[1] TBSI, Shenzhen 518055, Guangdong, Peoples R China
[2] Tsinghua Univ, Dept Elect Engn, State Key Lab Power Syst, Beijing 100084, Peoples R China
[3] Tsinghua Univ, Grad Sch Shenzhen, Shenzhen 518055, Guangdong, Peoples R China
[4] Sun Yat Sen Univ, Guangdong Engn Res Ctr Green Power Convers & Inte, Sch Phys, Guangzhou 510275, Guangdong, Peoples R China