Design and comparison of an optimized permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) with an induction motor with identical NEMA Frame stators

The performance of a synchronous reluctance motor (SynRM) depends on the direct axis inductance (Ld) and the quadrature axis inductance (Lq) of the machine. To achieve high torque density and power factor, increasing the saliency ratio Ld/Lq and making the difference of these inductances (Ld-Lq) large enough are well known methods. Otherwise, the performance of the motor will remain below that of a similar induction machine using similar stator. By placing a proper amount of permanent magnets inside of the rotor in proper position it will be possible to achieve a significant improvement in performance of this permanent magnet assisted SynRM (PMa-SynRM) which will be comparable with induction machines with same stators. This PMa-SynRM will have benefit of reduced price due to use of conventional induction machines stators. This study investigates the characteristic of an optimized PMa-SynRM rotor for a specific 36-slot NEMA-Frame stator used in 7.5 HP induction motor and the paper presents the comparison results between the PMa-SynRM, SynRM, and the induction motor obtained from FEM analysis.