A comparison between finite element techniques when modelling single phase line-start permanent magnet motors

There is an increasing demand for higher efficiency motors. This demand has been brought about by a combination of increased consumer pressure, and legislation introduced as a result of concern for the environment. The line-start permanent magnet motor has been shown to be capable of high efficiency performance. In small machines, where Joule losses dominate, there can be a significant reduction in losses when compared to same sized induction motors. However, the complexity of these motors makes it difficult to accurately predict their performance. In this paper, a comparison is made between two finite element modelling techniques, the coupled circuit method and the eddy current method. The eddy current method is shown to be considerably faster than the coupled circuit method, allowing the designer to carry out further investigations into factors affecting simulation accuracy.