Non-linear adaptive hysteresis band pulsewidth modulation control for hybrid active power filters to reduce switching loss

Abstract

Pulse-width modulations (PWMs) are widely investigated in active power filter (APF) applications. However, there are seldom PWMs proposed in hybrid APF (HAPF) applications because of their non-linear current characteristic. This study proposes a non-linear adaptive hysteresis band PWM controller for HAPFs to reduce the switching loss and keep the total harmonic distortion (THD) at an acceptable level. In contrast to previous studies, as the coupling LC impendence of an HAPF can yield a non-linear compensating current, the quasi-linear and non-linear regions are exploited to obtain a low switching frequency. In addition, an approximated THD index is proposed to assess THD in a simplified way in the control system, which results in a faster system response. Finally, the performance of the non-linear adaptive hysteresis band controller is verified by comparing simulation and experimental results with a state-of-the-art PWM for HAPFs.