Three-Phase On-board Charger with Three Modules of Single-stage Interleaved Soft-switching AC-DC Converter Byeongwoo Kim, Hyojun Kim and Sewan Choi Department of Electrical and Information Engineering Seoul National University of Science and Technology Seoul, Korea

Three-Phase On-board Charger with Three Modules of Single-stage Interleaved Soft-switching AC-DC Converter 
Byeongwoo Kim, Hyojun Kim and Sewan Choi 
Department of Electrical and Information Engineering Seoul National University of Science and Technology Seoul, Korea

 Abstract— This paper proposes a new three-phase on-board charger with three modules of single-phase single-stage interleaved soft-switching ac-dc converter. Each module has single-stage structure with reduced component counts. It achieves ZVS turn-on of all switches and ZCS turn-off of all diodes. Eliminating the low frequency component in the battery charging current, the proposed converter is able to charge the battery with dc current. A balancing control algorithm is proposed to limit the excessive current through each module caused by unbalanced three-phase input voltage. A preliminary prototype of the proposed converter has been built and tested to verify the validity of the proposed concept. 

Keywords—Three-phase; single-phase module; on-board charger; OBC; EV charger; single-stage; balancing control

I. INTRODUCTION 
The on-board battery charger is a key equipment that delivers power from the grid to the propulsion battery in electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs)[1]. Nowadays, the on-board battery charger available on the market is mostly plugged into single phase grid, and the power rating is in the range between 3kW and 3.5kW[2]-[3]. They should have high efficiency and high power density to maximize the energy utilization and the distance covered per charge. However, a 3kW battery charger requires a charging time of 5 to 8 hours to fully charge the EV battery. There has been a need for on-board battery chargers with higher power rating in order to reduce charging time. In regard to these concerns, a three-phase on-board battery charger with increased power rating has emerged [4]-[7]. The three phase battery charger composed of a three-phase PFC and the dc-dc converter has reduced component count, but cannot be plugged into single phase grid with full power capability[4]. The automobile industry is demanding on-board chargers to have capability of operating at full power with both single-phase grid and three-phase grid. This can be achieved by connecting three traditional 3kW single-phase modules in parallel for single-phase grid or connecting them in delta or wye for threephase grid.
LINK FULL PAPER
http://pefcl.snut.ac.kr/upload/study02/963a904e850b90ea083bd24125a5e234.pdf