A protection circuit and method with high-speed detection of igbt short-circuit fault

Abstract

The invention is a protection circuit with high-speed detection of IGBT short-circuit faults, including a detection control circuit, an HSF short-circuit detection circuit, a FUL short-circuit detection circuit, an OR gate logic circuit, a gate drive circuit, a soft turn-off circuit and a gate resistor R G . The invention also discloses a method for protecting the IGBT short-circuit fault. The present invention respectively detects two short-circuit types of hard switch short-circuit fault and on-load short-circuit fault, proposes a corresponding detection circuit, and sets a detection control circuit to control the working state of the short-circuit detection circuit; the soft-off circuit short-circuits the IGBT Turn off the processing, and lock the output signal of the drive circuit at the same time. Invention on gate voltage V GE and drive voltage V GG For detection, the detection circuit is simple, the short-circuit detection time is short, the short-circuit fault can be processed quickly and reliably, and the power device is effectively protected.

Description

technical field [0001] The invention belongs to the field of drive protection of power switching devices, and in particular relates to a short-circuit protection method and circuit using IGBT as a power switching device. Background technique [0002] Insulated Gate Bipolar Transistor (IGBT) has the advantages of on-state voltage drop, large current capacity, high input impedance, fast response, and simple control. Widely used in power electronic equipment. However, various faults are prone to occur when the power device IGBT is applied, and the IGBT short-circuit fault is one of the most common faults. Under normal circumstances, IGBT short-circuit faults can be divided into two categories, hard switching short-circuit fault (HSF, Hard Switching Fault) and load short-circuit fault (FUL, Fault UnderLoad). When the IGBT is turned on, the loop impedance is quite small. The on-load short-circuit fault refers to the short-circuit of the load after the IGBT has been turned on a...

AI Technical Summary

Problems solved by technology

The disadvantages of this short-circuit detection and protection scheme are: firstly, the circuit is not isolated from the power stage, and false detection is prone to occur; secondly, due to the existence of the delay circuit 1, the circuit needs a blanking time of 1~5us before the detection circuit can detect the short-circuit fault , so the HSF short-circuit fault cannot be quickly detected, and the short-circuit detection time is longer, which increases the risk of IGBT damage

Gate charge sensing circuit output voltage V QG represents the change in gate charge, the reference voltage V REFT3 is the gate voltage V GE related quantity, when the IGBT is operating normally, the voltage V QG higher than the reference voltage V REFT3 , when the IGBT is short-circuited, the voltage V QG below the reference voltage V REFT3 , the disadvantages of this method are: one is that the design of the gate charge detection circuit is difficult, and the other is that the gate charge change of the low-power IGBT is small, and it is not easy to distinguish

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