A single-phase shunt active power filter with an improved modulated carrier control

This paper proposes an improved modulated carrier control for single-phase shunt active power filter, which eliminates harmonic and reactive currents at ac sources drawn by nonlinear loads. This control method directly shapes line current to be sinusoidal and in phase with grid voltage by comparing a modulated carrier signal to the average line current and making duty ratio doubled. Since the line current compared to the carrier signal is not the peak, but the average value, dc-offset problem is effectively addressed. The proposed control technique extirpates the harmonic and reactive currents and solves the dc-offset problem. The operation of a shunt active power filter with the proposed control method is discussed, and experimental results verify its performance.