Electro-thermal simulations of a power electronic inverter for a hybrid car

This paper presents a way of determining the cooling requirements for a power electronic inverter controlling a traction motor in a hybrid car. The cooling requirements are determined through electro-thermal simulations. Several comparative electro-thermal simulations are carried out for different levels of cooling, i.e. convection coefficients, power module integration, switching frequencies and mission profiles. The importance of taking the thermal coupling, between devices within the power module, into account is discussed. The cooling requirements are determined both for a fixed and variable switching frequency. The results indicate that the cooling requirements can be reduced significantly by using a variable switching frequency.