Optimal Design and Control of a Wheel Motor for Electric Passenger Cars

• Published in: IEEE transactions on magnetics Vol. 43; no. 1; pp. 51 - 61
• Main Authors: Yang, Yee-Pien, Chuang, Down Su
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-01-2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applications; Applied sciences; Automobiles; Automotive engineering; Automotive wheels; Axial-flux wheel motor; Cross-disciplinary physics: materials science; rheology; Density; Design engineering; Design optimization; Driving; Electric vehicles; electrical vehicle; Engineering techniques in metallurgy. Applications. Other aspects; Exact sciences and technology; Finite element methods; Gears; Hybrid electric vehicles; Magnetism; Magnets; Materials science; Metals. Metallurgy; Motors; Optimal control; optimal driving current waveform; Optimization; Other topics in materials science; Physics; Ripples; Rotors; Sensitivity analysis; Stators; Torque; Wheels; Design; optimal driving current waveform; electrical vehicle; sensitivity analysis; Automotive industry; Wave forms; electric vehicles as a promising solution to the direct-driven electric vemcie. Index Terms-Axial-flux wheel motor; Magnetic materials; Electric-powered vehicles; Application; Magnetic properties
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2006.886153

An optimal design and control technology of a wheel motor is proposed for small electric passenger cars. The axial-flux sandwich-type disc motor is designed with a rotor embedded with neodymium-iron-boron (NdFeB) magnets and two plates of stators, and is directly mounted inside the wheel without mechanical transmission and differential gears. Sensitivity analyses are performed to choose critical design parameters, which are the most influential in design objectives, to maximize the driving torque, efficiency, rated speed, and to minimize the weight of motor under various constraints of size, materials, and power sources. The optimal driving current waveform is proven to be the same as the fundamental harmonic of the back electromotive force to produce maximum torque with least ripples. The finite-element refinement results in the motor prototype with a maximum torque over 38 kgmiddotm and a corresponding torque density of about 1.72 kgmiddotm/kg at the maximum allowable phase current of 50.25 A (rms). Two such rear driving wheels are able to drive a 600 kg passenger car to accelerate from 0 to 40 km/h in 5 s on a 15 degree incline. This dedicated wheel motor is applicable to pure or hybrid electric vehicles as a promising solution to the direct-driven electric vehicle