Abstract: Electric vehicle charging brings a series of power quality problems including voltage fluctuation, harmonic increase and phase imbalance. An application scheme of Unified Power Quality Controller (UPQC) is put forward to solve these problems. Based on mathematical model of UPQC in two-phase stationary axis, voltage control unit based on dual PI loop controller and current control unit with state feedback single loop PI controller are designed. PI parameter settings are determined based on controller transfer function. A 20 kW prototype of UPQC is developed based on proposed research results. The experiment results show that the application of UPQC can improve power quality of electric vehicle charging equipment.

Key words: Unified Power Quality Controller(UPQC), electric vehicles, charging equipment, the quality of electric energy, voltage compensation