電動車31kW內置磁石永磁同步馬達設計研究

Development of 31kW Interior Permanent-Magnet Synchronous Motor for Electric Vehicles

徐子庭(Tzu-Ting Hsu)

指導教授 ： 鄭榮和

國立臺灣大學/工學院/機械工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00014

摘要

目前，世界各國政府和各大車廠皆積極投入電動車相關技術的開發，以及充電站等基礎建設。然而，目前電動車所搭載的能量密度太低，價格太高，因此距離大眾市場的普及仍然有相當大的空間改善。本研究的目標係設計電動車專用的驅動馬達，Green Jumper 這輛純鋰電池電動車是由台達電和台大機械Formosun團隊共同開發。
IPM 馬達因使用了高能量密度的稀土族磁鐵，和弱磁的控制，因此有高功率密度和較寬的高速定功率區之優點，因此本研究是以IPM的馬達做為設計研究之目標。IPM馬達的轉子是馬達設計的核心技術，亦即磁鐵擺放形狀的設計，因此本研究將設計的焦點放在嵌入轉子內的磁鐵擺置設計上。
本研究中的磁鐵擺放設計目的是為了以最少的磁鐵用量達到最大的扭力輸出能力，希望藉此可以降低IPM馬達的材料成本。Toyota Prius ‘03的馬達設計是將磁鐵擺置為V型，此種設計的目的是考量了製造成本和磁阻扭力的最大化。因此本研究是以V型設計為基礎，提出設計改良。以相同用量的磁鐵，擺置為U型設計，希望能夠有效提高磁鐵磁通鏈的利用率，增加磁鐵扭力的成分，進而提升整體扭力輸出的效果。利用有限元素分析軟體的計算，可以得到U型設計跟V型設計比較，確實能夠提升最終扭力輸出的大小，並且主要是來自於磁鐵扭力的貢獻。因此，在本研究中所設計的IPM馬達是以U型設計為主，並進一步製造最終的馬達設計，以及測試驗證。
從實際測試的結果可以驗證模擬計算的準確度，因而推斷U型的擺放方式確實可以比V型設計提升扭力輸出的能力，亦即，以較少量的磁鐵達到相同的性能目標，降低最終所使用的材料成本。

關鍵字

鋰電池電動車 ； IPM馬達 ； 永久磁石 ； 磁鐵擺置設計

並列摘要

The objective of this work is to design a high-performance traction motor for a battery electric vehicle “Green Jumper” engineered in National Taiwan University. An important challenge of traction motor design for electric vehicle is to meet the requirements of different types of electric vehicles and of easy-to-construct configuration that can contribute to the overall cost reduction for the electric vehicle.
The interior permanent magnet (IPM) synchronous motor is the natural choice of such niche applications because of their higher efficiency, compact size and achieving constant-power operation over a wide speed range with limited magnet strength requirement. However, the cost of magnet material is high compared with the cost of the other materials used in electric motor, and design attributes that minimize the required amount of magnet material are important challenge for high-performance motor design.
The placement of the embedded permanent magnet is developed for the optimized design of high-performance IPM motor. The IPM motor with segmented magnet is first investigated in terms of its field weakening capability. Furthermore, this thesis proposed a design with permanent magnets being embedded in the U-shape flux barrier compared to the V-shape flux barrier of TOYOTA Prius. The comparisons of the average torque and no-load back EMF are given. The results of the motor performance comparisons are based on comprehensive use of finite element analysis tools (JMAG-Studio). From the FEA results, it shows that the U-shape flux barrier proposed in this work has better torque capability than the V-shape flux barrier adopted in TOYOTA Prius; that is, for a given torque, the design with U-shape flux barrier can yield a smaller motor with less amount of magnet and contribute to the overall reduction of the material cost.
A prototype motor was constructed on the basis of the final optimized design. The no-load back EMF and the torque performance were measured and compared with the predicted results for experimental verification. Finally, the measured performance analysis was found to closely match with the predicted results.

並列關鍵字

battery electric vehicle ； IPM motor ； embedded permanent magnet

參考文獻

[ ] Mark Hirschey, “What’s your strategy for the electric vehicle market?” Oliver Wyman, 2009

[ ] J. R. Hendershot, Jr., and T. Miller, Design of Brushless Permanent-Magnet Motors, Magna Physics Publishing, Hillsboro, OH, and Clarendon Press, Oxford, 1994.

[ ] T. J. E. Miller, Brushless Permanent-Magnet and Reluctance Motor Drives. Oxford: Clarendon Press, 1989.

[ ] T. M. Jahns, “Flux-Weakening Regime Operation of an Interior Permanent Magnet Synchronous Motor Drive,” IEEE Transactions on Industry Application, Vol. IA-23, No. , pp. 681 – 689, 1987.

[ ] B. K. Bose, “A High-Performance Inverter-Fed Drive System of an Interior Permanent Magnet Synchronous Motor,” IEEE Transactions on Industry Application, Vol. 24, No.6, pp. 987 – 997, Nov/Dec, 1988.