Design Method Using Winding Factor for Harmonic Current Reduction in Dual Three-phase Permanent Magnet Synchronous Motors

Dual three-phase motors offer numerous advantages, including the elimination of 6th-order torque ripple. However, they have the drawback of generating large harmonic currents when driven because of their small inductance for specific harmonics. In this study, inductance, which depends on the winding structure and harmonics, is formulated using the winding factor in order to reduce harmonic currents through winding design. The theoretical values of the formulated inductance are in good agreement with the FEA values. In addition, the magnitude of the harmonic currents generated during drive are quantitatively evaluated using these inductance values. Conventionally, when the winding factor for the 5th and 7th spatial harmonics is small, the 5th and 7th harmonics of back EMF can be reduced. However, dual three-phase motors with small winding factor for 5th and 7th spatial harmonics have the disadvantage of having very small inductance for specific harmonics, resulting in large harmonic currents. © 2023 The Institute of Electrical Engineers of Japan.