Passivity-Based Control for Interleaved Double Dual Boost Converters in DC Microgrids supplying Constant Power Loads

The interleaved double dual boost converter (IDDBC) is considered a promising and reliable approach to interface the low-voltage renewable energy sources (RESs), such as battery packs, fuel cells and photovoltaic (PV) panels, to the DC bus of the DC microgrids. It could give a higher voltage step-up ratio and reduce voltage and current stresses on the power devices. However, the connection of various tightly regulated power converters, which are known as constant power loads (CPLs), would cause negative incremental impedance. Meanwhile, the unmodeled dynamics and load perturbation disturbances are unavoidable in the DC microgrid. These issues would deteriorate the system stability and even lead to system failure. To address these problems, this paper proposes an adaptive passivity-based control (PBC) to handle the DC bus’s large-scale stability issues of the N-phase IDDBC feeding CPL system. A reduced and practical N-phase IDDBC model supplying CPL considering unmodeled dynamics and load perturbation disturbances is proposed to facilitate the controller design. Besides, a nonlinear disturbance observer (NDO) is incorporated with the proposed PBC to improve the robustness against parameter uncertainties and external disturbances. And the global stability of the closed-loop system is proved through the Lyapunov theorem. Finally, simulation and experimental results are demonstrated to verify the feasibility and effectiveness of the proposed controller.