A current sensorless IGBT junction temperature extraction method via parasitic parameters between power collector and auxiliary collector

The extraction of junction temperature Tj plays a critical role in the IGBT module reliability. In recent years, the extraction of Tj via parasitic parameters has drawn much attention for its ability to be integrated in the driver circuit. However, the aging of modules can affect the parasitic parameters, leading to the inaccuracy of Tj extraction when fatigue and aging occurs. Firstly, this paper analyzes the inner structure and equivalent circuit of IGBT modules in detail and proves the parasitic parameters of collector far less susceptible from aging than parameters of gate and emitter. Secondly, an enhanced Tj extraction method via the parasitic parameters between the power collector and auxiliary collector is presented. Besides, Due to the decoupling of this method from the driver current, the load current can be acquired accurately with an integrator, which exempts the extraction from the need of a current sensor. Finally, a series of verification tests are handled to verify the validation and accuracy of the method.