IGBT junction temperature estimation via gate voltage plateau sensing

A method for in-situ high bandwidth junction temperature estimation of Insulated Gate Bipolar Transistors (IGBTs) is introduced. The method is based on the acquisition of the gate voltage plateau during turn-on, which can be directly related to the junction temperature. This allows fast over temperature protection of the power device and thus enables operation at the boundary of the device safe operation area. Firstly, this paper discusses the underlying physical mechanisms. Secondly, the temperature sensitivity and the impact of interferences over the entire operation range of an IGBT. Finally, a sensing circuitry is presented, which allows accurate gate voltage plateau sensing every switching period as well as an easy integration into the gate driver. The performance of the proposed method is experimentally demonstrated over a wide range of temperatures and currents.