1. School of Electrical Engineering, Southwest Jiaotong University, Chengdu, China
2. SWJTU-Leeds Joint School and National Rail Transit Electrification and Automation Engineering Technique Research Center, Southwest Jiaotong University, Chengdu, China
3. Powerchina Huadong Company Ltd., Hangzhou, China
4. Key Laboratory of Railway Industry of Maglev, Tongji University, Shanghai, China