Capacitor voltage balancing control of cascaded multilevel inverter for high-power active power filters

High-power applications of cascaded multilevel inverter to active power filters (APF) is hindered by the problem of keeping capacitor voltage balance while retaining good filtering performances. This paper proposes a novel capacitor voltage balance control technique with closed-loop harmonic compensation for the cascaded multilevel inverter used in high-power APF. The proposed control method not only maintains capacitor voltage balance but also has good filtering performances, which suits for APF based on five-level and more level cascaded inverters. The steady state and dynamic experiment waveforms obtained from a prototype APF using cascaded multilevel inverter are presented to verify the validity and effectiveness of the proposed control methods.