JP2011066963A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter which turns off a switching element by applying a negative voltage while suppressing a loss. <P>SOLUTION: Positive voltages are always applied to a high-side driving circuit 111a and a low-side driving circuit 131a by a second power source 140 and a bootstrap circuit comprising a first capacitor 111c and a first diode 111d, and a negative voltage is always applied to the high-side driving circuit 111a by the first power source 111b. Moreover, while a high-side element 110 is OFF and a low-side element 130 is ON, the negative voltage is applied to the low-side driving circuit 131a, and the second capacitor 141 is charged by the first power source 111b. Then, while the high-side element 110 is ON and the low-side element 130 is OFF, the second capacitor 141 is discharged, and a negative voltage is applied to the low-side driving circuit 131a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power converter that performs inverter output.

  As a power converter that performs inverter output to a three-phase motor or the like, an inverter circuit in which switching elements are provided on a high side and a low side is known. When the switching element of such an inverter circuit is composed of an N-type power MOSFET, a separate positive voltage source that generates a positive voltage with the source terminal of each element as a reference potential is required to drive each switching element. It becomes. Here, it is conceivable to separately provide power supplies for these switching elements. However, a single power supply is generated by generating a positive voltage necessary for driving the high-side switching elements using a bootstrap circuit. Therefore, a method of driving these switching elements is often used.

  On the other hand, in order to speed up the turn-off of the switching element, a method of applying a negative gate voltage when turning off the switching element is known. In this case, driving each switching element requires a separate negative voltage source that generates a negative voltage based on the source terminal of each element in addition to the positive voltage described above. If a separate power source is provided as the negative voltage source, the cost increases.

  Therefore, in the power conversion device described in Patent Document 1, it has been proposed to generate a negative voltage necessary for driving both switching elements by a single power source by using a Zener diode. Specifically, an anode terminal is connected to the negative voltage side of the negative voltage supply power source provided to supply a negative voltage to the low side drive circuit via a resistor, and the cathode is connected to the source of the high side switching element. When a Zener diode with a terminal connected is provided and the anode terminal of the Zener diode is connected to the drive circuit on the high side, when the switching element on the high side is turned on, it occurs due to a voltage drop in the Zener diode. The negative voltage is supplied to the drive circuit on the high side.

JP 2006-314154 A

However, in the power converter described in Patent Document 1, since the current always flows through the Zener diode, the loss increases.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power converter that performs turn-off of a switching element by applying a negative voltage while suppressing loss.

  The invention according to claim 1, which has been made to solve the above-described problems, includes a high-side element that is a switching element connected to the positive potential side of the high voltage source, and a negative potential side of the high side element and the high voltage source. A low-side element that is a switching element connected in series with a reference potential that is a potential, and an output terminal provided at a contact point between a source terminal of the high-side element and a drain terminal of the low-side element to a load The present invention relates to a power converter that performs inverter output. The power converter applies a positive voltage with respect to the source terminal of the element to the high side element to turn on the element, and applies a negative voltage with respect to the source terminal to the element. A high-side drive circuit for turning off the element, and applying a positive voltage with respect to the source terminal of the element to the low-side element to turn on the element, and a negative voltage with respect to the source terminal to the element And a low side drive circuit that turns off the element. In addition, the power converter includes a first power source having a positive potential side connected to an output terminal, a negative potential side connected to a negative power source terminal of a high side drive circuit, and generating a voltage necessary for turning off the element, and a positive potential side having a low side. A positive power supply terminal of the drive circuit is provided with a second power supply that is connected to the reference potential on the negative potential side and generates a voltage necessary for turning on the element. The power converter is composed of a first diode and a first capacitor connected in series between the positive potential side of the second power supply and the output terminal. A bootstrap circuit that applies a positive voltage with respect to the source terminal of the side element; a second diode having a cathode terminal connected to the negative potential side of the first power supply; an end of which is an anode terminal of the second diode; and The negative power supply terminal of the low-side drive circuit includes a second diode and a second capacitor that forms a closed loop with the first power supply while the other end is connected to the reference potential and the low-side element is ON.

  For example, the anode terminal of the second diode and one end of the second capacitor may be connected via a current-limiting resistor, and each element is connected via an element such as a resistor. It also includes that.

  In this way, a positive voltage based on the source terminal of the corresponding switching element is always applied to both drive circuits by the second power supply and the bootstrap circuit constituted by the first capacitor and the first diode. At the same time, the high-side drive circuit is constantly applied with a negative voltage based on the source terminal of the high-side element by the first power supply. In addition, while the high-side element is OFF and the low-side element is ON, a negative voltage based on the source terminal of the low-side element is applied from the first power supply to the low-side drive circuit, and the first power supply Two capacitors are charged with negative charge. While the high-side element is ON and the low-side element is OFF, the second capacitor in which negative charges are accumulated is discharged, and a negative voltage with respect to the source terminal of the low-side element is applied to the low-side drive circuit. Applied.

  Thus, according to the power converter of the first aspect, a negative voltage can be applied to each drive circuit without providing a power source individually. In this power converter, since a negative voltage is applied to the low-side drive circuit by the second capacitor in which negative charges are stored, for example, when a voltage drop of a Zener diode is used as a negative voltage source, the power converter is driven. In order to generate a negative voltage to be applied to the circuit, it is not necessary to constantly pass a current. Therefore, the power converter according to claim 1 can turn off the switching element by applying a negative voltage while suppressing loss. By performing such turn-off, it is possible to reduce switching loss and to prevent malfunction of a three-phase motor or the like that is a target of inverter output.

  Furthermore, according to this power converter, a negative voltage to be applied to the low-side drive circuit is generated by the second capacitor, so that, for example, it is more stable than a case where a negative voltage is generated using a voltage drop of a Zener diode. Negative voltage can be generated.

Moreover, you may make the power converter of Claim 1 respond | correspond to the inverter output of multiple phases as follows.
That is, as described in claim 2, a high-side element, a high-side drive circuit that turns on and off the high-side element, a low-side element connected to the high-side element, and the low-side element are turned on The low-side drive circuit to be turned off / off, the first power supply connected to the high-side drive circuit, the bootstrap circuit corresponding to the high-side drive circuit, and the second diode connected to the first power supply as a block Also good. The power converter performs multi-phase inverter output, and a block corresponding to each phase is individually provided. The positive potential side of the second power supply is connected to the positive power supply terminal of the low side drive circuit in each block and the bootstrap. The one end of the second capacitor may be connected to the low-side drive circuit and the second diode in each block.

By carrying out like this, the multi-phase inverter output can be performed without separately providing the second power source and the second capacitor for each phase, and the cost can be reduced.
Further, as described in claim 3, in any of the blocks, the low-side drive circuit in the block is connected to the second power source via the first inductor individually provided corresponding to the block. And may be connected to the second capacitor via a second inductor provided individually corresponding to the block.

  In this way, the low-side drive circuit and the second power source are connected via the inductor, and the voltage source of the low-side drive circuit and the voltage source of the low-side drive circuit of the other block are separated from each other. The influence of noise on the reference potential line and the like on the circuit can be suppressed. For this reason, the malfunction of the low side element driven by the low side drive circuit connected via the inductor can be prevented.

  Further, as described in claim 4, in any block, the low-side drive circuit in the block is connected to the second power source via the first inductor individually provided corresponding to the block. In addition, the negative power supply terminal of the low-side drive circuit and the anode terminal of the second diode in the block are replaced with a second capacitor, and one end of a third capacitor provided individually corresponding to the block It may be connected to. The other end of the third capacitor is connected to a reference potential. While the low-side element of the block corresponding to the third capacitor is ON, the third capacitor is connected to the second diode of the block and A closed loop may be formed with the first power source.

  Thus, even when the voltage source of the low-side drive circuit is separated from the voltage source of the low-side drive circuit of another block by the inductor and the capacitor, the reference potential line for the low-side drive circuit is separated. It is possible to suppress the influence of noise generated in the upper class. Moreover, the size of the power converter can be reduced by using a capacitor instead of the inductor.

Moreover, the power converter may be configured as follows.
That is, as described in claim 5, the power converter applies a positive voltage with reference to the source terminal of the element to the high side element to turn on the element, and to the element, the power converter A high-side drive circuit that applies a negative voltage with reference to the source terminal to turn off the element, and a low-side element that applies a positive voltage with reference to the source terminal of the element to turn on the element. The element may be provided with a low side driving circuit that applies a negative voltage with respect to the source terminal to turn off the element. The power converter may include a first power source that generates a voltage required to turn on the element, with the positive potential side connected to the positive power supply terminal of the low-side drive circuit and the negative potential side connected to the reference potential. . In addition, the power converter includes a second power source for generating a voltage necessary for turning off the element, the positive potential side being connected to the reference potential and the negative potential side being connected to the negative power source terminal of the low side driving circuit, and the positive potential of the first power source. A positive voltage based on the source terminal of the high-side element is applied to the positive power supply terminal of the high-side drive circuit. A bootstrap circuit may be provided. In addition, the power converter has one end connected to the output terminal, the other end connected to the negative power supply terminal of the high side drive circuit, one end connected to the negative potential side of the second power supply, and the other end connected to the second power supply. There may be provided a control switching element connected to the other end of the two capacitors, and a control drive circuit for turning the control switching element ON / OFF in synchronization with ON / OFF of the low side element by the low side drive circuit. . The switching element may form a closed loop together with the second capacitor and the second power source when the low side element is turned on by the low side driving circuit.

  By doing so, a positive voltage based on the source terminal of the corresponding switching element is always applied to both drive circuits by the first power supply and the bootstrap circuit constituted by the first capacitor and the first diode. At the same time, the low-side drive circuit is constantly applied with a negative voltage based on the source terminal of the low-side element by the second power source. In addition, while the high-side element is OFF and the low-side element is ON, the switching element is in the ON state, and a negative voltage based on the source terminal of the high-side element is applied to the high-side drive circuit by the second power source. At the same time, the second capacitor is charged with a negative charge by the second power source. While the high side element is ON and the low side element is OFF, the switching element is in the OFF state, the second capacitor in which negative charges are accumulated is discharged, and the source terminal of the high side element with respect to the high side drive circuit A negative voltage with reference to is applied.

  Thus, according to the power converter of the fifth aspect, a negative voltage can be applied to each drive circuit without providing a power source individually. In this power converter, since a negative voltage is applied to the low-side drive circuit by the second capacitor in which negative charges are stored, for example, when a voltage drop of a Zener diode is used as a negative voltage source, the power converter is driven. In order to generate a negative voltage to be applied to the circuit, it is not necessary to constantly pass a current. Therefore, the power converter according to claim 5 can turn off the switching element by applying a negative voltage while suppressing loss. By performing such turn-off, it is possible to reduce switching loss and to prevent malfunction of a three-phase motor or the like that is a target of inverter output.

  Furthermore, according to this power converter, a negative voltage to be applied to the low-side drive circuit is generated by the second capacitor, so that, for example, it is more stable than a case where a negative voltage is generated using a voltage drop of a Zener diode. Negative voltage can be generated.

Moreover, you may make the power converter of Claim 5 respond | correspond to the inverter output of multiple phases as follows.
That is, as described in claim 6, a high-side element, a high-side drive circuit for turning on and off the high-side element, a low-side element connected to the high-side element, and turning on the low-side element A low-side driving circuit to be turned off, a bootstrap circuit corresponding to the high-side driving circuit, a second capacitor connected to the high-side driving circuit, and a control switching element connected to the second capacitor The control drive circuit for turning on / off the control switching element may be a block. Then, the power converter performs inverter output of a plurality of phases, blocks corresponding to each phase are individually provided, and the first power source is connected to the low side drive circuit and the bootstrap circuit in each block, The second power supply may be connected to the low side drive circuit and the switching element in each block.

By doing so, a plurality of inverter outputs can be performed without separately providing the first power source and the second power source for each phase, and the cost can be reduced.
Further, as described in claim 7, in any block, the low-side drive circuit in the block is connected to the first power source via the first inductor individually provided corresponding to the block. And may be connected to a second power source via a second inductor provided individually corresponding to the block.

  In this way, the low-side drive circuit and each power source are connected via the inductor, and the voltage source of the low-side drive circuit and the voltage source of the low-side drive circuit of the other block are separated from each other. On the other hand, the influence of noise generated on the reference potential line or the like can be suppressed. For this reason, the malfunction of the low side element driven by the low side drive circuit connected via the inductor can be prevented.

The control switching element may be an N-channel switching element as described in claim 8.
By doing so, the switching loss in the control switching element can be reduced.

Further, a positive voltage for turning on the control switching element may be input to the control drive circuit as follows.
That is, as described in claim 9, the control switching element has a source terminal connected to the second power source and a drain terminal connected to the other end of the second capacitor, and the control drive circuit includes a positive power source. The terminal may be connected to the positive potential side of the second power source.

  In this way, it is not necessary to provide a dedicated positive voltage source for the control drive circuit, and the cost can be reduced.

It is a circuit diagram of the power converter in a first embodiment. It is a circuit diagram of the power converter in a second embodiment. It is a circuit diagram of the power converter in a third embodiment. It is a circuit diagram of the power converter in 4th embodiment. It is a circuit diagram of the power converter of the modification of 2nd embodiment. It is a circuit diagram of the power converter of the modification of 3rd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments of the present invention are not limited to the following embodiments, and various forms can be adopted as long as they belong to the technical scope of the present invention.

[First embodiment]
[Description of configuration]
FIG. 1 is a circuit diagram illustrating a configuration of a power converter 100 according to the first embodiment. The power converter 100 generates an inverter waveform having the voltage output from the high voltage source 300 as the HI level voltage and outputs the inverter waveform to the load 200. The high voltage source 300 outputs a voltage corresponding to the type of the load 200. For example, the load 200 is a three-phase motor used in a hybrid vehicle, and the power converter 100 is connected to the three-phase motor. In the case of outputting one phase of the phase inverter outputs, the high voltage source 300 may output a voltage of about 300V. In the present embodiment, the potential on the negative potential side of the high voltage source 300 is set as the reference potential.

  The power converter 100 includes a high-side switching element 110 (a normally-off type N-type power MOSFET) having a drain terminal connected to the high voltage source 300 and a source terminal connected to an inverter output terminal 120 for the load 200. Hereinafter, the low-side switching element 130 (hereinafter referred to as a low-side element), which is a normally-off N-type power MOSFET, having a drain terminal connected to the inverter output terminal 120 and a source terminal connected to a reference potential. 130). These elements may be normally-on power MOSFETs that are turned off by applying a negative voltage with respect to the source terminal to the gate terminal.

  Further, the power converter 100 applies the positive voltage input to the positive power supply terminal to the gate terminal of the high side element 110 and turns on the element while the pulse signal input from the outside is at the HI level. At the same time, while the pulse signal is at the LO level, the negative voltage input to the negative power supply terminal is applied to the gate terminal to turn off the high-side element 110 and the high-side drive circuit 111a. A pulse signal complementary to the input pulse signal is input. While this pulse signal is at the HI level, a positive voltage input to the positive power supply terminal is applied to the gate terminal of the low-side element 130 to While this pulse signal is at the LO level, the negative voltage input to the negative power supply terminal is applied to the gate terminal to apply the low side element 13. And a low-side driver circuit 131a to turn OFF the.

  The power converter 100 has a positive potential side connected to the inverter output terminal 120 and a negative potential side connected to the negative power supply terminal of the high side drive circuit 111a, and is necessary for turning off the high side element 110 and the low side element 130. The first power supply 111b that generates a predetermined voltage (for example, 10V), the positive potential side is connected to the positive power supply terminal of the low side driving circuit 131a, and the negative potential side is connected to the reference potential, and the high side element 110 and the low side element 130 are turned on. A second power supply 140 for generating a predetermined voltage (for example, 10V) necessary for the first power supply, a first diode 111d having an anode terminal connected to the positive potential side of the second power supply 140, and one end of the second power supply 140 to the inverter output terminal 120, The other end is connected to the positive power supply terminal of the high side drive circuit 111a and the cathode terminal of the first diode 111d. The first capacitor 111c, which forms a bootstrap circuit with the first diode 111d, and the cathode terminal connected to the negative potential side of the first power supply 124 and the anode terminal connected to the negative power supply terminal of the low-side drive circuit 131a. A diode 111e and a second capacitor 141 having one end connected to the negative power supply terminal of the low-side drive circuit 131a and the other end connected to a reference potential are provided.

  The anode terminal of the first diode 111d is connected to the positive potential side of the second power supply 140 and the positive power supply terminal of the low side drive circuit 131a via the first current limiting resistor 142. The anode terminal of the second diode 111e is connected to the second capacitor 141 and the negative power supply terminal of the low-side drive circuit 131a via the second current limiting resistor 143.

Further, the first diode 111d and the second diode 111e may be composed of a Schottky barrier diode made of SiC.
According to the power converter 100 configured as described above, the positive power supply terminals of both the drive circuits are always provided by the second power supply 140 and the bootstrap circuit configured by the first capacitor 111c and the first diode 111d. A voltage of about 10 V based on the source terminal of the corresponding switching element is applied, and the negative power supply terminal of the high side drive circuit 111a is always connected to the source terminal of the high side element 110 by the first power supply 111b. A reference voltage of about −10V is applied. Further, while the high-side element 110 is OFF and the low-side element 130 is ON, the first power supply 111b is about -10V with respect to the negative power supply terminal of the low-side drive circuit 131a with respect to the source terminal of the low-side element 130. While a voltage is applied, the first power supply 111b charges the second capacitor 141 with a negative charge. Then, while the high side element 110 is ON and the low side element 130 is OFF, the second capacitor 141 in which negative charges are accumulated is discharged, and the low side element 130 has a negative power supply terminal with respect to the negative power supply terminal. A voltage of about −10 V with respect to the source terminal is applied.

[effect]
According to the power converter 100 of the first embodiment, it is possible to apply a negative voltage necessary for turning off the switching element without individually providing a power source for each drive circuit. In the power converter 100, a negative voltage necessary for turning off the low-side element 130 is applied to the low-side drive circuit 131a by the second capacitor 141 in which negative charges are accumulated. As in the case of using the voltage drop, it is not necessary to constantly flow current in order to generate the negative voltage applied to the drive circuit. Therefore, the power converter 100 can turn off the switching element by applying a negative voltage while suppressing loss. By performing such turn-off, it is possible to reduce switching loss and to prevent malfunction of a three-phase motor or the like that is a target of inverter output.

  Furthermore, according to the power converter 100, since the negative voltage applied to the low-side drive circuit 131a is generated by the second capacitor 141, for example, compared to a case where a negative voltage is generated using a voltage drop of a Zener diode. A more stable negative voltage can be generated.

[Second Embodiment]
[Description of configuration]
Next, the power converter 400 in 2nd embodiment is demonstrated. FIG. 2 is a circuit diagram illustrating the configuration of the power converter 400. The power converter 400 of the second embodiment generates an A-phase and B-phase two-phase inverter waveform using a voltage output from the high voltage source 300 similar to that of the first embodiment as a HI level voltage, not shown. Output to the load.

  The power converter 400 is a power MOSFET similar to that of the first embodiment, having a drain terminal connected to the high voltage source 300 and a source terminal connected to an A-phase inverter output terminal 420 for a load (not shown). A high-side element 410, a low-side element 430 that is a power MOSFET similar to that of the first embodiment, in which a drain terminal is connected to an A-phase inverter output terminal 420 and a source terminal is connected to a reference potential, and a drain terminal is high The voltage source 300 has a source terminal connected to the B-phase inverter output terminal 460, the high-side element 450, which is the same power MOSFET as in the first embodiment, and the drain terminal connected to the B-phase inverter output terminal 460. A low-side element 4 that is a power MOSFET similar to that of the first embodiment, the source terminal of which is connected to a reference potential. Including 0 and, the.

  The power converter 400 is a component similar to the first embodiment corresponding to the A-phase high-side element 410 and the low-side element 430, and is connected to the high-side drive circuit 411a similarly to the first embodiment. , First power supply 411b, first capacitor 411c, first diode 411d, second diode 411e, and low-side drive circuit 431a. The high side drive circuit 411a, the first power supply 411b, the first capacitor 411c, the first diode 411d, and the second diode 411e constitute an A1 block 411, and the low side drive circuit 431a constitutes an A2 block 431.

  The B-phase high-side element 450 and the low-side element 470 are also provided with a B1 block 451 that is a circuit similar to the A1 block 411 and a B2 block 471 that is a circuit similar to the A2 block 431. The a point, b point, c point, and d point of the A1 block 411 correspond to the a ′ point, b ′ point, c ′ point, and d ′ point of the B1 block 451, respectively, and the e point of the A2 block 431. , F point, and g point correspond to the e ′ point, f ′ point, and g ′ point of the B2 block 471, respectively.

  In the power converter 400, the positive potential side is connected to the anode terminal of the first diode 411d in the A1 block 411 and the positive power supply terminal of the low side drive circuit 431a in the A2 block 431, and the negative potential side is connected to the reference potential. One end is connected to the second power supply 440 similar to the first embodiment, the anode terminal of the second diode 411e in the A1 block 411, and the negative power supply terminal of the low-side drive circuit 431a in the A2 block 431. A second capacitor 441 similar to that of the first embodiment, the other end of which is connected to the reference potential.

  In FIG. 2, points a and a ′, points b and b ′, points e and h, points g and i are connected by lines (not shown). For this reason, the second power supply 440 is further connected at its positive potential side to the anode terminal of the first diode in the B1 block 451 and to the positive power supply terminal of the low-side drive circuit in the B2 block 471 via the first inductor 472. It is connected. One end of the second capacitor 441 is further connected to the anode terminal of the second diode in the B1 block 451, and is connected to the negative power supply terminal of the low-side drive circuit in the B2 block 471 via the second inductor 473. Yes.

[effect]
According to the power converter 400 of the second embodiment, a plurality of inverter outputs can be performed without providing the second power source 440 and the second capacitor 441 individually for each phase, and the cost can be reduced. it can.

  Further, the voltage source of the low-side drive circuit in the B2 block 471 is separated from the voltage source of the low-side drive circuit 431a in the A2 block 431, and is generated on the reference potential line with respect to the low-side drive circuit in the B2 block 471. The influence of noise can be suppressed. For this reason, the malfunction of the low side element 470 driven by the low side drive circuit in the B2 block 471 can be prevented.

[Third embodiment]
[Description of configuration]
Next, the power converter 500 in 3rd embodiment is demonstrated. FIG. 3 is a circuit diagram showing the configuration of the power converter 500. The power converter 500 of the third embodiment generates an inverter waveform having the voltage output from the high voltage source 300 similar to that of the first embodiment as the HI level voltage, and outputs the inverter waveform to the load 200.

  The power converter 500 includes a high side element 510 that is a power MOSFET similar to that of the first embodiment, the drain terminal is connected to the high voltage source 300, and the source terminal is connected to the inverter output terminal 520 for the load 200. The low-side element 530, which is a power MOSFET similar to that of the first embodiment, has a drain terminal connected to the inverter output terminal 520 and a source terminal connected to the reference potential.

  The power converter 500 includes a high-side drive circuit 511a and a low-side drive circuit 531a similar to those of the first embodiment, a positive potential side connected to a positive power supply terminal of the low-side drive circuit 531a, and a negative potential side connected to a reference potential. A first power source 540 that generates a predetermined voltage (for example, 10 V) necessary to turn on the high-side element 510 and the low-side element 530, and a positive potential side is a reference potential, and a negative potential side is a negative potential of the low-side drive circuit 531a. A second power source 541 that is connected to the power supply terminal and generates a predetermined voltage (for example, 10 V) necessary to turn off the high-side element 510 and the low-side element 530, one end to the inverter output terminal 520, and the other end to The first capacitor 511b connected to the positive power supply terminal of the high side drive circuit 511a, and the anode terminal are the first A cathode terminal is connected to the other end of the first capacitor 511b on the positive potential side of the source 540, a diode 511c that forms a bootstrap circuit together with the first capacitor 511b, one end to the inverter output terminal 520, and the other end to the high side. A second capacitor 511d connected to the negative power supply terminal of the drive circuit 511a, an N-type power whose drain terminal is connected to the other end of the second capacitor 511d and whose source terminal is connected to the negative potential side of the second power supply 541. For example, the control switching element 511e, which is a MOSFET, and the source terminal of the control switching element 511e are used as a reference, for example, about 10V is set at the HI level, and the same potential as the source terminal of the element is set at the LO level, and is input to the low side drive circuit 531a. HI level or LO level at the same timing as the pulse signal Input to the gate terminal of the generator to control switching elements 511e of the pulse signal of, a, and ON / OFF control drive circuit 511f of the element.

  The anode terminal of the diode 511c is connected to the positive potential side of the first power supply 540 and the positive power supply terminal of the low-side drive circuit 531a via the first current limiting resistor 542. The drain terminal of the control switching element 511e is connected to the other end of the second capacitor 511d through the second current limiting resistor 543.

Further, the diode 511c may be configured by a Schottky barrier diode made of SiC.
According to the power converter 500 configured as described above, the positive power supply terminals of both drive circuits are always supported by the first power supply 540 and the bootstrap circuit including the first capacitor 511b and the diode 511c. A voltage of about 10 V with respect to the source terminal of the switching element to be applied is applied, and the negative power supply terminal of the low-side drive circuit 531a is always referenced to the source terminal of the low-side element 530 by the second power supply 541. A voltage of about 10V is applied. Further, while the high-side element 510 is OFF and the low-side element 530 is ON, the control switching element 511e is in an ON state, and the second power supply 541 supplies the high-side to the negative power supply terminal of the high-side drive circuit 511a. A voltage of about −10 V with respect to the source terminal of the element 510 is applied, and a negative charge is charged in the second capacitor 511 d by the second power source 541. Then, while the high side element 510 is ON and the low side element 530 is OFF, the control switching element 511e is in the OFF state, the second capacitor 511d in which negative charges are accumulated is discharged, and the high side drive circuit 511a is negative. A voltage of about −10 V with respect to the source terminal of the high side element 510 is applied to the power supply terminal.

[effect]
According to the power converter 500 of the third embodiment, it is possible to apply a negative voltage necessary for turning off the switching element without individually providing a power source for each drive circuit. In the power converter 500, a negative voltage necessary for turning off the low-side element 530 is applied to the low-side drive circuit 531a by the second capacitor 511d in which negative charges are accumulated. As in the case of using the voltage drop, it is not necessary to constantly flow current in order to generate the negative voltage applied to the drive circuit. Therefore, the power converter 500 can turn off the switching element by applying a negative voltage while suppressing loss. By performing such turn-off, it is possible to reduce switching loss and to prevent malfunction of a three-phase motor or the like that is a target of inverter output.

  Furthermore, according to this power converter 500, since the negative voltage applied to the low-side drive circuit 531a is generated by the second capacitor 511d, for example, compared to the case where the negative voltage is generated using the voltage drop of the Zener diode. A more stable negative voltage can be generated.

[Fourth embodiment]
[Description of configuration]
Next, the power converter 600 according to the fourth embodiment will be described. FIG. 4 is a circuit diagram showing the configuration of the power converter 600. The power converter 600 of the fourth embodiment generates a two-phase inverter waveform of A phase and B phase with the voltage output from the high voltage source 300 similar to that of the first embodiment as the HI level voltage, not shown. Output to the load.

  The power converter 600 is a power MOSFET similar to that of the first embodiment, having a drain terminal connected to the high voltage source 300 and a source terminal connected to an A-phase inverter output terminal 620 for a load (not shown). A high-side element 610, a low-side element 630 that is a power MOSFET similar to the first embodiment, the drain terminal of which is connected to the A-phase inverter output terminal 620, and the source terminal of which is connected to the reference potential. The voltage source 300 has a source terminal connected to a B-phase inverter output terminal 660 and a high-side element 650 that is the same power MOSFET as the first embodiment, and a drain terminal connected to a B-phase inverter output terminal 660. A low-side element 6 that is a power MOSFET similar to that of the first embodiment, the source terminal of which is connected to a reference potential. Including 0 and, the.

  The power converter 600 is a component corresponding to the A-phase high-side element 610 and the low-side element 630, which is the same as that in the third embodiment, and is connected to the high-side drive circuit 611a in the same manner as in the third embodiment. , A first capacitor 611b, a diode 611c, a second capacitor 611d, a control switching element 611e, a control drive circuit 611f, and a low-side drive circuit 631a. The high side drive circuit 611a, the first capacitor 611b, the diode 611c, the second capacitor 611d, the control switching element 611e, and the control drive circuit 611f constitute the A1 block 611, and the low side drive circuit 631a constitutes the A2 block 631. Yes.

  The B-phase high-side element 650 and the low-side element 670 are also provided with a B1 block 651 that is a circuit similar to the A1 block 611 and a B2 block 671 that is a circuit similar to the A2 block 631. The points a, b, c, and d of the A1 block 611 correspond to points a ′, b ′, c ′, and d ′ of the B2 block 671, respectively, and the point e of the A2 block 631. , F point, and g point correspond to the e ′ point, the f ′ point, and the g ′ point of the B2 block 671, respectively.

  In the power converter 600, the positive potential side is connected to the anode terminal of the diode 611c in the A1 block 611 and the positive power supply terminal of the low side drive circuit 631a in the A2 block 631, and the negative potential side is connected to the reference potential. The first power source 640 similar to that of the third embodiment, the positive potential side is connected to the reference potential, the source terminal of the control switching element 611e in the A1 block 611, and the negative of the low-side drive circuit 631a in the A2 block 631 A second power source 641 similar to that of the third embodiment is connected to the power source terminal on the negative potential side.

  In FIG. 4, points a and a ′, points b and b ′, points e and h, points g and i are connected by lines (not shown). For this reason, the first power supply 640 is further connected on the positive potential side to the anode terminal of the diode in the B1 block 651 and to the positive power supply terminal of the low-side drive circuit in the B2 block 671 via the first inductor 672. The Further, the negative potential side of the second power supply 641 is further connected to the source terminal of the control switching element in the B1 block 651 and also connected to the negative power supply terminal of the low-side drive circuit in the B2 block 671 via the second inductor 673. Connected.

[effect]
According to the power converter 600 of the fourth embodiment, a plurality of phase inverter outputs can be performed without providing the first power source 640 and the second power source 641 individually for each phase, thereby reducing the cost. it can.

  In addition, the voltage source of the low side drive circuit in the B2 block 671 is separated from the voltage source of the low side drive circuit 631a in the A2 block 631, and is generated on the reference potential line with respect to the low side drive circuit in the B2 block 671. The influence of noise can be suppressed. For this reason, the malfunction of the low side element 670 driven by the low side drive circuit in the B2 block 671 can be prevented.

[Other Embodiments]
(1) The power converter 400 in the second embodiment may be configured as follows. That is, as described in FIG. 5, instead of the second inductor 473, one end is connected to the negative potential side of the second power source 440, the other end is the anode terminal of the second diode of the B1 block 451, and B2 A third capacitor 442 connected to the negative power supply terminal of the low-side drive circuit of the block 471 may be provided. Then, point a, point a ′, point e, and point h in FIG. 5 may be connected by lines (not shown).

  Even in such a configuration, the voltage source of the low-side drive circuit in the B2 block 471 can be separated from the voltage source of the low-side drive circuit 431a in the A2 block 431, and the low-side drive circuit in the B2 block 471 can be separated. On the other hand, the influence of noise generated on the reference potential line or the like can be suppressed. Further, by using the third capacitor 442 instead of the second inductor 473, the size of the power converter 400 can be reduced.

  (2) In the power converter 500 in the third embodiment, as shown in FIG. 6, the control drive circuit 511f has a positive power supply terminal on the positive potential side of the second power supply 541 and a negative power supply terminal controlled. May be connected to the source terminal of the switching element 511e. By doing so, the control drive circuit 511f can turn on and off the control switching element 511e without providing a dedicated voltage source, and the cost can be reduced.

Note that the positive power supply terminal and the negative power supply terminal of the control switching element in the fourth embodiment may be similarly connected.
(3) Moreover, in 2nd embodiment and 4th embodiment, although the power converter corresponding to a two-phase inverter output was demonstrated, by adding the block similar to the block corresponding to each phase, three-phase A power converter that performs the above inverter output can be configured.

  DESCRIPTION OF SYMBOLS 100 ... Power converter, 110 ... High side element, 111a ... High side drive circuit, 111b ... First power supply, 111c ... First capacitor, 111d ... First diode, 111e ... Second diode, 120 ... Inverter output terminal, 124 ... 1st power supply, 130 ... Low side element, 131a ... Low side drive circuit, 140 ... 2nd power supply, 141 ... 2nd capacitor, 142 ... 1st current limiting resistance, 143 ... 2nd current limiting resistance, 200 ... Load, 300 ... High voltage source, 400 ... power converter, 410 ... high side element, 411 ... A1 block, 411a ... high side drive circuit, 411b ... first power supply, 411c ... first capacitor, 411d ... first diode, 411e ... second Diode, 420 ... Inverter output terminal, 430 ... Low side element, 431 ... A2 block, 431a Low side drive circuit, 440 ... second power supply, 441 ... second capacitor, 442 ... third capacitor, 450 ... high side element, 451 ... B1 block, 460 ... inverter output terminal, 470 ... low side element, 471 ... B2 block, 472 ... first inductor, 473 ... second inductor, 500 ... power converter, 510 ... high side element, 511a ... high side drive circuit, 511b ... first capacitor, 511c ... diode, 511d ... second capacitor, 511e ... for control Switching element, 511f ... control drive circuit, 520 ... inverter output terminal, 530 ... low side element, 531a ... low side drive circuit, 540 ... first power supply, 541 ... second power supply, 542 ... first current limiting resistor, 543 ... first Two current limiting resistors, 600 ... Power converter, 610 ... High side element 611 ... A1 block, 611a ... high side drive circuit, 611b ... first capacitor, 611c ... diode, 611d ... second capacitor, 611e ... control switching element, 611f ... control drive circuit, 620 ... inverter output terminal, 630 ... Low-side element, 631 ... A2 block, 631a ... Low-side drive circuit, 640 ... First power supply, 641 ... Second power supply, 650 ... High-side element, 651 ... B1 block, 660 ... Inverter output terminal, 670 ... Low-side element, 671 ... B2 block, 672 ... first inductor, 673 ... second inductor.

Claims (9)

A high-side element that is a switching element connected to a positive potential side of a high voltage source, and a switching element that is connected in series between the high-side element and a reference potential that is a negative potential side potential of the high voltage source A power converter that outputs an inverter to a load from an output terminal provided at a contact point between a source terminal of the high side element and a drain terminal of the low side element,
A positive voltage based on the source terminal of the element is applied to the high side element to turn on the element, and a negative voltage based on the source terminal is applied to the element to turn off the element. A high-side drive circuit;
A low side that applies a positive voltage with respect to the source terminal of the element to the low side element to turn on the element, and applies a negative voltage with respect to the source terminal to the element to turn off the element. A drive circuit;
A first power source having a positive potential side connected to the output terminal and a negative potential side connected to a negative power source terminal of the high-side drive circuit, and generating a voltage necessary for turning off the element;
A second power source for generating a voltage required to turn on the element, with a positive potential side connected to a positive power supply terminal of the low-side drive circuit and a negative potential side connected to the reference potential;
A first diode and a first capacitor connected in series between the positive potential side of the second power source and the output terminal, and the source of the high side element is connected to the positive power source terminal of the high side driving circuit. A bootstrap circuit that applies a positive voltage with respect to the terminal;
A second diode having a cathode terminal connected to the negative potential side of the first power supply;
While one end is connected to the anode terminal of the second diode and the negative power supply terminal of the low-side drive circuit, the other end is connected to the reference potential, and the low-side element is ON, the second diode; A second capacitor that forms a closed loop with the first power source;
A power converter comprising: The power converter according to claim 1, wherein
The high-side element, the high-side drive circuit for turning on / off the high-side element, the low-side element connected to the high-side element, the low-side drive circuit for turning on / off the low-side element, The first power supply connected to the high-side drive circuit, the bootstrap circuit corresponding to the high-side drive circuit, and the second diode connected to the first power supply are made into a block,
The power converter performs inverter output of a plurality of phases, and the blocks corresponding to each phase are individually provided,
The positive potential side of the second power supply is connected to the positive power supply terminal of the low-side drive circuit and the bootstrap circuit in each of the blocks,
One end of the second capacitor is connected to the low-side drive circuit and the second diode in each block;
A power converter characterized by. The power converter according to claim 2, wherein
In any one of the blocks, the low-side drive circuit in the block is connected to the second power source via a first inductor individually provided corresponding to the block, and corresponds to the block. Connected to the second capacitor via a separately provided second inductor;
A power converter characterized by. The power converter according to claim 2, wherein
In any one of the blocks, the low-side drive circuit in the block is connected to the second power supply via a first inductor individually provided corresponding to the block, and the low-side drive circuit includes the low-side drive circuit. The negative power supply terminal and the anode terminal of the second diode in the block are connected to one end of a third capacitor individually provided corresponding to the block instead of the second capacitor,
The other end of the third capacitor is connected to the reference potential. While the low-side element of the block corresponding to the third capacitor is ON, the third capacitor Forming a closed loop with two diodes and the first power source;
A power converter characterized by. A high-side element that is a switching element connected to a positive potential side of a high voltage source, and a switching element that is connected in series between the high-side element and a reference potential that is a negative potential side potential of the high voltage source A power converter that outputs an inverter to a load from an output terminal provided at a contact point between a source terminal of the high side element and a drain terminal of the low side element,
A positive voltage based on the source terminal of the element is applied to the high side element to turn on the element, and a negative voltage based on the source terminal is applied to the element to turn off the element. A high-side drive circuit;
A low side that applies a positive voltage with respect to the source terminal of the element to the low side element to turn on the element, and applies a negative voltage with respect to the source terminal to the element to turn off the element. A drive circuit;
A first power source having a positive potential side connected to a positive power supply terminal of the low-side drive circuit, a negative potential side connected to the reference potential, and generating a voltage necessary for turning on the element;
A second power source that has a positive potential side connected to the reference potential and a negative potential side connected to a negative power supply terminal of the low-side drive circuit, and generates a voltage necessary to turn off the element;
A first diode and a first capacitor connected in series between the positive potential side of the first power supply and the output terminal, and the source of the high side element is connected to the positive power supply terminal of the high side drive circuit. A bootstrap circuit that applies a positive voltage with respect to the terminal;
A second capacitor having one end connected to the output terminal and the other end connected to a negative power supply terminal of the high-side drive circuit;
A control switching element having one end connected to the negative potential side of the second power supply and the other end connected to the other end of the second capacitor;
A control drive circuit for turning on / off the control switching element in synchronization with ON / OFF of the low side element by the low side drive circuit;
With
The switching element forms a closed loop together with the second capacitor and the second power source when the low side element is turned on by the low side driving circuit.
A power converter characterized by. The power converter according to claim 5, wherein
The high-side element, the high-side drive circuit for turning on / off the high-side element, the low-side element connected to the high-side element, the low-side drive circuit for turning on / off the low-side element, The bootstrap circuit corresponding to the high-side drive circuit, the second capacitor connected to the high-side drive circuit, the control switching element connected to the second capacitor, and the control switching element And the control drive circuit for turning ON / OFF a block,
The power converter performs inverter output of a plurality of phases, and the blocks corresponding to each phase are individually provided,
The first power supply is connected to the low side drive circuit and the bootstrap circuit in each of the blocks,
The second power supply is connected to the low-side drive circuit and the switching element in each of the blocks;
A power converter characterized by. The power converter according to claim 6, wherein
In any one of the blocks, the low-side drive circuit in the block is connected to the first power source via a first inductor individually provided corresponding to the block, and corresponds to the block. Being connected to the second power source via a separately provided second inductor;
A power converter characterized by. The power converter according to any one of claims 5 to 7,
The control switching element is composed of an N-channel switching element;
A power converter characterized by. The power converter according to claim 8, wherein
The control switching element has a source terminal connected to the second power source and a drain terminal connected to the other end of the second capacitor,
The control drive circuit has a positive power supply terminal connected to the positive potential side of the second power supply;
A power converter characterized by.

Images