An Improved Current Control Strategy of PWM Rectifier under Unbalanced Grid Voltage Condition

Three phase pulse width modulation (PWM) rectifiers has the problems of input current distortion and output voltage ripple under unbalanced grid voltage. In order to reduce the input current harmonics and the output voltage ripple of three phase PWM rectifiers under unbalanced voltage dips conditions, the stationary frame control strategy is adopted. However, its current loop error will cause higher harmonics of the input currents. To further reduce the input current harmonic, an improved control strategy of the current loop is proposed in this paper. In this control strategy, the current loop adopt an improved dual vector based model predictive current control with time delay compensation, which can effectively reduce the input current harmonics. The effectiveness of the proposed method is confirmed by simulation results.