1. Key Laboratory of Control of Power Transmission and Conversion, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
2. Electrical Engineering Department, Shanghai Jiao Tong University, Shanghai, China
3. School of Electrical Engineering, Chongqing University, Chongqing, China
4. Department of Electrical and Electronic Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong