Investigation of Low-Speed High-Power Density Spoke-Type FSCW PMSM with Similar PM Volume and Different Shapes Considering Magnetic Gearing Effect

This article investigates the air-gap magnetic flux density and the generated torque response in spoke-type permanent magnet (ST-PM) machines with distinct permanent magnet shapes having similar volumes. The rectangular and trapezoidal shapes of the PM are investigated in this analysis, and the corresponding air-gap flux density harmonics and torque production mechanisms are investigated. The FSCW ST-PM machine contains abundant air-gap magnetic field harmonics, impacting the machine’s torque response. Firstly FEA is used to analyze the ST-PM machine’s air-gap magnetic field harmonics, and then the traditional torque-generating mechanism in PMSM along with the magnetic gearing effect contributions to the average torque, are separately investigated for the analyzed machine design cases. A brief comparative analysis of the analytical and simulation results for the ST-PM machine designs with different PM shapes and similar volumes is also presented.