Design of a PEV battery charger with high power factor using half-bridge LLC-SRC operating at resonance frequency

This paper presents a two stage battery charger for plug-in electric vehicles (PEV) based on half-bridge LLC series resonant converter (SRC) operating at resonance frequency. The first stage is power factor correction (PFC) stage comprising of boost converter topology using hysteresis band control of inductor current. The PFC stage reduces the total harmonic distortion (THD) of the line current for achieving high power factor and regulates the voltage to follow the battery voltage at DC link capacitor. The input of the boost converter is a single phase 50 Hz, 220V AC from grid. At the second stage, a half-bridge LLC-SRC is used for constant-current, constant-voltage (CC-CV) based battery charging and for providing galvanic isolation. The resonant converter is designed to operate around resonance frequency to have maximum efficiency and low turn-off current of power switches to reduce switching losses. The circuit is simulated using MATLAB Simulink with 1.5 kW maximum output power. Simulation results show that the PFC stage achieves THD less than 0.07% and high power factor value as 0.9976. The DC/DC stage meets all the CC-CV charging requirements of the battery over wide voltage range 320V-420V for depleted to fully charged battery.