Rejection of Periodic Disturbances with Unknown Dominating Frequencies for a Class of Nonlinear Circuit Systems

In this paper, we consider the disturbance rejection problem for a class of nonlinear circuit systems. It is assumed that the disturbance is periodic with dominating frequencies. Specifically, by Fourier expansion, the periodic disturbance consists of two parts, namely, the dominating part and the residual part. The former one is made up of a constant bias and finitely many sinusoidal components with large amplitudes, while the latter one comprises infinitely many sinusoidal components with comparatively small amplitude. It is proved that, by integrating the sliding mode control approach with adaptive internal model technique, the dominating gain of the sliding mode controller can be further reduced, which would suppress the amplitude of the magnitude of control input chatting.