Four Port Bidirectional Converter with Sliding Mode Control for Hybrid Renewable Systems

This paper presents a comprehensive analysis of the control topology for a DC microgrid powered by a 2kW Photovoltaic (PV) array, a 2kW Proton Exchange Membrane Fuel Cell (PEMFC) stack, and a 48V, 25Ah battery pack. A four port DC-DC converter is employed to integrate multiple energy sources efficiently, enabling flexible power flow management, reduced component count, and enhanced energy utilization compared to conventional single-input single-output (SI-SO) converters. A sliding mode-based controller (SMC) is implemented to regulate the switching of the PV-integrated and bidirectional ports of the converter, ensuring improved dynamic response, rapid transient recovery, and robustness against parameter variations. To evaluate system performance, a separately excited DC motor is used as the primary load, operating under different load torque conditions. The study examines various converter modes—Dual Input-Single Output (DI-SO), Single Input-Dual Output (SIDO), Triple Input-Single Output (TI-SO), and Dual Input-Dual Output (DI-DO)—demonstrating the adaptability of the four port converter and sliding mode control across different operating modes. MATLAB-Simulink simulations help assess both the adaptability of the proposed converter and the advantages of sliding mode control, validating the effectiveness of the proposed system.