Disturbance-Observer based Compensation Characteristic of the Active Filter detecting the Source Current Harmonics

In case of the harmonic compensation based on the detection of the source-current, a problem of the resonance between the AF and an LC filter often arises if an LC filter is connected parallel to the AF. Thus the diturbance observer is introduced to solve this problem. By the estimation of the hamonics disturbance using the proposed disturbance observer, the compensation characteristics of the AF is improved and the resonant current is suppressed. The theoretical analysis and the simulation results are presented in this paper.