Design and Analysis of Axial Flux Permanent Magnet Motor with Variable Windings

可變繞組之軸向永磁馬達分析及設計

余志成(Jyh-Cheng Yu) ； 鄭明得(Ming-Te Cheng) ； 姚武松(Wu-Sung Yao)

《Journal of the Chinese Society of Mechanical Engineers》 37卷5期 (2016/10) Pp. 497-507

摘要

Direct drive hub motors drive a wheel directly without a transmission by incorporating the motor into the hub of wheel, which greatly simplifies the mechanical structure and improves driving performance. This paper presents an alternative approach to design axial flux permanent-magnet (AFPM) motor with winding switch for in-wheel drive vehicle applications. Emphasis is placed on theoretical modeling of AFPM motors with variable winding configuration. For electric vehicle application, a dual-wye winding configuration is proposed, which includes a variable windings between serial-wye and spaced-wye windings. The serial-wye winding is used for motor operation at low speed to generate high torque; while reaching a steady state, the motor is switched to a spaced-wye winding to increase speed. For the variable windings switch, a soft switch method is introduced to smoothly reduce the magnetic flux coupling and prevent jerking and jolting at the windings switching point. A prototype AFPM motor with rated 476W output power at 125 rad/s was constructed to validate the results obtained from the proposed analytical model. Also, the experimental results show that, by switching the serial-wye to wye windings, the magnetic field is reduced by 50% and the motor speed increases by 44% under a load of 5 Nm.

關鍵字

Axial flux permanent-magnet motor ； wye winding ； delta winding ； serial-wye

並列摘要

本文旨在探討軸向永磁馬達之設計開發，提出一創新的激磁繞組設計，作為提高轉速的功能。而典型的輪毂馬達，係以Wye接型式切換成Delta接型式的繞組來提高馬達轉速，但有產生火花的危險。本文以Dual-Wye的繞線方式切換成Skipped-Wye的繞線方式來進行集中繞線，取代變換電流角度，可降低耦合磁通量。當馬達速度達到穩態後，再切換成Skipped-Wye接型式，磁場強度降低一半，此時電流上升，馬達轉速就會隨之提高，等效達到弱磁控制模式及無段變速之效果，另為了在變速後不會在切換點產生瞬間極大的加速度，以雙Duty切換模式，以達到平滑的轉速。本方法在高速段可提升9.2%，且無產生火花的危險，大幅提升馬達安全性。