1. College of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, China
2. Engineering Technology Center of Power Integration and Energy Storage System, Qingdao University, Qingdao 266071, China
3. Energy Saving Business Division, CRRC Qingdao Sifang Rolling Stock Research Institute Co. Ltd., Qingdao 266031, China
4. School of Control Science and Engineering, Shandong University, Jinan 250061, China