A calorimetric method for measuring power losses in power semiconductor modules

In this paper, a calorimetric method is presented to measure the total inverter power losses, for the purpose of validation of automotive main inverter mission profile analysis. Automotive main inverters operate in the partial-load condition (less than a quarter of the nominal current) for more than 90% of their operating time. The main goal of this calorimetric method is to achieve less than 5% uncertainty, especially in the low-lossy partial load condition. Such low uncertainty is particularly necessary for comparing two different semiconductor technologies, e.g., Silicon IGBT and Silicon Carbide MOSFET, where the difference in total losses can be expected in the range of 10-20%. The proposed calorimetric method is experimentally compared to conventional power loss measurement techniques such as the electrical input-output based method or traditional calorimetric methods, and also simulations. The paper demonstrates that the proposed method is nearly as easy to perform as the electrical method. A detailed analysis of the sources of uncertainty is also performed.