Device for inhibiting voltage stress of IGBT

Abstract

The invention discloses a device for inhibiting voltage stress of IGBT, and the device comprises a driving unit which is used for driving an IGBT; an active clamping unit used for IGBT overvoltage protection and comprising at least one TVS and a diode which are connected in series; a detection unit that detects an operation signal of the active clamping unit; and a switch control unit, wherein an input end of the switch control unit is connected with the output end of the driving unit, the output end is connected with the gate pole of the IGBT, and the control end is connected with the output end of the detection unit; when the IGBT is in an overvoltage state, the detection unit detects an action signal and outputs a first signal for turning off the switch control unit, and when the IGBT works normally, the detection unit does not detect the action signal and outputs a second signal for turning on the switch control unit. According to the invention, the turn-off speed of the IGBT can be slowed down, the voltage stress between the collector electrode and the emitter electrode of the IGBT can be effectively suppressed, and the speed and the reliability are high; and the voltage between the collector electrode and the emitter electrode of the IGBT is effectively clamped.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a device for suppressing voltage stress of an IGBT. Background technique [0002] Insulated gate bipolar transistors (Insulated Gate Bipolar Transistor, IGBT) are widely used in power electronic circuit devices, and often work under high voltage and high current conditions. In high-voltage and high-power applications, IGBTs often bear relatively large currents, and IGBT overcurrent is an important cause of IGBT device damage. In practical applications, due to load overload, external interference, internal signal errors and other reasons, the current of the IGBT device will increase sharply and exceed its capacity limit. At this time, the IGBT device needs to be turned off for protection to avoid IGBT overheating and damage. [0003] In the process of IGBT over-current shutdown, the induced electromotive force generated on the stray inductance of the IGBT shutdown commu...

AI Technical Summary

Problems solved by technology

[0005] but yes figure 1 After analysis, it is found that when the TVS reversely breaks down, when the current is injected into the gate of the IGBT through the TVS, a part of i will also be bypassed by the drive circuit. Rg , In this way, the loss of injection current weakens the inhibitory effect on the gate voltage drop speed, so the IGBT gate voltage drop speed is accelerated, so that, on the one hand, the voltage stress between the IGBT collector and emitter increases, resulting in active clamping The effect is weakened. On the other hand, the increase in the voltage stress between the collector and the emitter will also lead to an increase in the breakdown of the TVS, and an increase in the breakdown current, which in turn leads to an increase in the TVS heat loss, and the TVS temperature rise is too large. At the same time, the clamping of the TVS voltage bias

[0006] Therefore, using figure 1 In the existing technology to suppress the reliability of the voltage stress between the collector and the emitter during the IGBT turn-off process, the reliability is poor, which affects the active clamping effect and the service life of the TVS

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