A Novel Efficient Electric Vehicle Fast Charging System Structure with Low Order Harmonic Current Suppression Capability

摘要

Aiming at improving the efficiency of the traditional electric vehicle (EV) fast chargers with two-stage structure, this paper comes up with a novel charger with single-stage structure, where the turn ratio of the transformer is specially designed to obtain a lower input line-to-line voltage (190V) for the single AC/DC converter. Followed by a fair comparison method, the power losses of transformers and converters in both two-stage and single-stage structures are analyzed. The better performances of the single-stage structure, which includes lower costs and higher power conversion efficiency (up to 2%), are approved by the results of calculation and simulation. To suppress the harmonic current getting into the battery packs in the single-stage structure, a small capacity bidirectional half bridge DC/DC converter is designed to function as a DC active power filter (DCAPF) to compensate the harmonics. Finally, both simulation and experimental results are carried out to validate the low order harmonic current compensation effect.