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 (L
_d
) and the quadrature axis inductance (L
_q
) of the machine. To achieve high torque density and power factor, increasing the saliency ratio L
_d
/L
_q
and making the difference of these inductances (L
_d
-L
_q
) 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.