1. Professor, Research Center for Advanced Powertrain Technology, Dept. of Energy and Power Engineering, Hunan Univ., Changsha 410082, Hunan, China.
2. Postgraduate, Research Center for Advanced Powertrain Technology, Dept. of Energy and Power Engineering, Hunan Univ., Changsha 410082, Hunan, China.
3. Professor, Research Center for Advanced Powertrain Technology, Dept. of Energy and Power Engineering, Hunan Univ., Changsha 410082, Hunan, China (corresponding author).