Novel method for line current detection type active filter using the disturbance observer

In case of the harmonic compensation based on the detection of the line current, a problem of the resonance between the active filter (AF) and an LC filter often arises if an LC filter is connected parallel to the AF. The disturbance observer based AF can suppress the antiresonance between the AF, an LC filter and the line, and have good compensation performance compared with the general proportional control based AF. In this paper, the robustness of the disturbance observer based AF is considered and the new control method using the phase lead compensation is proposed for improving the stability and the simulation results of the proposed method with good results are presented.