An Online Frequency-Domain Junction Temperature Estimation Method for IGBT Modules

This letter proposes a new frequency-domain thermal model for online junction temperature estimation of insulated-gate bipolar transistor (IGBT) modules. The proposed model characterizes the thermal behavior of an IGBT module by a linear time-invariant (LTI) system, whose frequency response is obtained by applying the fast Fourier transform (FFT) to the time derivative of the transient thermal impedance from junction to a reference position of the IGBT module. The junction temperature of the IGBT is then estimated using the frequency responses of the LTI system and the heat sources of the IGBT module. Simulation results show that the proposed method is computationally efficient for an accurate online junction temperature estimation of IGBT modules in both steady-state and transient loading conditions.