1. School of Mechanical Engineering, Hebei University of Technology, Tianjin 300130, China
2. School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
3. State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
4. School of Electrical Engineering, Hebei University of Technology, Tianjin 300130, China