1. School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou, China
2. School of Electrical and Information Engineering and the State Key Laboratory of Intelligent Agricultural Power Equipment, Zhengzhou University, Zhengzhou, Henan, China
3. School of Electrical and Information, Zhongyuan University of Technology, Zhengzhou, China
4. State Key Laboratory of Power System of Tractor, Luoyang, Henan, China
5. School of Electrical Engineering and Automation, Henan Institute of Technology, Xinxiang, Henan, China