volume | PIER Journals

Abstract

To address the trade-off between torque density and power factor in conventional permanent magnet vernier rim-driven motors under material cost constraints, this study proposes a novel permanent magnet fault-tolerant vernier rim-driven motor with an inclined modulation tooth (PMFTVRDM-IMT). Unlike the conventional straight-tooth configuration, the proposed design introduces an inclination angle to the modulation teeth, thereby altering the air-gap permeance distribution pathway while preserving both the permanent magnet volume and overall motor envelope. Through magnetic field harmonic analysis, the underlying mechanism for the synchronous improvement in the torque and power factor was revealed: the inclined modulation tooth structure enhances the effective working harmonics while suppressing the ineffective harmonic components. To further optimize the motor performance, a combined approach of single-parameter scanning and multi-objective optimization was adopted, and the resulting performance metrics, such as the output torque and power factor, were systematically validated using the finite element analysis (FEA). The results indicate that, with modifications only to the modulation tooth structure, the proposed motor design achieves an approximately 15% improvement in the power factor and a 2.5% increase in the torque density, thereby substantiating the feasibility and engineering value of the inclined modulation-tooth topology in mitigating the low power factor issue inherent to vernier machines.

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Dr. Defeng Zhao

Professor Jingwei Zhu

Dr. Yaqian Cai

Dr. Anni Wang