Project supported by the National Natural Science Foundation of China(Grant Nos.51007076,51475389);by the Fundamental Research Funds for the Central Universities(Grant No.2682014CX039);by the State Key Laboratory of Traction Power at Southwest Jiaotong University(Grant No.2013TPL_T05);by the National Innovation Training Project(Grant No.201410613049);by the Science and Technology Plan Project of Sichuan Province~~
supported by the National Natural Science Foundation of China(Grant Nos.50906093,51007076);the Fundamental Research Funds for the Central Universities(Grant No.SWJTU11ZT34);by the State Key Laboratory of Traction Power at Southwest Jiaotong University(Grant No.2013TPL_T05)~~