1D Thermo-Fluid Model for Electric Vehicle Traction Inverter

Thermal management solutions in power electronics applications are of prime importance to meet the needs of the ever-increasing demands on higher power and torque density of the traction motor and controller. Traction inverters are essential power electronic devices that convert direct current (DC) supply from the battery pack of the vehicle to three-phase alternating current (AC) output and vice versa. Estimation of die junction temperatures and cooling system pressure drop is necessary for assessing the maximum heat load capacity of the traction inverter system and coolant pump capacity requirements. The system comprises of a power module and a water–glycol–based cooling domain with heat sink. This article proposes a 1D model for accurate predictions of junction temperatures on the SiC die, temperature rise of the cooling medium, and pressure drop across a custom heat sink fluid domain. The model is built to handle steady-state and transient conditions for varying heat loads on the die. Validation of the model is carried out by comparing the results and calibrating it with computational fluid dynamic simulations. The cooling domain is optimized by controlling the parameters of the heat sink to provide better cooling efficiency and maintain uniform temperatures across different power modules. The 1D model is able to predict thermal performance within 5% error from the CFD results. The developed model can also be used for other power electronic cooling or heat exchanger systems with liquid cooling.