with a certain freedom as a function of the load to be supplied, in order to optimize the performance of the circuit, for example to reduce the peak current in the inductor or to limit the maximum operating frequency. It is necessary that the serial interleaved double chopper has an elevation ratio greater than 2. According to another aspect, the invention also proposes the application of a serial interleaved double chopper to the high voltage power supply of a generator. X-rays.
    [0007] DESCRIPTION OF THE FIGURES Other objectives, features and advantages will become apparent from the detailed description which follows with reference to the drawings given by way of non-limiting illustration, among which: FIG. 1 represents a simple chopper of the state of the art in phase accumulation; Fig. 2 shows a simple state-of-the-art chopper in the energy transfer phase; Fig. 3 shows a double interlaced chopper of the state of the art; FIG. 4 represents the sequencing of the switches of an interlace double chopper of the state of the art; - Figure 5 shows a double interlace chopper series according to the invention; FIGS. 6 and 7 show the sequencing of the switches of a serial interlaced double chopper according to the invention. DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 5, a series 100 interleaved double chopper includes a voltage source Ve, a positive chopper and a negative chopper.
    [0008] The positive chopper comprises a first inductance L1 whose first terminal is connected to the positive terminal of said voltage source Ve, a first diode D1 whose anode is connected to the second terminal of said first inductor L1, a first filter capacitor. C1 whose first terminal is connected to the cathode of said first diode D1, a first current switch T1 connected between said second terminal of said first inductor L1 and a midpoint but not connected to the midpoint of the power source. The negative chopper comprises a second inductor L2 whose first terminal is connected to the negative terminal of said voltage source Ve, a second diode D2 whose anode is connected to the second terminal of said second inductor L2, a second filter capacitor C2 whose first terminal is connected to the cathode of said second diode D2, a second switch T2 connected between said second terminal of said inductor L2 and the midpoint but not connected to the midpoint of the power source. A charge Rch is connected between the cathodes of the two diodes D1 and D2.
    [0009] A capacitor Cla and C2a for switching assistance is placed in parallel with each switch T1 and T2. A diode D1 a (respectively D2a) is advantageously placed in parallel with the switch T1 (respectively T2).
    [0010] In practice, the switches T1 and T2 are electronic switches such as MOS or IGBT transistors. The switches T1 and T2 and the diodes D1 and D2 have to support only half of the voltage across the load (Vs / 2), which makes it possible to usually choose 600V components and not 1200V, as in a single lift chopper or parallel interlaced choppers, with better performance and lower cost.
    [0011] Let Vs be the voltage across the load Rch, the elevation ratio Vs / Ve defined as the ratio of the voltages at the terminals of the source Ve and the load Rch is chosen to be greater than 2.
    [0012] The inductances L1 and L2 have been described as two separate inductances for the sake of clarity but they can be combined into one or two separate windings on the same magnetic circuit. The interlaced double chopper 100 also includes a control circuit 9 providing control signals, A2 and A3 respectively to control inputs of the switches T1 and T2. The control of the switches T1 and T2 is made by the control circuit 9, consisting for example of a voltage regulating circuit Vs across the load Rch and a control circuit incorporating a state machine, based on the voltage state variables Vs across the load, and inductive current / L provided by one or more current sensors 11 measuring the current / L flowing in the inductors L1 and L2 and supply the measured values to the circuit 9. The control circuit 9 of the switches T1 and T2 is adapted to control, at first, the opening of one of the switches, the other remaining closed, the two switches being initially closed, in a second time, the opening of the switch remained closed and in a third time, the closure of the two switches. In FIG. 6 and 7 are represented, at the top, the state of the first switch, in the middle the state of the second switch, and below the inductive current, the voltage at the terminals of the first switch, and the voltage at the terminals of the second switch. . More precisely, the control circuit 9 of the switches T1 and T2 is adapted to control the closing and opening of the switches T1 and T2 according to the sequencing described below with reference to FIG.
    [0013] During an initialization sequence SO, the voltage across the load, initially zero, is brought to a voltage equal to the voltage Ve across the source by a known charging circuit that will not be described here. The voltage across the load is then raised to a voltage equal to twice the voltage Ve during a known chopper control sequence which will not be described here. In the case where the power is applied without load, as is the case in radiology, one possibility is to take advantage of the natural resonance between the input inductor L1 or L2 and the two capacitors C1 and C2, to raise, in a single alternation of resonance, the voltage across the load Vs at a voltage equal to twice the voltage Ve. This phenomenon is also observed in conventional choppers, however it is not desirable in conventional Boost choppers, and although desirable in the series double chopper, it is of little use because the current pulse is very high.
    [0014] It is also possible to put a switch and an auxiliary diode, forming with the inductor Ll a step-down chopper, to preload the capacitor C1 at a voltage equal to the voltage Ve across the source. In the double series chopper, the capacitance C1 and C2 can be preloaded at a voltage equal to the voltage Ve at the terminals of the source, by alternately closing the switch TI or T2 of the chopper opposite it. During a first energy storage sequence SI, the two switches TI and T2 are closed (on state), which causes the increase of the current in the inductances L1 and L2, thus the storage of a quantity of energy. energy in the form of magnetic energy. Diodes DI and D2 are then blocked and the load is disconnected from the power supply. When the current L 2 flowing in the first inductance L1 exceeds a first threshold value LS h 1 -1 set by the control circuit, the control circuit 9 triggers the opening of the first switch TI. During a second sequence S 2, the first switch is open. the second closed switch. In a first step (Phase 2A), the capacitor C1 has in parallel with the first the switch TI charges until the voltage at these terminals reaches half of the voltage across the source is S / 2. In a second step (Phase 2B), there is a transfer of energy through the first diode. The first switch TI being open, the first inductance is then in series with the generator and its electromotive force is added to that of the generator (booster effect). The current flowing through the first inductance L1 then passes through the first diode DI, the first capacitor C1 and the load Rch. This results in a transfer of the energy accumulated in the first inductance L1 to the first capacitance C1 through the first diode DI.
    [0015] The control circuit 9 controls the opening of the second switch before the end of the energy transfer phase through the first diode. For example, when the inductive current / 1 flowing in the inductors L1 and L2 falls below a second threshold value LSeuil_2, the control circuit 9 triggers the opening of the second switch T2, this second threshold value being defined by the time constant of the resonant circuit formed by the inductance L1 and the capacitor C1a and chosen so that it is reached by the inductive current before the end of the energy transfer phase through the first diode D1. In a third sequence S3, the two switches are open. In a first step (Phase 3A), the first inductance L1 resonates with the capacitor C1 positioned in parallel with the first switch T1. The capacitor C1 positioned in parallel with the first switch T1 discharges until the current flowing through it is negative. The voltage across the first switching assist capacitor is then zero. Indeed, in the absence of the first diode D2, the voltage across the first switching aiding capacitor Cl a would be equal to E + (ES) = 2E-S, 2E-S being negative since the ratio of S / E elevation is greater than 2. In the presence of the first diode D2, the voltage across the first switching assist capacitor is therefore zero.
    [0016] When the current / 1, flowing in the first inductance L1 passes below a third negative threshold value LSeuil_3, the control circuit 9 controls the simultaneous closing of the two switches T1 and T2. Since the voltage across the first capacitor C1 with switching assistance is zero when the first switch T1 is opened, the switching operation is zero voltage switching (ZVS Zero Voltage Switching) and therefore a lossy switching. substantially zero. Alternatively, the closing of the switches T1 and T2 is triggered at a time interval of the opening of the second switch T2. This time interval being defined by the time constant of the resonant circuit formed by the first inductance L1 and the capacitor C1a in parallel with the first switch and calculated so as to ensure that the voltage across the first capacitor C1 has aids in the switching is zero when closing the switches T1 and T2.
    [0017] The three sequences described above are repeated with reversal of the roles of the switches T1 and T2. More precisely, during a fourth sequence S4, the two switches T1 and T2 are closed again. The circuit 100 is again in a phase of energy accumulation. The current increases in the inductances L1 and L2, which causes the storage of a quantity of energy in the form of magnetic energy. The diodes D1 and D2 are then blocked and the load is disconnected from the power supply. When the current / 1, flowing in the second inductance L2 passes above the first threshold value LSeuil_1, the control circuit 9 triggers the opening of the second switch T2.
    [0018] During a fifth sequence S5, the second switch is open, the first switch closed. In a first step (Phase 2A), the capacitor C2a in parallel with the second switch T2 charges until the voltage at these terminals reaches half of the voltage across the source is S / 2. In a second step (Phase 2B), there is a transfer of energy through the second diode D2. The second switch T2 being open, the second inductor L2 is then in series with the generator and its electromotive force is added to that of the generator (booster effect). The current flowing through the second inductor L2 then passes through the second diode D2, the second capacitor C2 and the load R. This results in a transfer of the energy accumulated in the second inductor L2 to the second capacitor C2. The control circuit 9 controls the opening of the first switch before the end of the energy transfer phase through the second diode. For example, when the current / 1, flowing in the inductors L1 and L2 passes below a second threshold value LSeuil_2, the control circuit 9 triggers the opening of the first switch T2, this second threshold value being defined by the constant time of the resonant circuit formed by the second inductor L2 and the capacitor C2a in parallel with the second switch and selected so that it is reached by the inductive current before the end of the energy transfer phase through the second diode. In a sixth sequence S6, the two switches are open. In a first step (Phase 3A), the second inductor L2 resonates with the capacitor C2a positioned in parallel with the second switch T2. The capacitor C2a positioned in parallel with the second switch T2 discharges until the current flowing through it is negative. The voltage across the second switching assist capacitor is then zero. When the current / 1, flowing in the second inductance L2 passes below a third negative threshold valueLSeu / 3, the control circuit 9 controls the simultaneous closing of the two switches T1 and T2. Since the voltage at the terminals of the second switching aid capacitor C2a is zero when the second switch T2 is opened, the switching operation is a zero voltage switching (ZVS Zero Voltage Switching) and therefore a substantially lossless switching. nothing.
    [0019] The six sequences described above are repeated periodically. It should be noted that the control of the switches of an interlaced double chopper 100 described above is only suitable for choppers having an elevation ratio greater than 2. Indeed, when the elevation ratio is less than 2 , does not allow full discharge of switching capacitor and the ZVS condition is not fulfilled. It should be noted that the elevation ratio limit at 2 can be slightly lowered since the reverse current of the diode a little helps.
    [0020] It should be noted that the second threshold value LSeuil_2 triggering the closed switch opening is a degree of freedom that can be exploited for secondary applications. It is for example possible to limit the frequency deviation by playing on the second threshold value LSeuil_2 triggering the opening of the switch remained closed. The second threshold value LSeuil_2 can for example be adapted to the load. It will be lower for a low load and higher for a high load. FIGS. 6 and 7 show the sequencing of the switches with different second threshold values LS.sub.e-2. In the example of Figure 7, the second threshold value LSeuil_2 is higher than in the example of Figure 6. It is observed that the inductive current drop is faster during the resonance. Since the average current is not equal to the average of the maximum current and the minimum current (contrary to what is observed in the bidirectional Boost), the setting of the second threshold value LSeuil_2 makes it possible to reduce the peak current, which is particularly important for inductance sizing which is given by the square of the peak current. It is known to use auxiliary switches placed in parallel with the diodes. In some cases these switches already exist as in the case of bidirectional double BOOST / BUCK, used in particular in car battery chargers or dynamic braking (regenerative braking in English). However, the addition of auxiliary switches requires a command and gate controllers (gate drive circuit in English). In addition, the double bi-directional BOOST / BUCK has a number of disadvantages, in particular, it does not allow cell balancing in the case of multicell batteries. An independent charger is also preferable for isolation and multiple cell-balanced inputs and outputs, which is especially true when the cells are supercapacitors and not batteries. In addition, unlike the double bidirectional BOOST / BUCK, the interlaced double chopper described above makes it possible to limit the design voltage and therefore the use of lower repetitive peak voltage (VRRM) diodes (for example 500 or 600V). which have less switching losses than higher repetitive peak reverse voltage (VRRM) diodes (eg 1200V). The control circuit 9 described here can be adapted to an assembly comprising several interleaved choppers connected in series or in parallel to increase the degree of interleaving.
    权利要求:
    Claims (11)
    [0001]
    REVENDICATIONS1. Interleaved dual chopper series (100) having two single choppers each having a diode (D1; D2), an input inductor (L1, L2), a switch (T1, T2) connected to the anode of the diode (D1; D2) and a filtering capacitor (C1, C2) connected to the cathode of the diode (D1; D2), the two switches (T1, T2) and the two filtering capacitors (C1, C2) being connected at a mid-point , the double interlaced chopper series (100) being characterized in that it further comprises a control circuit (9) switches (T1 and T2) adapted to control: in a first time, the opening of a first switch the other remaining closed, the two switches (T1, T2) being initially closed; in a second step, the opening of the second switch remained closed; and in a third step, the closing of the two switches (T1, T2).
    [0002]
    2. Dual interlace series chopper (100) according to the preceding claim, characterized in that it further comprises a switching aid capacitor (C1a and C2a) placed in parallel with each of the switches (T1, T2).
    [0003]
    The intertwined double chopper (100) according to one of the preceding claims, further comprising a current sensor (11) measuring the current flowing in the input inductors (L1 and L2) and supplying the measured values to the choke circuit. control (9).
    [0004]
    4. dual interlace chopper series (100) according to one of the preceding claims, the cathodes of the diodes (D1, D2) being connected to a load (Rch), the control circuit (9) consisting of a control circuit the voltage (Vs) across the load (Rch) and a control circuit incorporating a state machine, based on the voltage (Vs) across the load (Rch), and the inductive current (IL) .
    [0005]
    5. intertwined dual chopper (100) according to one of claims 1 to 4, the cathodes of the diodes (D1, D2) being connected to a load (Rch), the control circuit (9) being adapted to trigger the opening of the first switch when the inductive current / L goes above a first threshold value set by the voltage regulation circuit (Vs) across the load (Rch).
    [0006]
    6. dual interlace series chopper (100) according to one of the preceding claims, the control circuit (9) being adapted to trigger the opening of the second switch when the current / inductive L passes below a second threshold value.
    [0007]
    A serial interlace double chopper (100) according to claim 6, wherein the cathodes of the diodes (D1, D2) are connected to a load (Rch), the second threshold value being set according to the value of the load.
    [0008]
    8. Double interlace chopper series (100) according to one of the preceding claims, characterized in that the closing of the two switches (T1, T2) is simultaneous.
    [0009]
    Interleaved dual chopper series (100) according to one of the preceding claims, characterized in that the control circuit (9) controls the simultaneous closing of both switches (T1 and T2) when the inductive current / L drops below a third negative threshold value.
    [0010]
    The serial interlace double chopper (100) according to claim 9, the third threshold value being set according to the value of the load.
    [0011]
    11.Application of a series interlaced double chopper (100) according to one of claims 1 to 10, to the high voltage supply of an X-ray generator.
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    同族专利:
    公开号 | 公开日
    US20150180340A1|2015-06-25|
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    US9729054B2|2017-08-08|
    引用文献:
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    法律状态:
    2015-12-17| PLFP| Fee payment|Year of fee payment: 3 |
    2016-12-27| PLFP| Fee payment|Year of fee payment: 4 |
    2017-12-27| PLFP| Fee payment|Year of fee payment: 5 |
    2019-11-20| PLFP| Fee payment|Year of fee payment: 7 |
    2021-09-10| ST| Notification of lapse|Effective date: 20210805 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1363270A|FR3015805B1|2013-12-20|2013-12-20|SWEET SWITCHING INTERLETING HOPPER|FR1363270A| FR3015805B1|2013-12-20|2013-12-20|SWEET SWITCHING INTERLETING HOPPER|
    US14/574,505| US9729054B2|2013-12-20|2014-12-18|Interleaved soft switching boost converter|
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