Soft-Switching Current-Source Rectifier Based Onboard Charging System for Electric Vehicles

In this article, a novel soft-switching current-source rectifier (CSR) based bidirectional on-board charger (OBC) system is proposed for electric vehicles (EVs) comprising multiple battery sets. Besides the CSR's inherent advantages of higher-quality input voltage waveforms, enhanced short-circuit-current tolerant capability and long lifetime of dc choke, the cascaded configuration of dc choppers can implement the higher dc-link voltage with multiple low-voltage battery sets, and the low-voltage devices can be used. With the auxiliary resonant circuit in dc link, the soft-switching operation can be achieved for all power switches in the proposed power conversion circuits. Moreover, the high dv/dt caused by high-speed switching silicon carbide devices can be reduced with the capacitor in the auxiliary circuit. The collaborative operation strategy is proposed for the CSR and the dc choppers, which enables reduction of switching frequency of dc choppers and current ripple in dc link simultaneously. The experimental results are presented to verify the performance of the proposed the OBC system.