Active Harmonic Filtering with A Low Switching Frequency Inverter

Abstract

In recent years, the uninterrupted power system with active harmonic filtering has been developed to reduce the harmonic pollution from the non-linear load. With the increasing power level, the UPS with a switching frequency inverter becomes popular due to the demands of the customers with high efficiency, but it also leads to a long control delay because of the low control frequency closely related to the switching frequency. Such long control delay much degrades the performance of UPS in active harmonic filtering, so this study focuses on the relationship between the controller and the control delay. In addition, this paper also investigates the effect of the current transformer (CT) probe on the measured signals for a long-distance compensation of the non-linear loads, and a CT model will be taken into discussion. A one-step deadbeat controller under consideration of the CT model is presented to meet the demands with the control delay compensation and the correction of the distorted measured signals. Finally, the laboratory test results will be used to support the aforementioned analysis.