1. Department of Mechanical Engineering, Xuancheng Campus, Hefei University of Technology, Xuancheng 242000, Anhui, China
2. Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center, Hong Kong
3. Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
4. Research Institute, Northeastern University, Shenyang 110004, China