This book is essential and valuable reference for graduate students and academics majored in power electronics, engineers engaged in developing distributed grid-connected inverters, and senior undergraduate students majored in electrical engineering and automation engineering. Soft-switching (SS) technique is an important way to achieve high conversion efficiency and high switching frequency for power converters, which is beneficial to improve power density and reduce volume and cost of power electronics equipment. This book mainly discusses SS technique for transformerless grid-connected inverters (TLIs), and a SS configuration named as Freewheeling-Resonance-Tank Inverters is proposed for TLIs fulfilling requirements of switching loss-free, full power factor range, and constant common-mode voltage performance. The detailed theoretical analysis and experimental validations are presented from ZCT and ZVT type topologies, respectively. 

Huafeng (Henry) Xiao received the B.S., M.S. and Ph.D. degrees in electrical engineering from Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing, China, in 2004, 2007, and 2010, respectively. From 2015 to 2017, he was a postdoctoral fellow at Laboratory of Electric Drives and Application Research (LEDER), Ryerson University, Toronto, Canada, and at Electric Energy Systems Laboratory (EESL), McGill University, Montreal, Canada, respectively. He is currently a Professor at School of Electrical Engineering, Southeast University, China. He has authored or coauthored over 70 journal and conference papers as well as 2 books, and held 36 China Patents. His main research interests include Topology, control, and protection techniques of renewable energy generation systems, Multi-terminal MMC-HVDC, WBG devices applications.Dr. Xiao has received a gold medal from 47th International Exhibition of Inventions Geneva, a silver medal of China PatentAward, and Technology Invention Award of Ministry of Education of the Peoples Republic of China. he served as an Associate Editor for IEEE Transactions on Industrial Electronics, and IET Power Electronics.Ruibin Wang received the B.S., and M.S. degrees in electrical engineering from Hebei University of Technology, Tianjing, China, and Southeast University, Nanjing, China, in 2018, and 2021, respectively. His research interests include high frequency soft-switching conversion.Chenhui Niu, Senior Engineer in IEEE, received the B.S. in Power System and Automation from North China Electric Power University(NCEPU), Beijing, China in 2006, and the M.S. in Photovoltaic and Solar Energy from University of New South Wales, Sydney, Australia in 2010. He is currently a director at science and technology center, Huaneng Jiangsu Energy Development Co., Ltd, China. He has authored or coauthored over 10 papers, and held 15 China Patents. His main research interests include PV plant grid-connected evaluation, standardization and produce certification.He has received award with twice of 1906 AWARD in International electrotechnical Commission(IEC), which is the top expert award in IEC, leading published 3IEC standard, and participate published 3 IEC standards.Yun Liu received the B.S. and M. S. degrees in automation from Qingdao University of technology, Shandong, China, in 2017 and 2020. Currently, she is pursuing the Ph.D. degree in Southeast University, Nanjing, China. Her research interests include grid-connected inverters and high frequency soft-switching techniques.Qian Kairong, a senior engineer, received a B.S. degree in thermal power engineering of power plants from Huazhong University of Science and Technology. Now Mr. Qian is working in Huaneng Jiangsu Energy Development Co., Ltd, China, as the vice general engineer and director of productionmanagement and environmental protection department. Mr. Qian currently serves as a member of the Jiangsu Society of Electrical Engineering, a member of Jiangsu Electric Power Technology Standardization Association, and a member of Jiangsu Electric Power Industry Association Standardization Professional Technical Committee. Mr. Qian has been devoted to the management of thermal and clean energy production for a long time. He has won the first prize of the 2021 Electric Power Technology Innovation Award of the China Electricity Council and the second prize of the 2021 Electric Power Construction Science and Technology Progress Award of the China Electric Power Construction Association. 

Introduction.- High-Frequency Transformerless Grid-Connected Inverters and Related Issues.- Zero-Current-Transition TLIs with Switching-Loss-Free.- Zero-Current-Transition TLIs with Full Power Factor Range.- Zero-Voltage-Transition TLIs with Single-Quadrant Resonance Networks.- Zero-Voltage-Transition TLIs with Two-Quadrant Resonance Networks.- Summary.