Reducing capacitances of DC capacitors in smart charger for electric vehicles in single-phase three-wire distribution feeders with sinusoidal charging and discharging for Li-ion batteries

摘要

This paper discusses reduction of capacitances of dc capacitors in the previously proposed smart charger (SC) with a sinusoidal charging-discharging lithium-ion battery for electric vehicles in single-phase three-wire distribution feeders. The dc-capacitor current of the three-leg pulse-width modulated (PWM) rectifier, which is included in the SC, is detected, and then added to the reference value of the battery-charging or - discharging current for a bidirectional dc-dc converter. Addition of the detected dc-capacitor current to the reference value for the dc-dc converter sinks the voltage ripples in the dc capacitors of both the PWM rectifier and bidirectional converter. This results in a substantial reduction in the capacitances of the dc capacitors. Simulation results demonstrate that balanced source currents with a unity power factor are achieved, reducing the capacitances of the dc capacitors in the previously proposed SC.