Finite element surrogate model for electric machines with revolving field — application to IPM motors

The model allows the ultra-fast simulation of the steady-state performance of synchronous machines and is particularly suitable for brushless motors with non-overlapping windings having coils concentrated around the teeth. Finite element analysis (FEA) is employed only for calculating the magnetic vector potential in the coils. For the example IPM motors presented, as little as one magnetostatic FE solution was used for fundamental flux linkage and average torque computation. Two FE solutions were employed for core flux density waveforms and power loss estimation. A minimum of three solutions is recommended for torque ripple, back emf and induced voltage. A substantial reduction of one to two orders of magnitude was achieved for the solving time as compared with detailed time-stepping FEA. The surrogate FE model can also be tuned for increased speed, comparable with that of magnetic equivalent circuit solvers. The general applicability of the model is discussed and recommendations are provided. Successful validation was performed against detailed FEA and experiments.