Optimized Design of Sub-Harmonic Synchronous Machines

This article presents an optimized design approach for sub-harmonic synchronous machines (SHSMs) to minimize torque ripple and improve performance for high-power electric vehicle applications. The proposed design incorporates a novel rotor harmonic winding configuration and utilizes advanced skewing techniques to achieve optimal spatial distribution of magnetic forces. Using Ansys Maxwell software, finite element analysis (FEA) was conducted on eight-pole, 48-slot SHSMs with a rated output of 1.3 kW and 900 r/min. Compared to earlier designs, the optimized two-layer and three-layer SHSMs demonstrated significant reductions in torque ripple—83.94% and 86.84%, respectively. This improvement is attributed to the uniform distribution of harmonic windings and carefully calibrated rotor skewing, both of which enhance spatial efficiency and magnetic field uniformity across the rotor. These configurations achieve lower torque ripple and maintain high efficiency and competitive average torque output, making them suitable alternatives to conventional wound rotor synchronous machines (WRSMs) and permanent magnet synchronous machines (PMSMs). The findings validate the potential of the optimized SHSMs as high-performance, brushless solutions for electric vehicle propulsion, contributing to advancements in synchronous machine design and sustainable transportation technologies.