• 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:
    A supply circuit for supplying LEDs (LED1, LED2) from a primary DC voltage (UB), wherein in the circuit of at least one LED, a control transistor (T) and a current sensor (RS) and a comparator (K) is provided, the output of which Control input of the control transistor is connected, wherein a first input of the comparator, a set value (ss) for the current (IS) in the LED circuit and a second input of the comparator is detected by the current sensor detected actual value (si) of the LED circuit, wherein between the LED circuit, which comprises the series circuit of the LED circuit (LED1, LED2), the control transistor (T) and the current sensor (RS), and the primary DC voltage (UB) a capacitive pre-converter (KV) is arranged in Dependent on the level of the primary DC voltage, this converts to a DC link voltage (UZ) with a set value desired for the LED circuit.
    公开号:AT519927A1
    申请号:T50337/2017
    申请日:2017-04-26
    公开日:2018-11-15
    发明作者:Weber Emanuel；Koller Jan
    申请人:Zkw Group Gmbh；
    IPC主号:
    专利说明:

    Summary
    A supply circuit for supplying LEDs (LED1, LED2) from a primary DC voltage (Ub), with at least one LED in the circuit comprising a control transistor (T) and a current sensor (R S ) and a comparator (K), the output of which is provided is connected to the control input of the control transistor, a setpoint (ss) for the current (Is) in the LED circuit being fed to a first input of the comparator and an actual value (si) of the LED circuit being detected by the current sensor being fed to a second input of the comparator, wherein between the LED circuit, which comprises the series circuit of the LED circuit (LED1, LED2), the control transistor (T) and the current sensor (Rs), and the primary DC voltage (Ub), a capacitive pre-converter (KV) is arranged, the depending on the level of the primary DC voltage, this converts it to an intermediate circuit voltage (Uz) with a specified value desired for the LED circuit.
    Fig. 2/12
    P15889
    Supply circuit for supplying LEDs from a primary DC voltage
    The invention relates to a supply circuit for supplying LEDs from a primary DC voltage, wherein in the circuit of at least one LED there is a control transistor and a current sensor and a comparator is provided, the output of which is connected to the control input of the control transistor, a first input of the comparator a setpoint for the current in the LED circuit and a second input of the comparator is supplied with an actual value of the LED circuit which is detected by the current sensor.
    Today LEDs are used in different lighting areas and are controlled in higher quality applications with electronic supply circuits. Especially when using LEDs as high-performance light sources, very high demands are placed on the exact adherence to the supply current. An example of this is the use of LEDs in headlight systems in motor vehicles. In order to keep the luminous flux emitted as constant as possible, various types of current regulators must be used, such as switching converters and linear current sources.
    The difficulty in controlling LEDs in the automotive sector is that the available supply voltage is not constant and typically ranges between 9 volts and 18 volts in the case of 12 volt power supplies in motor vehicles. If linear controllers are used in this case, there are always operating states in which extremely high power losses occur on the controller. For this reason, switching converters are also used, but their use is not always desirable for cost reasons.
    An object of the invention is to provide a supply circuit for supplying LEDs, which is particularly, if not exclusively, suitable for use in motor vehicle headlight systems, the focus being on good efficiency at low costs and thus avoiding the disadvantages mentioned above ,
    This object is achieved with a supply circuit of the type mentioned at the outset, in which, according to the invention, a capacitive pre-converter is arranged between the LED circuit, which comprises the series circuit of the D circuit, the control transistor and the current sensor, and the primary DC voltage, which is dependent on the level of the primary DC voltage converts it to an intermediate circuit voltage with a specified value desired for the LED circuit.
    / 12
    P15889
    The invention is based on a modification of linear controllers, the solution obtained now resulting in low component costs, low manufacturing costs, high current accuracy and reduced power loss.
    In an expedient embodiment of the invention it is provided that the capacitive pre-converter has a controlled series switch located between the primary DC voltage and an intermediate circuit capacitor, which is controlled by a PWM output of a microcontroller, a voltage value proportional to the primary DC voltage being supplied to an input of the microcontroller and the microcontroller contains a look-up table with a relation between the value of the supplied voltage value and the duty cycle of a signal at the PWM output in order to convert the primary DC voltage into the intermediate circuit voltage with the specified value desired for the LED circuit, the LED circuit is located on the intermediate circuit capacitor. The controlled series switch expediently contains a switching transistor.
    Another advantageous variant provides that the capacitive pre-converter is designed as a charge pump and has two diodes connected in the forward direction and in series in a series branch between the primary DC voltage and an intermediate circuit capacitor, a charge-reversal capacitor between the connection point of the two diodes and one of one Clock-controlled switch is located, which switches the capacitor to one of the two poles of the primary DC voltage. It is also expediently provided here that the clock is controlled by a microcontroller, a voltage value proportional to the primary DC voltage being fed to an input of the microcontroller and the microcontroller having a look-up table with a relation between the value of the supplied voltage value and the pulse duty factor of the clock contains to convert the primary DC voltage to the DC link voltage with the specified value desired for the LED circuit.
    The invention and further advantages are explained in more detail below on the basis of exemplary embodiments which are illustrated in the drawing. In this show
    1 shows a supply circuit for LEDs according to the prior art with an analog linear regulator,
    Fig. 2 is a schematic diagram of a supply circuit for LEDs according to the invention with a capacitive precharge, / 12th
    P15889
    3 shows an embodiment of a feed circuit for LEDs according to the invention with a controlled switch in the series branch,
    Fig. 4 shows a feed circuit of FIG. 3 in a detailed representation with a microcontroller and
    Fig. 5 shows a further embodiment of a feed circuit for LEDs according to the invention, in which a charge pump is provided for the capacitive pre-conversion.
    1 shows a supply circuit for supplying LEDs, here a series connection of two LEDs LED1, LED2, from a primary DC voltage Ub. In the associated circuit, in which a current Is flows, there are also a control transistor T and a current sensor Rs designed here as a resistor. A comparator K is also provided, the output of which is connected to the control input of the control transistor T, a first input of the comparator K, a desired value Ss for the current in the LED circuit and a second input of the comparator K is from the current sensor R S detected actual value s i of the LED current I S, ie this current proportional voltage value is supplied. In general, an input capacitor Ce is parallel to the supply voltage, which suppresses brief voltage fluctuations or disturbances.
    If, in this simple supply circuit according to the prior art, there are 2x3 volts on the LED series circuit, for example, and the primary DC voltage UB in the worst case is 16 volts, approximately 10 volts are present at the control transistor T. Depending on the set current, this results in a high power loss in the transistor, which is often too high to be dissipated to the extent that no thermal damage to components occurs.
    Fig. 2 shows schematically a solution according to the invention, which consists in inserting a capacitive pre-converter KV between the analog, linear controller and the primary DC voltage UB, which converts this to an intermediate circuit voltage U z with a depending on the level of the primary DC voltage UB converts the specified value desired for the LED circuit. For this purpose, the voltage is modified by means of logic as a function of the input voltage. For example, a table is stored in the logic, which modifies the voltage depending on the input voltage. For this purpose, only a table is stored in the logic, which assigns a primary PWM value to the primary direct voltage UB in order to obtain a desired intermediate circuit voltage accordingly by a switching means.
    3 goes into more detail in this regard and shows a control circuit AST which controls a controlled series switch S which lies between the primary DC voltage UB and an intermediate circuit capacitor Cz. The control circuit AST is the primary DC voltage UB / 12
    P15889 or a value proportional to this is supplied and it controls the series switch S, for example in accordance with the above-mentioned intermediate circuit voltage Uz table and pulse-width-modulated logic, in such a way that a desired intermediate circuit voltage Uz results. If, for example, the primary direct voltage Ub is too high and is 16 volts, an intermediate circuit voltage Uz of 9 volts is generated for the switch S according to a duty cycle specified by the table, so that only 3 volts are present at the control transistor T if the voltage at the series circuit of the LEDs is 6 volts. The power loss and the thermal load are reduced accordingly.
    FIG. 4 shows further details of an exemplary embodiment, starting from FIG. 3. The switch S is implemented here as an FET transistor T2 with a conventional circuitry by means of a resistor R2 and a diode D2, and is operated by a microcontroller μΰ via an npn transistor T 3 controlled. A resistor R4 lies between the collector of transistor T3 and the control electrode of transistor T2, and a resistor R5 lies between the base and the emitter of transistor T3. The transistor T3 is driven by the interposition of a resistor R 6 by an output GPIO (general purpose input / output) of the microcontroller μC. The microcontroller μC also has an input ADC (analog to digital conversion), to which an analog voltage value, which is proportional to the primary direct voltage Ub, is supplied, which is converted into a digital value in the microcontroller μC. A voltage divider R7, R8 is provided for the primary DC voltage Ub, from the division point of which a resistor R 9 leads to the input ADC of the microcontroller μC. The mentioned table LUT is contained in or assigned to the microcontroller μC, which is referred to in FIG. 4 as LookUpTable. This table LUT contains values for the duty cycle of the switch S as a function of the level of the primary DC voltage Ub, four exemplary values being given in the drawing. It should be clear that these values, which determine the level of the intermediate circuit voltage, depend in particular on the voltage at the series connection of the LEDs and also on the data of the LEDs used and of the control transistor T.
    The circuit shown in FIG. 5 shows a variant of the invention in which the capacitive pre-converter is designed as a charge pump. This consists of two forward-connected and series-connected diodes D3 and D4 in a series branch between the primary DC voltage Ub and an intermediate circuit capacitor C Z , which corresponds to the intermediate circuit capacitor C Z of FIG. 4, a charge-reversal capacitor C U between the connection point of the two diodes and a changeover switch S U controlled by a clock generator TG, which switches the charge-reversal capacitor Cu to one of the two poles of the primary direct voltage Ub.
    / 12
    P15889
    The clock generator TG is contained, for example, in a microcontroller μΰ, which in principle corresponds to that according to FIG. 4 and also contains a table corresponding to that shown in FIG. 4. The primary DC voltage Ub or a value proportional to this is of course also supplied to the microcontroller μΰ here, the voltage divider shown in FIG. 4 being omitted here for the sake of simplicity. In this variant, too, a switchover takes place in accordance with the pulse duty factor specified by the microcontroller μΰ in accordance with assignments stored in a table to the primary DC voltage U b in a manner which has already been described above and which leads to voltage fluctuations in the primary DC voltage U b in be compensated for in a way that avoids excessive thermal stress on the analog control transistor T.
    / 12
    P15889
    权利要求:
    Claims (5)
    [1]
    claims
    1. Supply circuit for supplying LEDs (LED1, LED2) from a primary DC voltage (Ub), with at least one LED in the circuit having a control transistor (T) and a current sensor (R S ) and a comparator (K), the output of which is provided is connected to the control input of the control transistor, a setpoint (ss) for the current (Is) in the LED circuit being fed to a first input of the comparator and an actual value (s i ) of the LED circuit being detected by the current sensor being fed to a second input of the comparator is characterized in that between the LED circuit, which comprises the series circuit of the LED circuit (LED1, LED2), the control transistor (T) and the current sensor (Rs), and the primary DC voltage (Ub), a capacitive pre-converter (KV ) is arranged, which, depending on the level of the primary DC voltage, converts it to an intermediate circuit voltage (Uz) with a specified value desired for the LED circuit.
    [2]
    2. Supply circuit according to claim 1, characterized in that the capacitive pre-converter has a controlled series switch (S) lying between the primary DC voltage (Ub) and an intermediate circuit capacitor (Cz), which is controlled by a PWM output of a microcontroller (gC), wherein an input of the microcontroller is supplied with a voltage value proportional to the primary DC voltage and the microcontroller contains a look-up table (LUT) with a relation between the value of the supplied voltage value and the duty cycle of a signal at the PWM output in order to adjust the primary DC voltage to the To convert the intermediate circuit voltage (Uz) with the specified value desired for the LED circuit, the LED circuit lying on the intermediate circuit capacitor.
    [3]
    3. Supply circuit according to claim 2, characterized in that the controlled series switch (S) includes a switching transistor (T2).
    [4]
    4. Supply circuit according to claim 1, characterized in that the capacitive pre-converter (KV) is designed as a charge pump and two diodes (D 3 , D4) connected in the forward direction and in series in a series branch between the primary DC voltage (Ub) and an intermediate circuit capacitor ( Cz), a charge capacitor (Cu) between the connection point of the two diodes and a switch (Su) controlled by a clock generator (TG), which switches the capacitor to one of the two poles of the primary DC voltage.
    7/12
    P15889
    [5]
    5. Power supply circuit according to claim 4, characterized in that the clock generator (TG) is controlled by a microcontroller (gC), an input of the microcontroller being supplied with a voltage value proportional to the primary DC voltage and the microcontroller having a look-up table (LUT) contains a relation between the value of the supplied voltage value and the pulse duty factor of the clock generator in order to convert the primary DC voltage to the intermediate circuit voltage (Uz) with the specified value desired for the LED circuit.
    8/12
    1.2
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
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    GB2492833A|2011-07-14|2013-01-16|Softkinetic Sensors Nv|LED boost converter driver circuit for Time Of Flight light sources|
    US9343960B2|2013-07-22|2016-05-17|Avago Technologies General Ip Pte. Ltd.|Feedback/feed forward switched capacitor voltage regulation|CN111845584A|2020-07-15|2020-10-30|诸暨路酷汽车零部件有限公司|Automobile peripheral AI lighting system|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50337/2017A|AT519927B1|2017-04-26|2017-04-26|Supply circuit for supplying LEDs from a primary DC voltage|ATA50337/2017A| AT519927B1|2017-04-26|2017-04-26|Supply circuit for supplying LEDs from a primary DC voltage|
    EP18166306.3A| EP3397025B1|2017-04-26|2018-04-09|Power supply circuit for supplying leds from a primary dc voltage|
    CN201810384421.7A| CN108811235B|2017-04-26|2018-04-26|Supply circuit for supplying an LED with a primary DC voltage|
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