1. School of Electrical Engineering, Hebei University of Technology, Tianjin, China
2. Department of Electrical Engineering, Hebei University of Technology, Tianjin, China
3. Zhejiang University, Hangzhou, China
4. CRRC Qingdao Sifang Vehicle Research Institute Company, Ltd., Qingdao, China
5. Hebei University of Technology, Tianjin, China