Adaptive Passivity-Based Control of DC-DC Buck Power Converter with Constant Power Load in DC Microgrid Systems

This paper presents a robust nonlinear control strategy to solve the instability problem of dc-dc buck power converter with constant power load (CPL) in DC microgrid systems. Based on the Passivity-Based Control (PBC), a nonlinear disturbance observer (NDO) is designed to improve the control robustness against both load and line variation, whereas the PBC guarantees the system stability due to its property of transient energy dissipation. By applying the disturbance estimation technique, NDO works in parallel with the PBC controller to compensate the disturbances through a feed-forward channel. This strategy ensures large signal stability as well as fast recovery performance of the system during disturbance/uncertainty as compared to other nonlinear control methods. Hardware-in-loop (HIL) experiment is performed on an OPAL-RT real time simulator. MATLAB simulation and HIL results are provided to verify the proposed control strategy. Further validations are presented using a real hardware experiment to emphasize the robustness of the proposed controller.