JP2023047023A - Gate drive device for power semiconductor elements and power conversion device - Google Patents

Abstract

To suppress unbalance of a voltage to be applied to an element by aligning switching timing regarding an ON operation and an OFF operation of each power semiconductor element even if there is variations in gate signal transmission time or power semiconductor element characteristics, in a gate drive device for a plurality of power semiconductor elements connected in series and a power conversion device comprising the same.SOLUTION: A gate drive device for a plurality of power semiconductor elements QA and QB connected in series, comprises: gate drive voltage varying units 11-A and 11-B which are provided correspondingly to the power semiconductor elements QA and QB and output variable gate drive voltages; gate lines 12-A and 12-B for supplying the gate drive voltages outputted from the gate drive voltage varying units 11-A and 11-B to gate terminals of the corresponding power semiconductor elements QA and QB; and a magnetic coupling unit 13 for magnetically coupling the gate lines 12-A and 12-B with each other.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gate drive device and a power conversion device for power semiconductor devices.

2. Description of the Related Art Various devices have been proposed as gate drive devices for turning on and off each of a plurality of semiconductor switching elements, which are power semiconductor elements connected in series.

For example, a semiconductor comprising a plurality of voltage-driven semiconductor elements connected in series to form an arm, and a gate drive circuit that supplies a gate signal to the gate terminal of each of the plurality of voltage-driven semiconductor elements in each arm. In the switch circuit, the voltage-driven semiconductor elements connected in series are magnetically coupled to each other through the gate lines connecting the gate driving circuit and the gate terminals of the voltage-driven semiconductor elements in the respective arms. is known (see, for example, Patent Document 1).

For example, a gate drive device for turning on and off a plurality of voltage-driven semiconductor devices connected in series to each arm of a power conversion device, wherein the voltage applied to the voltage-driven semiconductor device is detected. and an overdrive circuit for turning on the voltage-driven semiconductor element at a voltage higher than a normal forward bias voltage when the voltage-driven semiconductor element is turned on. Due to the difference in turn-on timing of the voltage-driven semiconductor elements, an imbalance occurs in the voltages applied to the respective voltage-driven semiconductor elements. A voltage-driven semiconductor device characterized in that by turning on the applied voltage-driven semiconductor device with a voltage higher than a normal forward bias voltage, application of overvoltage to the voltage-driven semiconductor device and subsequent element breakdown are prevented. 2. Description of the Related Art A gate drive device for a semiconductor device is known (see, for example, Patent Document 2).

Japanese Patent No. 4396036 Japanese Patent No. 4449190

In the invention described in Patent Document 1 (Japanese Patent No. 4396036), each gate line of a voltage-driven semiconductor element is magnetically coupled so that a current flows through each gate line when the voltage-driven semiconductor element is turned on or off. If the values differ, the impedance of the gate line is changed instantaneously according to the difference, thereby matching the gate currents and suppressing variations in switching timing. However, in the invention described in Patent Document 1 (Japanese Patent No. 4396036), when the voltage-driven semiconductor devices have the same gate threshold voltage (gate voltage at which the voltage-driven semiconductor device starts to turn on), has the effect of correcting the time difference of the gate voltage due to the delay of the gate voltage signal and aligning the switching timing of the ON operation or the OFF operation, but the effect is small when the gate threshold voltages are different. In many cases, the gate threshold voltage varies depending on the voltage-driven semiconductor device, so the effect of aligning the switching timings of the ON operation and the OFF operation is poor, and the imbalance of the applied voltage during the ON operation and the OFF operation becomes large. .

For example, by applying a technique of setting a high gate voltage in advance for an element that turns on slowly like the invention described in Patent Document 2 (Japanese Patent No. 4449190) to the invention described in Patent Document 1, a plurality of Although it is possible to align the switching timings of the ON operations of the voltage-driven semiconductor devices, it is impossible to align the switching timings of the OFF operations of the plurality of power semiconductor devices. In addition, if the gate voltage is set high, the ON operation of the voltage-driven semiconductor element, which operates slowly due to the delay of the gate voltage signal, can be accelerated, and the switching timing can be aligned. Since the operation is delayed as compared with the case where the voltage is not increased, the switching timings of the voltage-driven semiconductor elements are greatly shifted when they are turned off, and the imbalance of the applied voltages becomes large.

Therefore, in a gate drive device for a plurality of power semiconductor devices connected in series and a power conversion device including the same, even if there are variations in the transmission time of the gate signal and the characteristics of the power semiconductor devices, the power semiconductor devices There is a demand for a technique for aligning the switching timings of the on-operations and off-operations of the power semiconductor elements and suppressing imbalance in the voltages applied to the power semiconductor elements.

According to one aspect of the present disclosure, a gate drive device for a plurality of power semiconductor devices connected in series is provided corresponding to the power semiconductor devices, and includes a gate drive voltage variable unit that outputs a variable gate drive voltage. , a gate line for supplying the gate drive voltage output from the gate drive voltage variable section to each gate terminal of the corresponding power semiconductor element, and a magnetic coupling section for magnetically coupling the gate lines to each other.

Here, in the gate drive device described above, the gate drive voltage variable section may vary the potential of the output gate drive voltage according to the difference in electrical characteristics between the power semiconductor elements.

Further, in the above gate drive device, the gate drive voltage variable part corresponding to the power semiconductor device having the first gate threshold voltage is the power semiconductor device having the second gate threshold voltage higher than the first gate threshold voltage. The positive side potential and the negative side potential of the gate drive voltage may be output that are lower than the positive side potential and the negative side potential of the gate drive voltage output by the gate drive voltage variable section corresponding to .

In the gate drive device, each of the gate drive voltage variable sections is connected in series to a positive potential output section for outputting a positive potential of the gate drive voltage and a positive potential output section. a negative side potential output section for outputting a side potential, in each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section; The potential at the output terminal of the power semiconductor element corresponding to the gate drive voltage variable section is the same potential, and the positive voltage output by the gate drive voltage variable section corresponding to the power semiconductor element having the second gate threshold voltage is output. The potential difference between the side potential and the potential at the intermediate terminal is greater than the potential difference between the positive side potential output by the gate drive voltage variable section corresponding to the power semiconductor element having the first gate threshold voltage and the potential at the intermediate terminal. may be

In the gate drive device, each of the gate drive voltage variable sections is connected in series to a positive potential output section for outputting a positive potential of the gate drive voltage and a positive potential output section. a negative side potential output section for outputting a side potential, in each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section; The potential at the output terminal of the power semiconductor element corresponding to the gate drive voltage variable section is the same potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having the second gate threshold voltage. The potential difference between the potential and the negative potential output by the gate drive voltage variable section is equal to the potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having the first gate threshold voltage and the gate drive voltage variable section. It may be smaller than the potential difference from the negative side potential output by the unit.

Further, in the above gate drive device, the gate drive voltage variable part corresponding to the power semiconductor device having the first gate threshold voltage is the power semiconductor device having a third gate threshold voltage lower than the first gate threshold voltage. A positive potential and a negative potential of the gate drive voltage higher than the positive potential and the negative potential of the gate drive voltage output by the gate drive voltage variable section corresponding to .

In the gate drive device, each of the gate drive voltage variable sections is connected in series to a positive potential output section for outputting a positive potential of the gate drive voltage and a positive potential output section. a negative side potential output section for outputting a side potential, in each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section; The potential at the output terminal of the power semiconductor element corresponding to the gate drive voltage variable section is the same potential, and the positive voltage output by the gate drive voltage variable section corresponding to the power semiconductor element having the third gate threshold voltage is output. The potential difference between the side potential and the potential at the intermediate terminal is smaller than the potential difference between the positive side potential output by the gate drive voltage variable section corresponding to the power semiconductor element having the first gate threshold voltage and the potential at the intermediate terminal. may be

In the gate drive device, each of the gate drive voltage variable sections is connected in series to a positive potential output section for outputting a positive potential of the gate drive voltage and a positive potential output section. a negative side potential output section for outputting a side potential, in each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section; The potential at the output terminal of the power semiconductor element corresponding to the gate drive voltage variable section is the same potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having the third gate threshold voltage. The potential difference between the potential and the negative potential output by the gate drive voltage variable section is equal to the potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having the first gate threshold voltage and the gate drive voltage variable section. may be larger than the potential difference from the negative potential output by the unit.

In addition, the gate drive device further includes a temperature sensor provided corresponding to each of the power semiconductor elements, and each of the gate drive voltage variable sections responds to the temperature of the power semiconductor element detected by the corresponding temperature sensor. The positive potential and negative potential of the gate drive voltage may be changed accordingly.

In the gate drive device, each of the positive potential and the negative potential of the gate drive voltage output from the gate drive voltage variable section corresponding to the power semiconductor element corresponding to the temperature sensor that detects the first temperature is , the positive potential and the negative potential of the gate drive voltage output from the gate drive voltage variable section corresponding to the power semiconductor element corresponding to the temperature sensor that detects the second temperature lower than the first temperature. It may be low.

Further, in the above gate drive device, the gate drive voltage variable part corresponding to the power semiconductor element corresponding to the temperature sensor that detects the first temperature is connected to the temperature sensor that detects the third temperature higher than the first temperature. Even if the positive side potential and the negative side potential of the gate drive voltage are output higher than the positive side potential and the negative side potential of the gate drive voltage output by the gate drive voltage variable section corresponding to the corresponding power semiconductor element. good.

Further, according to one aspect of the present disclosure, a power conversion device includes an arm provided with the gate drive device and a plurality of power semiconductor elements connected in series, and performs on/off operation of the power semiconductor elements. and a power conversion control unit configured to control the power conversion operation of the power conversion circuit unit.

Here, in the above power conversion device, each of the gate drive voltage variable units may change the positive potential and the negative potential of the gate drive voltage according to the value of the current output from the power conversion circuit unit. .

Further, in the above power conversion device, each of the gate drive voltage variable units changes the positive side of the gate drive voltage according to the value of the current command generated by the power conversion control unit to control the on/off operation of the power conversion circuit unit. The potential and the negative potential may be changed.

According to one aspect of the present disclosure, in a gate drive device for a plurality of power semiconductor devices connected in series and a power conversion device including the same, there is variation in the transmission time of the gate signal and the characteristics of the power semiconductor devices. Also, the switching timings of the ON and OFF operations of the power semiconductor elements can be aligned to suppress imbalance in the voltages applied to the power semiconductor elements.

1 is a circuit diagram illustrating a gate driver according to an embodiment of the disclosure; FIG. FIG. 10 is a circuit diagram showing a modification of the gate drive voltage variable section in the gate drive device according to the embodiment of the present disclosure; FIG. 2 illustrates a magnetic coupling portion in a gate drive according to an embodiment of the present disclosure; 1 illustrates a power converter with a gate drive according to an embodiment of the present disclosure; FIG. 5 is a circuit diagram showing an arm provided in the power converter shown in FIG. 4; FIG. FIG. 4 is a diagram for explaining the definition of the gate voltage imbalance when two power semiconductor elements have different characteristics, (A) showing the definition of the gate voltage imbalance during off operation, and (B) showing the definition of the gate voltage imbalance. indicates the definition of gate voltage imbalance during on-operation. FIG. 10 is a diagram illustrating simulation results of imbalance with and without magnetic coupling of gate lines in Patent Document 1 (Japanese Patent No. 4396036) when characteristics of power semiconductor elements vary. FIG. 10 is a diagram illustrating simulation results regarding the degree of imbalance in an embodiment of the present disclosure when there are variations in the characteristics of power semiconductor devices; FIG. 4 is a circuit diagram showing a gate driving device for turning on and off three power semiconductor devices connected in series according to an embodiment of the present disclosure; FIG. 4 is a circuit diagram showing a gate drive device according to a first modification of an embodiment of the present disclosure; FIG. 10 is a diagram illustrating a simulation result of the degree of imbalance in the first modification of the embodiment of the present disclosure when there are variations in characteristics of power semiconductor devices; FIG. 4 is a diagram illustrating the relationship between the temperature of a power semiconductor device, the gate-source voltage, and the drain current; FIG. 4 is a circuit diagram showing a gate drive device according to a second modification of an embodiment of the present disclosure;

A gate drive device and a power conversion device for a power semiconductor device will be described below with reference to the drawings. In each drawing, similar parts are provided with similar reference numerals. Also, to facilitate understanding, the scales of these drawings are appropriately changed. The illustrated forms are examples of implementations and are not limited to these forms.

A gate drive device according to each embodiment of the present disclosure turns on and off a plurality of power semiconductor devices connected in series. Examples of power semiconductor devices include MOSFETs, IGBTs, thyristors, GTOs, and transistors. A MOSFET has as its terminals a gate terminal, a drain terminal and a source terminal. An IGBT has as its terminals a gate terminal, an emitter terminal and a collector terminal. The transistor has as its terminals a base terminal, an emitter terminal and a collector terminal. Thyristors and GTOs have as their terminals a gate terminal, an anode terminal and a cathode terminal. As an example, a case where the power semiconductor element is composed of a MOSFET will be described below, but the embodiments of the present disclosure can also be applied to an IGBT, a thyristor, a GTO, or a transistor. Further, when the power semiconductor device is configured with an IGBT, the "drain" is read as the "collector", and the "source" is read as the "emitter", respectively, and each embodiment of the present disclosure is applied. Further, when the power semiconductor element is composed of a transistor, the "gate" is replaced with the "base", the "drain" is replaced with the "collector", and the "source" is replaced with the "emitter". Applies. again. When the power semiconductor element is composed of a thyristor or a GTO, the "gate" is replaced with the "base", the "drain" is replaced with the "anode", and the "source" is replaced with the "cathode", respectively. applies. The "output terminal of the power semiconductor element" corresponds to the "source terminal" of the MOSFET, the "emitter terminal" of the IGBT and transistor, and the "cathode terminal" of the thyristor and GTO.

FIG. 1 is a circuit diagram illustrating a gate driver according to one embodiment of the present disclosure. Hereinafter, the same reference numerals in different drawings denote components having the same function.

The gate drive device 1 according to an embodiment of the present disclosure turns on and off a plurality of power semiconductor devices connected in series. Here, as an example, two power semiconductor devices connected in series An example in which Q _A and Q _B are turned on and off will be described.

A diode D _A is connected in antiparallel to the power semiconductor element Q _A . Similarly, a diode D _B is connected in anti-parallel to the power semiconductor element Q _B .

The gate drive device 1 includes gate drive voltage variable sections 11 -A and 11 -B, gate lines 12 -A and 12 -B, and a magnetic coupling section 13 .

The gate drive voltage variable section 11-A is provided corresponding to the power semiconductor element _QA , and the gate drive voltage variable section 11-B is provided corresponding to the power semiconductor element _QB . One or both of the gate drive voltage variable sections 11-A and 11-B outputs a variable gate drive voltage according to the difference in electrical characteristics between the power semiconductor devices, especially the difference in gate threshold voltage. . Details of the gate drive voltage variable section 11-A and the gate drive voltage variable section 11-B will be described later.

The gate line 12-A supplies the gate drive voltage output from the gate drive voltage variable section 11-A to the corresponding gate terminal of the power semiconductor element Q _A . The gate line 12-B supplies the gate drive voltage output from the gate drive voltage variable section 11-B to the corresponding gate terminal of the power semiconductor element Q _B .

The magnetic coupling portion 13 magnetically couples the gate line 12-A and the gate line 12-B. FIG. 3 is a diagram illustrating a magnetic coupling part in a gate drive according to one embodiment of the present disclosure; The magnetic coupling portion 13 has a magnetic body 30 . The gate lines 12-A and 12-B are wound around the magnetic material 30. FIG. For example, when a gate current Ig ₁ flows as shown in FIG. 3, a magnetic flux Φ1 is generated in the magnetic body 30 and crosses the gate line 12-B. Similarly, when gate current Ig ₂ flows, magnetic flux Φ2 is generated in magnetic material 30 and crosses gate line 12-A. As a result, the gate line 12-A and the gate line 12-B are magnetically coupled. When gate current Ig ₁ and gate current Ig _{2 are} equal, |Φ1 _| = |Φ2| so that Φ1 and Φ2 have opposite polarities when the gate currents _Ig1 and _Ig2 have opposite polarities.

For example, when the power semiconductor element Q _A and the power semiconductor element Q _B are turned off at different timings and the power semiconductor element Q _A turns off before the power semiconductor element Q _B , the gate current Ig ₁ flows before the gate current Ig ₂ , the magnetic flux Φ1 and the magnetic flux Φ2 are not equal to each other. Therefore, a magnetic flux |Φ1−Φ2| At this time, an inductance L ₁ is generated in the gate line 12-A and an inductance L ₂ is generated in the gate line 12-B, and these inductances L ₁ and L ₂ are proportional to |Φ1−Φ2|. The larger the imbalance between the gate currents _Ig1 and _Ig2 , the larger the inductances _L1 and _L2 . Also, as the inductances L ₁ and L ₂ increase, the impedance of the gate lines 12-A and 12-B increases, making it difficult for the gate currents Ig ₁ and Ig ₂ to flow. As a result, the impedance of the gate lines ₁₂ -A and 12-B changes according to the imbalance between the gate currents Ig1 and _Ig2 , and the gate currents _Ig1 and _Ig2 are matched. can be operated.

Next, details of the gate drive voltage variable section 11-A and the gate drive voltage variable section 11-B will be described.

One or both of the gate drive voltage variable sections 11-A and 11-B outputs a variable gate drive voltage.

The gate drive voltage variable section 11-A is connected in series to a positive potential output section 21P-A that outputs a positive potential VP _A of the gate drive voltage and a positive potential output section 21P-A. It has a negative potential output section 21N- _A that outputs a negative potential VNA, a positive switch 23P-A, and a negative switch 23N-A. In addition, the gate drive voltage variable section 11-B is connected in series to a positive potential output section 21P-B that outputs a positive potential VP _B of the gate drive voltage, and a positive potential output section 21P-B. It has a negative potential output section 21N-B that outputs a negative potential VN _B of voltage, a positive switch 23P-B, and a negative switch 23N-B.

The positive side switch 23P-A in the variable gate drive voltage section 11-A and the positive side switch 23P-B in the variable gate drive voltage section 11-B are synchronously turned on and off. The on/off timings of the side switches 23P-A and 23P-B match. Similarly, the negative side switch 23N-A in the variable gate drive voltage section 11-A and the negative side switch 23N-B in the variable gate drive voltage section 11-B perform ON and OFF operations synchronously. That is, the on/off timings are the same between the negative side switches 23N-A and 23N-B. In one embodiment of the present disclosure, gate drive voltage variable section 11-A and gate drive voltage variable section 11-B each generate a variable gate drive voltage as described below, and then positive side switch 23P-A , 23P-B and the negative side switches 23N-A and 23N-B are turned on and off to control the voltage applied to the gate terminals of the power semiconductor elements Q _A and Q _B .

In the gate _drive voltage variable section 11-A, the potential difference "VP _{A -} VN _A '' is kept constant, the potential VR _A at the intermediate terminal 22-A, which is the connection point between the positive potential output section 21P-A and the negative potential output section 21N-A, and the gate The potential _VQA at the source terminal, which is the output terminal of the power semiconductor element _QA corresponding to the drive voltage variable section 11-A, is controlled to be the same potential. For example, by connecting the intermediate terminal 22-A and the source terminal of the power semiconductor element Q _A , VR _A =VQ _A is realized, and then the positive potential VP _A output by the positive potential output section 21P-A is applied. and the negative potential VN _A output by the negative potential output section 21N-A is kept constant, the positive potential _VP output by the positive potential output section 21P- _A is kept constant. and the potential VR _A at the intermediate terminal 22 _{-A, and the potential difference between the potential VR A at the intermediate} terminal 22-A and the negative potential VNA output from the negative potential output section 21N- _A. One or both of the potential difference "VR _A -VN _A " is made variable.

In the gate drive voltage variable section 11-B, the potential difference between the positive potential VP B output from the positive potential output section 21P-B and the negative potential VN _B output from the negative potential output section 21N- _B is "VP _B - VN _B '' is kept constant, the potential VR _B at the intermediate terminal 22-B, which is the connection point between the positive potential output section 21P-B and the negative potential output section 21N-B, and the gate The potential _VQB at the source terminal, which is the output terminal of the power semiconductor element _QB corresponding to the driving voltage variable section 11-B, is controlled to be the same potential. For example, by connecting the intermediate terminal 22-B and the source terminal of the power semiconductor element Q _B to achieve VR _B =VQ B, the positive potential VP _B output by the positive potential output section 21P- _B and the negative potential VN _B output by the negative potential output section 21N-B is kept constant, while the positive potential _VP output by the positive potential output section 21P- _B is kept constant. and the potential VR _B at the intermediate terminal 22-B, and the potential difference between the potential _{VR B} at the intermediate terminal 22-B and the negative potential VN _B output from the negative potential output section 21N- _{B .} One or both of the potential difference "VR _B -VN _B " is made variable.

Further, for example, when the power semiconductor device Q _A has a first gate threshold voltage V _thA and the power semiconductor device Q _B has a second gate threshold voltage V _thB higher than the first gate threshold voltage (that is, when V _thA <V _thB ) is the positive side of the gate drive voltage output from the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the first gate threshold voltage V _thA Each of the potential VPA _{and the} negative potential _VNA is the positive side of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the power semiconductor element _QB having the second gate drive voltage VthB. It should be lower than each of the potential VP _B and the negative potential VN _B .

More specifically, when V _thA <V _thB , for example, the positive potential output section _21P -A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA is Gate drive lower than the positive potential VP _B of the gate drive voltage output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB The negative potential output section 21N- _A of the gate drive voltage variable section 11-A outputs the positive potential VPA of the voltage, and the gate drive voltage corresponding to the power semiconductor element _QB having the gate threshold voltage _VthB . It outputs a negative potential VN _A of a gate drive voltage lower than the negative potential VN _B of the gate drive voltage output by the negative potential output section 21N-B of the voltage variable section 11-B. Here, the positive potential VP _B output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the intermediate terminal 22-B The potential difference “VP _B −VR _{B ”} between the potential VR B and the potential VR B at V _thA is determined by the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA . The potential difference between the output positive potential VP _A and the potential at the intermediate terminal 22-A is set to be larger than "VP _A -VR _A ". Further/or alternatively, the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the negative side of the gate drive voltage variable section 11-B The potential difference “VR _B −VN _B ” from the negative potential VN _B output by the potential output section 21N-B is the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA . becomes smaller than the potential difference “VR _A −VN _{A ”} between the potential VR _A at the intermediate terminal 22-A of the gate drive voltage variable section 11-A and the negative potential VNA output from the negative potential output section 21N-A of the gate drive voltage variable section 11-A. make it

Further, for example, when the power semiconductor device Q _A has a first gate threshold voltage V _thA and the power semiconductor device Q _B has a third gate threshold voltage V _thB lower than the first gate threshold voltage (that is, when V _thA >V _thB ), the positive side of the gate drive voltage output from the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the first gate threshold voltage V _thA Each of the potential VPA _and the negative _{potential VNA} is the positive side of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the power semiconductor element _QB having the third gate drive voltage VthB. It should be higher than each of the potential VP _B and the negative potential VN _B .

That is, when V _thA >V _thB , for example, the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA has a gate threshold voltage of V thA . A gate drive voltage higher than the positive potential _VPB of the gate drive voltage output by the positive potential output section 21P-B of the gate drive _voltage variable section 11-B corresponding to the power semiconductor element _QB having the voltage VthB. The negative potential output section 21N-A of the gate drive voltage variable section 11-A, which outputs the positive potential VP _A , outputs a variable gate drive voltage corresponding to the power semiconductor element _QB having the gate threshold voltage _VthB . It outputs the negative potential VNA of _the gate drive voltage higher than the negative potential VN _B of the gate drive voltage output by the negative potential output section 21N-B of the section 11-B. Here, the positive potential VP _B output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the intermediate terminal 22-B The potential difference “VP _B −VR _{B ”} between the potential VR B and the potential VR B at V _thA is determined by the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA . The potential difference between the output positive potential VP _A and the potential VR _A at the intermediate terminal 22-A is set to be smaller than "VP _A -VR _A ". Further/or alternatively, the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the negative side of the gate drive voltage variable section 11-B The potential difference “VR _B −VN _B ” from the negative potential VN _B output by the potential output section 21N-B is the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA . becomes larger than the potential difference “VR _A −VN _{A ”} between the potential VR _A at the intermediate terminal 22-A of the gate drive voltage variable section 11-A and the negative potential VNA output from the negative potential output section 21N-A of the gate drive voltage variable section 11-A. make it

Thus, one or both of the gate drive voltage variable sections 11-A and 11-B output variable gate drive voltages. When both the gate drive voltage variable sections 11-A and 11-B output variable gate drive voltages, the width of the voltage to be changed can be reduced, and the positive side of the gate drive voltage of the power semiconductor element can be reduced. Since the absolute values of the potential and the negative potential are small, there is an advantage that the load on the power semiconductor element can be reduced.

FIG. 2 is a circuit diagram showing a modification of the gate drive voltage variable section in the gate drive device according to the embodiment of the present disclosure. In FIG. 2, illustration of the power semiconductor elements _QA and _QB is omitted.

The gate drive voltage variable section 11-A has a plurality of DC power supplies 21-A connected in series and a changeover switch 26-A. Intermediate taps are provided between the respective DC power supplies, and the changeover switch 26-A is connected to one of the intermediate taps to change the positive potential VP _A and the potential VRA of the changeover switch 26- _A (Fig. 1 _{) ,} and _the potential _{difference "} VR _{A -VNA} ” changes.

Similarly, the gate drive voltage variable section 11-B has a plurality of DC power supplies 21-B connected in series and a changeover switch 26-B. An intermediate tap is provided between each DC power supply, and the changeover switch 26-B is connected to one of the intermediate taps so that the positive potential VP _B and the potential VR _B of the changeover switch 26-B (Fig. 1), and the potential difference "VR _B -VN _B " between the potential VR _{B of} the changeover switch ₂₆ - _B and the negative potential VN _B ” changes.

Thus, the gate drive voltage variable sections 11-A and ₁₁ -B shown in FIG. 2 can also output potentials VP _A , VR _B , VN _A , VP B , VR _B and VN _B similar to those in FIG. can be done. Relations between gate threshold voltages V _thA and V _thB and potential differences “VP _A −VR _A ”, “VR _A −VN _A ”, “VP _B −VR _B ” and “VR _B −VN _B ”, power semiconductors _{The relationship between the potentials VQA and VQB and the potentials VRA} and _VRB at the source terminals of the elements QA and QB is similar to that described with reference to FIG.

The above-described gate drive device 1 can turn on and off the power semiconductor devices even in a power conversion device configured by connecting in series a plurality of arms provided with a plurality of power semiconductor devices connected in series. can be done.

FIG. 4 is a diagram illustrating a power converter with a gate drive according to one embodiment of the present disclosure. Moreover, FIG. 5 is a circuit diagram showing an arm provided in the power converter shown in FIG. Here, as an example, an example in which the arm 50 is composed of two power semiconductor devices _QA and _QB connected in series will be described.

A power conversion device 100 according to an embodiment of the present disclosure has an arm 50 provided with the above-described gate drive device 1 and a plurality of power semiconductor elements connected in series, and performs on/off operation of the power semiconductor elements. and a power conversion control unit 3 for controlling the power conversion operation of the power conversion circuit unit 2 .

As shown in FIG. 5, the arm 50 is composed of, for example, two power semiconductor elements _QA and _QB connected in series. _A terminal _P1 is led out from the drain terminal of the power semiconductor element QA, and a terminal _P2 is led out from the source terminal of the power semiconductor element _QB . In the power conversion circuit unit 2, the terminal _P2 of one arm 50 is connected to the terminal _P1 of the other arm 50, and the connection point is connected to one terminal of the load. In the example shown in FIG. 4 , two arms 50 are connected in series to form one leg 60 , and the two legs 60 form the power conversion circuit unit 2 .

A DC power supply 200 is connected to a leg 60 composed of arms 50 connected in series. Also, between terminal T ₁ between the series-connected arms 50 in leg 60 and terminal T ₂ between the series-connected arms 50 in the other leg 60 , load 300 is connected.

A gate driving device 1 is provided corresponding to the arm 50 . The power semiconductor element Q _A and the power semiconductor element Q _B in each arm 50 are turned on and off by the corresponding gate driving device 1 . That is, the gate drive voltage variable section 11-A and the gate drive voltage variable section 11-B respectively generate variable gate drive voltages as described above, and then each of the positive side switches 23P-A and 23P-B and each of the negative side switches 23P-A and 23P-B. By turning on and off the side switches 23N-A and 23N-B, the voltage applied to the gate terminals of the power semiconductor elements Q _A and Q _B is controlled.

The power conversion control unit 3 controls the on-operation and off-operation of each positive side switch 23P-A and 23P-B and each negative side switch 23N-A and 23N-B in each gate drive device 1. FIG. That is, the power conversion control unit 3 controls the ON and OFF operations of the positive side switches 23P-A and 23P-B and the negative side switches 23N-A and 23N-B in each gate drive device 1. , controls the voltage applied to the gate terminals of the power semiconductor devices _QA and _QB , thereby turning the power semiconductor devices _QA and _QB on and off. As a result, the power conversion circuit unit 2 converts the DC power supplied from the DC power supply 200 into desired power and supplies the power to the load 300 . For example, the power conversion control unit 3 controls each positive terminal in each gate drive device 1 so that the deviation between the detected value i of the current flowing from the positive terminal T ₁ to the load 300 and the current command i ^* , which is the control target value, is eliminated. It generates gate command signals for controlling the ON and OFF operations of the side switches 23P-A and 23P-B and each of the negative side switches 23N-A and 23N-B.

An arithmetic processing unit (processor) is provided in the power converter 100 . This arithmetic processing unit has a power conversion control unit 3 . The power conversion control part 3 which an arithmetic processing unit has is a functional module implement|achieved by the computer program run on a processor, for example. For example, when constructing the power conversion control unit 3 in the form of a computer program, the function can be realized by operating the arithmetic processing unit according to the computer program. A computer program for executing the processing of the power conversion control unit 3 may be provided in a form recorded in a computer-readable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. Alternatively, the power conversion control unit 3 may be implemented as a semiconductor integrated circuit in which a computer program that implements the function is written.

Next, the imbalance of the gate voltages during the on-operation and the off-operation when the two power semiconductor elements Q _A and Q _B have different characteristics will be described.

FIG. 6 is a diagram explaining the definition of the gate voltage imbalance when the characteristics of the two power semiconductor devices are different, and (A) shows the definition of the gate voltage imbalance during the off operation. , (B) shows the definition of the gate voltage imbalance during the ON operation. As an example, if the power semiconductor device Q _A has a first gate threshold voltage V _thA and the power semiconductor device Q _B has a second gate threshold voltage V _thB higher than the first gate threshold voltage ( That is, the case where V _thA <V _thB ) will be described.

As shown in FIG. 6A, as a phenomenon when the power semiconductor elements _QA and _QB are turned off, power is generated when the gate potential of the power semiconductor element _QA is changed from a positive potential to a negative potential. When the drain-source voltage of the power semiconductor element Q _A changes from 0 [V] to Vds _A [V], and the gate potential of the power semiconductor element Q _B is changed from a positive potential to a negative potential, the power Assume that the drain-source voltage of the semiconductor element Q _B changes from 0 [V] to Vds _B [V]. At this time, ΔVds _off [%], which is the imbalance of the gate voltages during the OFF operation, is defined as shown in Equation (1).

Further, as shown in FIG. 6(B), the drain-source voltage when the power semiconductor elements Q _A and Q _B are in the OFF state when the gate potentials of the power semiconductor elements Q _A and Q _B are negative. is the average value of Vds _ave [V], and the gate potential of the power semiconductor elements Q _A and Q _B is changed from a negative potential to a positive potential, and the power semiconductor elements Q _A and Q _B are turned on. When Vp [V] is the difference between the maximum rising voltage, which is the jump of the drain-source voltage of either power semiconductor element, and Vds _ave [V], the degree of gate voltage imbalance during ON operation is ΔVds _on [%] is defined as in Equation 2.

FIG. 7 exemplifies a simulation result of imbalance with and without magnetic coupling of gate lines in Patent Document 1 (Japanese Patent No. 4396036) when there is variation in the characteristics of power semiconductor elements. It is a diagram.

As shown in FIG. 7, according to the invention described in Patent Document 1, when the characteristics of the power semiconductor elements Q _A and Q _B are different (V _thA <V _thB ), the magnetic coupling of the gate lines The degree of imbalance is high in both cases, and even if there is magnetic coupling of the gate lines, the power semiconductor element Q _A and the power semiconductor element Q _B have the effect of aligning the timing of the ON operation and the timing of the OFF operation. is small.

FIG. 8 is a diagram exemplifying a simulation result regarding the degree of imbalance in one embodiment of the present disclosure when there are variations in the characteristics of power semiconductor devices.

Suppose that 3.3 kV withstand voltage SiC-MOSFET power semiconductor devices Q _A and Q _B (V _thA <V _thB ) having different characteristics are connected in series and a current of 750 A flows when a voltage of 3.6 kV is applied. , the simulation was performed assuming that there is no delay in each gate signal. Further, in this simulation, the difference between the positive potential VP _A and the negative potential VN _A output from the gate drive voltage variable section 11-A, ie, VP _A −VN _A , was kept constant at 28 V, and the gate drive voltage variable section 11-A -B, _the difference between the positive potential VP _B and the negative potential VN _B is fixed at 28 V, and the positive potential _{VP B output} from the variable gate drive voltage section 11-B is 17V is constant, and the negative potential VN _B is constant at -11V. Under these conditions, the positive side potential VP _A /negative side potential _VNA in the gate drive voltage variable section 11-A are set to "17 V/-11 V", "16.75 V/-11.25 V", "16. 5 V/−11.5 V”, “16.25 V/−11.75 V”, etc., the imbalance between ON and OFF as shown in FIG. 8 was obtained. From FIG. 8, if the positive side voltage VP _A /negative side voltage VN _A of the power semiconductor element Q _A is set between 16.5 V/−11.5 V and 16.25 V/−11.75 V, and off-time imbalance can be reduced.

As described above, an example in which two power semiconductor devices connected in series are turned on and off has been described. can be turned on and off.

FIG. 9 is a circuit diagram showing a gate driving device for turning on and off three power semiconductor devices connected in series according to an embodiment of the present disclosure. As an example, an example in which three power semiconductor devices Q _A , Q _B and Q _C connected in series are turned on and off will be described.

A diode D _A is connected in antiparallel to the power semiconductor element Q _A . Similarly, a diode D _B is connected in anti-parallel to the power semiconductor element Q _B , and a diode D _C is connected in anti-parallel to the power semiconductor element Q _C .

The gate drive device 1 includes gate drive voltage variable sections 11-A, 11-B and 11-C, gate lines 12-A, 12-B and 12-C, and a magnetic coupling section 13. FIG.

The gate drive voltage variable section 11-A is provided corresponding to the power semiconductor element Q _A , the gate drive voltage variable section 11-B is provided corresponding to the power semiconductor element Q _B , and the gate drive voltage variable section 11 -C is provided corresponding to the power semiconductor element Q _C . Some or all of the gate drive voltage variable sections 11-A, 11-B and 11-C respectively output variable gate drive voltages.

The gate drive voltage variable section 11-A is connected in series to a positive potential output section 21P-A that outputs a positive potential VP _A of the gate drive voltage and a positive potential output section 21P-A. It has a negative potential output section 21N- _A that outputs a negative potential VNA, a positive switch 23P-A, and a negative switch 23N-A. In addition, the gate drive voltage variable section 11-B is connected in series to a positive potential output section 21P-B that outputs a positive potential VP _B of the gate drive voltage, and a positive potential output section 21P-B. It has a negative potential output section 21N-B that outputs a negative potential VN _B of voltage, a positive switch 23P-B, and a negative switch 23N-B. The gate drive voltage variable section 11-C is connected in series to a positive potential output section 21P- _C that outputs a positive potential VPC of the gate drive voltage and a positive potential output section 21P-C to drive the gate. It has a negative side potential output section 21N-C that outputs a negative side potential VN _C of voltage, a positive side switch 23P-C, and a negative side switch 23N-C.

Positive side switch 23P-A in gate drive voltage variable section 11-A, positive side switch 23P-B in gate drive voltage variable section 11-B, and positive side switch 23P-C in gate drive voltage variable section 11-C means that the ON and OFF operations are synchronously performed, that is, the ON/OFF timings of the positive side switches 23P-A, 23P-B and 23P-C match. Similarly, the negative side switch 23N-A in the gate drive voltage variable section 11-A, the negative side switch 23N-B in the gate drive voltage variable section 11-B, and the negative side switch in the gate drive voltage variable section 11-C 23N-C perform ON and OFF operations synchronously with each other, that is, the ON/OFF timings of these negative side switches 23N-A, 23N-B and 23N-C are the same. In one embodiment of the present disclosure, gate drive voltage variable section 11-A, gate drive voltage variable section 11-B, and gate drive voltage variable section 11-C each generate variable gate drive voltages as described below. Then, the power semiconductor devices Q _A and Q It controls the voltage applied to the gate terminals of _B and _QC .

In the gate drive voltage _variable section 11-A, the potential difference "VP _{A -} VN _A '' is kept constant, the potential VR _A at the intermediate terminal 22-A, which is the connection point between the positive potential output section 21P-A and the negative potential output section 21N-A, and the gate The potential _VQA at the source terminal, which is the output terminal of the power semiconductor element _QA corresponding to the drive voltage variable section 11-A, is controlled to be the same potential. For example, by connecting the intermediate terminal 22-A and the source terminal of the power semiconductor element Q _A , VR _A =VQ _A is realized, and then the positive potential VP _A output by the positive potential output section 21P-A is applied. and the negative potential VN _A output by the negative potential output section 21N-A is kept constant, the positive potential _VP output by the positive potential output section 21P- _A is kept constant. and the potential VR _A at the intermediate terminal 22 _{-A, and the potential difference between the potential VR A at the intermediate} terminal 22-A and the negative potential VNA output from the negative potential output section 21N- _A. One or both of the potential difference "VR _A -VN _A " is made variable.

In the gate drive voltage variable section 11-B, the potential difference between the positive potential VP B output from the positive potential output section 21P-B and the negative potential VN _B output from the negative potential output section 21N- _B is "VP _B - VN _B '' is kept constant, the potential VR _B at the intermediate terminal 22-B, which is the connection point between the positive potential output section 21P-B and the negative potential output section 21N-B, and the gate The potential _VQB at the source terminal, which is the output terminal of the power semiconductor element _QB corresponding to the driving voltage variable section 11-B, is controlled to be the same potential. For example, by connecting the intermediate terminal 22-B and the source terminal of the power semiconductor element Q _B to achieve VR _B =VQ B, the positive potential VP _B output by the positive potential output section 21P- _B and the negative potential VN _B output by the negative potential output section 21N-B is kept constant, while the positive potential _VP output by the positive potential output section 21P- _B is kept constant. and the potential VR _B at the intermediate terminal 22-B, and the potential difference between the potential _{VR B} at the intermediate terminal 22-B and the negative potential VN _B output from the negative potential output section 21N- _{B .} One or both of the potential difference "VR _B -VN _B " is made variable.

In the gate drive voltage _variable section 11-C, the potential difference "VP _{C -} VN _C '' is controlled to be constant, the potential VR _C at the intermediate terminal 22-C, which is the connection point between the positive potential output section 21P-C and the negative potential output section 21N-C, and the gate The potential VQ _C at the source terminal, which is the output terminal of the power semiconductor element Q _C corresponding to the drive voltage variable section 11-C, is controlled to be the same potential. For example, by connecting the intermediate terminal 22-C and the source terminal of the power semiconductor element Q _C to achieve VR _C =VQ C, the positive potential VP _C output by the positive potential output section 21P- _C and the negative potential VN _C output by the negative potential output section 21N-C is kept constant, while the positive potential _VP output by the positive potential output section 21P- _C is kept constant. and the potential VR _C at the intermediate terminal 22-C _{, and the potential difference between the potential VR C at the intermediate} terminal 22-C and the negative potential VNC output from the negative potential output section 21N- _C . One or both of the potential difference "VR _C -VN _C " is made variable.

Further, for example, the gate threshold voltage V _{thA of} the power semiconductor element Q _A , the gate threshold voltage V thB of the power semiconductor element Q _B , and the gate threshold voltage V _thC of the power semiconductor element Q _C are V _thA <V _thB < When there is a magnitude relationship of V _thC , the positive potential VPA and the negative potential _VPA of the gate drive voltage output from the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA Each of the potentials VN _A is the positive potential VP _B and the negative potential VN _B of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate drive voltage V _thB . lower than each of the Further/or, each of the positive side potential VP _B and the negative side potential VN _B of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB is , lower than each of the positive potential _VPC and the negative potential _VNC of the gate drive voltage output from the gate _drive voltage variable section 11-C corresponding to the power semiconductor element _QC having the gate drive voltage VthC. make it

More specifically, when V _thA <V _thB <V _thC , the positive potential output section _21P -A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA is , the gate lower than the positive potential VP _B of the gate drive voltage output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB The negative potential output section 21N-A of the gate drive voltage variable section 11-A outputs the positive potential VP _A of the drive voltage, and the gate corresponding to the power semiconductor element _QB having the gate threshold voltage _VthB . It outputs the negative potential VNA of the gate _drive voltage lower than the negative potential VN _B of the gate drive voltage output by the negative potential output section 21N-B of the drive voltage variable section 11-B. Here, the positive potential VP _B output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the intermediate terminal 22-B The potential difference “VP _B −VR _{B ”} between the potential VR B and the potential VR B at V _thA is determined by the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA . The potential difference between the output positive potential VP _A and the potential at the intermediate terminal 22-A is set to be larger than "VP _A -VR _A ". Further/or alternatively, the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the negative side of the gate drive voltage variable section 11-B The potential difference “VR _B −VN _B ” from the negative potential VN _B output by the potential output section 21N-B is the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA . becomes smaller than the potential difference “VR _A −VN _{A ”} between the potential VR _A at the intermediate terminal 22-A of the gate drive voltage variable section 11-A and the negative potential VNA output from the negative potential output section 21N-A of the gate drive voltage variable section 11-A. make it

Similarly, when V _thA <V _thB <V _thC , the positive potential output section _21P -B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V thB is Gate drive lower than the positive potential VPC of the gate drive voltage output by the positive potential output section 21P-C of the gate drive voltage variable section 11-C corresponding to _the power semiconductor element _QC having the gate threshold voltage V _thC The negative potential output section 21N-B of the gate drive voltage variable section 11-B outputs the positive potential VP _B of the voltage, and the gate drive voltage corresponding to the power semiconductor element Q _C having the gate threshold voltage V _thC It outputs the negative potential VN _B of the gate drive voltage lower than the negative potential VN _C of the gate drive voltage output by the negative potential output section 21N-C of the voltage variable section 11-C. Here, the positive side potential VP _C output by the positive side potential output section 21P-C of the gate drive voltage variable section 11-C corresponding to the power semiconductor element Q _C having the gate threshold voltage V _thC and the intermediate terminal 22-C The potential difference “VP _C −VR _C ” between the potential VR _C and the potential VR C at V _thB is determined by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V thB . The potential difference between the output positive potential VP _B and the potential at the intermediate terminal 22-B is set to be larger than "VP _B -VR _B ". Further/or alternatively, the potential VR _C at the intermediate terminal 22-C of the gate drive voltage variable section 11-C corresponding to the power semiconductor element Q _C having the gate threshold voltage V _thC and the negative side of the gate drive voltage variable section 11-C The potential difference “VR _C −VNC _” from the negative potential VN _C output by the potential output section 21N-C is the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB . becomes smaller than the potential difference “VR _B −VN _B ” between the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable part 11-B and the negative potential VN _B output by the negative potential output part 21N-B of the gate drive voltage variable part 11-B. make it

Further, for example, the gate threshold voltage V _thA of the power semiconductor element Q _A , the gate threshold voltage V _thB of the power semiconductor element Q _B , and the gate threshold voltage V _thC of the power semiconductor element Q _C satisfy V _thA >V _thB > When there is a magnitude relationship of V _thC , the positive potential VPA and the negative potential _VPA of the gate drive voltage output from the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA Each of the potentials VN _A is the positive potential VP _B and the negative potential VN _B of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate drive voltage V _thB . to be higher than each of the Further/or, each of the positive side potential VP _B and the negative side potential VN _B of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB is , higher than each of the positive potential _{VPC and} the negative potential VNC of the gate drive voltage output from the gate drive voltage variable section 11-C corresponding to the power semiconductor element _QC having the gate drive voltage _VthC . make it

That is, when V _thA >V _thB >V _thC , for example, the positive potential output section _21P -A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA is , a gate higher than the positive potential VP _B of the gate drive voltage output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB The negative potential output section 21N-A of the gate drive voltage variable section 11-A outputs the positive potential VP _A of the drive voltage, and the gate corresponding to the power semiconductor element _QB having the gate threshold voltage _VthB . It outputs the negative potential VN A of the gate drive voltage _higher than the negative potential VN _B of the gate drive voltage output by the negative potential output section 21N-B of the drive voltage variable section 11-B. Here, the positive potential VP _B output by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the intermediate terminal 22-B The potential difference “VP _B −VR _{B ”} between the potential VR B and the potential VR B at V _thA is determined by the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V thA . The potential difference between the output positive potential VP _A and the potential VR _A at the intermediate terminal 22-A is set to be smaller than "VP _A -VR _A ". Further/or alternatively, the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB and the negative side of the gate drive voltage variable section 11-B The potential difference “VR _B −VN _B ” from the negative potential VN _B output by the potential output section 21N-B is the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the gate threshold voltage V _thA . becomes larger than the potential difference “VR _A −VN _{A ”} between the potential VR _A at the intermediate terminal 22-A of the gate drive voltage variable section 11-A and the negative potential VNA output from the negative potential output section 21N-A of the gate drive voltage variable section 11-A. make it

Similarly, when V _thA >V _thB >V _thC , for example, the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB is higher than the positive potential _VPC of the gate drive voltage output by the positive potential output section 21P-C of the gate drive voltage variable section 11-C corresponding to the power semiconductor element _QC having the gate threshold voltage V _thC The negative potential output section 21N-B of the gate drive voltage variable section 11-B, which outputs the positive potential VP _B of the gate drive voltage, corresponds to the power semiconductor element Q _C having the gate threshold voltage V _thC . It outputs the negative potential _VNC of the gate drive voltage higher than the negative potential _VNC of the gate drive voltage output by the negative potential output section 21N-C of the gate drive voltage variable section 11-C. Here, the positive side potential VP C output by the positive side potential output section 21P-C _of the gate drive voltage variable section 11-C corresponding to the power semiconductor element Q _C having the gate threshold voltage V _thC and the intermediate terminal 22-C The potential difference “VP _C −VR _C ” between the potential VR _C and the potential VR C at V _thB is determined by the positive potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V thB . The potential difference between the output positive potential VP _B and the potential VR _B at the intermediate terminal 22-B is made smaller than "VP _B -VR _B ". Further/or alternatively, the potential VR _C at the intermediate terminal 22-C of the gate drive voltage variable section 11-C corresponding to the power semiconductor element Q _C having the gate threshold voltage V _thC and the negative side of the gate drive voltage variable section 11-C The potential difference “VR _C −VNC _” from the negative potential VN _C output by the potential output section 21N-C is the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the gate threshold voltage V _thB . becomes larger than the potential difference “VR _B −VN _B ” between the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable part 11-B and the negative potential VN _B output by the negative potential output part 21N-B of the gate drive voltage variable part 11-B. make it

The gate line 12-A supplies the gate drive voltage output from the gate drive voltage variable section 11-A to the corresponding gate terminal of the power semiconductor element Q _A . The gate line 12-B supplies the gate drive voltage output from the gate drive voltage variable section 11-B to the corresponding gate terminal of the power semiconductor element Q _B . The gate line 12-C supplies the gate drive voltage output from the gate drive voltage variable section 11-C to the corresponding gate terminal of the power semiconductor element Q _C .

The magnetic coupling portion 13 magnetically couples the gate lines 12-A and 12-B, and magnetically couples the gate lines 12-B and 12-C.

In this way, the gate drive device 1 according to an embodiment of the present disclosure is provided with the same number of gate drive voltage variable sections and gate lines as the number of power semiconductor devices connected in series. It has a configuration in which each of the gate lines is magnetically coupled to each other. According to an embodiment of the present disclosure, even if there are variations in the transmission time of the gate signal and the characteristics of the power semiconductor elements, the switching timings for the ON and OFF operations of each of the power semiconductor elements are aligned to suppress imbalance in the voltages applied to the power semiconductor devices.

Next, a first modification of the embodiment of the present disclosure will be described.

FIG. 10 is a circuit diagram showing a gate drive device according to a first modification of one embodiment of the present disclosure. As an example, an example in which two power semiconductor devices _QA and _QB connected in series are turned on and off will be described. A first modification is applicable. As an example, a case where the gate drive voltage variable sections 11-A and 11-B have the configuration shown in FIG. 2 will be described. The first modified example is applicable even when having the configuration.

As described with reference to FIGS. 4 and 5, in the power conversion circuit unit 2 configured by the arm 50 having a plurality of power semiconductor devices connected in series, the gate drive device 1 controls the power in the arm 50. can be turned on and off. Since the characteristics of the power semiconductor element change depending on the magnitude of the current flowing between the drain and the source, in the gate driving device 1 according to the first modification, the gate driving voltage is adjusted according to the current flowing between the drain and the source. Even if the positive side potential and the negative side potential are changed and the characteristics of each power semiconductor device are changed due to the magnitude of the current flowing between the drain and source, the ON operation and OFF operation of each power semiconductor device are aligned to suppress voltage imbalance applied to the power semiconductor devices.

The power conversion control unit 3 uses the value i of the current output from the power conversion circuit unit 2 or the current command generated by the power conversion control unit 3 to control the power conversion operation of the power conversion circuit unit 2 as information about the current. holds the value i ^* of Each of the gate drive voltage variable units 11-A and 11-B is set to the current value i output from the power conversion circuit unit 2 or the power conversion control unit 3 to control the power conversion operation of the power conversion circuit unit 2. The positive side potential and the negative side potential of the gate drive voltage are changed according to the value i ^* of the current command to be generated. Therefore, as shown in FIG. 10, the variable gate drive voltage section 11-A further includes a selector circuit 24-A, and the variable gate drive voltage section 11-B further includes a selector circuit 24-B.

An intermediate tap is provided between each of a plurality of DC power supplies 21-A connected in series, and each intermediate tap is connected to an intermediate terminal 22-A via a switch section composed of a MOSFET. On/off of the MOSFETs of each switch section is controlled by a selector circuit 24-A. The selector circuit 24-A selects the value i of the current output from the power conversion circuit unit 2 or the value i ^* of the current command generated by the power conversion control unit 3 to control the power conversion operation of the power conversion circuit unit 2. Accordingly, by turning on one of the plurality of MOSFETs, the potential difference “VP A −VR A ” between the positive potential VP _A and the potential VR _A of the intermediate terminal 22-A and the potential difference “VP _A −VR _A ” of the intermediate terminal 22-A The potential difference “VR _{A −VNA ”} between the potential VR _A and the negative potential VNA is changed.

Similarly, an intermediate tap is provided between each of a plurality of DC power supplies 21-B connected in series, and each intermediate tap is connected to an intermediate terminal 22-B via a switch section composed of a MOSFET. ing. The on/off of the MOSFET of each switch section is controlled by a selector circuit 24-B. The selector circuit 24-B selects the value i of the current output from the power conversion circuit unit 2 or the value i ^* of the current command generated by the power conversion control unit 3 to control the power conversion operation of the power conversion circuit unit 2. Accordingly, by turning on one of the plurality of MOSFETs, the potential difference “VP B −VR B ” between the positive potential VP _B and the potential VR _B of the intermediate terminal 22-B, and the potential difference “VP _B −VR _B ” of the intermediate terminal 22-B The potential difference “VR _B −VN _B ” between the potential VR _B and the negative potential VN _B is changed.

FIG. 11 is a diagram exemplifying a simulation result of the degree of imbalance in the first modification of the embodiment of the present disclosure when there are variations in the characteristics of power semiconductor devices.

SiC-MOSFET power semiconductor elements Q _A and Q _B (V _thA <V _thB ) with different characteristics and a withstand voltage of 3.3 kV are connected in series, and when a voltage of 3.6 kV is applied, the drain-source The simulation was performed by setting the flowing current to 750A, 500A, and 50A. In this simulation, it is assumed that there is no delay in each gate signal, and the difference "VP _{A -VNA "} between the positive potential VP _A and the negative potential VNA output from the gate drive voltage variable section 11-A is 28 V is kept constant, and the difference between the positive potential VP _B and _{the negative potential VN B output from} the gate drive voltage variable section 11-B is kept at 28 V, and the gate drive voltage variable section 11-B is kept constant at 28 V. The positive side potential VP _B output from is set at a constant 17V, and the negative side potential VN _B is set at -11V. Under these conditions, for currents 750 A, 500 A, and 50 A flowing between the drain and source, the positive potential VP _A /negative potential VN _A output from the gate drive voltage variable section 11-A is set to "17 V. /-11V", "16.75V/-11.25V", "16.5V/-11.5V", and "16.25V/-11.75V". On and off imbalances were obtained as shown. From FIG. 11, when the current flowing between the drain and the source is 750 A, the positive potential _VPA /negative potential _VNA is between 16.5V/-11.5V and 16.25V/-11.25V. , when the current flowing between the drain and source is 300A, the current flowing between the drain and source is 50A when the positive potential VP _A /negative potential _VNA is 16.5V/−11.5V. In this case, when the positive side potential VP _A /negative side potential VN _A is "17 V/−11 V", it can be seen that the off imbalance degree ΔVds _off can be reduced.

Next, a second modification of the embodiment of the present disclosure will be described.

FIG. 12 is a diagram illustrating the relationship between the temperature of the power semiconductor device, the gate-source voltage, and the drain current.

The temperature of the power semiconductor element rises due to self-heating during on/off operation. Therefore, for example, due to design restrictions and arrangement positions of the power semiconductor elements, a temperature difference may occur between the power semiconductor elements in the power converter. FIG. 12 shows, as an example, the relationship between the gate-source voltage Vgs [V] and the drain current Id [A] when the temperature of the power semiconductor element made of SiC-MOSFET is 25° C. and 175° C. . From FIG. 12, it can be seen that the gate threshold voltage decreases as the temperature of the power semiconductor device increases. As described above, the gate threshold voltage varies due to the temperature difference of the power semiconductor element, so that the imbalance of the applied voltage during the ON operation and the OFF operation becomes large. Therefore, in the second example of one embodiment of the present disclosure, the positive potential and negative potential of the gate drive voltage are changed according to the temperature of the power semiconductor device, and the heat generation of each power semiconductor device causes the characteristic , the switching timings of the ON and OFF operations of the power semiconductor elements are aligned to suppress imbalance in the voltages applied to the power semiconductor elements.

FIG. 13 is a circuit diagram showing a gate drive device according to a second modification of one embodiment of the present disclosure. As an example, an example in which two power semiconductor devices _QA and _QB connected in series are turned on and off will be described. A second variant is applicable. As an example, a case where the gate drive voltage variable sections 11-A and 11-B have the configuration shown in FIG. 2 will be described. The second modified example is applicable even if there is a configuration.

The gate drive device 1 further includes temperature sensors 25-A and 25-B provided corresponding to the power semiconductor elements _QA and _QB , respectively. It is preferable that each of the temperature sensors 25-A and 25-B is installed at a portion of each of the power semiconductor elements Q _A and Q _B that generates the most heat. Each of the gate drive voltage variable sections 11-A and 11-B changes the positive and negative potentials of the gate drive voltage according to the temperature of the power semiconductor element detected by the corresponding temperature sensors 25-A and 25-B. change the side potential. Therefore, as shown in FIG. 13, the variable gate drive voltage section 11-A further includes a selector circuit 24-A, and the variable gate drive voltage section 11-B further includes a selector circuit 24-B.

An intermediate tap is provided between each of the plurality of DC power supplies 21-A connected in series, and each intermediate tap is connected to an intermediate terminal 22-A via a lead provided with a MOSFET. The on/off of the MOSFET on each conductor is controlled by a selector circuit 24-A. The selector circuit 24-A turns on one of the plurality of MOSFETs in accordance with the temperature of the power semiconductor element Q _A detected by the temperature sensor 25-A, so that the positive potential VP _A and the intermediate terminal 22-A potential VR _A , and the potential difference "VR _{A -VNA} " between the potential VRA _of the intermediate terminal ₂₂ - _A and the negative potential _VNA are changed.

Similarly, an intermediate tap is provided between each of a plurality of DC power supplies 21-B connected in series, and each intermediate tap is connected to an intermediate terminal 22-B via a conductor provided with a MOSFET. there is The on/off of the MOSFET on each conductor is controlled by a selector circuit 24-B. The selector circuit 24-B turns on one of the plurality of MOSFETs in accordance with the temperature of the power semiconductor element Q _B detected by the temperature sensor 25-B, so that the positive potential VP _B and the intermediate terminal 22-B, _and the potential difference "VR _B -VN _{B "} between the potential VR _{B of} the intermediate terminal 22-B and the negative potential VN _B are changed.

For example, the power semiconductor element Q A detected by the temperature sensor 25- _A is at a first temperature Temp _A , and the power semiconductor element Q _B detected by the temperature sensor 25-B is at a first temperature lower than the first temperature Temp _A. 2 temperature Temp _B (that is, when Temp _A >Temp _B ), the gate drive voltage corresponding to the power semiconductor element Q _A corresponding to the temperature sensor 25-A that detected the first temperature Temp _A Each of the positive side potential VP _A and the negative side potential VN _B of the gate drive voltage output from the variable section 11-A is applied to the power semiconductor element Q corresponding to the temperature sensor 25-B that detects the second temperature Temp _{B. B} is made lower than each of the positive potential VP _B and the negative potential VN _B of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to B.

More specifically, when Temp _A >Temp _B , for example, the positive potential output section 21P-A of the gate drive voltage variable section 11- _{A corresponding to the power semiconductor element Q A having} the temperature Temp A is set at the temperature Temp The positive side of the gate drive voltage lower than the positive side potential VP _B of the gate drive voltage output by the positive side potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having _B The negative side potential output section 21N-A of the gate drive voltage variable section 11-A, which outputs the potential VP _A , is the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the temperature Temp _B. outputs a negative potential VN _A of a gate drive voltage lower than the negative potential VN _B of the gate drive voltage output by the negative potential output section 21N-B. Here, the positive side potential VP B output by the positive side potential output section 21P-B _of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the temperature Temp _B and the potential at the intermediate terminal 22-B The potential difference “VP _B −VR _B ” with VR _B is the positive potential output from the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having temperature Temp _A. The potential difference between the potential VP _A and the potential at the intermediate terminal 22-A is set to be larger than the potential difference "VP _A -VR _A ". Further/or alternatively, the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the temperature Temp _B and the negative potential output of the gate drive voltage variable section 11-B The potential difference “VR _B −VN _B ” from the negative potential VN _B output by the section 21N-B is the intermediate terminal 22 of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the temperature Temp _{A. -A} and the negative potential VNA output from the negative potential output section 21N-A of the gate drive voltage variable section 11- _A is made smaller than the potential difference "VR _{A -VNA} ".

Further, for example, the power semiconductor element Q A detected by the temperature sensor 25- _A is at the first temperature Temp _A , and the power semiconductor element Q B detected by the temperature sensor 25- _B is higher than the first temperature Temp _A. When the third temperature Temp _B is high (that is, when Temp _A < Temp _B ), the gate corresponding to the power semiconductor element Q _A corresponding to the temperature sensor 25- _A that detected the first temperature Temp A Each of the positive side potential VP _A and the negative side potential VN _A of the gate drive voltage output from the drive voltage variable section 11-A is a power semiconductor corresponding to the temperature sensor 25-B that detects the third temperature Temp _B. It is made higher than each of the positive side potential VP _B and the negative side potential VN _B of the gate drive voltage output from the gate drive voltage variable section 11-B corresponding to the element Q _B .

More specifically, when Temp _A <Temp _B , for example, the positive potential output section 21P-A of the gate drive voltage variable section 11- _{A corresponding to the power semiconductor element Q A having} the temperature Temp A is set at the temperature Temp The positive side of the gate drive voltage higher than the positive side potential VP _B of the gate drive voltage output by the positive side potential output section 21P-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having _B The negative side potential output section 21N-A of the gate drive voltage variable section 11-A, which outputs the potential VP _A , is the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the temperature Temp _B. outputs _a negative potential VNA of the gate drive voltage higher than the negative potential VN _B of the gate drive voltage output by the negative potential output section 21N-B. Here, the positive side potential VP B output by the positive side potential output section 21P-B _of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the temperature Temp _B and the potential at the intermediate terminal 22-B The potential difference “VP _B −VR _B ” with VR _B is the positive potential output from the positive potential output section 21P-A of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having temperature Temp _A. It is made smaller than the potential difference "VP _A -VR _A " between the potential VP _A and the potential at the intermediate terminal 22-A. Further/or alternatively, the potential VR _B at the intermediate terminal 22-B of the gate drive voltage variable section 11-B corresponding to the power semiconductor element Q _B having the temperature Temp _B and the negative potential output of the gate drive voltage variable section 11-B The potential difference “VR _B −VN _B ” from the negative potential VN _B output by the section 21N-B is the intermediate terminal 22 of the gate drive voltage variable section 11-A corresponding to the power semiconductor element Q _A having the temperature Temp _{A. -A} and the negative potential VNA output from the negative potential output section 21N-A of the gate drive voltage variable section 11- _A is made larger than the potential difference "VR _{A -VNA} ".

In addition, the first modification and the second modification described above may be implemented in combination, and in this case, the value of the current output from the power conversion circuit unit 2 or the power conversion control unit 3 is the power conversion circuit The positive side potential and the negative side potential of the gate drive voltage are changed according to the value of the current command generated to control the power conversion operation of the unit 2 and the temperature of the power semiconductor element detected by the temperature sensor. Let

As described above, according to the embodiment and each of the modifications of the present disclosure, even if there are variations in the transmission time of the gate signal on the gate line and the characteristics of the power semiconductor elements, each power semiconductor element Switching timings for on-operation and off-operation can be aligned, and imbalance in the voltage applied to the power semiconductor device can be suppressed.

1 Gate drive device 2 Power conversion circuit unit 3 Power conversion control unit 11-A, 11-B, 11-C Gate drive voltage variable unit 12-A, 12-B, 12-C Gate line 13 Magnetic coupling unit 21-A , 21-B DC power supply 21P-A, 21P-B, 21P-C Positive side potential output section 21N-A, 21N-B, 21N-C Negative side potential output section 22-A, 22-B, 22-C Intermediate Terminal 23P-A, 23P-B, 23P-C Positive side switch 23N-A, 23N-B, 23N-C Negative side switch 24-A, 24-B Selector circuit 25-A, 25-B Temperature sensor 26-A , 26-B, 26-C Changeover switch 30 Magnetic material 50 Arm 60 Leg 100 Power converter 200 DC power supply 300 Load C Capacitor D _A , D _B , D _C Diode P ₁ , P ₂ Terminals Q _A , Q _B , Q _C power semiconductor device _T1 terminal _T2 terminal

Claims (14)

A gate drive device for a plurality of power semiconductor devices connected in series,
a gate drive voltage variable unit provided corresponding to the power semiconductor element and outputting a variable gate drive voltage;
a gate line for supplying the gate drive voltage output from the gate drive voltage variable section to each gate terminal of the corresponding power semiconductor element;
a magnetic coupling unit that magnetically couples each of the gate lines to each other;
A gate drive. 2. The gate driving device according to claim 1, wherein said gate driving voltage varying section varies the potential of said gate driving voltage to be output according to a difference in electrical characteristics between said power semiconductor elements. The gate drive voltage variable part corresponding to the power semiconductor device having a first gate threshold voltage corresponds to the power semiconductor device having a second gate threshold voltage higher than the first gate threshold voltage. 3. The gate drive device according to claim 2, wherein a positive potential and a negative potential of a gate drive voltage that are lower than each of the positive potential and the negative potential of the gate drive voltage output by a gate drive voltage variable unit are output. . Each of the gate drive voltage variable sections is connected in series to a positive potential output section that outputs a positive potential of the gate drive voltage and the positive potential output section, and outputs a negative potential of the gate drive voltage. and a negative potential output section for
In each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section, and the power semiconductor corresponding to the gate drive voltage variable section. and the potential at the output terminal of the element are the same potential,
A potential difference between the positive potential output by the gate driving voltage variable section corresponding to the power semiconductor element having the second gate threshold voltage and the potential at the intermediate terminal has the first gate threshold voltage. 4. The gate drive device according to claim 3, wherein the potential difference between said positive side potential output by said gate drive voltage variable section corresponding to said power semiconductor element and the potential at said intermediate terminal is larger. Each of the gate drive voltage variable sections is connected in series to a positive potential output section that outputs a positive potential of the gate drive voltage and the positive potential output section, and outputs a negative potential of the gate drive voltage. and a negative potential output section for
In each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section, and the power semiconductor corresponding to the gate drive voltage variable section. and the potential at the output terminal of the element are the same potential,
The potential difference between the potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having the second gate threshold voltage and the negative side potential output from the gate drive voltage variable section is The potential difference between the potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor device having a gate threshold voltage of 1 and the negative side potential output from the gate drive voltage variable section is smaller than the potential difference. 5. The gate drive device according to 3 or 4. The gate drive voltage variable section corresponding to the power semiconductor device having a first gate threshold voltage corresponds to the power semiconductor device having a third gate threshold voltage lower than the first gate threshold voltage. 4. A gate drive voltage variable unit outputs a positive potential and a negative potential of a gate drive voltage higher than each of the positive potential and the negative potential of the gate drive voltage output by the variable gate drive voltage unit. A gate drive device according to any one of claims 1 to 3. Each of the gate drive voltage variable sections is connected in series to a positive potential output section that outputs a positive potential of the gate drive voltage and the positive potential output section, and outputs a negative potential of the gate drive voltage. and a negative potential output section for
In each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section, and the power semiconductor corresponding to the gate drive voltage variable section. and the potential at the output terminal of the element are the same potential,
A potential difference between the positive potential output by the gate driving voltage variable section corresponding to the power semiconductor element having the third gate threshold voltage and the potential at the intermediate terminal has the first gate threshold voltage. 7. The gate drive device according to claim 6, wherein the potential difference between the positive potential output by the gate drive voltage variable section corresponding to the power semiconductor element and the potential at the intermediate terminal is smaller. Each of the gate drive voltage variable sections is connected in series to a positive potential output section that outputs a positive potential of the gate drive voltage and the positive potential output section, and outputs a negative potential of the gate drive voltage. and a negative potential output section for
In each of the gate drive voltage variable sections, a potential at an intermediate terminal that is a connection point between the positive side potential output section and the negative side potential output section, and the power semiconductor corresponding to the gate drive voltage variable section. and the potential at the output terminal of the element are the same potential,
The potential difference between the potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having the third gate threshold voltage and the negative side potential output from the gate drive voltage variable section is The potential difference between the potential at the intermediate terminal of the gate drive voltage variable section corresponding to the power semiconductor element having a gate threshold voltage of 1 and the negative side potential output from the gate drive voltage variable section is larger than the potential difference. 8. The gate drive device according to 6 or 7. further comprising a temperature sensor provided corresponding to each of the power semiconductor elements,
2. Each of said gate drive voltage varying sections changes the positive side potential and the negative side potential of said gate drive voltage according to the temperature of said power semiconductor element detected by said corresponding temperature sensor. 9. The gate drive device according to any one of 8. The gate drive voltage variable section corresponding to the power semiconductor element corresponding to the temperature sensor that detects the first temperature corresponds to the temperature sensor that detects a second temperature lower than the first temperature. outputting a positive potential and a negative potential of a gate drive voltage lower than each of the positive potential and the negative potential of the gate drive voltage output by the gate drive voltage variable section corresponding to the power semiconductor element; Item 10. The gate drive device according to item 9. The gate drive voltage variable section corresponding to the power semiconductor element corresponding to the temperature sensor that detects the first temperature corresponds to the temperature sensor that detects a third temperature higher than the first temperature. outputting a positive potential and a negative potential of the gate drive voltage higher than each of the positive potential and the negative potential of the gate drive voltage output by the gate drive voltage variable section corresponding to the power semiconductor element; Item 11. The gate drive device according to item 9 or 10. A gate driving device according to any one of claims 1 to 11;
a power conversion circuit unit having an arm provided with a plurality of the power semiconductor devices connected in series, and performing a power conversion operation according to the on/off operation of the power semiconductor devices;
A power conversion control unit that controls the power conversion operation of the power conversion circuit unit;
A power conversion device. 13. The power conversion according to claim 12, wherein each of said gate drive voltage variable units changes the positive side potential and negative side potential of said gate drive voltage according to the value of the current output from said power conversion circuit unit. Device. Each of the gate drive voltage variable sections has a positive side potential and a negative side potential of the gate drive voltage according to the value of the current command generated by the power conversion control section to control the power conversion operation of the power conversion circuit section. 13. The power converter according to claim 12, wherein the side potential is changed.

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