A simple and low-cost control strategy for active power filters connected in cascade

A simple and low-cost control strategy for active power filters implemented with pulsewidth modulation voltagesource inverters (PWM–VSI’s) connected in cascade is presented and analyzed in this paper. The principal component of the control circuit is an INTEL 8031 AH microcontroller, which generates the current reference waveforms and respective switching patterns for each inverter. The switching pattern is obtained by using a vector control technique. The proposed active power filter consists of two PWM–VSI’s, connected in cascade, each one operating at a different switching frequency. This paper presents the proposed control strategy in terms of principles of operation, circuit design, and implementation. Finally, predicted results are verified experimentally on a 10-kVA breadboard model.