Gate drive circuit and power conversion device

Abstract

A gate drive circuit according to the present invention controls a gate voltage applied to a gate terminal of a switching element to drive the switching element, and comprises an overcurrent detection circuit that detects an overcurrent state on the basis of the value of a current flowing through the switching element. The overcurrent detection circuit receives input of a monitor voltage of a power supply line connected to the switching element to supply power to the switching element. The overcurrent detection circuit detects the same being in the overvoltage state when the monitor voltage is equal to or larger than a predetermined threshold value.

Description

[Technical field]

[0001] The present invention relates to a gate drive circuit and a power conversion device. [Background technology]

[0002] 2. Description of the Related Art Power conversion devices that drive switching elements to convert DC power into AC power and vice versa are known to include a plurality of detection circuits that detect an overcurrent state of a switching element or an overvoltage state applied to a switching element. For example, Patent Document 1 discloses a known technique for detecting an overvoltage by measuring the voltage of a high-voltage line and performing an overvoltage protection operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2012 / 077187 Summary of the Invention [Problem to be solved by the invention]

[0004] When an abnormality occurs in the overvoltage detection section, the overvoltage protection operation cannot be performed normally. Therefore, it is possible to make the overvoltage detection section redundant, but this has the problem of complicating the circuit configuration and increasing circuit costs. [Means for solving the problem]

[0005] A gate drive circuit according to the present invention is a gate drive circuit that controls a gate voltage applied to a gate terminal of a switching element provided in a semiconductor device constituting an inverter circuit or a DC-DC converter, and drives the switching element, and includes a gate drive unit that receives a PWM signal and outputs a drive signal for controlling the gate voltage based on the PWM signal, and an overcurrent detection circuit that detects an overcurrent state or an overvoltage state of the inverter circuit or the DC-DC converter, and outputs an off signal for stopping the output of the drive signal and turning off the switching element, and the gate drive unit has a low voltage side to which the PWM signal is input and a high voltage side to which the drive signal is output, which are insulated from each other, and the off signal output from the overcurrent detection circuit is input to the high voltage side in the gate drive unit without passing through the low voltage side, thereby causing the gate drive unit to stop outputting the drive signal. the overcurrent detection circuit includes a detection line connected, via a first diode, to a first signal output line that outputs an overcurrent detection voltage corresponding to a current flowing through the switching element, and connected, via a second diode, to a second signal output line that outputs a monitor voltage corresponding to a voltage of a power supply line connected to an input side of the inverter circuit or an output side of the DC-DC converter, and to which the higher of the overcurrent detection voltage or the monitor voltage is input, and a comparator that compares the voltage of the detection line with a predetermined threshold and outputs the off signal when the voltage of the detection line is equal to or higher than the threshold. . Effect of the Invention

[0006] According to the present invention, the circuit configuration for detecting an overcurrent state or an overvoltage state can be simplified, and an increase in circuit costs can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] 1 is an overall configuration diagram of a power conversion device; [Diagram 2] FIG. 2 is a detailed configuration diagram of a power conversion device. [Diagram 3] 6A to 6F are timing charts showing the operation of overvoltage protection when the sensor circuit and the overcurrent detection circuit are normal. [Figure 4] 6A to 6F are timing charts showing the operation of overvoltage protection when the sensor circuit is abnormal. [Diagram 5] FIG. 13 is a detailed configuration diagram of a modified example of the power conversion device. [Figure 6] 13A to 13F are timing charts showing the operation of overvoltage protection when an abnormality occurs in the sensor circuit in the modified example of the power conversion device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

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

[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 a switching element in the semiconductor device 300. The gate drive circuit 400b drives a switching element in the semiconductor device 301.

[0011] A controller 100 of the power conversion device 200 receives commands for driving the motor, such as torque commands and rotation commands, from a higher-level controller (not shown), and the controller 100 outputs PWM signals to the gate drive circuits 400a, 400b in response to the commands.

[0012] The voltage supplied from the high voltage battery 902 is supplied via 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 through the power supply lines 302a and 302b.

[0013] The gate drive circuit 400b performs a switching operation on the switching element of the semiconductor device 301 in response to the PWM signal, and controls the switching element to boost the DC voltage supplied to the motor 900 in cooperation with the reactor 302. That is, the gate drive circuit 400b drives the switching element that constitutes the DC-DC converter.

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

[0015] The gate drive circuit 400a drives the switching elements of the semiconductor device 300 in response to the PWM signal, and controls the torque and rotation 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 the semiconductor devices 300 and 301 has a sense emitter and outputs a current sense signal Es to the gate drive circuits 400a and 400b. The gate drive circuits 400a, 400b and a sensor circuit 140b, which will be described later, are separated by an insulating element 101 into a high voltage side HV and a low voltage side LV.

[0017] In addition, a smoothing capacitor 500b and a voltage dividing circuit 141b are provided in parallel between the positive pole P and the negative pole N of the power supply lines 300a and 300b. The voltage dividing circuit 141b is configured by connecting a plurality of resistors in series between the positive pole P and the negative pole N of the power supply line 300a. The voltage divided by the voltage dividing circuit 141b is input to the gate driving circuit 400b as an HV monitor voltage for overvoltage detection. The HV monitor voltage is input to the gate driving circuit 400b in order to stop the operation of the switching element constituting the DC-DC converter of the semiconductor device 301 when an overvoltage occurs between the positive pole P and the negative pole N of the power supply lines 300a and 300b.

[0018] Furthermore, the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b is input to the sensor circuit 140b. The sensor circuit 140b detects the voltage between the positive pole P and the negative pole N, and outputs the voltage detection signal V2 to the controller 100. Furthermore, the sensor circuit 140b detects an overvoltage between the positive pole P and the negative pole N, and outputs an overvoltage detection signal OV2 to one side of the AND gate 450. A PWM signal is input from the controller 100 to the other side of the AND gate 450. As a result, 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 rotational position sensor 901 is provided in the motor 900, and a detection value thereof is output to the controller 100. A current sensor 20 is provided between an output terminal of the semiconductor device 300 and an output terminal of the power conversion device 200, and a detection value thereof is output to the controller 100. In this way, the controller 100 controls the voltage, current, and rotation speed according to the torque of the motor 900.

[0020] Although not shown in FIG. 1, the semiconductor device 301 may have the following configuration. A voltage divider circuit is provided between the positive pole P and the negative pole N of the power supply lines 302a and 302b in parallel with the smoothing capacitor 500a, and the voltage divided by this voltage divider circuit is input to the gate drive circuit 400b as an HV monitor voltage for overvoltage detection. When an overvoltage occurs between the positive pole P and the negative pole N of the power supply lines 302a and 302b, the HV monitor voltage is input to the gate drive circuit 400b to stop the operation of the switching element constituting the DC-DC converter of the semiconductor device 301. Furthermore, a sensor circuit is provided to which the voltage between the positive pole P and the negative pole N of the power supply lines 302a and 302b is input. This sensor circuit detects the voltage between the positive pole P and the negative pole N and outputs the voltage detection signal to the controller 100.

[0021] In the following example, the present embodiment will be described as being applied to the gate drive circuit 400b, but it may also be applied to the gate drive circuit 400a. When applied to the gate drive circuit 400a, the gate drive circuit 400a detects the occurrence of an overvoltage and stops the operation of the switching elements that constitute the inverter circuit of the semiconductor device 300.

[0022] Fig. 2 is a detailed configuration diagram of the power conversion device 200. In Fig. 2, the gate drive circuit 400b shows a circuit corresponding to the lower arm, and the circuit corresponding to the upper arm is omitted, but the circuit corresponding to the upper arm has a similar configuration. In Fig. 2, the same parts as in Fig. 1 are given the same reference numerals and their explanations are omitted.

[0023] The sensor circuit 140b includes a comparator 144 that detects the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b, and the detected voltage V2 is input to the controller 100. The detected voltage V2 is also input to one terminal of a comparator 145. A threshold voltage HV_OV2 is input to the other terminal of the comparator 145. Therefore, when the detected voltage V2 exceeds the threshold voltage HV_OV2, the comparator 145 outputs an overvoltage detection signal OV2 to one terminal of an AND gate 450, and cuts 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 includes a pre-driver circuit 420, a comparator 430, an amplifier 440, a buffer circuit BF, an insulating element 101, and the like.

[0025] In a normal state where the overvoltage detection signal OV2 is not output, the PWM signal output from the controller 100 is input to the pre-driver circuit 420 via the buffer circuit BF and the insulating element 101. Then, the driver circuit 421 applies the PWM signal as a drive signal PWM_OUT 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 to drive the switching element.

[0026] A current sense signal Es is output from the switching element via a resistor Rs. An overcurrent detection voltage applied to the resistor Rs is output to one side of a comparator 430 via a diode D5. A threshold voltage Vref is input to the other side of the comparator 430. When the overcurrent detection voltage exceeds the threshold voltage Vref, the comparator 430 changes an off signal E_off from low to high via a buffer circuit BF. When the off signal E_off is high, the FET is brought into a conductive state, thereby changing a terminal G_off applied to the gate of the switching element via a resistor Rsft to low, and the switching element is soft-turned off.

[0027] The overcurrent detection circuit detects the current sense signal Es using resistor Rs, diode D5, and comparator 430, and turns off the switching element using a FET and resistor Rsft.The overcurrent detection circuit detects an overcurrent state based on the value of the current flowing through the switching element, and turns off the switching element.

[0028] The voltage divided by the voltage divider circuit 141b is connected to the detection line OC on the output side of the diode D5 of the overcurrent detection circuit as an HV monitor voltage for overvoltage detection via the diode D4. That is, the overcurrent detection circuit detects the voltage value of the detection line OC output by converting the current value into a voltage value, but the output of the voltage divider circuit 141b, which divides the voltage of the power supply line, is connected to this detection line OC. The overcurrent detection circuit detects an overcurrent state or an overvoltage state when the voltage value of the detection line OC is equal to or higher than a predetermined threshold value. Then, when the comparator 430 detects an overcurrent state or an overvoltage state, it outputs a fail signal FAIL to the controller 100 via the buffer circuit BF and the insulating element 101. In this way, in this embodiment, the circuit configuration for detecting an overcurrent state or an overvoltage state can be simplified, and an increase in circuit costs can be suppressed. Furthermore, although the sensor circuit 140b also detects an overvoltage, the detection circuit can be made redundant while simplifying the circuit configuration and suppressing an increase in circuit costs.

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

[0030] The overvoltage state is a state in which the voltage between the positive pole P and negative pole N of the power supply lines 300a, 300b becomes higher than the rated voltage of the semiconductor device 301, the smoothing capacitor 500b, etc. The overvoltage state is redundantly detected by both the sensor circuit 140b and the overcurrent detection circuit in the gate drive circuit 400b. In this case, there are cases in which both the sensor circuit 140b and the overcurrent detection circuit are operating normally and cases in which the sensor circuit 140b is operating abnormally.

[0031] The controller 100 receives the detection voltage V2 from the sensor circuit 140b, and the sub-detection voltage Sub_HV and the failure signal FAIL from the gate drive circuit 400b. The controller 100 determines that the sensor circuit 140b is abnormal if the difference between the detection voltage V2 and the sub-detection voltage Sub_HV is equal to or greater than a predetermined voltage at a voltage level at which no overvoltage occurs.

[0032] Moreover, when the detection voltage V2 and the secondary detection voltage Sub_HV are each equal to or lower than the threshold value, and the fail signal FAIL is input, the controller 100 determines that an overcurrent state exists. Furthermore, when at least one of the detection voltage V2 and the sub-detection voltage Sub_HV exceeds a threshold value and the difference between the detection voltage V2 and the sub-detection voltage Sub_HV is equal to or smaller than a predetermined voltage, the controller 100 determines that an overvoltage state has occurred.

[0033] Fig. 3 is a timing chart showing the operation of the overvoltage protection when both the sensor circuit 140b and the overcurrent detection circuit are normal. Fig. 3(A) shows the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b, Fig. 3(B) shows the voltage (solid line) of the detection line OC of the overcurrent detection circuit and the detection voltage V2 (dash line) of the sensor circuit 140b, Fig. 3(C) shows the fail signal FAIL, Fig. 3(D) shows the overvoltage detection signal OV2, Fig. 3(E) shows the drive signal PWM_OUT output from the driver circuit 421, and Fig. 3(F) shows the drive signal PWM output from the controller 100.

[0034] As shown in FIG. 3(A), the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b starts to rise at time t1. Then, when it reaches a predetermined voltage V_PN2 at time t2, the detection voltage V2 of the sensor circuit 140b exceeds the threshold voltage HV_OV2 as shown by the dashed line in FIG. 3(B). In this case, as shown in FIG. 3(D), the sensor circuit 140b outputs an overvoltage detection signal OV2. This overvoltage detection signal OV2 is output to one side of the AND gate 450, and blocks the PWM signal output from the controller 100. As shown in FIG. 3(E), the drive signal PWM_OUT of the gate drive IC 410 goes low, turning off the switching element. Also, at the same time t2, as shown by the solid line in Fig. 3(B), the voltage of the detection line OC to which the HV monitor voltage of the voltage dividing circuit 141b is connected becomes higher than the threshold voltage Vref, and the overcurrent detection circuit constituted by the comparator 430 and the like performs overvoltage protection in the same manner as the overcurrent protection of the switching element.Then, the switching element is turned off. Furthermore, as shown in Fig. 3(C), the overcurrent detection circuit inputs a fail signal FAIL to the controller 100.

[0035] That is, when both the sensor circuit 140b and the overcurrent detection circuit are normal, an overvoltage state is detected by both circuits and an overvoltage protection operation is performed.

[0036] Fig. 4 is a timing chart showing the operation of the overvoltage protection when the sensor circuit 140b is abnormal and the detection voltage V2 is outputted lower than normal. Fig. 4(A) shows the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b, Fig. 4(B) shows the voltage (solid line) of the detection line OC of the overcurrent detection circuit and the detection voltage V2 (dashed line) of the sensor circuit 140b, Fig. 4(C) shows the fail signal FAIL, Fig. 4(D) shows the overvoltage detection signal OV2, Fig. 4(E) shows the drive signal PWM_OUT outputted from the driver circuit 421, and Fig. 4(F) shows the drive signal PWM outputted from the controller 100.

[0037] As shown in FIG. 4A, the voltage between the positive pole P and the negative pole N of the power supply lines 300a and 300b starts to rise at time t1. Then, even if the voltage reaches a predetermined voltage V_PN2 at time t2, the sensor circuit 140b is abnormal and the detection voltage V2 is outputted at a low level, so the detection voltage V2 of the sensor circuit 140b does not exceed the threshold voltage HV_OV2 as shown by the dashed line in FIG. 4B. Therefore, even if the voltage between the positive pole P and the negative pole 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 shown in FIG. 4D, the voltage rises until it reaches a predetermined 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 the overvoltage detection signal OV2 is outputted. Therefore, there is a risk that the voltage between the positive pole P and the negative pole N will exceed the rated voltage of the semiconductor device 300, 301, the smoothing capacitor 500b, and the like. However, in this embodiment, since the HV monitor voltage of the voltage dividing circuit 141b is connected to the detection line OC, as shown by the solid line in FIG. 4B, at time t2 when the detection line OC exceeds the threshold voltage Vref, overvoltage protection is normally performed by the same operation as overcurrent protection. Then, as shown in FIG. 4E, the drive signal PWM_OUT of the gate driving IC 410 becomes low, turning off the switching element. Furthermore, as shown in FIG. 4C, a fail signal FAIL is input from the overcurrent detection circuit to the controller 100.

[0038] That is, even if the sensor circuit 140b is abnormal and outputs a low detection voltage V2, the overcurrent detection circuit detects an overvoltage state and performs an overvoltage protection operation.

[0039] In this embodiment, the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b is detected by the sensor circuit 140b and the overcurrent detection circuit, so that the circuit configuration can be simplified and the increase in circuit costs can be suppressed compared to the case where a circuit equivalent to the sensor circuit 140b is further provided independently.

[0040] Fig. 5 is a detailed configuration diagram of a modified example of the power conversion device 200. In Fig. 5, the gate drive circuit 400b shows a circuit corresponding to the lower arm, and the circuit corresponding to the upper arm is omitted, but the circuit corresponding to the upper arm is similar. The same reference numerals are used to designate the same parts as in Figs. 1 and 2, and the description thereof will be omitted.

[0041] In the modified example of the power conversion device 200 shown in FIG. 5, differences from the power conversion device 200 shown in FIG. 2 will be described below. The gate driving IC 410 has a built-in comparator 460 that detects an HV monitor voltage from the voltage between the positive pole P and negative pole N of the power supply lines 300a, 300b and a threshold voltage Vref_OV. That is, when the HV monitor voltage exceeds the threshold voltage Vref_OV, the comparator 460 changes an off signal E_off from Low to High via a buffer circuit BF. The circuitry following the output of the comparator 460 is shared with the overcurrent detection circuit.

[0042] Fig. 6 is a timing chart showing the operation of overvoltage protection when the sensor circuit 140b is abnormal and the detection voltage V2 is outputted lower in the power conversion device 200 shown in Fig. 5. Fig. 6(A) shows the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b, Fig. 6(B) shows the HV monitor voltage (solid line) and the detection voltage V2 (dashed line) of the sensor circuit 140b, Fig. 6(C) shows the failure signal FAIL, Fig. 6(D) shows the overvoltage detection signal OV2, Fig. 6(E) shows the drive signal PWM_OUT outputted from the driver circuit 421, and Fig. 6(F) shows the drive signal PWM outputted from the controller 100.

[0043] In the power conversion device 200 shown in FIG. 5, the timing chart showing the operation of the overvoltage protection when the sensor circuit 140b and the overcurrent detection circuit are both normal is similar to that in FIG. 3, and therefore description thereof will be omitted.

[0044] As shown in FIG. 6A, the voltage between the positive pole P and the negative pole N of the power supply lines 300a and 300b starts to rise at time t1. Then, even if it reaches a predetermined voltage V_PN2 at time t2, the sensor circuit 140b is abnormal and the detection voltage V2 is outputted at a low level, so that the detection voltage V2 of the sensor circuit 140b does not exceed the threshold voltage HV_OV2 as shown by the dashed line in FIG. 6B. Therefore, even if the voltage between the positive pole P and the negative pole 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 shown in FIG. 6D, it 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, there is a risk that the voltage between the positive pole P and the negative pole N will exceed the rated voltage of the semiconductor device 300, 301, the smoothing capacitor 500b, and the like. However, according to this embodiment, the HV monitor voltage of the voltage dividing circuit 141b is detected by the comparator 460. Therefore, at time t2 when the HV monitor voltage exceeds the threshold voltage Vref_OV, the comparator 460 normally performs overvoltage protection in the same operation as overcurrent protection. Then, as shown in FIG. 6(E), the drive signal PWM_OUT of the gate driving IC 410 becomes low, turning off the switching element. Furthermore, as shown in FIG. 6(C), a fail signal FAIL is input from the overcurrent detection circuit to the controller 100.

[0045] That is, even if the sensor circuit 140b is abnormal and outputs a low detection voltage V2, the overcurrent detection circuit detects an overvoltage state and performs an overvoltage protection operation.

[0046] 2 to 6, the gate drive circuit 400b of the switching element constituting the DC-DC converter in Fig. 1 has been described as an example, but the gate drive circuit 400a of the switching element constituting the inverter circuit is basically configured in the same way and performs the same overvoltage protection operation. That is, the inverter circuit is composed of switching elements, a sensor circuit that detects the voltage of the power supply line, and a controller to which the detection results of the sensor circuit and the overcurrent detection circuit are input, and the controller determines an abnormality in the sensor circuit based on the detection results of the sensor circuit and the overcurrent detection circuit.

[0047] In this embodiment, the voltage between the positive pole P and the negative pole N of the power supply lines 300a, 300b is detected by the sensor circuit 140b and the overcurrent detection circuit, so that the circuit configuration can be simplified and the increase in circuit costs can be suppressed compared to the case where a circuit equivalent to the sensor circuit 140b is further provided independently.

[0048] According to the embodiment described above, the following advantageous effects can be obtained. (1) The gate drive circuits 400a, 400b control the gate voltage applied to the gate terminal of the switching element to drive the switching element. The gate drive circuits 400a, 400b include an overcurrent detection circuit that detects an overcurrent state based on the value of the current flowing through the switching element. The overcurrent detection circuit receives a monitor voltage of the power supply lines 300a, 300b that are connected to the switching element and supply power to the switching element, and detects an overvoltage state when the monitor voltage is equal to or higher than a predetermined threshold. This simplifies the circuit configuration for detecting an overcurrent state or an overvoltage state, and suppresses an increase in circuit costs.

[0049] The present invention is not limited to the above-described embodiments, and other forms that are conceivable within the scope of the technical idea of ​​the present invention are also included in the scope of the present invention as long as they do not impair the characteristics of the present invention. [Explanation of symbols]

[0050] 10 low-voltage battery, 100 controller, 101 isolation element, 140b sensor circuit, 141b voltage divider circuit, 144, 145, 430, 460 comparator, 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-driver circuit, 440 amplifier, 450 AND gate, 500a, 500 b···Smoothing capacitor, 900···Motor, 902···High-voltage battery, 903···Contactor, BF···Buffer circuit, Rg, Rsft···Resistor, D4, D5···Diode, OC···Detection line, Vref, Vref_OC, Vref_OV···Threshold voltage, Sub_HV···Sub detection voltage, PWM, PWM_OUT···Drive signal, E_off···Off signal, Es···Current sense signal, V2···Voltage detection signal, OV2···Overvoltage detection signal, FAIL···Not possible signal.

Claims

1. A gate drive circuit that controls a gate voltage applied to a gate terminal of a switching element provided in a semiconductor device constituting an inverter circuit or a DC-DC converter, and drives the switching element, a gate driver that receives a PWM signal and outputs a drive signal for controlling the gate voltage based on the PWM signal; an overcurrent detection circuit that detects an overcurrent state or an overvoltage state of the inverter circuit or the DC-DC converter and outputs an OFF signal for stopping output of the drive signal and turning off the switching element, The gate driver has a low voltage side to which the PWM signal is input and a high voltage side to which the drive signal is output, the low voltage side being insulated from the high voltage side, The off signal output from the overcurrent detection circuit is input to the high voltage side of the gate driver without passing through the low voltage side, thereby causing the gate driver to stop outputting the drive signal; The overcurrent detection circuit includes: a detection line connected via a first diode to a first signal output line that outputs an overcurrent detection voltage corresponding to a current flowing through the switching element, and connected via a second diode to a second signal output line that outputs a monitor voltage corresponding to a voltage of a power supply line connected to the input side of the inverter circuit or the output side of the DC-DC converter, and into which the higher of the overcurrent detection voltage or the monitor voltage is input; a comparator that compares the voltage on the detection line with a predetermined threshold and outputs the off signal when the voltage on the detection line is equal to or greater than the threshold.

2. 2. The gate drive circuit of claim 1, the overcurrent detection circuit outputs a predetermined disable signal to an external device when the overcurrent state or the overvoltage state is detected; The gate drive circuit, in which the off signal and the disable signal are insulated from each other.

3. A gate drive circuit according to claim 1 or 2; The DC-DC converter; a sensor circuit for detecting a voltage of the power supply line connected to an output side of the DC-DC converter; a controller to which the detection results of the sensor circuit and the overcurrent detection circuit are input, The controller determines whether or not the sensor circuit is abnormal based on detection results of the sensor circuit and the overcurrent detection circuit.

4. A gate drive circuit according to claim 1 or 2; The inverter circuit; a sensor circuit for detecting a voltage of the power supply line connected to an input side of the inverter circuit; a controller to which the detection results of the sensor circuit and the overcurrent detection circuit are input, The controller determines whether or not the sensor circuit is abnormal based on detection results of the sensor circuit and the overcurrent detection circuit.

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