Constant DC-capacitor voltage-control-based strategy for harmonics compensation of smart charger for electric vehicles in single-phase three-wire distribution feeders with reactive power control

Abstract

This paper proposes a novel and simple harmonics compensation strategy that can control the fundamental reactive current in the previously proposed smart charger (SC) for electric vehicles (EVs) in single-phase three-wire distribution feeders (SPTWDFs). The proposed harmonics compensation strategy uses only constant dc-capacitor voltage control (CDCVC), which is typically used in grid-connected pulse-width modulated inverters including active power line conditioners. Calculation blocks of the load-side fundamental active-reactive currents and harmonic currents are not required. Thus the authors offer the simplest harmonics compensation strategy for the SC in SPTWDFs with reactive power control. The basic principle of the proposed control strategy is discussed in detail. A digital computer simulation is implemented to confirm the validity and high-practicability of the proposed harmonics compensation strategy using PSIM software. Simulation results demonstrate that balanced and sinusoidal source-currents with a predefined power factor of 0.9 on the source side, which is an acceptable value in Japanese home appliances, are achieved on the secondary side of the pole-mounted distribution transformer using a CDCVC-based algorithm during battery charging and discharging operations in EVs. Simulation results also demonstrate that maintaining the power factor at 0.9 reduces the capacity of the SC by 31.5 % compared with that of the SC with the previously proposed control strategy.