Transient Thermal Impedance Measurement of HPD Power Modules

HybridPACK Drive (HPD) power modules, which exhibit high power density and high reliability, have gained significant traction in the realm of electric vehicles. In order to evaluate thermal performance of the device, transient thermal impedance of HPD power modules holds great significance. This study focuses on HPD power IGBT modules, with the objective of examining transient thermal impedance measurement results under various test conditions through multiple sets of experiments, encompassing cooling liquid flow, heating methods, measurement terminals, inlet temperature, and liquid types. It is demonstrated that cooling liquid flow and types of liquids do not significantly impact the junction-to-baseplate thermal resistance, while the baseplate-to-liquid and steady-state thermal resistance are affected. When heating the upper and lower switches of the same phase simultaneously, the observed results are greater than those under other conditions, as a result of thermal coupling. In addition, it is indicated that inlet temperature has minimal influence on the measurement results. Finally, the utilization of sensor terminals is necessary for measuring voltage, while load terminals are not recommended due to potential interference from external wires.