1. Measurement Technology and Instrumentation Key Lab of Hebei Province, Department of Electrical Engineering, Yanshan University, Qinhuangdao, Hebei, P. R. China
2. School of Vehicles and Energy, Yanshan University, Qinhuangdao, Hebei, P. R. China
3. School of Information Science and Engineering, Yanshan University, Qinhuangdao, Hebei, P. R. China