Input disturbance suppression for port-controlled hamiltonian system via the internal model method

This paper investigates the input disturbance suppression problem for nonlinear Port-Controlled Hamiltonian (PCH) system and presents a number of new results on the controllers design via the internal model approach. Different from the existing results on this topic we consider two cases. Firstly, the case of the disturbance generated from a linear Hamiltonian system acts through a channel other than the input channel is studied by adopting a method of decomposing the control into two parts and designing an internal model to zero the effect of the exogenous disturbance. Secondly, the case of the disturbance generated from a bounded nonlinear exosystem is studied by presenting a procedure of designing a nonlinear internal model to cancel the effect of the disturbance under two fundamental assumptions. Moreover, to further improve the suppression, a more effective internal model is also designed under less hypotheses. Finally, as an useful application, a corollary is presented by applying these results on PCH system to general nonlinear affine system. Simulations of a third-order synchronous generator model with disturbance generated from a nonlinear exosystem show the effectiveness of the designed internal model.