JP2001197724A - Gate drive circuit for power semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an over-current detection function in gate drive circuit of a power semiconductor element. SOLUTION: In a gate drive circuit 30 for IGBT2a, a collector-to-emitter voltage of IGBT2a is detected via a resistor 31 and a diode 32. When this detected value exceeds the voltage of a reference power supply 24a built in the over-current determining circuits 33, 34, it is determined that the IGBT2a is in the over-current condition. In this case, the IGBT2a is gradually turned OFF by operating a software cut-off circuit 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate drive circuit of a power semiconductor device forming a power converter such as an inverter.

[0002]

2. Description of the Related Art FIG. 11 is a diagram showing a main circuit configuration of a three-phase inverter comprising a power semiconductor device of this kind and a gate drive circuit thereof.
Is a semiconductor switch circuit composed of an anti-parallel circuit of an IGBT and a diode and a gate drive circuit (GDU) of the IGBT; 8 is a snubber capacitor of an inverter circuit in which semiconductor switch circuits 2 to 7 are connected in a three-phase bridge as shown in the figure;
Is an electric motor as a load of the three-phase inverter.

FIG. 12 is a detailed circuit diagram showing a conventional example of the semiconductor switch circuit 2 as one set of the semiconductor switch circuits 2 to 7 shown in FIG.

The gate drive circuit 20 insulates and converts an external ON / OFF command (not shown) and converts it into an ON / OFF command which will be described later.
An interface circuit 21 for outputting as an off signal, a gate voltage control circuit 22 for generating a gate voltage for turning on and off the IGBT 2a based on the on and off signals,
A soft shutoff circuit 23 for soft shutting off the GBT 2a,
Shunt resistor 2b for detecting the emitter current of GBT 2a
An overcurrent judging circuit 24 for monitoring the voltage between the two terminals and, when the voltage exceeds the judgment value, disabling the gate voltage control circuit 22 and operating the soft cutoff circuit 23;
And a drive power supply 25.

[0005] When the semiconductor switch circuit 2 shown in FIG.
4 is inactive (= the output is at the logic "L" level), and the soft cutoff circuit 23 is also inactive (the switch 23a is open).

For example, if the ON signal is active at a logic "L" level and the OFF signal is active at a logic "H" level, the output of the logic circuit 22a is at the logic "L" level when the ON signal is active. Logic circuit 22
b is at the logic "L" level, switch 22c is closed,
The switch 22d is open, and the voltage of the drive power supply 25 is applied between the gate and the emitter of the IGBT 2a via the resistor 22e, and the IGBT 2a is turned on. When the off signal becomes active, the output of the logic circuit 22a goes to the logic "H" level, and the logic circuit 22b
Is at a logic "H" level, the switch 22c is open and the switch 22d is closed, the voltage between the gate and the emitter of the IGBT 2a is discharged via the resistor 22f, and the IGBT 2a is turned off.

In the three-phase inverter shown in FIG.
For example, an overcurrent flows through the semiconductor switch circuit 2 when the IGBT or the diode of the semiconductor switch circuit 3 is in a short-circuit destruction state or when the motor 9 is overloaded, short-circuited, or grounded. The overcurrent is converted into a voltage across the shunt resistor 2b. When the voltage across the shunt resistor 2b exceeds a determination value output from a reference power supply 24a constituting the overcurrent determination circuit 24, the comparator 24b operates to output the voltage. At the logic "H" level. Therefore, the output of the logic circuit 22a is at the logic "H" level, and the output of the logic circuit 22b is at the logic "L" level.
The level, the switch 22c and the switch 22d are in an open state, and as a result, the gate voltage control circuit 22 is inoperative, while the switch 23a of the soft cutoff circuit 23 is in a closed state.

At this time, the resistance of the resistor 23b is
By setting the resistance to a value larger than d, the IGB
The voltage between the gate and the emitter of T2a gradually discharges through the resistor 23b, and thus the IGBT 2a slowly turns off. As a result, the surge voltage at the time of turn-off is suppressed, and for example, the capacity of the snubber capacitor 8 does not need to be increased.

FIG. 13 is a detailed circuit configuration diagram showing a conventional example of a semiconductor switch circuit 2 different from that of FIG.

That is, in this circuit configuration, the IGBT 2a
Is an IGBT with a current sense terminal, and the voltage between both ends of the shunt resistor 2c connected between the current sense terminal and the emitter terminal is monitored by the gate drive circuit 20a. The operation is the same as that of the configuration.

[0011]

According to the circuit configuration of the conventional gate drive circuit shown in FIG. 12, a large shunt resistor for passing the main circuit current is required, and as a result, the entire power converter becomes large, and the cost is reduced. There was a problem of getting up.

Further, according to the conventional gate drive circuit shown in FIG. 13, as is well known, the frequency characteristic of the current sense terminal is poor and the high-speed response to overcurrent is hindered.

An object of the present invention is to provide a gate drive circuit for a power semiconductor device which solves the above problems.

[0014]

According to a first aspect of the present invention, there is provided a gate drive circuit of a power semiconductor device forming a power conversion device, wherein the gate drive circuit includes an external ON,
An interface circuit for converting an off command into an on / off signal; a gate voltage control circuit for generating a gate voltage for turning on / off the power semiconductor element based on the on / off signal; and a soft cutoff of the power semiconductor element A soft cutoff circuit that monitors the voltage between the main terminals of the power semiconductor element during which the ON signal is generated, and disables the gate voltage control circuit when the voltage between the main terminals exceeds a determination value. And an overcurrent determination circuit for operating the soft cutoff circuit.

According to a second aspect of the present invention, in the gate drive circuit, the gate drive circuit includes an interface circuit for converting an external ON / OFF command into an ON / OFF signal;
A gate voltage control circuit for generating a gate voltage for turning on and off the power semiconductor device based on the on / off signal, a soft cutoff circuit for soft cutting off the power semiconductor device, and The voltage between the main terminals of the power semiconductor element is monitored, and when the confirmation time has elapsed in a state where the voltage between the main terminals has exceeded the determination value, the gate voltage control circuit is disabled and the soft cutoff circuit is provided. And an overcurrent judging circuit for operating the circuit.

According to a third aspect of the present invention, in the gate drive circuit, the gate drive circuit includes an interface circuit for converting an external ON / OFF command into an ON / OFF signal;
A gate voltage control circuit for generating a gate voltage for turning on and off the power semiconductor device based on the on / off signal, a soft cutoff circuit for soft cutting off the power semiconductor device, and The voltage between the main terminals of the power semiconductor element is monitored, and when the confirmation time has elapsed in a state where the voltage between the main terminals has exceeded the determination value, or when the OFF signal is issued during this state, An overcurrent determination circuit for disabling the voltage control circuit and operating the soft cutoff circuit.

According to a fourth aspect of the present invention, in the gate drive circuit, the gate drive circuit includes an interface circuit for converting an external ON / OFF command into an ON / OFF signal;
A gate voltage control circuit for generating a gate voltage for turning on and off the power semiconductor device based on the on / off signal, a soft cutoff circuit for soft cutting off the power semiconductor device, and Monitoring the voltage between the main terminals of the power semiconductor element, and turning off the power semiconductor element via the gate voltage control circuit when the voltage between the main terminals exceeds the first determination value; When the voltage between the main terminals exceeds a second determination value (> first determination value), the gate voltage control circuit is deactivated,
An overcurrent determination circuit for operating the soft cutoff circuit.

According to a fifth aspect of the present invention, in the gate drive circuit, the gate drive circuit includes an interface circuit for converting an external ON / OFF command into an ON / OFF signal;
A gate voltage control circuit for generating a gate voltage for turning on and off the power semiconductor device based on the on / off signal, a soft cutoff circuit for soft cutting off the power semiconductor device, and When the voltage between the main terminals of the power semiconductor element is monitored, and the first confirmation time has passed while the voltage between the main terminals has exceeded the first determination value,
The power semiconductor element is turned off via the gate voltage control circuit, and a second confirmation time period is set in a state where the voltage between the main terminals being monitored exceeds a second determination value (> first determination value). And an overcurrent judging circuit for disabling the gate voltage control circuit and operating the soft cutoff circuit when elapses.

According to a sixth aspect of the present invention, in the gate drive circuit, the gate drive circuit includes an interface circuit for converting an external ON / OFF command into an ON / OFF signal;
A gate voltage control circuit for generating a gate voltage for turning on and off the power semiconductor device based on the on / off signal, a soft cutoff circuit for soft cutting off the power semiconductor device, and When the voltage between the main terminals of the power semiconductor element is monitored, and the first confirmation time has passed while the voltage between the main terminals has exceeded the first determination value,
The power semiconductor element is turned off via the gate voltage control circuit, and a second confirmation time period is set in a state where the voltage between the main terminals being monitored exceeds a second determination value (> first determination value). And when the off signal is issued during this state, the gate voltage control circuit is disabled and the soft cutoff circuit is activated. And

The present invention has been made in view of the fact that, in a power semiconductor conversion device, as the current between the main terminals of the device increases, the voltage between the main terminals also increases.

Therefore, the voltage between the main terminals of the power semiconductor element during the ON period is monitored, and when the voltage between the main terminals exceeds a predetermined judgment value, it is judged that the element is in an overcurrent state. it can.

[0022]

FIG. 1 is a circuit diagram showing a semiconductor switch circuit according to a first embodiment of the present invention. The semiconductor switch circuit having the same functions as those of the conventional circuit shown in FIGS. The same reference numerals are given.

That is, as the gate drive circuit 30 for the IGBT 2a, in addition to the interface circuit 21, the gate voltage control circuit 22, the soft cutoff circuit 23, and the drive power supply 25, a resistor 31, a diode 32, and overcurrent determination circuits 33 and 34. And either.

As shown in the figure, the voltage between the collector and the emitter of the IGBT 2a can be detected by the resistor 31 and the diode 32 connected to each other. That is, while the IGBT 2a is on, the driving power supply 25 → the resistor 31 → the diode 32 → IGB
A current also flows through the path from T2a to the drive power supply 25, and a voltage is generated at the anode terminal of the diode 32 based on the collector-emitter voltage of the IGBT 2a.
During the off period of 2a, the voltage of the drive power supply 25 is substantially generated. Therefore, each of the overcurrent determination circuits 33 and 34 monitors the voltage of the anode terminal of the diode 32.

FIG. 2 is a detailed circuit diagram of the overcurrent judging circuit 33 shown in FIG. 1. 33a is a reference power supply for outputting a judging value, and 33b compares the judging value with the voltage of the anode terminal of the diode 32. The comparator 33c is a logic circuit.

In the circuit configuration of FIG.
The voltage of the anode terminal increases with an increase in the current of the IGBT 2a, and when this voltage exceeds a judgment value from the reference power supply 33a, the comparator 33b operates to output a logic "H" level. When an ON signal (logic "L" level) is issued from the interface circuit 21 in the state of the logic "H" level, that is, when the IGBT 2a is in the ON period, the output of the logic circuit 33c also has the logic "H" level. Therefore, the output of the logic circuit 22a is at a logic "H" level, the output of the logic circuit 22b is at a logic "L" level, and the switches 22c and 22d are in an open state. On the other hand, the switch 23a of the soft cutoff circuit 23 is closed, and the voltage between the gate and the emitter of the IGBT 2a gradually discharges through the resistor 23b, and thus the IGBT 2a
Turns off slowly.

FIG. 3 is a detailed circuit diagram of the overcurrent judging circuit 34 shown in FIG. 1. This overcurrent judging circuit 34 includes a reference power source 33a having the same function as the above-described overcurrent judging circuit 33,
In addition to the comparator 33b and the logic circuit 33c, the delay circuit 3
4a is added.

The delay circuit 34a includes an IGBT 2a
Is provided for the purpose of not operating the overcurrent determination circuit 34 during the turn-on operation period (about several microseconds), but is also effective in preventing noise malfunction of the comparator 33b.

FIG. 4 is a circuit diagram of a semiconductor switch circuit according to a second embodiment of the present invention. Components having the same functions as those of the circuit of the embodiment shown in FIG. I have.

That is, as the gate drive circuit 40 for the IGBT 2a, the interface circuit 21, the gate voltage control circuit 22, the soft cutoff circuit 23, the drive power supply 25,
In addition to the resistor 31 and the diode 32, an overcurrent determination circuit 41
It has.

FIG. 5 is a detailed circuit diagram of the overcurrent judging circuit 41 shown in FIG. 4. The overcurrent judging circuit 41 includes a reference power source 3 having the same function as the above-mentioned overcurrent judging circuits 33 and 34.
3a, comparator 33b, logic circuit 33c, delay circuit 3
4a, a flip-flop circuit 41a and an OR circuit 4
1b is added.

The flip-flop circuit 41a is reset at the falling edge of the ON signal inputted to the terminal R, the output terminal Q goes to the logic "L" level, and the input terminal D goes to the logic "H" level (comparator). 33b is input), and the output terminal Q changes from the logic “L” level to the logic “H” level at the rise of the off signal input to the terminal C.

That is, in the overcurrent determination circuit 41, in addition to the function of the overcurrent determination circuit 34, the delay circuit 34a
When the off signal is issued during the measurement of the confirmation time period, the IGBT 2a is in an overcurrent state, so that the IGBT 2
a has a function of slowly turning off.

FIG. 6 is a circuit diagram showing a semiconductor switch circuit according to a third embodiment of the present invention. Components having the same functions as those of the embodiment shown in FIG. I have.

That is, as the gate drive circuit 50 for the IGBT 2a, the interface circuit 21, the soft cutoff circuit 23, the drive power supply 25, the resistor 31, the diode 32
In addition, the gate voltage control circuit 51 and the overcurrent determination circuit 5
2, 53.

The gate voltage control circuit 51 includes a logic circuit 22 having the same function as the gate voltage control circuit 22 shown in FIG.
a, switches 22c and 22d, resistors 22e and 22f, an OR circuit 51a and a logic circuit 51b.

When the semiconductor switch circuit 2 shown in FIG. 11 performs a normal switching operation, an overcurrent determination circuit
2 and 53 are non-operational (= both outputs are at logic “L” level)
And the soft cutoff circuit 23 is also inoperative (switch 23a
Is open circuit).

For example, assuming that the ON signal has a logic "L" level active and the OFF signal has a logic "H" level active, the output of the logic circuit 22a becomes the logic "L" level when the ON signal becomes active. OR circuit 51
a is at the logic "L" level, the output of the logic circuit 51b is at the logic "L" level, the switch 22c is closed, the switch 2
2d is in an open state, and the voltage of the drive power supply 25 is
The voltage is applied between the gate and the emitter of the IGBT 2a via 2e, so that the IGBT 2a is turned on. Also,
When the OFF signal becomes active, the logic circuit 22a
Is at a logic "H" level, the output of the OR circuit 51a is at a logic "H" level, the output of the logic circuit 51b is at a logic "H" level, the switch 22c is open and the switch 22d is closed, and the gate of the IGBT 2a is turned off. The voltage between the emitters discharges through the resistor 22f, and thus the IGBT 2a turns off.

FIG. 7 is a detailed circuit diagram of the overcurrent judging circuit 52 shown in FIG. 6. The overcurrent judging circuit 52 includes a reference power source 33a having the same function as the above-described overcurrent judging circuit 33,
In addition to the comparator 33b and the logic circuit 33c, the reference power supply 52
a, a comparator 52b, and a logic circuit 52c.
It is assumed that the voltage of the reference power supply 52a is set to be larger than the voltage of the reference power supply 33a.

In the circuit configuration of FIG.
The voltage of the anode terminal increases with an increase in the current of the IGBT 2a, and when this voltage exceeds a judgment value from the reference power supply 33a, the comparator 33b operates to output a logic "H" level. When an ON signal (logic "L" level) is issued from the interface circuit 21 in the state of the logic "H" level, that is, when the IGBT 2a is in the ON period, the output of the logic circuit 33c also has the logic "H" level. Accordingly, the output of the logic circuit 22a is at the logic "H" level, the output of the OR circuit 51a is at the logic "H" level, the output of the logic circuit 52b is at the logic "H" level, and the switch 22c
Is open and the switch 22d is closed. As a result, the voltage between the gate and the emitter of the IGBT 2a becomes the resistance 2
Discharge via 2f, thus turning off IGBT 2a.

During operation of the comparator 33b, the voltage at the anode terminal of the diode 32 further increases with an increase in the current of the IGBT 2a, and when this voltage exceeds a judgment value from the reference power supply 52a, the comparator 52b operates. Operates to output a logic "H" level. When an ON signal (logic “L” level) is issued from the interface circuit 21 in the state of the logic “H” level, ie, the IGBT 2a
Is in the ON period, the output of the logic circuit 52c is also at the logic "H" level, so that the output of the logic circuit 22a is at the logic "H" level and the output of the logic circuit 52b is at the logic "L" level.
The level, the switch 22c and the switch 22d are in an open state, and as a result, the gate voltage control circuit 22 is inoperative, while the switch 23a of the soft cutoff circuit 23 is in a closed state, and the voltage between the gate and the emitter of the IGBT 2a is a resistance. 23b and slowly discharges through Ib
GBT 2a turns off slowly.

FIG. 8 is a detailed circuit diagram of the overcurrent judging circuit 53 shown in FIG. 6. This overcurrent judging circuit 53 includes a reference power source 3 having the same function as the above-mentioned overcurrent judging circuits 34 and 52.
3a, comparator 33b, logic circuit 33c, delay circuit 3
4a, reference power supply 52a, comparator 52b, logic circuit 52c
In addition, a delay circuit 53a is provided.

The delay circuits 34a and 53a
The GBT 2a is provided during the turn-on operation period (about several microseconds) so as not to operate the above-mentioned turn-off function and soft cut-off function in the overcurrent determination circuit 53. Is also effective.

FIG. 9 is a circuit diagram of a semiconductor switch circuit according to a fourth embodiment of the present invention. Components having the same functions as those of the circuit of the embodiment shown in FIG. I have.

That is, as the gate drive circuit 60 for the IGBT 2a, the interface circuit 21, the soft cutoff circuit 23, the drive power supply 25, the resistor 31, the diode 3
2. In addition to the gate voltage control circuit 51, the overcurrent determination circuit 6
1 is provided.

FIG. 10 shows the overcurrent judging circuit 61 shown in FIG.
The overcurrent determination circuit 61 includes a reference power supply 33 having the same function as the above-described overcurrent determination circuit 53.
a, comparator 33b, logic circuit 33c, delay circuit 34
a, reference power supply 52a, comparator 52b, logic circuit 52c,
In addition to the delay circuit 53a, a flip-flop circuit 61
a and an OR circuit 61b.

The flip-flop circuit 61a is reset at the falling edge of the ON signal inputted to the terminal R, the output terminal Q goes to the logic "L" level, and the input terminal D goes to the logic "H" level (comparator). 52b is operated) and the output terminal Q changes from the logic "L" level to the logic "H" level at the rise of the off signal input to the terminal C.

That is, in the overcurrent determination circuit 61, in addition to the function of the overcurrent determination circuit 53, the delay circuit 53a
When the off signal is issued during the measurement of the confirmation time period, the IGBT 2a is in an overcurrent state, so that the IGBT 2
a has a function of slowly turning off.

[0049]

According to the present invention, in the power semiconductor device, the voltage between the main terminals increases with an increase in the current between the main terminals of the device. The main terminal voltage is monitored, and when the main terminal voltage exceeds a predetermined judgment value, it is possible to detect that the element is in an overcurrent state, and it is possible to detect a main circuit current as in a conventional large-sized circuit. IGB with shunt resistor and current sense terminal
T becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a gate drive circuit according to a first embodiment of the present invention;

FIG. 2 is a partial detailed circuit configuration diagram of FIG. 1;

FIG. 3 is a partial detailed circuit configuration diagram of FIG. 1;

FIG. 4 is a circuit diagram of a gate drive circuit according to a second embodiment of the present invention;

FIG. 5 is a partial detailed circuit configuration diagram of FIG. 4;

FIG. 6 is a circuit configuration diagram of a gate drive circuit according to a third embodiment of the present invention.

FIG. 7 is a partial detailed circuit configuration diagram of FIG. 6;

FIG. 8 is a partial detailed circuit configuration diagram of FIG. 6;

FIG. 9 is a circuit configuration diagram of a gate drive circuit according to a fourth embodiment of the present invention.

FIG. 10 is a partial detailed circuit configuration diagram of FIG. 9;

FIG. 11 is a main circuit configuration diagram of a three-phase inverter,

FIG. 12 is a circuit configuration diagram of a gate drive circuit showing a conventional example.

FIG. 13 is a circuit configuration diagram of a gate drive circuit showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2-7 ... Semiconductor switch circuit, 8 ... Snubber capacitor, 9 ... Electric motor, 2a ... IGBT, 2b, 2
c: shunt resistor, 20, 20a: gate drive circuit, 2
1: Interface circuit, 22: Gate voltage control circuit,
23 ... soft cutoff circuit, 24 ... overcurrent judgment circuit, 30 ...
Gate drive circuit, 31: resistor, 32: diode, 3
3, 34: overcurrent determination circuit, 40: gate drive circuit, 4
DESCRIPTION OF SYMBOLS 1 ... Overcurrent determination circuit, 50 ... Gate drive circuit, 51 ... Gate voltage control circuit, 52,53 ... Overcurrent determination circuit, 60
... gate drive circuit, 61 ... overcurrent determination circuit.

Claims (6)

[Claims] 1. A gate drive circuit for a power semiconductor device forming a power converter, comprising: an interface circuit for converting an external ON / OFF command into an ON / OFF signal; A gate voltage control circuit that generates a gate voltage for turning on and off the power semiconductor element based on an off signal; a soft cutoff circuit that softly cuts off the power semiconductor element; and the power semiconductor that is generating the on signal. An overcurrent judging circuit for monitoring a voltage between main terminals of the element and, when the main terminal voltage exceeds a judgment value, disabling the gate voltage control circuit and operating the soft cutoff circuit. A gate drive circuit for a power semiconductor device, characterized in that: 2. A gate drive circuit for a power semiconductor device forming a power converter, comprising: an interface circuit for converting an external ON / OFF command into an ON / OFF signal; A gate voltage control circuit that generates a gate voltage for turning on and off the power semiconductor element based on an off signal; a soft cutoff circuit that softly cuts off the power semiconductor element; and the power semiconductor that is generating the on signal. The voltage between the main terminals of the element is monitored, and when the confirmation time has elapsed while the voltage between the main terminals has exceeded the determination value, the gate voltage control circuit is disabled and the soft cutoff circuit is operated. A gate drive circuit for a power semiconductor device, comprising: an overcurrent determination circuit. 3. A gate drive circuit for a power semiconductor device forming a power converter, comprising: an interface circuit for converting an external ON / OFF command into an ON / OFF signal; A gate voltage control circuit that generates a gate voltage for turning on and off the power semiconductor element based on an off signal; a soft cutoff circuit that softly cuts off the power semiconductor element; and the power semiconductor that is generating the on signal. The gate voltage control circuit monitors the voltage between the main terminals of the element, and when the confirmation time elapses in a state where the voltage between the main terminals exceeds the determination value, or when the off signal is issued during this state, A gate drive circuit for a power semiconductor device, comprising: an overcurrent judging circuit for disabling the circuit and operating the soft cutoff circuit. 4. A gate drive circuit for a power semiconductor device forming a power conversion device, the gate drive circuit comprising: an interface circuit for converting an external ON / OFF command into an ON / OFF signal; A gate voltage control circuit that generates a gate voltage for turning on and off the power semiconductor element based on an off signal; a soft cutoff circuit that softly cuts off the power semiconductor element; and the power semiconductor that is generating the on signal. Monitoring the voltage between the main terminals of the element, and turning off the power semiconductor element via the gate voltage control circuit when the voltage between the main terminals exceeds a first determination value; The terminal-to-terminal voltage is equal to the second determination value (> first
A gate drive circuit for a power semiconductor device, comprising: an overcurrent determination circuit that disables the gate voltage control circuit and activates the soft cutoff circuit when the threshold value exceeds the threshold value. . 5. A gate drive circuit for a power semiconductor device forming a power converter, comprising: an interface circuit for converting an external ON / OFF command into an ON / OFF signal; A gate voltage control circuit that generates a gate voltage for turning on and off the power semiconductor element based on an off signal; a soft cutoff circuit that softly cuts off the power semiconductor element; and the power semiconductor that is generating the on signal. Monitoring the voltage between the main terminals of the element, and when the first confirmation time has elapsed in a state where the voltage between the main terminals exceeds the first determination value, the power semiconductor element via the gate voltage control circuit; Is turned off, and the voltage between the main terminals being monitored is equal to a second determination value (> first
And an overcurrent determination circuit that activates the soft cutoff circuit while the gate voltage control circuit is deactivated when the second confirmation time has elapsed in a state exceeding the threshold value. A gate drive circuit for a power semiconductor device. 6. A gate drive circuit for a power semiconductor device forming a power converter, the gate drive circuit comprising: an interface circuit for converting an external ON / OFF command into an ON / OFF signal; A gate voltage control circuit that generates a gate voltage for turning on and off the power semiconductor element based on an off signal; a soft cutoff circuit that softly cuts off the power semiconductor element; and the power semiconductor that is generating the on signal. Monitoring the voltage between the main terminals of the element, and when the first confirmation time has elapsed in a state where the voltage between the main terminals exceeds the first determination value, the power semiconductor element via the gate voltage control circuit; Is turned off, and the voltage between the main terminals being monitored is equal to a second determination value (> first
When the second confirmation time period has passed in a state where the threshold voltage has exceeded the threshold value, or when the OFF signal has been issued during this state, the gate voltage control circuit is deactivated and the soft cutoff circuit is activated. A gate drive circuit for a power semiconductor device, comprising: an overcurrent determination circuit that operates the circuit.