关键词: 永磁体磁动势, 谐波调控, 直驱式外转子永磁同步电机, 高效低噪

Abstract: To address the demanding requirements of high efficiency and low noise in direct-drive outer-rotor permanent magnet motors for washing machine applications, this study presents an innovative design and optimization methodology based on harmonic control of permanent magnet magnetomotive force ( MMF) . The proposed approach involves dividing each magnetic pole into n subsections, systematically optimizing the arc coefficients K_i and magnetization angles Δθ_i ,thereby enhancing the fundamental MMF component and effectively suppressing other harmonic components. Taking a 36-slot 48-pole outer-rotor permanent magnet motor as an example, a multi-objective optimization focusing on torque
maximization and 12th-order radial force minimization was conducted, with two-segment and three-segment configurations optimized. Comparative analysis reveals that relative to conventional radial magnetization designs,the optimized two-segment and three-segment configurations achieve approximately 8. 2% and 17. 8% improvement in fundamental MMF amplitude, respectively,along with over 19% enhancement in washing efficiency for both configurations. During the spinning operation, the optimized designs demonstrate significant reductions in 12th-order radial force by 41. 6% and 2. 72%, respectively, accompanied by noise level reductions of 7. 3 dB and 5. 5 dB. These results demonstrate the effectiveness of the proposed methodology in meeting the critical requirements for high efficiency and noise reduction in direct-drive outer-rotor permanent magnet motor applications.

Key words: permanent magnet magnetomotive force, harmonic control, direct-drive external rotor permanent magnet synchronous motor;high efficiency and low-noise