Modeling and Simulation of Junction Temperature Rise of GaN Devices for Class D Resonant Converters

Reliability of power electronic devices is related to their thermal performance. This paper presents the development of an electro-thermal model used to estimate junction temperature rise from self-heating effect in a GaN FET. Transient thermal impedances of the power device and the customized heat sink are extracted as a Foster thermal network before converting to a Cauer network to allow direct integration between multiple thermal networks. The proposed thermal impedance networks provide junction temperature information to the temperature-dependent SPICE model of the GaN FET so that self-heating effect is captured. The model is validated in SPICE simulation using a class D resonant converter as a case study. The results reveal the tendency of mismatch device temperature over a period of time posing a concern for the converter.