1. School of Materials Science and Engineering, Tianjin University, Tianjin, China
2. School of Electrical Engineering, Tiangong University, Tianjin, China
3. Bradley Department of Electrical and Computer Engineering, Center for Power Electronics Systems, Virginia Tech, Blacksburg, VA, USA
4. China North Vehicle Research Institute, Beijing, China
5. College of Information Science and Engineering, Huaqiao University, Xiamen, China