1. School of Mechanical and Automobile Engineering, Qingdao University of Technology, Qingdao 266520, China
2. China National Heavy Machinery Research Institute Co., Ltd., Xi’an 710032, China
3. State Key Laboratory of Metal Extrusion and Forging Equipment Technology, Xi’an 710032, China
4. Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle, Hubei University of Arts and Science, Xiangyang 441053, China