WEI Wenxiang1,2, LIU Guorong1,3
(1. College of Electrical and Information Engineering, Hunan Univ, Changsha, Hunan410082, China; 2. Engineering Research Center of Advanced Mining Equipment, Ministry of Education, Hunan Univ of Science and Technology, Xiangtan, Hunan411201, China; 3. Dept of Electrical and Information Engineering, Hunan Institute of Engineering, Xiangtan, Hunan411104, China)