Estimation Method for Turn-off Collector Voltage of IGBTs Using Emitter-auxiliary Inductor

This paper presents a method for estimating the instantaneous turn-off collector voltage of high-power IGBT modules. Because of the parasitic inductors in circuit, the fast turn-off collector current usually leads to a voltage overshoot on IGBT modules during the turn-off transition. In terms of highvoltage and high-power IGBT module, there exists an emitterauxiliary inductor between the power emitter and Kelvin emitter. The same variable di(c)/dt during turn-off transition will also induce a measurable voltage veE across the emitter-auxiliary inductor LeE. As a result, the hazardous turn-off peak collector voltage can be reflected by the induced veE in the case of fixed commutation loop inductors and emitter auxiliary inductor. Finally, a double pulse test platform is used to validate the effectiveness of estimation method. The estimation curves of turn-off collector voltage are in accordance with the experimental results.