volume | PIER Journals

Abstract

To address the problems of flux barriers' excessive torque ripple and complicated multi-parameter optimization in conventional permanent magnet-assisted synchronous reluctance motors (PMa-SynRMs), this paper proposes a novel asymmetric external-rotor ferrite-assisted synchronous reluctance motor (AERFa-SynRM). By adopting an asymmetric magnet shifting arrangement, the magnetic circuit configuration is optimized, which improves air-gap flux density and permanent magnet torque without increasing material and manufacturing costs. The magnetic circuit characteristics and torque generation mechanism of symmetric and asymmetric rotor structures are compared and analyzed by establishing mathematical and electromagnetic models. Taking key rotor geometric parameters as design variables and average torque, torque ripple, and efficiency as multi-objective optimization indices, a BP-Kriging hybrid surrogate model is constructed, and the NSGA-II algorithm is adopted for global parameter optimization. The finite element simulation results demonstrate that the proposed asymmetric rotor structure can effectively enhance air-gap flux density and no-load back-EMF performance. After multi-objective optimization, the average torque and motor efficiency are greatly improved, while the torque ripple is sharply reduced. The asymmetric angle adjustment realizes the peak-valley mutual cancellation between permanent magnet torque and reluctance torque, which fundamentally suppresses electromagnetic torque ripple. The proposed topology and collaborative optimization strategy provide an effective solution for the performance improvement and torque ripple reduction of low-cost ferrite PMa-SynRMs.

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Dr. Chaozhi Huang

Mr. Wen Kuang

Mr. Fangrong Wang

Dr. Ji Zhang

Dr. Zhihong Liu