Modularized three-phase four-wire active power filter

A modularized three-phase four-wire active power filter (APF) is proposed in this paper. This modularized APF uses only one control module send a set of pulse-width-modulation (PWM) signals to control one to four power modules. The control module can automatically detect the installation number of the power modules and control appropriately each power module such that all the power modules can jointly provide a total compensation capacity to match the load demand. The compensation function of the proposed APF is selectable, and it includes fundamental reactive power compensation, attenuation of a mixture of harmonic current of specific orders, and the combination of them. Besides, the attenuation ratio of the harmonic current of specific orders is adjustable. The proposed modularized APF has the advantages of flexible installation number, short maintenance time, easy mass production, and low cost. The experimental results verify the performance of the proposed modularized APF.