Three-level hybrid active power filter with Quasi-Resonant DC-Link technique in three-phase four-wire system

This paper presents a three-level hybrid active power filter (HAPF) combined with Quasi-Resonant DC-Link (QRDCL) soft-switching circuits in a three-phase four-wire system. Hybrid active power filter is a combined system of passive filter and active power filter, so it can compensate system harmonic current, reactive power and neutral current with a low dc voltage. Quasi-resonant dc-link circuits use the mirror symmetrical approach to achieve zero voltage switching for main switching devices in a three-level inverter in order to decrease switching power losses. By combining the hybrid active power filter and the soft-switching circuits, the proposed topology not only has a lower inverter rating but can also reduce switching power losses. Simulation results of this soft-switching hybrid active power filter are provided to verify this proposed system and its control strategy.