Power Model Free Voltage Ripple Suppression Method of Three-Phase PWM Rectifier Under Unbalanced Grid.

Under the condition of the unbalanced grid, the second-order harmonic voltage ripple exists on the dc bus of the three-phase PWM rectifier. In this article, the internal relationship between the dc bus voltage ripple and the dc bus impedance is revealed. In addition, this article proposes a voltage ripple suppression method free from the power model, which can improve the system robustness against the parameter variations. By shaping the dc bus impedance, the voltage ripple is effectively suppressed without adding additional devices. In addition, the design criterion and the implementation of the virtual capacitor are analyzed in detail. Finally, experimental results show the accuracy of the theoretical analysis and the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]