1. North China Electric Power University,Department of Electrical Engineering,Baoding,China,071003
2. Hebei Provincial Key Laboratory of Electromagnetic and Structural Performance of Power Transmission and Transformation Equipment,Baoding,China,071056
3. Saga University,Department of Electrical and Electronic Engineering,Saga,Japan,840-8502
4. Oita University,Division of Mechatronics,Oita,Japan,870-1192
5. Mentor Infolytica, A Siemens Business,Montreal,Canada,QC H2X 4B3