1. School of Information Engineering, Nanchang University, Nanchang 330031, China
2. School of Engineering, University of Leicester, Leicester LE1 7RH, UK
3. Department of Electrical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
4. Power Electronics, Machines and Control (PEMC), University of Nottingham, Nottingham NG7 2RD, UK