Thermal Impedance Computation of a SiC Power Module for Traction Inverter in Electric Vehicle Applications

In this work, a method to thermally characterize a power semiconductor module based on silicon carbide for traction inverters is presented. In general, this is important in order to determine the real thermal behavior of the system and, consequently, to forecast the application reliability performances. Thermal impedance is measured by a dedicated bench, capable to heat power module by applying a constant current, yet ensuring a controlled liquid cooling environment. The obtained experimental curve is then translated into a system made by several RC ports, obtained employing convolution’s algorithms. Solving the related differential equations, temperature profile can be obtained as function of time. Considering the actual application power loss, the related temperature profile can be calculated and collected in a discrete number of different load cases characterized by a duration and a thermal swing.