A New Approach for Improvement of the Efficiency and Torque Ripple of the High-Speed Permanent Magnet Synchronous Motor

In this paper, the design, simulation and construction of two high-speed permanent magnet motors with an interior permanent magnet (IPM) rotor and two different stators with and without slot have been investigated. In high-speed motors, due to high excitation frequency, problems such as high mechanical loss, attraction force between rotor and stator, high core losses in stator and skin effect on wire etc. occur. In this article, it is proved that by removing the stator slots of high-speed motors, many of these mentioned problems are solved. The electromagnetic design of two motors was investigated according to nominal values and design equations. In this case, the number of poles, coils and outer diameter of two motors were assumed to be the same. Due to the elimination of the slots, the air gap flux density in the slot-less stator is lower than the structure with a slotted stator, which leads to the higher number of coils turns per phase. Then the simulation of the two motors was evaluated using the finite element method for comparison, and some parameters of the two motors such as air gap flux density, torque, Back-EMF, etc. were compared. By comparing the obtained results, it was concluded that the motor without slots provides a more suitable performance compared to the one with slot. Finally, the steps related to motor construction and experimental results were reviewed. Finally, it is proved that the experimental results are very close to the results presented in the analytical section.