A kind of igbt overcurrent protection circuit and method thereof

Abstract

The invention discloses an IGBT over-current protection circuit and method. The IGBT over-current protection circuit comprises a current collecting circuit which uses a current sensor to acquire a current flowing through C and E ends of an IGBT and convert the current into a voltage signal to output; a signal conditioning circuit for processing the voltage signal and outputting a current signal; a peak value circuit for holding the current signal; and a comparison circuit which uses a comparator to comparing the current signal with a protective threshold, and outputting a pulse signal to turn off the IGBT. For the IGBT, the IGBT damage caused by overlarge break-over current of the IGBT is prevented, the risk of the over-current of the IGBT is reduced, the service life of the device is prolonged, and the reliability of a system using the IGBT device is improved. The peak-holding circuit is used to achieve turn-off delay protection, and once the protection is triggered, the IGBT break-over control is ineffective in the holding time.

Description

technical field [0001] The invention relates to the field of electronic devices, in particular to an IGBT overcurrent protection circuit, the shutdown overvoltage protection caused by the overcurrent protection, and an overcurrent and overvoltage protection method thereof. Background technique [0002] Insulated gate bipolar transistor IGBT has the characteristics of high input impedance, fast switching speed, low driving power, low saturation voltage, simple control circuit and large current, so it is widely used in power electronic equipment. [0003] When the IGBT is short-circuited and over-current, if it is not protected quickly, it is easy to exceed the thermal limit, latch-up effect, device over-voltage breakdown, etc., resulting in device failure. For example, when the IGBT is turned off, its collector current drops at a high rate, especially in the case of a short-circuit fault. If no soft-off measures are taken, its critical current drop rate will reach thousands o...

AI Technical Summary

Problems solved by technology

[0003] When the IGBT is short-circuited and over-current, if it is not protected quickly, it is easy to exceed the thermal limit, the latch-up effect, and the overvoltage breakdown of the device will cause the device to fail.

For example, when the IGBT is turned off, its collector current drops at a high rate, especially in the case of a short-circuit fault. If no soft-off measures are taken, its critical current drop rate will reach thousands of amperes per microsecond, so Will cause damage to the IGBT, and even cause the device to fail

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