Extended state feedback control for active power filter

An extended state feedback controller for current control of paralleled three-phase three-leg active power filter is presented. The primary goal is to eliminate the impacts of time delay caused by sampling and calculation. The controller is developed in synchronous rotating frame, so the decoupled discrete-time model is deduced at first. Then, a proportional feedback and an integral feedback constitute an extended state feedback controller, the impacts of time delay is analyzed. Moreover, in order to remove these effects, a state observer is introduced. Finally, the simulation results show that the APF based on the proposed controller has good steady and transient performance.