Study of closed-loop control scheme for source current detection type Active Power Filter

Compared to traditional load current detection type Active Power Filter (APF), source current detection type APF belongs to closed-loop control in control theory, which can improve its filtering performance dramatically. At first, this paper introduces two conventional APF control schemes with source current detection-proportional control and non-harmonic detection control. By analyzing, we points out these two schemes´ defects which limit their practical use: proportional control scheme has serious conflict between filtering performance and system stability, while non-harmonic detection control scheme make APF´s dc-link voltage easily influenced by fluctuation from load side. Then a new control scheme named voltage source control, which also based on source current detection, is proposed on base of analysis above. Principle and realization of this new control scheme are introduced to express its superiority. Finally, computer simulations and experiment results are presented to verify conclusions got from this paper and effectiveness of proposed control scheme.