1. School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
2. State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
3. Engineering Research Center of Power Safety and Efficiency, Ministry of Education, Wuhan, Hubei 430074, China