Thermal design and cooling of IGBTs in a traction drive

As an electrical engineer designing a power converter, it is very easy to concentrate on the electrical aspects and relegate mechanical and thermal issues to the back of the design process, to be considered once the electrical elements have been specified. The mechanical and electrical issues, however, are inextricably linked and to obtain the best from an IGBT power circuit, must be resolved simultaneously. This compromise will significantly impact on the design of the cooling system. To illustrate the issues at the heart of IGBT circuit design and hence thermal design, this paper uses as an example the 750 V, 200 kW traction inverter drive