A Novel PMSM with Optimized Asymmetric Eccentric Air-Gap for High-Power Electric Motorcycle

Abstract

In order to improve power density of high-power electric motorcycle driving motor, the air-gap length is usually minimized, which aggravates the influence of armature reaction on air-gap magnetic field. Considering the fact of unidirectional driving of electric motorcycle, the eccentric air-gap is used in each pole air-gap magnetic field strengthened area to suppress armature reaction, thus an asymmetric eccentric air-gap structure is designed. The torque and efficiency of motor are improved by asymmetric structure optimizing to improve the comfort, load capacity and battery life of vehicle, the ratio of maximum air-gap to minimum air-gap is eventually determined to be 3.2. The results of simulation and experiment show that, for the specified rotation direction, the distortion of air-gap magnetic density and back electromotive force (back-EMF) caused by armature reaction can be significantly suppressed by the determined asymmetric structure, hence the torque ripple and iron loss are reduced by 70.66% and 20.9% under rated load, respectively. Meanwhile, the proposed motor can provide a wide speed range and superior speed control performance, thus, verifying the validity and feasibility of the proposed asymmetric eccentric air-gap structure.

Keywords:

• electric motorcycle
• PMSM
• armature reaction
• asymmetric eccentric air-gap
• torque ripple
• iron loss

Additional information

Notes on contributors

Wei Cui

Wei Cui received the B.S., M.S. from the School of Automation, Xi’an University of Technology, Xi’an, China, in 1994 and 1997, respectively, and the Ph.d. degree from the School of Mechatronics Engineering and Automation, Shanghai University, Shanghai, China, in 2004. He was a visiting scholar in Hong Kong University, Hong Kong, China, from Dec. 2004 to May. 2005 and in Sheffield University, UK from Jan. 2011 to Jan. 2012. Presently, he is an associate professor at Shanghai University. His fields of interest are power electronics and high-performance ac motor drive.

Bowen Hu

Bowen Hu received the B.S. from the Department of Automation, Shanghai University, Shanghai, China, in 2017. He is currently working toward M.S. degree in the Department of Electrical Engineering, Shanghai University, Shanghai, China. His main research interest is focused on the design of high-performance permanent magnet synchronous motor.

Taohong Pan

Taohong Pan received the B.S. and M.S. degrees from the School of Engineering, Shanghai Normal University and Department of Electrical Engineering, Shanghai University, respectively. Since 2019, she has been working as design engineer of high-performance permanent magnet synchronous motor in SAIC Motor, Shanghai, China. Her main research interest is focused on the design of high-performance permanent magnet synchronous motor.