Practical modifications of a repetitive-based controller aimed to compensate 6ℓ ± 1 harmonics

In this paper, a modified repetitive-based scheme for the compensation of 6lscr plusmn 1 harmonic components is proposed. The proposed modifications are aimed to alleviate the phase shift caused by, first, the introduction of the damping gain, which were introduced to limit the infinite gain produce by the controller, and, second, the introduction of auxiliary low pass filters, which were intended to restrict the bandwidth of the controller and to reinforce the stability when the controller is installed in a closed-loop system. Experimental results on a digital implementation are provided to illustrate the benefits of the modified scheme.