Variable structure PI controller in DC-link voltage control of active power filter

DC-link voltage is significant to harmonics suppression and stability of active power filter(APF). There are many literatures studied on DC-link voltage regulation, however, haven’t released the nature mechanism of DC-link voltage and presented optimal controller. This paper analysis the characteristic of DC-link voltage, and proposed variable structure proportional integral (VS-PI) control algorithm to regulate the DC-link voltage. This controller accomplished a small PI in steady-state and a large PI in transient-state, thus obtained excellent performance in harmonics suppression and resistance to interference. Finally, simulation and experiment proved that the proposed method is fast convergence, stable and have excellent performance in harmonics suppression.