Simple harmonics compensation method for smart charger with constant DC-capacitor voltage-control for electric vehicles in single-phase three-wire distribution feeders

Abstract

This paper discusses harmonic current compensation of the constant dc-capacitor voltage-control (CDCVC)-based strategy for smart charger for electric vehicles (EVs) in single-phase three-wire distribution feeders (SPTWDFs) under distorted load current conditions. The basic principle of the CDCVC-based harmonics compensation strategy under distorted load current conditions is discussed in detail. The instantaneous power flowing into the three-leg pulse-width modulated (PWM) rectifier, which acts as a smart charger, shows that the CDCVC-based strategy achieves balanced and sinusoidal source currents with a unity power factor (PF). The CDCVC-based harmonics compensation strategy does not require any calculation blocks of fundamental reactive, unbalanced active, and harmonic currents. Thus, the authors propose a simplified algorithm to compensate for reactive, unbalanced active, and harmonic currents. Simulation and experimental results demonstrate that balanced and sinusoidal source currents with a unity PF in SPTWDFs are obtained on the secondary side of the pole-mounted distribution transformer during both the battery-charging and battery-discharging operations in EVs, compensating the reactive, unbalanced active, and harmonic currents.