Active power filter based on feed-forward control

A feed-forward control strategy is proposed for active power filter.The feed-forward controller and the current controller are designed based on the state-space averaging model and the voltage controller is designed based on the power model.Since the grid voltage may generate big impulsive current during system startup,the feed-forward controller reduces effectively the effect of perturbing grid voltage and DC voltage on controlled current to improve the dynamic performance of system.The reference current for grid current control is directly obtained from the DC voltage control loop,which simplifies the control algorithm.The detection of load current or inverter output current and the PLL(Phase Locked Loop) are cancelled,resulting in low cost.The control circuit is realized with analogue devices and the experimental results demonstrate the validity of the proposed control strategy.