Analysis and experimental validation of a controller for a single-phase active power filter based on a 3L-NPC topology

Abstract

Summary In this paper, a controller for a shunt active power filter based on a 3-level neutral point clamped inverter is presented. The proposed controller guarantees compensation of harmonic and reactive powers caused by nonlinear loads connected at the point of common coupling. The controller comprises three control loops, namely, a current tracking loop, a voltage regulation loop, and a voltage balance loop. The current tracking loop is aimed to inject the appropriate current by means of the power inverter to compensate reactive power and harmonic distortion assuring a power factor close to unity. The voltage regulation loop is designed to assure that the DC-link reaches a desired constant voltage level, while the voltage balance loop is aimed to regulate each capacitor voltage on the DC-link towards the same voltage value. The performance of the proposed controller is experimentally validated on a 1 kW prototype.