Current sharing of IGBT modules in parallel with thermal imbalance

For large current, switching devices such as MOSFET and IGBT, often have to be connected in parallel. Due to this reason, derating and preselection of the switching devices become necessary to develop high-power converters. The current imbalance can be produced by stray inductances, device characteristic difference or asymmetric circuit. Moreover, thermal imbalance is another important reason for current balancing. The static and transient characteristics of an IGBT vary sensitively with its junction temperature. This paper focuses on the current sharing of IGBTs in parallel with thermal imbalance. In this paper, an active gate control method which can achieve current balancing of the IGBTs in parallel with thermal imbalance, is explained and verified by experiments. This method can be applied to an actual 160kW/380V power electronics converter prototype for improving the utilization of the switching devices and enhancing system reliability.