Power Conversion Device

Abstract

A power conversion device capable of protecting a power semiconductor using a simple method is provided. [Solution] The power conversion device includes a power semiconductor element, a gate substrate including a gate circuit for driving the power semiconductor element, a control substrate including a control circuit that outputs a gate signal to control the gate circuit, and a short-circuit protection substrate between the power semiconductor element and the gate substrate for detecting a short circuit of the power semiconductor element based on the collector-emitter voltage of the power semiconductor element.

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device. [Background technology]

[0002] In recent years, power semiconductors have been used in power conversion equipment, and short-circuit protection has become extremely important from the perspective of protecting the equipment and preventing damage from spreading.One method of short-circuit protection is to use the circuit that drives the power semiconductor, and it is required to operate at high speed and without malfunction, without being affected by equipment noise, etc.

[0003] In this regard, a method has been proposed in the past to protect power semiconductors by detecting short circuits in a gate circuit (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-5913 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in the case of a method of detecting short circuits in the gate circuit, there is a problem that there may be variation in the cable length between the gate circuit and the power semiconductor, which causes variations in the short circuit detection constant and requires adjustment.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a power conversion device that can protect power semiconductors using a simple method. [Means for solving the problem]

[0007] The power conversion device of the present disclosure includes a power semiconductor element, a gate substrate including a gate circuit for driving the power semiconductor element, a control substrate including a control circuit that outputs a gate signal for controlling the gate circuit, and a short-circuit protection substrate between the power semiconductor element and the gate substrate for detecting a short circuit of the power semiconductor element based on the collector-emitter voltage of the power semiconductor element.

[0008] Preferably, the short circuit protection substrate is disposed near the power semiconductor element. Preferably, the short circuit protection board includes a communication circuit that transmits the short circuit detection signal to the control circuit by wireless communication.

[0009] Preferably, the control circuit receives the short-circuit detection signal transmitted from the communication circuit and stops the gate signal output to the gate circuit. [Effects of the Invention]

[0010] The power conversion device of the present disclosure can protect the power semiconductors in a simple manner. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a configuration of a power conversion device 1 based on an embodiment. [Figure 2] 10 is a diagram illustrating the relationship between a substrate on which a circuit for driving a switching element Q is mounted, which is a comparative example. FIG. [Figure 3] 10A and 10B are diagrams illustrating the relationship between a substrate on which a circuit for driving a switching element Q is mounted according to an embodiment. [Figure 4] 10A and 10B are diagrams illustrating the relationship between a substrate on which a circuit for driving a switching element Q is mounted according to a modified example of the embodiment. [Figure 5] 10A and 10B are diagrams illustrating the configuration of a short-circuit protection substrate DP# based on a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present embodiment will be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0013] Fig. 1 is a diagram illustrating the configuration of a power conversion device 1 according to an embodiment. Referring to Fig. 1, the power conversion device 1 includes a converter 3 connected to an AC system and generating a DC voltage, a smoothing capacitor 5 smoothing the output voltage of the converter 3, and an inverter 2 converting the DC voltage into a three-phase AC voltage.

[0014] The three-phase AC voltage from the inverter 2 is supplied to a motor, which is a load. Inverter 2 is composed of upper switching elements Q1, Q3, Q5 (hereinafter also referred to as switching elements Q) for the U, V, and W phases, lower switching elements Q2, Q4, and Q6 for the U, V, and W phases, and diodes connected in anti-parallel to each of switching elements Q1 to Q6.

[0015] A current sensor 6 is provided to detect the output current from the inverter 2 to the motor. A signal detected by the current sensor 6 is input to a control circuit 50.

[0016] The control circuit 50 outputs a gate signal for controlling the motor to the gate drive circuit 10 based on the frequency command and the signal detected by the current sensor 6. The gate drive circuit 10 applies a gate drive signal to each of the switching elements Q1 to Q6 based on the gate signal from the control circuit 50.

[0017] This configuration makes it possible to control the motor according to a given frequency command. The switching elements Q1 to Q6 are assumed to be made up of, for example, high-voltage insulated gate bipolar transistors (IGBTs), although the invention is not limited to this example.

[0018] Fig. 2 is a diagram illustrating the relationship between a substrate mounted with a circuit for driving a switching element Q, which is a comparative example. Referring to Fig. 2, a conventional configuration is shown as a comparative example. Specifically, a gate drive circuit 100, a short-circuit detection circuit 200, and a photocoupler 300 are provided on a gate substrate GP. A control circuit 500 is provided on a control substrate CP.

[0019] The gate drive circuit 100 outputs a gate drive signal to control the switching element Q. It controls the voltage between the gate and emitter of the IGBT. The short circuit detection circuit 200 detects a short circuit in the switching element Q, which is an IGBT. Specifically, the short circuit detection circuit 200 detects the collector-emitter voltage (Vce) of the IGBT, and based on voltage information (Vce information) indicating the Vce detection result, if a short circuit current flows through the corresponding switching element Q, the short circuit detection circuit 200 detects the short circuit current and outputs the signal to the control circuit 500. At this time, a short circuit detection signal is output to the control circuit 500 of the control board CP using a photocoupler 300. When a short circuit occurs due to an IGBT element failure, a large current flows, causing the voltage across the element to rise even though the element is in the on state due to the element's characteristics. Therefore, the short circuit current can be detected by monitoring this voltage.

[0020] When the control circuit 500 receives a short circuit detection signal from the short circuit detection circuit 200 via the photocoupler 300, it stops outputting the gate signal to the gate drive circuit 100.

[0021] On the other hand, it is necessary to set an optimal detection filter constant in order to detect a short circuit with the short circuit detection circuit 200. In this regard, if the wiring length between the short circuit detection circuit 200 provided on the gate substrate GP and the IGBT switching element changes, the parasitic parameters derived from the wiring also change, so it was necessary to set adjustment parameters for each IGBT switching element.

[0022] 3 is a diagram illustrating the relationship between substrates on which a circuit for driving a switching element Q according to an embodiment is mounted. Referring to FIG. 3, the configuration of the embodiment differs from the configuration of FIG. 2 in that a short-circuit protection substrate DP is newly provided.

[0023] The short-circuit protection substrate DP includes a short-circuit detection circuit 20. The short-circuit protection substrate DP is disposed near the switching element, which is an IGBT.

[0024] The short circuit detection circuit 20 detects the collector-emitter voltage (Vce) of the IGBT, and based on voltage information (Vce information) indicating the Vce detection result, if a short circuit current flows through the corresponding switching element Q, it detects the short circuit current and outputs a short circuit detection signal to the photocoupler 30. The photocoupler 30 outputs the short circuit detection signal to the control circuit 50 on the control board CP. When a short circuit occurs due to an IGBT element failure, a large current flows, causing the voltage across the element to rise despite the element being in the on state due to the element's characteristics, and therefore the short circuit current can be detected by monitoring this voltage.

[0025] When the control circuit 50 receives a short circuit detection signal from the short circuit detection circuit 20 via the photocoupler 30, it stops outputting the gate signal to the gate drive circuit 10.

[0026] Compared to the configuration of the comparative example, the short circuit detection circuit 20 according to the embodiment is provided near the switching element. Therefore, it is possible to suppress variations in the wiring length between the short circuit detection circuit 20 provided on the short circuit protection substrate DP and the IGBT switching element, and it is also possible to suppress variations in parasitic parameters due to the wiring. In other words, since it is not necessary to set adjustment parameters for each IGBT switching element, highly accurate short circuit detection is possible, and it is possible to protect the power semiconductor with a simple method.

[0027] (Variation) 4 is a diagram illustrating the relationship between a substrate mounted with a circuit for driving a switching element Q according to a modified example of the embodiment. Referring to FIG. 4, the configuration of the modified example of the embodiment differs from the configuration of FIG. 3 in that a short circuit detection signal is transmitted via wireless communication.

[0028] Specifically, a short-circuit protection substrate DP# is provided in place of the short-circuit protection substrate DP, a gate substrate GP# is provided in place of the gate substrate GP, and a control substrate CP# is provided in place of the control substrate CP.

[0029] The short-circuit protection substrate DP# further includes a communication IC 40 in comparison with the short-circuit protection substrate DP. The communication IC 40 is connected to the short circuit detection circuit 20 and transmits the short circuit detection signal output by the short circuit detection circuit 20 as a wireless communication failure signal.

[0030] Compared to the control board CP, the control board CP# further includes a communication IC 60. The communication IC 60 is provided so as to be communicatively connectable to the communication IC 40. In this example, the communication IC 60 receives a wireless communication fault signal transmitted from the communication IC 40 and outputs the received signal to the control circuit 50.

[0031] When the control circuit 50 receives a short circuit detection signal from the short circuit detection circuit 20 via the communication IC 40 and the communication IC 20, the control circuit 50 stops outputting the gate signal to the gate drive circuit 10.

[0032] The gate substrate GP# differs from the gate substrate GP in that the photocoupler 30 is omitted.

[0033] In the configuration of this example, the short-circuit detection signal is transmitted via wireless communication, which allows for a reduction in the amount of wiring to the gate substrate GP#. Furthermore, the wireless communication fault signal can be transmitted directly to the control substrate CP# without going through the gate substrate GP#, allowing for the short-circuit detection signal to be notified to the control circuit 50 at high speed. Furthermore, the elimination of photocoupler 30 also allows for a reduction in the layout of the gate substrate GP#.

[0034] 5A and 5B are diagrams illustrating the configuration of a short-circuit protection substrate DP# based on a modified example of the embodiment. Referring to Fig. 5A, the appearance of the short-circuit protection substrate DP# is shown.

[0035] The short-circuit protection substrate DP# is provided near the substrate of the IGBT switching element. The short-circuit protection substrate DP# also includes a communication IC 40. The short-circuit protection substrate DP# is provided as a configuration in which the short-circuit detection circuit 20 and the communication IC 40 are integrated into a single package.

[0036] 5(B), a top view of the IGBT switching element substrate and short circuit protection substrate DP# is shown. The short circuit protection substrate DP# includes a short circuit detection circuit 20 and a communication IC 40. A connector CN is also provided so as to be connectable to a connector CNP provided on the IGBT switching element substrate.

[0037] 5(C), a side view of the IGBT switching element substrate and the short circuit protection substrate DP# is shown. The connector CN provided on the short circuit protection substrate DP# is docked with the connector CNP by inserting it from above into the connector CNP on the IGBT switching element substrate.

[0038] By connecting the packaged short-circuit protection substrate DP# and the switching element substrate via a connector, it is possible to fix the detection filter constant of the short-circuit detection circuit 20. In other words, since it is possible to fix the adjustment parameters for each IGBT switching element, highly accurate short-circuit detection becomes possible, and it is possible to protect the power semiconductor with a simple method.

[0039] In this embodiment, information on the collector-emitter voltage (Vce) of each switching element is used to detect the short-circuit current flowing through that switching element, but the present invention is not limited to this example. The short-circuit current can also be detected using information other than the above-mentioned Vce (for example, information on the gate charge (Qq) obtained by integrating the gate current (Ig) of the corresponding switching element, information on the gate-emitter voltage (Vge), or information on the arm current flowing through one arm formed by each switching element).

[0040] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0041] 1 Power conversion device, 2 Inverter, 3 Converter, 5 Smoothing capacitor, 6 Current sensor, 10,100 Gate drive circuit, 20,200 Short circuit detection circuit, 30,300 Photocoupler, 50,500 Control circuit, CP,CP# Control board, DP,DP# Short circuit protection board, GP,GP# Gate board.

Claims

1. a power semiconductor element; a gate substrate including a gate circuit for driving the power semiconductor element; a control board including a control circuit that outputs a gate signal for controlling the gate circuit; A power conversion device comprising: a short-circuit protection substrate between the power semiconductor element and the gate substrate for detecting a short circuit of the power semiconductor element based on a collector-emitter voltage of the power semiconductor element.

2. The power conversion device according to claim 1 , wherein the short-circuit protection board is disposed near the power semiconductor element.

3. The power conversion device according to claim 1 , wherein the short circuit protection board includes a communication circuit that transmits a short circuit detection signal to the control circuit by wireless communication.

4. The power conversion device according to claim 1 , wherein the control circuit receives a short-circuit detection signal transmitted from a communication circuit and stops outputting the gate signal to the gate circuit.

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