1. School of Electrical Engineering and Automation and the National Engineering Laboratory of Energy-Saving Motor and Control Technology, Anhui University, Hefei, China
2. School of Electrical Engineering and Automation, National Engineering Laboratory of Energy-Saving Motor and Control Technology, Anhui Key Laboratory of Industrial Energy-Saving and Safety, Anhui University, Hefei, China
3. School of Electrical Engineering and Automation, Anhui University, Hefei, China