Modeling and Analysis of a Liquid-Cooled Heat Sink for Inverters Used in Hybrid Electric Vehicles

Abstract

This study presents the experimental characterization and dynamic thermal modeling of a liquid-cooled inverter heatsink for electric vehicle traction applications. The proposed approach considers the entire inverter housing as the heatsink and experimentally validates its thermal behavior under realistic operating conditions. Specifically, the heat transfer system was modeled using a Cauer equivalent circuit. The characterization yielded a thermal resistance of 16.75 mC/W and a thermal capacitance of 6444.3 J/C. The model validation was performed on a dynamometer bench with the inverter operating at an input power of 65.86 kW. Under these conditions, the system dissipated 2.34 kW of total power losses, resulting in average IGBT case temperatures of approximately 77 C. The comparison between the experimental measurements and the model estimates, which predicted a case temperature of 80.48 C, demonstrates the accuracy and reliability of the developed thermal model for this inverter-heatsink configuration.