Adaptive Passivity-Based Control for Bidirectional DC-DC Power Converter Supplying Constant Power Loads in DC Shipboard Microgrids

Hybrid-electric ferry (HEF) is one of the most successful dc shipboard microgrids (SMGs) applications, where hybrid power sources supply the propulsion motors and hotel load through a common dc bus. Thanks to the bidirectional dc-dc power converter (BDPC), the power can be exchanged between the batteries and the dc bus in both directions (charging/discharging). Due to the uncertain working nature of ships on a sea, the dc bus voltage control and stability are crucial matters. The dynamic of the propulsion and hotel loads as constant power loads (CPLs) is the main reason impacting the stability of dc SMGs. To ensure dc bus voltage regulation, this paper presents a nonlinear passivity-based control (PBC) strategy for the BDPC supplying CPLs in HEF. Based on the PBC, the nonlinear disturbance observer is added to improve the control robustness against CPL variations. The proposed PBC strategy provided large-signal stability and swift reaction during CPL variations. The mathematical modeling has been verified using the MATLAB/Simulink platform.