Torque Ripple Minimization of IPM Spoke Type Motor

The rising demand for high-performance and efficient electric drive systems in E-bikes has intensified the need for optimized motor designs that balance torque density, low ripple, and energy efficiency. Spoke-type Interior Permanent Magnet Synchronous Motors (IPMSMs) offer a promising solution due to their superior torque characteristics; however, they inherently suffer from high torque ripple and harmonic distortions that lead to undesirable noise and vibration. This study addresses the challenge of minimizing torque ripples while enhancing average torque output in spoke-type IPMSMs. Finite Element Analysis (FEA) is employed to evaluate and compare three configurations-Base Model, Optimized Model (via genetic algorithm-based geometric refinement), and Optimized Skewed Model (with rotor skewing). Simulations analyze back EMF waveforms, harmonic spectra, flux distribution, and torque profiles. The Optimized Skewed design achieves the highest average torque (2.223 Nm) with the lowest torque ripple (1.92 %), compared to the Reference Model (2.089 Nm, 3.16% ripple). Harmonic analysis confirms minimal trade-offs in THD (<5%) for significantly improved performance. The study concludes that integrating design optimization with rotor skewing effectively enhances electromagnetic performance, reduces torque ripple, and contributes to quieter, smoother E-bike operation.