Digital repetitive plug-in controller for odd-harmonic periodic references and disturbances
A digital repetitive plug-in controller is presented. The reference signal and the disturbance are odd-harmonic frequencies of a fixed sinusoidal one. The particularity of the proposed scheme is that it introduces an infinite gain only at odd-harmonics; in this way an improvement of the internal stability is obtained. The key of the problem is to construct a repetitive loop for odd-harmonics. The overall performance of the scheme is derived and a proposition containing conditions which ensure the internal stability is presented. Finally, a numerical example is given: the signal to be tracked is a sinusoidal one \((f=50\)\,Hz) whereas the disturbance is composed by the first nine odd-harmonics. The sampling frequency was \(f_s=20\)\,kHz, a multiple of the fundamental one.
scientific article; zbMATH DE number 2131546