Four switch three phase active filter with reduced current sensors

This paper presents an active filter with reduced numbers of power switches and current sensors. The power circuit is a four-switch voltage source topology with a self-controlled DC bus. Two power switches are eliminated, the third phase being connected to the capacitor center tap. Harmonic compensation is achieved by forcing the line current to be sinusoidal and no harmonic current extraction is therefore required. The proposed the algorithm is robust and there are no spikes in the line current. The active filter operates effectively in the presence of unbalanced and distorted AC mains. Simulation and experimental results confirm the feasibility of the proposed filter.