Comparison of Synchronous Reluctance and Inter-Modular Biased-Flux Stator Permanent Magnet Motors

This paper draws a complete comparison between Synchronous Reluctance motor (SynRM) and intermodular permanent magnet (IMPM) motor. This comparison is important since both of the structures have distinct geometric characteristics that might make it difficult to choose between one of them considering a specific application. This comparison is different from a simple and common comparison between SynRM and Permanent Magnet Synchronous Motor (PMSM) because the IMPM structure is distinctly different from other stator-PM or rotor-PM structures. The operation principle of these structures is totally different from each other. This paper aims to investigate important characteristics of each motor especially the power factor by referring to the operation principle of each structure. It is shown that in the same motor volume, the IMPM structure supersedes the SynRM in torque density and power factor. The major down side of the IMPM structure is its reliance on permanent magnets which might be important for low-cost applications. It is also demonstrated that there are specific measures that help preventing demagnetization of the IMPM’s magnets. Different schemes of optimization have been performed to draw a fair comparison between the two structures. The no-load and full-load performance of them is analyzed using 2D finite element method.