Direct power control of three phase active filter with minimum energy storage components

Conventional active filters are implemented using two cascaded loops, a current control loop and a DC capacitor voltage regulation loop. This paper proposes a novel control structure based on the simultaneous control of line current and capacitor voltage based on instantaneous power control. The instantaneous active and reactive power concept is derived and explained. It is applied to the control of an active filter using two hysteresis comparators and an optimum switching table. The features of the proposed technique are illustrated by means of simulation and preliminary experimental results. Advantages include fast dynamic response for both AC current and DC bus voltage. This allows better tracking of harmonics and reduction in the DC bus energy-storage capacitor. In addition, the scheme gives good results under unbalanced load conditions