A novel thermal management algorithm for improved lifetime and overload capabilities of traction converters

A novel active thermal management for an FOC controlled electric car is proposed, which reduces the maximum junction temperature and the load cycling stress of the traction converter by dynamic variation of switching frequency and current limit. By this means, the power losses of the converter can be decreased temporarily in high load situations, like the start-up process, to achieve lower thermal stress and so an extended lifetime. By using offline precalculations, this approach does not need to directly consider junction temperatures. Furthermore, a predictive behavior and, thus, an improved overload capability is reached. The thermal management is tested in simulations and measurements. The expected lifetime extension is determined for the New-European-Driving Cycle (NEDC) by simulation.