High-Efficiency Single-Stage On-Board Charger for Electrical Vehicles

This paper presents an isolated single-stage on-board electric vehicle charger without an intermediate DC-link capacitor. Based on an isolated current-source topology, the converter features soft-switching in semiconductors regardless of load variation for the full AC line voltage range. Moreover, it requires no external snubber or clamp circuits. The power factor correction and voltage regulation are provided by a relatively simple phase shift modulation, while the amount of circulating energy is kept minimal. The charger is distinguished by its efficiency characteristic – the maximum is achieved in the constant power charging mode. The control method, component stresses, and design constraints of the topology are analyzed. The concept is verified using a 3 kW experimental SiC semiconductor based prototype, which reaches a peak efficiency of 96.4%. Moreover, the charger has demonstrated efficiencies above 95% with the THD of 4.1% when operating in constant power mode at the maximal power.This work was supported in part by the Estonian Research Council (grant PRG1086), in part by the European Economic Area (EEA) and Norway Financial Mechanism 2014–2021 under Grant EMP474, in part by the Estonian Centre of Excellence in Zero Energy and Resource Efficient Smart Buildings and Districts under Grant 2014-2020.4.01.15-0016 funded by the European Regional Development Fund, and in part by the project NPRP12S-0214-190083 from the Qatar National Research Fund (a member of Qatar Foundation)