1. School of Electrical Engineering, Southwest Jiaotong University, Chengdu Sichuan 611756, China
2. Technology-oriented R&D Department of National Engineering Research Center for Railway Vehicle, CRRC Changchun Railway Vehicle Co., Ltd., Changchun, Jilin 130113, China
3. College of Instrumentation & Electrical Engineering, Jilin University, Changchun, Jilin 130061, China
4. Admas University, Addis Ababa, Ethiopia