JP2006074937A - Gate drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit an excessive current from passing through an IGBT for the prevention of the destruction of the IGBT by detecting an accident such as a short circuit at a power conversion device or on the load side of the power conversion device. <P>SOLUTION: If a voltage applied to the IGBT 3 does not lower although a pulse is outputted from a pulse generation circuit 6, a short-circuit detection circuit 9 detects it so that a gate voltage of the IGBT 3 is clamped by a gate voltage clamp circuit 10. If the saturated current value of the IGBT 3 is small due to a variation in saturated current characteristics in each IGBT and a distributed voltage of the IGBT 3 increases, an over-voltage detection circuit 8 detects it to make the gate voltage clamp circuit 10 increase the gate voltage of the IGBT3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gate drive device for driving a power switching element.

  In recent years, MOS gate type power switching devices such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) that can increase capacity and speed have been developed, and power using these IGBTs and MOSFETs. Conversion devices have also become widely used.

  Such IGBTs and MOSFETs are non-latching power switching elements that do not self-continue in an on / off state, and have higher gate control characteristics than a latching power switching element such as a thyristor, for example, a collector of a power switching element, When a voltage is applied between the emitters and a pulse voltage is applied to the gate of the power switching element, the power switching element is turned on simply by turning on the power switching element and releasing the pulse voltage applied to the gate. It has a high gate control characteristic that it can be turned off.

  Furthermore, such IGBTs and MOSFETs control the gate voltage and the like during the switching transition period when the power switching element is turned on and off, thereby controlling the slope of the current output from the power switching element, the voltage slope, and the surge. Voltage, surge current, etc. can be suppressed.

  At this time, in many application circuits, the power switching element is controlled by using a so-called active gate drive technology that controls the power switching element by feeding back the output voltage and output current of the power switching element in the switching transition period to the gate. Etc. are controlled.

  Among them, in a power conversion device that performs high-voltage power conversion by connecting a large number of power switching elements in series, an off timing shift that occurs when each power switching element is turned off using only an active gate control technology. Since the voltage sharing of each power switching element can be made uniform by minimizing, compared to the conventional power converter, a circuit that divides the main current in parallel and equalizes the voltage sharing, such as a snubber circuit, etc. There is an advantage that the manufacturing cost can be reduced by that amount.

  FIG. 5 is a circuit diagram of a gate driving device used in the multi-series power conversion device disclosed in Patent Document 1 among gate driving devices using such an active gate driving technique.

  In the gate driving devices 100a to 100d shown in this figure, free-wheeling diodes 101a to 101d are connected in parallel to the collector and emitter, and the IGBTs 102a to 102d connected in series are the IGBTs to be controlled. A voltage source 103 that outputs a power supply voltage with an emitter potential set to a reference potential (ground potential); a pulse generator 104 that generates a pulse under a specified condition using the power supply voltage and ground voltage output from the voltage source 103; A voltage divider 107 configured by a high-voltage side voltage dividing resistor 105 and a low-voltage side voltage dividing resistor 106 connected in series, dividing a voltage between the collector and emitter of the IGBT to be controlled, and outputting a divided voltage; The voltage value output from the pulse generator 104 and the divided voltage output from the voltage divider 107 are compared, and based on this comparison result. The gate voltage of the IGBT to be controlled is increased each time a pulse is output from the pulse generator 104 while controlling the gate voltage of the IGBT to be controlled to prevent excessive voltage sharing. And a comparator 108 for turning it on.

  Then, for each of the gate driving devices 100a to 100d, while the pulses are output from the pulse generator 104 under the specified conditions, the comparators 108 turn on / off the IGBTs 102a to 102d to be controlled, The high voltage frequency conversion, voltage conversion, and the like are performed by an arm (an arm of a multi-series power conversion device) constituted by each IGBT 102a to 102d and an arm (not shown) paired with this arm.

  Further, if the saturation current characteristics of the IGBTs 102a to 102d vary, and any one of the IGBTs 102a to 102d constituting the arm, for example, the saturation current value of the IGBT 102a is small, the shared voltage of the IGBT 102a increases, and a predetermined voltage When the value is exceeded, the divided voltage output from the voltage dividing circuit 107 provided in the gate driving device 100a controlling the IGBT 102a increases, and the comparator 108 outputs the gate voltage corresponding to the divided voltage. Then, the saturation current value of the IGBT 102a is increased.

As a result, the voltage shared by the IGBT 102a is lowered, and the voltage shared by the IGBTs 102a to 102d is prevented from exceeding a certain voltage value.
JP 2003-69401 A

  By the way, in such conventional gate drive devices 100a to 100d, a short circuit accident or the like occurs in the arm constituted by the IGBTs 102a to 102d, or the arm paired with the arms, and the like of each IGBT 102a to 102d. When the applied voltage increases, the saturation current value of each of the IGBTs 102a to 102d is increased from several times to several tens of times the normal value by the voltage dividing circuit 107 and the comparison circuit 108, and each of these IGBTs 102a to 102d is within 10 microseconds. There was a problem that would be destroyed.

  For this reason, in such a multi-series power conversion device using a large number of IGBTs 102a to 102d, when a short-circuit accident occurs, this is detected within 10 microseconds, and a cutoff operation is performed to protect each IGBT 102a to 102d. There has been a strong demand for the development of a gate driving device that can do this.

  In view of the above circumstances, the present invention controls the saturation current value of the power switching element in accordance with the applied voltage of the power switching element, and prevents an excessive voltage from being applied to the power switching element, while short-circuiting. When an accident or the like occurs, the gate voltage of the power switching element is kept within the clamp voltage value, so that an excessive current does not flow through the power switching element, and the power switching element can be prevented from being destroyed. The main object is to provide a gate driving device.

  In order to achieve the above object, the present invention provides a gate driving device that controls the power switching element by controlling the gate voltage of the power switching element, wherein a pulse is applied to the gate of the power switching element. When the applied voltage of the power switching element does not decrease at this time, it is determined that a short circuit accident has occurred, and a short circuit detection circuit that generates a gate voltage clamp instruction signal and the power switching element are set in advance. When a voltage exceeding the voltage value is applied, it is determined that the power switching element is in an overvoltage state, and an overvoltage detection circuit that generates a saturation current increase instruction signal; and the gate voltage clamp instruction from the short circuit detection circuit When a signal is being output, the gate voltage of the power switching element is less than the clamp voltage value. To maintain the collector current of the power switching element within a specified current value, and when the saturation voltage increase instruction signal is output from the overvoltage detection circuit, the gate voltage of the power switching element is increased. And a gate voltage clamp circuit for lowering the voltage applied to the power switching element.

  According to the present invention, the saturation current value of the power switching element is controlled according to the applied voltage of the power switching element to prevent an excessive voltage from being applied to the power switching element, and a short circuit accident or the like can occur. When it occurs, the gate voltage of the power switching element can be held within the clamp voltage value so that an excessive current does not flow through the power switching element, and the power switching element can be prevented from being destroyed.

<First Embodiment>
FIG. 1 is a block diagram showing a first embodiment of a gate driving apparatus according to the present invention.

  The gate drive device 1a shown in this figure is connected in series to another IGBT that constitutes the arm of the power converter with respect to the collector and emitter, and the emitter potential of the IGBT 3 to which the freewheeling diode 2 is connected in parallel is used as a reference potential ( A positive-side gate drive voltage source 4 that outputs a positive-side power supply voltage set to a ground potential), a negative-side gate drive voltage source 5 that outputs a negative-side power supply voltage using the emitter potential of the IGBT 3 as a reference potential (ground potential); A pulse generation circuit 6 for generating a pulse under a specified condition using the positive power supply voltage output from the positive gate drive voltage source 4 and the negative power supply voltage output from the negative gate drive voltage source 5; A gate resistor 7 for guiding a pulse output from the generation circuit 6 to the gate of the IGBT 3, and a predetermined voltage in which a voltage between the collector and emitter (shared voltage) of the IGBT 3 is set in advance. Overvoltage detection circuit 8 that detects this and outputs a saturation current increase instruction signal having a magnitude proportional to the difference between the shared voltage of IGBT 3 and a predetermined voltage value, and the collector-emitter voltage of IGBT 3 When the voltage applied to the IGBT 3 does not drop to a predetermined level while the pulse is output from the pulse generation circuit 6, it is determined that a short-circuit accident has occurred and a gate voltage clamp instruction signal is output. When the saturation current increase instruction signal is output from the short circuit detection circuit 9 and the overvoltage detection circuit 8, the gate voltage of the IGBT 3 is raised to increase the saturation current value of the IGBT 3, and the gate voltage clamp from the short circuit detection circuit 9 When the instruction signal is output, the gate voltage of the IGBT 3 is set to a specified clamp voltage value, for example, the rated voltage of the IGBT 3. And a gate voltage clamping circuit 10 which holds within required voltage value for suppressing the same current value as the motor current value or a current value of about two times.

  In the gate drive device 1a having the above-described configuration, the gate voltage of the IGBT 3 is increased or decreased based on the pulse output from the pulse generation circuit 6, and this is turned on / off. As a result, high voltage frequency conversion, voltage conversion, etc. are achieved by an arm constituted by the IGBT 3 and another IGBT connected in series with the IGBT 3 and an arm (not shown) paired with the arm. Is done.

  Further, if the saturation current characteristics of the IGBT 3 and the saturation current characteristics of other IGBTs connected in series with the IGBT 3 vary, and the saturation current value of the IGBT 3 is smaller than the saturation current value of the other IGBT, the voltage of the IGBT 3 is When the voltage shared by the IGBT 3 exceeds the predetermined voltage value, the overvoltage detection circuit 8 detects this and outputs a saturation current increase instruction signal having a magnitude proportional to the difference between the predetermined voltage value and the voltage shared by the IGBT 3. Is done.

  As a result, the gate voltage of the IGBT 3 is increased by the gate voltage clamp circuit 10, the saturation current value of the IGBT 3 is increased, and the shared voltage of the IGBT 3 is lowered to the same voltage value as the shared voltage of each other IGBT.

  In addition, even if a short circuit accident occurs in the arm constituted by the IGBT 3 or other IGBTs, or in an arm paired with this arm, etc., even if a pulse is output from the pulse generating circuit 6, it is applied to the IGBT 3. When the detected voltage does not drop to a predetermined level, the short circuit detection circuit 9 monitoring the voltage of the IGBT 3 determines that a short circuit accident has occurred and outputs a gate voltage clamp instruction signal.

  As a result, the gate voltage clamp circuit 10 clamps the gate voltage of the IGBT 3 within a preset clamp voltage value, and the collector current value of the IGBT 3 is the same current value as the rated collector current value or a current value that is about twice as high. And the destruction of the IGBT 3 is prevented.

  As described above, in the first embodiment, even when a pulse is output from the pulse generation circuit 6, when the voltage applied to the IGBT 3 does not decrease, the short-circuit detection that monitors the voltage of the IGBT 3 is performed. The circuit 9 determines that a short-circuit accident has occurred, causes the gate voltage clamp circuit 10 to clamp the gate voltage of the IGBT 3, and causes other IGBTs due to variations in saturation current characteristics of the IGBTs constituting the arm. If the saturation current value of the IGBT 3 is smaller than the saturation current value of the IGBT 3, the voltage of the IGBT 3 rises, the shared voltage of the IGBT 3 increases, and when it exceeds a predetermined voltage value, this is detected by the overvoltage detection circuit 8, Since the gate voltage of the IGBT 3 is increased in the gate voltage clamp circuit 10, the power conversion is performed together with the IGBT 3. When a short circuit accident or the like occurs while controlling the saturation current value of the IGBT 3 in accordance with the applied voltage of each IGBT that constitutes the stationary arm and preventing an excessive voltage from being applied to the IGBT 3, the IGBT 3 By keeping the gate voltage within the clamp voltage value, it is possible to prevent an excessive current from flowing through the IGBT 3 and to prevent the IGBT 3 from being destroyed.

  In the first embodiment, the short-circuit detection circuit 9 that monitors the voltage of the IGBT 3 when the voltage applied to the IGBT 3 does not decrease even though the pulse is output from the pulse generation circuit 6. Therefore, it is determined that a short circuit accident has occurred, and the gate voltage clamp circuit 10 clamps the gate voltage of the IGBT 3 so that the collector current of the IGBT 3 is kept within a range of 1 to 2 times the rated collector current value. Therefore, when a short-circuit accident or the like occurs and the collector current of the IGBT 3 increases, the collector current of the IGBT 3 can be held within a specified range, thereby preventing the IGBT 3 from being destroyed due to the short-circuit accident.

<Second Embodiment>
FIG. 2 is a block diagram showing a second embodiment of the gate driving apparatus according to the present invention. In this figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

  The gate drive device 1b shown in this figure is different from the gate drive device 1a shown in FIG. 1 in that when the saturation voltage increase instruction signal is output from the overvoltage detection circuit 8, an equivalent current is injected into the gate of the IGBT 3 A variable current source 11 for reducing resistance is provided, and when a surge voltage or the like is applied to the IGBT 3 and a large value saturation current increase instruction signal is output from the overvoltage detection circuit 8, a current is supplied from the variable current source 11 to the gate of the IGBT 3 In order to reduce the equivalent resistance of the IGBT 3 and prevent the destruction of the IGBT 3 due to a surge voltage or the like.

  As described above, in the second embodiment, when a surge voltage or the like is applied to the IGBT 3 and a large value saturation instruction signal is output from the overvoltage detection circuit 8, the variable current source 11 supplies the gate of the IGBT 3. The current is injected to reduce the equivalent resistance of the IGBT 3 and the applied voltage of the IGBT 3 is reduced. Therefore, when a surge voltage or the like is applied to the IGBT 3, a current is injected into the gate of the IGBT 3 to obtain a saturation current. It is possible to increase the value so that the IGBT 3 is not applied with a voltage higher than the withstand voltage, and when a short circuit accident occurs, the short circuit detection circuit 9 clamps the gate voltage of the IGBT 3 within the clamp voltage value, It is possible to prevent an excessive current from flowing through the IGBT 3 and prevent the IGBT 3 from being destroyed.

  Also in the second embodiment, as in the first embodiment, when the pulse applied from the pulse generation circuit 6 does not decrease, the voltage applied to the IGBT 3 does not decrease. The short-circuit detection circuit 9 that monitors the voltage determines that a short-circuit accident has occurred, causes the gate voltage clamp circuit 10 to clamp the gate voltage of the IGBT 3, and causes the collector current of the IGBT 3 to be 1 to 2 times the rated collector current value. When the collector current of the IGBT 3 increases due to the occurrence of a short-circuit accident or the like, the IGBT 3 collector current value is held within the specified range and the IGBT 3 resulting from the short-circuit accident is generated. Can be prevented in advance.

<Third Embodiment>
FIG. 3 is a block diagram showing a third embodiment of a gate driving apparatus according to the present invention. In this figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

  The gate drive device 1c shown in this figure is different from the gate drive device 1a shown in FIG. 1 in that when the saturation voltage increase instruction signal is output from the overvoltage detection circuit 8, an equivalent current is injected into the gate of the IGBT 3 A variable current source 12 for reducing the resistance and supplying a current to the gate voltage clamp circuit 10 to increase the clamp voltage is provided, and a surge voltage or the like is applied to the IGBT 3 so that a saturation current increase instruction signal is output from the overvoltage detection circuit 8. Is output from the variable current source 12 to the gate voltage clamp circuit 10 to increase the gate voltage (clamp voltage) of the IGBT 3 and to inject current from the variable current source 12 to the gate of the IGBT 3. In this case, the equivalent resistance of the IGBT 3 is reduced and the destruction of the IGBT 3 due to a surge voltage or the like is prevented. A.

  As shown in the circuit diagram of FIG. 4, the gate voltage clamp circuit 10 includes a field effect transistor 14 for clamping on / off, the source of which is connected to the ground line 13 and the gate of which is connected to the output terminal of the short circuit detection circuit 9, and the anode. Is connected to the drain of the field effect transistor 14 for generating a clamp voltage, and one end is connected to the cathode of the Zener diode 15 and the other end is connected to the output terminal of the variable current source 12 for increasing the clamp voltage. A resistor 16, a base connected to the other end of the resistor 16, a collector connected to the ground line 13, and an emitter connected to the gate of the IGBT 3.

  Even if a short circuit accident or the like occurs in the IGBT 3, an arm constituted by other IGBTs, or an arm paired with this IGBT, even if a pulse is output from the pulse generation circuit 7, it is applied to the IGBT 3. Therefore, the short-circuit detection circuit 9 that monitors the voltage of the IGBT 3 determines that a short-circuit accident has occurred and outputs a gate voltage clamp instruction signal.

  As a result, the field effect transistor 14 is turned on, and a current flows from the base of the IGBT 3 to the ground line through the path of the gate of the IGBT 3 → the transistor 17 → the resistor 16 → the Zener diode 15 → the field effect transistor 14 → the ground line 13. As a result, the base voltage of the IGBT 3 is lowered to the clamp voltage value, and the collector current of the IGBT 3 is lowered to the same current value as the rated collector current value or a current value that is about twice that of the rated collector current value, thereby preventing the IGBT 3 from being destroyed.

  In this state, when the IGBT 3 enters an overvoltage state due to a surge voltage or the like and a saturation current increase instruction signal is output from the overvoltage detection circuit 8, this is detected by the variable current source 12, and the variable current source 12 → resistor 16 → A current is supplied to the resistor 16 through the path of the Zener diode 15 → the field effect transistor 14 → the ground line 13, the voltage across the resistor 16 is increased, the base voltage and the emitter voltage of the transistor 17 are increased, and variable. The current source 12 → the gate of the IGBT3 is supplied to the gate of the IGBT3 to increase the gate voltage.

  As a result, the collector current of the IGBT 3 is temporarily increased, the collector voltage is lowered, and the destruction of the IGBT 3 due to a surge voltage or the like is prevented.

  Thus, in the third embodiment, the occurrence of a short-circuit accident is detected by the short-circuit detection circuit 9, and the IGBT 3 is in a state where the gate voltage clamp circuit 10 keeps the gate of the IGBT 3 below the clamp voltage value. When a surge voltage or the like is applied to the overvoltage detection circuit 8 and a saturation current increase instruction signal is output from the overvoltage detection circuit 8, a current is injected from the variable current source 12 to the gate of the IGBT 3 to reduce the equivalent resistance of the IGBT 3 and Since the current is supplied from the current source 12 to the gate voltage clamp circuit 10 to increase the gate voltage of the IGBT 3, the gate voltage of the IGBT 3 is clamped to a clamp voltage value or less when a short circuit accident occurs. , Prevent excessive current from flowing through the IGBT 3 and prevent the IGBT 3 from being destroyed. When a charge voltage is applied, the clamp voltage of the gate voltage clamp circuit 10 is increased while injecting a current into the gate of the IGBT 3, thereby increasing the gate voltage of the IGBT 3 and preventing the IGBT 3 from being destroyed. Can do.

  In the third embodiment, when a surge voltage is applied to the IGBT 3, a current is output from the variable current source 12, and the variable current source 12 → the resistor 16 → the Zener diode 15 → the field effect transistor 14 → the ground line. Since a current is passed through the resistor 16 through a path 13 to increase the voltage generated across the resistor 16 and the base voltage of the transistor 17 is increased, an inexpensive device such as the resistor 16 or a simple circuit is provided. When the surge voltage is applied to the IGBT 3 while the gate voltage of the IGBT 3 is clamped while the manufacturing cost is kept low and the gate voltage of the IGBT 3 is clamped, the clamp voltage is temporarily increased. The collector current of the IGBT 3 can be temporarily increased to prevent the IGBT 3 from being destroyed.

  Also in the third embodiment, similarly to the first and second embodiments, the voltage applied to the IGBT 3 does not decrease even though the pulse is output from the pulse generation circuit 6. The short-circuit detection circuit 9 monitoring the voltage of the IGBT 3 determines that a short-circuit accident has occurred, causes the gate voltage clamp circuit 10 to clamp the gate voltage of the IGBT 3, and sets the collector current value of the IGBT 3 to the rated collector current value. Since it is held within the range of 1 to 2 times, when a short circuit accident occurs and the collector current of the IGBT 3 increases, the collector current value of the IGBT 3 is held within the specified range, and a short circuit accident occurs. It is possible to prevent the IGBT 3 from being destroyed due to the above.

<Other embodiments>
In the first to third embodiments described above, when the gate voltage clamp instruction signal is output from the short circuit detection circuit 9, the gate voltage clamp circuit 10 causes the gate voltage of the IGBT 3 to be clamped to cause an excessive short circuit to the IGBT 6. The current is prevented from flowing and the IGBT 3 is prevented from being destroyed, but when the gate voltage clamp instruction signal is output from the short circuit detection circuit 9, the pulse generation operation of the pulse generation circuit 6 is stopped. Thus, the pulse supply to the gate of the IGBT 3 may be cut off.

  Thereby, when a short circuit accident etc. generate | occur | produces, IGBT3 is hold | maintained in an OFF state, it can prevent that collector current flows into IGBT3, and destruction of IGBT3 resulting from a short circuit accident can be prevented beforehand.

  In the first to third embodiments described above, when the gate voltage clamp instruction signal is output from the short circuit detection circuit 9, the gate voltage clamp circuit 10 clamps the gate voltage of the IGBT 3 to overload the IGBT 3. In order to prevent the IGBT 3 from being destroyed by preventing a short-circuit current from flowing, signal transmission for generating a short-circuit detection signal when a gate voltage clamp instruction signal is output from the short-circuit detection circuit 9 A circuit is provided, and a short-circuit detection signal output from the signal transmission circuit is transmitted to the main control circuit of the power converter, and the operation of the pulse generation circuit 6 is stopped under the control of the main control circuit. Also good.

  As a result, when a short-circuit accident or the like occurs, the main control circuit of the power conversion apparatus is notified of the occurrence of the short-circuit accident, and the pulse supply to each IGBT constituting the power conversion apparatus is stopped at the same time. It is possible to prevent the load from concentrating on each other and to prevent the destruction of each IGBT.

  In the first to third embodiments described above, the IGBT 3 is controlled by the gate driving devices 1a to 1c. However, other non-latch type power switching elements such as MOSFETs may be controlled. .

  In the first to third embodiments described above, the voltage of the IGBT 3 is monitored when the voltage applied to the IGBT 3 does not decrease to a predetermined level even though the pulse is output from the pulse generation circuit 6. The short-circuit detection circuit 9 determines that a short-circuit accident has occurred, causes the gate voltage clamp circuit 10 to clamp the gate voltage of the IGBT 3, and causes the collector current of the IGBT 3 to range from 1 to 2 times the rated collector current value. (The current value is larger than the output current value of the power conversion device within the guaranteed operation range of the manufacturer).

  Even in this case, the actual IGBT 3 often has a collector current that is lower than the rated collector current value during normal operation, and when the IGBT 3 is in a short circuit state, Due to the large inductance component of the system, the output current of the power converter becomes a substantially constant current value. Therefore, when a short circuit accident occurs, the collector current of the IGBT 3 is 1 to 2 times the rated collector current value. If it is within the range, the current flowing through the IGBT 3 can be made larger than the maximum output current value of the power converter.

  However, when the performance of a heatsink attached to the IGBT3 is high, the current capacity at the time of a short-circuit accident is increased by exceeding the manufacturer's cut-off operation guarantee range by the amount of margin for the heat dissipation performance, and the short-circuit accident You may make it raise the tolerance with respect to.

1 is a block diagram showing a first embodiment of a gate driving device according to the present invention. FIG. It is a block diagram which shows 2nd Embodiment of the gate drive device by this invention. It is a block diagram which shows 3rd Embodiment of the gate drive device by this invention. FIG. 4 is a circuit diagram showing a specific configuration example of a gate voltage clamp circuit shown in FIG. 3. It is a block diagram which shows an example of the gate drive device known conventionally.

Explanation of symbols

1a, 1b, 1c: Gate drive device 2: Freewheeling diode 3: IGBT
4: Positive side gate drive voltage source 5: Negative side gate drive voltage source 6: Pulse generation circuit 7: Gate resistance 8: Overvoltage detection circuit 9: Short circuit detection circuit 10: Gate voltage clamp circuit 11, 12: Variable current source 13: Ground line 14: Field effect transistor 15: Zener diode 16: Resistor 17: Transistor

Claims (8)

In a gate drive device that drives and controls the power switching element by controlling the gate voltage of the power switching element,
A short-circuit detection circuit that determines that a short-circuit accident has occurred and generates a gate voltage clamp instruction signal when a voltage applied to the power switching element does not decrease when a pulse is applied to the gate of the power switching element; ,
An overvoltage detection circuit that determines that the power switching element is in an overvoltage state when a voltage exceeding a preset voltage value is applied to the power switching element, and generates a saturation current increase instruction signal; ,
When the gate voltage clamp instruction signal is output from the short circuit detection circuit, the gate voltage of the power switching element is kept within a clamp voltage value, and the collector current of the power switching element is within a specified current value. And a gate voltage clamp circuit that raises a gate voltage of the power switching element and lowers an applied voltage of the power switching element when a saturation current increase instruction signal is output from the overvoltage detection circuit. ,
A gate driving device comprising: The gate driving device according to claim 1,
When the gate voltage clamp instruction signal is output from the overvoltage detection circuit, a variable current source is provided that injects a current into the gate of the power switching element to reduce an equivalent resistance.
A gate driving device characterized by that. The gate driving device according to claim 1,
When the gate voltage clamp instruction signal is output from the overvoltage detection circuit, current is injected into the gate of the power switching element to reduce the equivalent resistance and supply current to the gate voltage clamp circuit. A variable current source for increasing the clamp voltage is provided;
A gate driving device characterized by that. The gate driving apparatus according to claim 3, wherein
The gate voltage clamp circuit temporarily increases a clamp voltage when the current is output from the variable current source in a state where the gate voltage clamp instruction signal is output from the short circuit detection circuit, and the power Temporarily increase the collector current of the switching element for
A gate driving device characterized by that. The gate drive device according to any one of claims 1 to 4,
The gate voltage clamp circuit holds the gate voltage of the power switching element within a clamp voltage value when the gate voltage clamp instruction signal is output from the short circuit detection circuit, and the collector of the power switching element Keep the current value within the range of 1 to 2 times the rated collector current value,
A gate driving device characterized by that. The gate drive device according to any one of claims 1 to 5,
The gate voltage clamp circuit shuts off a pulse input to the gate of the power switching element when the gate voltage clamp instruction signal is output from the short circuit detection circuit.
A gate driving device characterized by that. The gate drive device according to any one of claims 1 to 6,
When it is determined by the short-circuit detection circuit that a short-circuit accident has occurred, a signal transmission circuit that generates a short-circuit detection signal and transmits it to an external device,
A gate driving device comprising: In the gate drive device according to any one of claims 1 to 7,
The power switching element is connected in series with another power switching element to constitute an arm of a power converter.
A gate driving device characterized by that.

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