JP2002142443A - Protection circuit of ic for driving power semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakdown by protecting an IC for driving a power semiconductor device from malfunction. SOLUTION: Diodes 8 and 9 are connected between the anode of a diode (DS) 4 for detecting a voltage VCE between a collector and an emitter when a device 1 is turned on to a driving IC 3 for driving the power semiconductor device 1 such as IGBTs and the positive and ground sides of a power supply 5 for driving ICs, and the reverse recovery current of the DS 4 and a current flowing when the transition of a FWD 2 is on are allowed to flow to the diodes 8 and 9 to protect the IC 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection circuit for an IC (integrated circuit) for driving a power semiconductor element such as an insulated gate bipolar transistor (abbreviated as IGBT).

[0002]

2. Description of the Related Art FIG. 3 shows a conventional example. In the figure, 1
Is an IGBT, 2 is a freewheeling diode (FW
D), 3 denotes an element driving IC for driving the IGBT 1, 4 denotes a diode (DS), and 5 denotes an IC driving power supply. Here, the diode DS4 can detect the collector-emitter voltage V _CE when the IGBT 1 is on when controlling the on / off of the IGBT 1, and can detect the V _CE voltage at the lowest cost. It has been widely used. The detection of the V _CE voltage is
Specifically, as shown in FIG. 4, a constant current Iic is supplied from the current source I in the IC 3 in the direction of the arrow, and the V _CE0 voltage in the IC 3 is measured, thereby _{obtaining the} value from the following equation (1). . V _CE = V _CE0 −R · Iic−V _DS (1)

[0003]

In the circuit of FIG. 3, IG
When BT1 turns off, DS recovers in reverse. At this time, the reverse recovery current Ir flows as shown by the dotted line in FIG. 4, and when the current value is large, a positive voltage VA as shown by the following equation (2) is applied to the input terminal a of the IC, If this exceeds the IC standard, it may be destroyed. Note that V _CC
Indicates a power supply voltage for driving the IC. VA = V _cc + Ir · R (2) Further, when a large current flows through the diode D1 inside the IC, a parasitic circuit inside the IC operates and causes a malfunction of the IC.

On the other hand, a voltage having a polarity as shown in FIG. 5 is generated by a transient on-voltage of the FWD connected in parallel with the IGBT. At this time, not only does the current flow through the IC as indicated by the dotted line, but also a negative voltage is applied to the input terminal a, and there is a possibility that the IC will break down and a malfunction will occur due to the current flowing through the diode D2. . Therefore, an object of the present invention is to provide an IC for driving a power semiconductor element.
On the other hand, it is an object of the present invention to prevent the reverse recovery current of the DS or the current at the time of the transient ON of the FWD from flowing, thereby protecting the IC from destruction or malfunction.

[0005]

In order to solve the above-mentioned problems, according to the present invention, in a protection circuit of an IC for driving a power semiconductor device of a power converter, a collector circuit of the power semiconductor device is provided. In order to detect an emitter-to-emitter voltage, a second diode and a third diode are respectively connected between the anode of the first diode connected to the collector of the power semiconductor element and the positive power supply and ground potential of the IC driving power supply. It is characterized by connecting.

According to a second aspect of the present invention, in a protection circuit of an IC for driving a power semiconductor device of a power converter, a collector of the power semiconductor device is detected to detect a collector-emitter voltage of the power semiconductor device. A second diode is provided between the anode of the first diode connected to the first power supply and the positive power supply of the IC drive power supply, and a second diode is provided between the anode of the first diode and the ground potential side of the IC drive power supply. It is characterized in that Zener diodes are connected respectively.

[0007]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. As is apparent from FIG.
To detect the collector-emitter voltage V _CE of GBT1, diode D is connected to the collector of IGBT1
Diodes 8 and 9 are connected between the anode of S4 and the positive potential and ground potential of the IC driving power supply 5, respectively. As a result, the reverse recovery current of the DS4 and the current flowing when the FWD is transiently turned on are reduced by the diodes 8, 9
, The IC can be protected from destruction or malfunction.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention. This shows a modification of FIG. 1, and is configured by replacing the diode 9 of FIG. This ensures that the potential of the input terminal a of the IC circuit is suppressed to the Zener voltage or less.

[0009]

According to the present invention, the current flows through the diode or the Zener diode connected outside the IC circuit even during the reverse recovery current of the DS or the transient ON of the FWD, so that the potential of the input terminal of the IC circuit is reduced. Does not become higher or lower than a certain potential, and IC destruction and malfunction can be avoided. Further, by connecting a Zener diode instead of a diode between the ground and the ground, the potential of the input terminal of the IC circuit is reliably suppressed to a Zener voltage or less, so that the reliability can be improved as compared with the diode.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a conventional example.

FIG. 4 is an explanatory diagram of a reverse recovery current of DS in FIG. 3;

5 is an explanatory diagram of a reverse recovery voltage of the FWD in FIG.

[Explanation of symbols]

1. IGBT (insulated gate bipolar transistor),
2 ... FWD (free wheeling diode), 3 ... I
C (integrated circuit), 4 ... diode for current detection (DS),
5: IC drive power supply, 6, 7, 8, 9 ... diode, 10
... Zener diode, I ... current source.

Continued on the front page F-term (reference)

Claims (2)

[Claims] 1. A protection circuit for an IC for driving a power semiconductor device of a power conversion device, wherein a protection circuit connected to a collector of the power semiconductor device for detecting a collector-emitter voltage of the power semiconductor device. A protection circuit for a power semiconductor element driving IC, wherein a second diode and a third diode are respectively connected between an anode of one diode and a positive power supply and a ground potential side of the IC driving power supply. 2. A protection circuit for an IC for driving a power semiconductor device of a power conversion device, wherein a protection circuit connected to a collector of the power semiconductor device for detecting a collector-emitter voltage of the power semiconductor device. A second diode is connected between the anode of the first diode and the positive power supply of the IC driving power supply, and a Zener diode is connected between the anode of the first diode and the ground potential side of the IC driving power supply. A protection circuit for an IC for driving a power semiconductor element.