Automated copper loss analysis for switched reluctance machines

Copper loss calculation of electrical machines, in particular in switched reluctance machines (SRMs), is essential to predict efficiency and temperature hotspots in the machine and to optimize design and control. SRMs are highly non-linear systems. Therefore, optimized design of the machine and the torque controller cannot be separated. Conventional analytical approaches for ac copper loss simulations give fast results but are relatively inaccurate. On the other hand, finite-element simulations, which are more accurate, require much work for model build-up and handling and require substantially more computer processing power. This paper introduces an automated tool that shortens the time and reduces the effort for building the finite-element model, performing the simulation and postprocessing. The current and the loss distribution within the coils of a SRM are derived in the time domain based on a precalculated phase-current trajectory. The winding loss results are sufficiently detailed for identification of loss causes and, hence, for optimizing the design and the control. Moreover, the effort is sufficiently low for embedding the analysis of ac copper losses in the electro-magnetic and control optimization procedure of SRMs.