Optimal Design Method of Torque Harmonics Reduction for Fractional-Slot Concentrated-Winding SPM Motor Based on Kriging Surrogate Model

Fractional-slot concentrated-winding (FSCW) synchronous permanent magnet (PM) machines have many advantages such as high torque density and low cogging torque. But FSCW PM machines generate magnetomotive force (MMF) harmonics, increasing torque harmonics and rotor losses. Many studies have suggested how to lower the harmonics, but these techniques are difficult to apply directly because of low efficiency and productivity. This paper reports an optimal design process for decreasing torque harmonics by analyzing the sensitivity of design variables and determining the best configuration of motor. As a verification about the proposed design method, the result of comparison between the torque ripple optimized model and the torque harmonics optimized model is shown. For evaluating characteristics of the motor, the finite element analysis is used considering torque harmonics.