Stabilization of DC-DC buck power converter feeding a mixed load using passivity-based control with nonlinear disturbance observer

This paper aims to design a robust closed-loop control strategy for the conventional DC-DC buck power converter feeding a mixed load (Resistive load + Constant Power Load). The strategy has been designed based on passivity-based control (PBC) approach with nonlinear disturbance observer (NDO). PBC approach guarantees the system stability due its property of energy dissipation through damping injection, while NDO insures the robustness against parameter uncertainties and disturbances of the system. Based on disturbance estimation technique, NDO works as a “patch” to existing controller by compensating the undesired disturbances through feed-forward channel. To verify the control performance of the proposed controller, a fair comparison had been obtained between; passivity-based control, passivity-based control plus integral (PBC+I), and proposed criterion PBC+NDO. PBC+NDO presents the fastest recovery performance, less overshoot, and shortest settling time during disturbance occurrence. The results have been validated using OPAL-RT real-time digital simulator.