Sinusoidal Charging-Discharging Method of LiBs for Reducing Capacitances of DC-Capacitors in Smart Charger for EVs in Single-Phase Three-Wire Distribution Feeders

This paper proposes a sinusoidal charging-discharging method of the lithium-ion batteries (LiBs) to reduce the capacitances of the dc-capacitors in the previously proposed smart charger (SC) for electric vehicles (EVs) in single-phase three-wire distribution feeders with power quality compensator. The dc-capacitor current in the three-leg pulse-width-modulated (PWM) rectifier is detected, and then added to the reference value for the output current of the bidirectional dc-dc converter that is used to charge or discharge the LiBs. The addition of the detected dc-capacitor current to the reference value of the bidirectional dc-dc converter achieves the sinusoidal charging- and discharging-operations of the LiBs in EVs. The sinusoidal charging- and discharging-operations sink the voltage ripples in the dc-capacitors of both the PWM rectifier and bidirectional dc-dc converter in the SC. This achieves the substantial reduced dc-capacitors in the SC. The simulation results demonstrate that balanced and sinusoidal source currents with a unity power factor can be achieved reducing the capacitances of dc-capacitors in the SC.