3-D Negative-Sequence Current Reconstruction Method for DC Bus Voltage Ripple Suppression

The negative-sequence components in the unbalanced grid will lead to the dc bus voltage ripple, as well as the grid current harmonics. Existing methods rely on the grid voltage, inductance, and rectifier voltage to calculate the compensation current or power to suppress the voltage ripple. Once the parameters are not accurately obtained, the performance of these methods will be affected. In this article, a 3-D cone model is established to describe the relationship between the negative-sequence active, reactive currents, and the dc bus voltage ripple amplitude. Based on this model, a 3-D negative-sequence current reconstruction method is proposed to suppress the dc bus voltage ripple. By detecting the point coordinates on the 3-D cone model, the positions of the cone vertices can be reconstructed, which means the negative-sequence currents that eliminate the dc bus voltage ripple can be found. Finally, the accuracy of the theoretical analysis and the effectiveness of the proposed method are verified experimentally, and more than 94% fluctuating voltage can be effectively suppressed.