A Repetitive-Based Controller for the Compensation of $6\ell\pm 1$ Harmonic Components

In this paper, a repetitive-based controller for the compensation of 6 lscr plusmn 1 harmonic components is proposed. This control scheme is more appropriate for processes that involve the use of six-pulse converters or other converters that mainly produce harmonic components at those frequencies. The control scheme is based on the feedback array of two delay lines plus a feedforward path that compensates only the 6 lscr plusmn 1 multiples of the fundamental frequency, thereby reducing the possibility of reinjecting unnecessary distortion into the system. The proposed scheme is, then, plugged into a generic feedback control system where a stability analysis is carried out. In addition, the passivity properties of the proposed scheme are presented, which open the possibility of control design following the passivity-based approach. Experiments that are based on a simple digital implementation are provided to illustrate the merits of our solution. These results include the open-loop responses of the proposed scheme and the responses in a practical example to validate its effectiveness in an application. For this latter result, the proposed scheme has been used in the controller of a 2-kVA shunt active filter to compensate the current harmonic distortion.