Gate drive circuit and power conversion device

Abstract

The present application relates to a kind of gate drive circuits.The gate drive circuit controls the gate voltage applied on the gate terminal of switching element, drives the switching element, the gate drive circuit has overcurrent detection circuit according to the current value flowing through the switching element detects overcurrent state, the monitoring voltage of power supply line is input to the overcurrent detection circuit and is supplied to the switching element with the power of the switching element connection, in the case where the monitoring voltage is above the specified threshold value, the overcurrent detection circuit detects as overvoltage state.

Description

Technical Field

[0001] This invention relates to a gate drive circuit and a power conversion device. Background Technology

[0002] In power conversion devices that drive switching elements to convert DC power and AC power to each other, there are known detection circuits that detect the overcurrent state of the switching elements and the overvoltage state applied to the switching elements. For example, patent document 1 is known as a technology for measuring the voltage of a high-voltage line, performing overvoltage detection, and executing overvoltage protection actions. Existing technical documents Patent documents

[0003] Patent Document 1: International Publication No. WO 2012 / 077187 Summary of the Invention The problem the invention aims to solve

[0004] When the overvoltage detection unit malfunctions, it cannot perform overvoltage protection actions normally. Therefore, redundancy of the overvoltage detection unit is considered, but this leads to problems such as increased circuit complexity and higher circuit costs. Technical means to solve the problem

[0005] The gate driving circuit of the present invention controls the gate voltage applied to the gate terminal of the switching element to drive the switching element. The gate driving circuit includes an overcurrent detection circuit that detects an overcurrent state based on the current value flowing through the switching element. A monitoring voltage of a power supply line connected to the switching element and supplying power to the switching element is input to the overcurrent detection circuit. If the monitoring voltage is above a predetermined threshold, the overcurrent detection circuit detects an overvoltage state. The effects of the invention

[0006] According to the present invention, the circuit configuration for detecting overcurrent or overvoltage conditions can be simplified, and the increase in circuit cost can be suppressed. Attached Figure Description

[0007] Figure 1 This is an overall structural diagram of the power conversion device. Figure 2 This is a detailed structural diagram of a power conversion device. Figure 3 (A) to (F) are timing diagrams representing the operation of overvoltage protection when the sensor circuit and overcurrent detection circuit are normal. Figure 4 (A) to (F) are timing diagrams representing the operation of overvoltage protection when the sensor circuit malfunctions. Figure 5This is a detailed structural diagram of a modified example of a power conversion device. Figure 6 (A) to (F) are timing diagrams representing the operation of overvoltage protection when the sensor circuit malfunctions in a modified example of a power conversion device. Detailed Implementation

[0008] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention; appropriate omissions and simplifications have been made to clarify the description. The present invention may also be implemented in various other ways. Unless otherwise specified, the constituent elements may be singular or plural.

[0009] Figure 1 This is an overall configuration diagram of the power conversion device 200. DC power is supplied from the high-voltage battery 902 to the power conversion device 200 via the contactor 903. The power conversion device 200 converts the DC power into AC power and supplies the AC power to the motor 900. In addition, the low-voltage battery 10 supplies the operating voltage to the controller 100 and the low-voltage side LV such as the gate drive circuits 400a and 400b in the power conversion device 200.

[0010] The power conversion device 200 includes a controller 100, gate drive circuits 400a and 400b, a semiconductor device 300 constituting an inverter circuit, a semiconductor device 301 constituting a DC-DC converter, a voltage divider circuit 141b, etc. The gate drive circuit 400a drives the switching elements within the semiconductor device 300. The gate drive circuit 400b drives the switching elements within the semiconductor device 301.

[0011] The upper controller (not shown) inputs torque commands, rotation commands, and other commands for driving the motor to the controller 100 of the power conversion device 200. The controller 100 outputs PWM signals to the gate drive circuits 400a and 400b according to the commands.

[0012] The voltage supplied from the high-voltage battery 902 is supplied from the power supply lines 302a and 302b, which pass through the smoothing capacitor 500a and the reactor 302, to the intermediate connection point of the two series-connected switching elements constituting the semiconductor device 301.

[0013] The gate drive circuit 400b switches the switching elements of the semiconductor device 301 according to the PWM signal, and works in conjunction with the reactor 302 to control the DC voltage supplied to the motor 900 by boosting it. That is, the gate drive circuit 400b drives the switching elements that constitute the DC-DC converter.

[0014] The voltage output from semiconductor device 301 is supplied from power supply lines 300a and 300b to the inverter circuit constituting semiconductor device 300. The inverter circuit has switching elements that form upper and lower arms constituting three phases.

[0015] The gate drive circuit 400a drives the switching elements of the semiconductor device 300 according to the PWM signal, thereby controlling the torque and speed of the motor 900. That is, the gate drive circuit 400a drives the switching elements that constitute the inverter circuit.

[0016] Each switching element of semiconductor devices 300 and 301 has a sensing emitter, which outputs the current sensing signal Es to the gate drive circuits 400a and 400b. The gate drive circuits 400a and 400b, as well as the sensor circuit 140b described later, are separated into a high-voltage side (HV) and a low-voltage side (LV) by an insulating element 101.

[0017] Furthermore, a smoothing capacitor 500b and a voltage divider circuit 141b are connected in parallel between the positive terminal P and the negative terminal N of the power supply lines 300a and 300b. The voltage divider circuit 141b is constructed by connecting multiple resistors in series between the positive terminal P and the negative terminal N of the power supply line 300a. To detect overvoltage, the voltage divided by the voltage divider circuit 141b is input to the gate drive circuit 400b as an HV monitoring voltage. In the event of an overvoltage between the positive terminal P and the negative terminal N of the power supply lines 300a and 300b, the HV monitoring voltage is input to the gate drive circuit 400b to stop the operation of the switching elements constituting the DC-DC converter of the semiconductor device 301.

[0018] Furthermore, the voltage between the positive terminal P and the negative terminal N of the power supply lines 300a and 300b is input to the sensor circuit 140b. The sensor circuit 140b detects the voltage between the positive terminal P and the negative terminal N and outputs the voltage detection signal V2 to the controller 100. Then, the sensor circuit 140b detects an overvoltage between the positive terminal P and the negative terminal N and outputs an overvoltage detection signal OV2 to one side of the AND gate 450. The PWM signal is input from the controller 100 to the other side of the AND gate 450. Therefore, the PWM signal output from the controller 100 to the gate drive circuit 400b is cut off when the overvoltage detection signal OV2 is output.

[0019] A rotary position sensor 901 is provided on the motor 900, and its detected value is output to the controller 100. A current sensor 20 is provided between the output terminal of the semiconductor device 300 and the output terminal of the power conversion device 200, and its detected value is output to the controller 100. Thus, the controller 100 controls the voltage, current, and speed according to the torque of the motor 900.

[0020] In addition, Figure 1The diagram is omitted, but the configuration can also be as follows: A voltage divider circuit is connected in parallel with a smoothing capacitor 500a between the positive terminal P and the negative terminal N of the power supply lines 302a and 302b. To detect overvoltage, the voltage divided by this voltage divider circuit is input as an HV monitoring voltage to the gate drive circuit 400b. In the event of an overvoltage between the positive terminal P and the negative terminal N of the power supply lines 302a and 302b, the HV monitoring voltage is input to the gate drive circuit 400b to stop the operation of the switching elements constituting the DC-DC converter of the semiconductor device 301. Furthermore, a sensor circuit is provided that receives the voltage between the positive terminal P and the negative terminal N of the power supply lines 302a and 302b. This sensor circuit detects the voltage between the positive terminal P and the negative terminal N and outputs the voltage detection signal to the controller 100.

[0021] Furthermore, in the following examples, we will describe the case where this embodiment is applied to the gate drive circuit 400b, but it can also be applied to the gate drive circuit 400a. When applied to the gate drive circuit 400a, the generation of overvoltage is detected, and the gate drive circuit 400a stops the operation of the switching elements constituting the inverter circuit of the semiconductor device 300.

[0022] Figure 2 This is a detailed structural diagram of the power conversion device 200. Figure 2 In the diagram, the gate drive circuit 400b shows the circuit corresponding to the lower arm, while the circuit corresponding to the upper arm is omitted, but the circuit corresponding to the upper arm has the same configuration. Figure 2 In the middle, to and Figure 1 The same symbols are used to mark the same parts, and their descriptions are omitted.

[0023] The sensor circuit 140b includes a comparator 144 that detects the voltage between the positive terminal P and the negative terminal N of the power supply lines 300a and 300b. The detected voltage V2 is input to the controller 100. Additionally, the detected voltage V2 is input to one side of the comparator 145. A threshold voltage HV_OV2 is input to the other side of the comparator 145. Therefore, if the detected voltage V2 exceeds the threshold voltage HV_OV2, the comparator 145 outputs an overvoltage detection signal OV2 to one side of the AND gate 450, cutting off the PWM signal output from the controller 100.

[0024] The gate drive circuit 400b includes a gate drive IC 410. The gate drive IC 410 consists of a pre-drive circuit 420, a comparator 430, an amplifier 440, a buffer circuit BF, an insulating element 101, etc.

[0025] In the normal state where the overvoltage detection signal OV2 is not output, the PWM signal output from the controller 100 is input to the pre-drive circuit 420 via the buffer circuit BF and the insulating element 101. Then, as the drive signal PWM_OUT, it is applied from the drive circuit 421 to the gate terminal of the switching element via the resistor Rg. That is, the gate drive circuit 400b controls the gate voltage applied to the gate terminal of the switching element, driving the switching element.

[0026] The current sensing signal Es is output from the switching element via resistor Rs. Then, the overcurrent detection voltage applied to resistor Rs is output to one side of comparator 430 via diode D5. The threshold voltage Vref is input to the other side of comparator 430. If the overcurrent detection voltage exceeds the threshold voltage Vref, comparator 430 changes the off-signal E_off from Low to High via buffer circuit BF. When the off-signal E_off is High, by turning on the FET, the terminal G_off applied to the gate of the switching element is turned low via resistor Rsft, thus soft-disconnecting the switching element.

[0027] The circuit that uses resistor Rs, diode D5, and comparator 430 to detect the current sensing signal Es, and uses FET and resistor Rsft to turn off the switching element is an overcurrent detection circuit. It detects the overcurrent state based on the current value flowing through the switching element and turns off the switching element.

[0028] For overvoltage detection, the voltage divided by the voltage divider circuit 141b is used as the HV monitoring voltage and connected to the detection line OC on the output side of the diode D5 of the overcurrent detection circuit via diode D4. That is, the overcurrent detection circuit detects the voltage value of the detection line OC, which is output after converting the current value into a voltage value, and the output of the voltage divider circuit 141b, which divides the voltage of the power supply line, is connected to this detection line OC. If the voltage value of the detection line OC is above a predetermined threshold, the overcurrent detection circuit detects an overcurrent or overvoltage state. Then, if an overcurrent or overvoltage state is detected in the comparator 430, a fail signal FAIL is output to the controller 100 via the buffer circuit BF and the insulating element 101. Thus, in this embodiment, the circuit configuration for detecting overcurrent or overvoltage states can be simplified, suppressing the increase in circuit cost. Furthermore, while overvoltage is also detected in the sensor circuit 140b, the circuit configuration can be simplified, the increase in circuit cost can be suppressed, and the detection circuit can be made redundant.

[0029] In addition, for overvoltage detection, the voltage divided by the voltage divider circuit 141b is input to the amplifier 440 as the HV monitoring voltage. This voltage is output to the controller 100 as the sub-detection voltage Sub_HV via the buffer circuit BF and the insulating element 101.

[0030] An overvoltage condition is a state in which the voltage between the positive terminal P and the negative terminal N of the power supply lines 300a and 300b exceeds the rated voltage of the semiconductor device 301 and the smoothing capacitor 500b. Furthermore, the overvoltage condition is redundantly detected by both the sensor circuit 140b and the overcurrent detection circuit within the gate drive circuit 400b. In this case, there are possibilities where both the sensor circuit 140b and the overcurrent detection circuit operate normally, and possibilities where the sensor circuit 140b malfunctions.

[0031] The sensor circuit 140b inputs the detection voltage V2 to the controller 100, and the gate drive circuit 400b inputs the secondary detection voltage Sub_HV and the failure signal FAIL to the controller 100. If the difference between the detection voltage V2 and the secondary detection voltage Sub_HV is above a specified voltage at a voltage level that does not generate overvoltage, the controller 100 determines that the sensor circuit 140b is abnormal.

[0032] Furthermore, if the detection voltage V2 and the secondary detection voltage Sub_HV are both below the threshold, and an FAIL signal is input, the controller 100 determines that the current is in an overcurrent state. Furthermore, if at least one of the detection voltage V2 or the sub-detection voltage Sub_HV exceeds a threshold and the difference between the detection voltage V2 and the sub-detection voltage Sub_HV is below a specified voltage, the controller 100 determines that it is in an overvoltage state.

[0033] Figure 3 This is a timing diagram showing the operation of the overvoltage protection when both the sensor circuit 140b and the overcurrent detection circuit are functioning normally. Figure 3 (A) represents the voltage between the positive terminal P and the negative terminal N of power supply lines 300a and 300b. Figure 3 (B) represents the voltage (solid line) of the detection line OC of the overcurrent detection circuit and the detection voltage V2 (dotted line) of the sensor circuit 140b. Figure 3 (C) indicates the FAIL signal. Figure 3 (D) represents the overvoltage detection signal OV2. Figure 3 (E) represents the drive signal PWM_OUT output from the drive circuit 421. Figure 3 (F) represents the drive signal PWM output from controller 100.

[0034] like Figure 3 As shown in (A), the voltage between the positive terminal P and the negative terminal N of power supply lines 300a and 300b begins to rise at time t1. Then, when the specified voltage V_PN2 is reached at time t2, as... Figure 3As shown by the dotted line in (B), the detection voltage V2 of sensor circuit 140b exceeds the threshold voltage HV_OV2. At this time, as... Figure 3 As shown in (D), sensor circuit 140b outputs an overvoltage detection signal OV2. This overvoltage detection signal OV2 is output to one side of AND gate 450, cutting off the PWM signal output from controller 100, as shown in (D). Figure 3 As shown in (E), the drive signal PWM_OUT of the gate driver IC 410 becomes Low, causing the switching element to turn off. Additionally, at the same time t2, as... Figure 3 As shown by the solid line in (B), the voltage of the detection line OC, which is connected to the HV monitoring voltage of the voltage divider circuit 141b, is higher than the threshold voltage Vref. The overcurrent detection circuit, composed of comparator 430, etc., performs overvoltage protection with the same operation as the overcurrent protection of the switching element. Then, the switching element is disconnected. Furthermore, as... Figure 3 As shown in (C), the overcurrent detection circuit inputs a FAIL signal to the controller 100.

[0035] That is, when both the sensor circuit 140b and the overcurrent detection circuit are functioning normally, the overvoltage condition is detected by the circuits of both circuits, and the overvoltage protection action is executed.

[0036] Figure 4 This is a timing diagram showing the overvoltage protection action when the sensor circuit 140b outputs a low detection voltage V2 due to an abnormality. Figure 4 (A) represents the voltage between the positive terminal P and the negative terminal N of power supply lines 300a and 300b. Figure 4 (B) represents the voltage (solid line) of the detection line OC of the overcurrent detection circuit and the detection voltage V2 (dotted line) of the sensor circuit 140b. Figure 4 (C) indicates the FAIL signal. Figure 4 (D) represents the overvoltage detection signal OV2. Figure 4 (E) represents the drive signal PWM_OUT output from the drive circuit 421. Figure 4 (F) represents the drive signal PWM output from controller 100.

[0037] like Figure 4 As shown in (A), the voltage between the positive terminal P and the negative terminal N of power supply lines 300a and 300b begins to rise at time t1. Furthermore, even when the specified voltage V_PN2 is reached at time t2, the sensor circuit 140b outputs a lower detection voltage V2 due to an malfunction, so as... Figure 4As shown by the dotted line in (B), the detection voltage V2 of the sensor circuit 140b will not exceed the threshold voltage HV_OV2. Therefore, even if the voltage between the positive terminal P and the negative terminal N is in an overvoltage state, the voltage continues to rise due to the operation of the DC-DC converter of the semiconductor device 301. Then, as... Figure 4 As shown in (D), the voltage rises until it reaches the specified voltage V_PN3 (V_PN3 > V_PN2) at time t3, that is, until the detection voltage V2 of the sensor circuit 140b exceeds the threshold voltage HV_OV2 and outputs an overvoltage detection signal OV2. Therefore, the voltage between the positive terminal P and the negative terminal N may exceed the rated voltage of the semiconductor devices 300, 301, the smoothing capacitor 500b, etc. However, in this embodiment, since the HV monitoring voltage of the voltage divider circuit 141b is connected to the detection line OC, as Figure 4 As shown by the solid line in (B), at the moment t2 when the detection line OC exceeds the threshold voltage Vref, overvoltage protection is normally implemented with the same operation as overcurrent protection. Then, as... Figure 4 As shown in (E), the drive signal PWM_OUT of the gate driver IC 410 becomes Low, disconnecting the switching element. Furthermore, as... Figure 4 As shown in (C), the overcurrent detection circuit inputs a FAIL signal to the controller 100.

[0038] That is, even if the sensor circuit 140b outputs a low detection voltage V2 due to an abnormality, the overvoltage state can still be detected by the overcurrent detection circuit, and overvoltage protection action can be performed.

[0039] In this embodiment, the voltage between the positive P and negative N terminals of the power supply lines 300a and 300b is detected by the sensor circuit 140b and the overcurrent detection circuit. Therefore, compared with the case where a circuit equivalent to the sensor circuit 140b is set up separately, the circuit configuration can be simplified and the increase in circuit cost can be suppressed.

[0040] Figure 5 This is a detailed structural diagram of a modified example of the power conversion device 200. Figure 5 In the diagram, gate drive circuit 400b shows the circuit corresponding to the lower arm, while the circuit corresponding to the upper arm is omitted, but the circuit corresponding to the upper arm is the same. Regarding... Figure 1 , Figure 2 The same parts are given the same symbol and their descriptions are omitted.

[0041] The following explanation is in Figure 5 In the modified example of the power conversion device 200 shown, and Figure 2 The power conversion device 200 shown differs in some places. The gate driver IC 410 is configured with a built-in comparator 460, which detects the HV monitoring voltage and the threshold voltage Vref_OV between the positive P and negative N terminals of the power supply lines 300a and 300b. Specifically, if the HV monitoring voltage exceeds the threshold voltage Vref_OV, the comparator 460 changes the disconnect signal E_off from Low to High via the buffer circuit BF. The circuitry following the output of comparator 460 is used in conjunction with an overcurrent detection circuit.

[0042] Figure 6 It means in Figure 5 The timing diagram shows the overvoltage protection operation when the sensor circuit 140b outputs a low detection voltage V2 abnormally in the power conversion device 200 shown. Figure 6 (A) represents the voltage between the positive terminal P and the negative terminal N of power supply lines 300a and 300b. Figure 6 (B) represents the HV monitoring voltage (solid line) and the detection voltage V2 (dotted line) of sensor circuit 140b. Figure 6 (C) indicates the FAIL signal. Figure 6 (D) represents the overvoltage detection signal OV2. Figure 6 (E) represents the drive signal PWM_OUT output from the drive circuit 421. Figure 6 (F) represents the drive signal PWM output from controller 100.

[0043] In addition, Figure 5 The timing diagram of the overvoltage protection operation in the power conversion device 200 shown, when both the sensor circuit 140b and the overcurrent detection circuit are normal, is shown in the figure. Figure 3 Since they are the same, their description is omitted.

[0044] like Figure 6 As shown in (A), the voltage between the positive terminal P and the negative terminal N of power supply lines 300a and 300b begins to rise at time t1. Furthermore, even when the specified voltage V_PN2 is reached at time t2, the sensor circuit 140b outputs a lower detection voltage V2 due to an malfunction, so as... Figure 6 As shown by the dotted line in (B), the detection voltage V2 of the sensor circuit 140b will not exceed the threshold voltage HV_OV2. Therefore, even if the voltage between the positive terminal P and the negative terminal N is in an overvoltage state, the voltage continues to rise due to the operation of the DC-DC converter of the semiconductor device 301. Then, as... Figure 6As shown in (D), the voltage rises until it reaches the threshold voltage V_PN3 at time t3, that is, until the detection voltage V2 of the sensor circuit 140b exceeds the threshold voltage HV_OV2. Therefore, the voltage between the positive terminal P and the negative terminal N may exceed the rated voltage of the semiconductor devices 300, 301, the smoothing capacitor 500b, etc. However, according to this embodiment, the HV monitoring voltage of the voltage divider circuit 141b is detected by the comparator 460. Therefore, at time t2 when the HV monitoring voltage exceeds the threshold voltage Vref_OV, the comparator 460 normally implements overvoltage protection with the same operation as overcurrent protection. Then, as Figure 6 As shown in (E), the drive signal PWM_OUT of the gate driver IC 410 becomes Low, disconnecting the switching element. Furthermore, as... Figure 6 As shown in (C), the overcurrent detection circuit inputs a FAIL signal to the controller 100.

[0045] That is, even if the sensor circuit 140b outputs a low detection voltage V2 due to an abnormality, the overvoltage state can still be detected by the overcurrent detection circuit, and overvoltage protection action can be performed.

[0046] In addition, Figures 2-6 In, to constitute Figure 1 The example described uses the gate drive circuit 400b of the switching element in the DC-DC converter, but the gate drive circuit 400a of the switching element constituting the inverter circuit is basically the same and performs the same overvoltage protection operation. That is, it includes: an inverter circuit composed of switching elements; a sensor circuit for detecting the voltage of the power supply line; and a controller that receives the detection results from the sensor circuit and the overcurrent detection circuit, and determines an abnormality in the sensor circuit based on the detection results from the sensor circuit and the overcurrent detection circuit.

[0047] In this embodiment, the voltage between the positive P and negative N terminals of the power supply lines 300a and 300b is detected by the sensor circuit 140b and the overcurrent detection circuit. Therefore, compared with the case where a circuit equivalent to the sensor circuit 140b is set up separately, the circuit configuration can be simplified and the increase in circuit cost can be suppressed.

[0048] The following effects can be obtained by implementing the methods described above. (1) Gate drive circuits 400a and 400b control the gate voltage applied to the gate terminal of the switching element and drive the switching element. Gate drive circuits 400a and 400b include an overcurrent detection circuit that detects an overcurrent state based on the current flowing through the switching element. A monitoring voltage of the power supply lines 300a and 300b connected to and supplying power to the switching element is input to the overcurrent detection circuit. If the monitoring voltage is above a predetermined threshold, the overcurrent detection circuit detects an overvoltage state. This simplifies the circuit configuration for detecting overcurrent or overvoltage states and reduces the increase in circuit cost.

[0049] This invention is not limited to the above-described embodiments. Other methods considered within the scope of the technical concept of this invention, as long as they do not impair the features of this invention, are also included within the scope of this invention. Symbol Explanation

[0050] 10…Low-voltage battery, 100…Controller, 101…Insulating element, 140b…Sensor circuit, 141b…Voltage divider circuit, 144, 145, 430, 460…Comparators, 200…Power conversion device, 300a, 300b…Power supply line, 300, 301…Semiconductor device, 302…Reactor, 400a, 400b…Gate drive circuit, 410…Gate drive IC, 420…Pre-drive circuit, 440…Amplifier, 450…AND gate, 500a, 500… b… smoothing capacitor, 900… motor, 902… high voltage battery, 903… contactor, BF… buffer circuit, Rg, Rsft… resistors, D4, D5… diodes, OC… detection line, Vref, Vref_OC, Vref_OV… threshold voltage, Sub_HV… secondary detection voltage, PWN, PWM_OUT… drive signal, E_off… disconnect signal, Es… current sensing signal, V2… voltage detection signal, OV2… overvoltage detection signal, FAIL… not working signal.

Claims

1. A gate driving circuit that controls a gate voltage applied to the gate terminal of a switching element to drive the switching element, the switching element being disposed in a semiconductor device constituting an inverter circuit or a DC-DC converter, characterized in that... have: A gate driving section, which receives a PWM signal and outputs a drive signal for controlling the gate voltage based on the PWM signal; and An overcurrent detection circuit detects the overcurrent or overvoltage state of the inverter circuit or DC-DC converter, and outputs a disconnect signal to stop the output of the drive signal and turn off the switching element. The overcurrent detection circuit has the following features: A detection line, connected to a first signal output line via a first diode and to a second signal output line via a second diode, receives a voltage that is higher than either an overcurrent detection voltage or a monitoring voltage. The first signal output line outputs the overcurrent detection voltage corresponding to the current flowing through the switching element, and the second signal output line outputs the monitoring voltage corresponding to the voltage on the power supply line connected to the input side of the inverter circuit or the output side of the DC-DC converter. A comparator compares the voltage of the detection line with a predetermined threshold, and outputs the disconnect signal if the voltage of the detection line is above the threshold.

2. The gate driving circuit according to claim 1, characterized in that, When the overcurrent detection circuit detects the overcurrent state or the overvoltage state, it outputs a specified fail signal to the outside. The disconnect signal and the unavailable signal are mutually insulated.

3. A power conversion device, characterized in that, have: The gate driving circuit according to claim 1 or 2; The DC-DC converter composed of the aforementioned switching elements; A sensor circuit for detecting the voltage of the power supply line connected to the output side of the DC-DC converter; as well as The controller receives the detection results from the sensor circuit and the overcurrent detection circuit. The controller determines the abnormality of the sensor circuit based on the detection results of the sensor circuit and the overcurrent detection circuit.

4. A power conversion device, characterized in that, have: The gate driving circuit according to claim 1 or 2; The inverter circuit composed of the aforementioned switching elements; A sensor circuit for detecting the voltage of the power supply line connected to the input side of the inverter circuit; as well as The controller receives the detection results from the sensor circuit and the overcurrent detection circuit. The controller determines the abnormality of the sensor circuit based on the detection results of the sensor circuit and the overcurrent detection circuit.

Images