Application of a Short-Circuit Protection by Using Gate Charge Characteristic to Three Parallel Connected IGBT Modules

This paper describes an application of a protection circuit with gate charge characteristic against hard-switching fault (HSF) to multiple parallel connected IGBT modules. Gate charge characteristic under HSF differs from that under normal turn-on operations because the gate-emitter voltage has no Miller plateau under HSF. Hence, HSF can be detected by monitoring a gate-emitter voltage and a gate charge. The authors have presented that the method was applicable to discrete power devices such as Si-IGBT or SiC-MOSFET and single IGBT module.For multiple parallel connected power modules, only one detection circuit is enough for detecting and protecting the IGBT modules because the gate charge characteristic of each IGBT module connected in parallel is almost the same. However, no papers have been reported on the application of the protection methods including the one which monitors gate charge characteristic.The proposed circuit can detect HSF and turn off the IGBTs within 750 ns later after the collector current starts flowing through the IGBT modules. Experimental results verify that the method is applicable to three parallel connected IGBT modules.