Resonant Control with Differentiated Phase Correction for High Power Converters with Negative Sequence Elimination Featuring Double-sided Frequency Asymmetry

Significant control and modulation delay presents in the current regulation of high-power voltage source converters. The proportional-resonant controller (PR) with equalized phase correction (EPC), commonly used in the active power filter, can be referred here to suppress the negative sequence current better than the PI controller, and increase the phase margin with EPC. After introducing the current feedback (CF), proved to increase the tracking performance similarly to that in the dq-axis, the double-sided frequency domain becomes asymmetric, making EPC less effective. In this paper, the PR controller with differentiated phase correction (DPC) is proposed, with two independent phase correction angles and gains at the positive and negative poles. Analyzed with double-sided bode diagram, the stability margins are improved with the two extra freedom degrees. Moreover, the function related to the conjugate symmetry about the fundamental frequency is used to quantitively describe the response of such asymmetric system. Finally, simulation and experiment are implemented to verify the improved dynamic performance of the proposed one versus the compared schemes.