Smart charger for electric vehicles with power quality compensator on single-phase three-wire distribution feeders

In this paper, we propose a smart charger for electric vehicles (EVs) with a power quality compensator. The proposed smart charger consists of four-leg IGBTs. Three legs are used for a single-phase full-bridge-based PWM rectifier, which converts power from ac to dc during the battery-charging operation, or from dc to ac during the battery-discharging operation. This PWM rectifier can compensate reactive and unbalanced active currents on single-phase three-wire distribution systems because the third leg is connected to the neutral line of single-phase three-wire distribution feeders. The fourth leg is used as a bidirectional dc-dc converter for battery-charging and discharging operations. The three-leg PWM rectifier uses only constant dc-capacitor voltage control, which is commonly used in active power line conditioners. Thus, the authors have developed the simplest possible control method for a single-phase power quality compensator. The basic principle of the proposed smart charger is discussed in detail, and then confirmed by digital computer simulation using PSIM software. A prototype experimental model is constructed and tested. Experimental results demonstrate that balanced source currents are obtained on the secondary side of the pole-mounted distribution transformer for battery-charging and discharging operations.