98.2% Efficiency, Low Cost, 6.6-kW AC/DC Converter for HEV/EV On-Board Charger

The paper examines a new structure of an AC/DC power supply for single-phase on-board chargers. The transfer of the AC power to the DC circuit is performed at high frequency (1-120 kHz). The transistors operate in a soft switching mode (ZCS) with a variable switching frequency. This reduces the switching power losses of the transistors. The charger architecture includes several identical functional modules which operate with phase shift in the input circuits. Thus, the value of the smoothing capacitor of the input filter can be reduced and also the power grid pollution with the current higher harmonics. Verification of the proposed solution was done by mathematical simulations and by testing a 1650W laboratory module prototype. The AC supply voltage can vary between 85-265V, and the DC output voltage between 250-450V. The resulted volume indicator of the converter is 4.2 kW / dm3.