A Three Terminal Active Power Decoupling Circuit for Single-Phase Single-Stage On-Board Charger

Single-phase single-stage On-Board Charger (OBC) for Electric Vehicles (EVs) are advantageous due to their high efficiency and low component count. The output power provided by this OBC has a second harmonic ripple component. This ripple component of power causes overheating of the Li-ion battery pack and reduces its round trip efficiency by up to 2 % as reported in literature. The conventional techniques for decoupling the second harmonic ripple power may not work satisfactorily due to very low impedance of battery pack. This paper proposes a Three Terminal Active Power Decoupling Circuit (3T-APDC) to decouple the second harmonic ripple power. The proposed circuit ensures charging of battery pack with almost ripple free power. It consists of a series blocking capacitor and two bidirectional power converters. These converters process a fraction of total power supplied to the battery pack. This significantly limits the additional power loss and cost of the proposed 3T-APDC. Simulation studies are conducted to evaluate the proposed circuit in accordance with TATA Nexon EV's specifications for single-phase OBC. As per the reported simulation results, the proposed circuit limits the ripple in battery current close to 5 %.