Vector active filter without current hysteresis controllers

Abstract

This paper presents the theoretical fundamentals and the digital simulation of a three-phase power active filter, whose control strategy is strictly vector-based. This vector control strategy determines first the region, within the inverter voltage vector hexagon, where the compensation current deviation instantaneous space vector /spl Delta/i/sub c/ is located. Afterwards the vector control computes the required inverter output voltage vector, e/sub 0/, that makes this current deviation equal to zero. Under the knowledge of these vector regions, a set of inverter switching commutation tables are created to produce the best switching action. The vector nature of this control makes unnecessary the "conventional" use of the three current hysteresis controllers of the variable switching frequency for the compensating inverter output currents. Therefore, the inverter switching frequency produced by this vector-based-control is inherently constant both for steady and transient states.