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

This paper presents an improvement in the harmonics compensation performance of a previously proposed smart charger (SC) with a constant dc-capacitor voltage-control (CDCVC)-based strategy for electric vehicles (EVs) in single-phase three-wire distribution feeders (SPTWDFs). A current controller of a three-leg pulse-width modulated rectifier with proportional-integral (PI) controllers in d-q coordinates are added for the third-order harmonic currents to the current controller with PI controllers in d-q coordinates for fundamental component in the previously proposed SC. This addition improves the harmonics compensation performance on the source side. The basic principle of the CDCVC-based algorithm for harmonic currents compensation is discussed in detail. The simulation results demonstrate that balanced and sinusoidal source currents with a unity power factor are obtained on the secondary side of a pole-mounted distribution transformer during both battery charging and discharging operations in EVs, thus compensating the harmonic, fundamental reactive and unbalanced active currents. Furthermore, the experimental results demonstrate that the addition of PI controllers in d-q coordinates for the third-order components improves harmonics compensation performance on the source side.