Experimental verification of line current detection type active filter combined with disturbance-observer

In this paper, we proposed a new control method for the AF to improve the harmonics compensation performance, in which the proposed control law is realized by the deadbeat control The disturbance observer is introduced to improve the harmonics compensation performance. By the estimation of the harmonics using the proposed disturbance observer, the compensation characteristics of the AF is very much improved. The deadbeat control can provide good current regulation without the calculation time delay. The current control is achieved by controlling the intermediate voltage of the inverter output filter so that the AF output current is regulated and the pulse width of the PWM inverter is determined by the deadbeat control law. The disturbance observer is effectively and stably realized by the proposed current regulation. As a result, the total harmonics compensation characteristics is much improved. The control method, mathematical analysis and the experimental results are presented in this paper.