Simulation Verification of Fuzzy Control of Lithium Battery SOC in a Hybrid System of Fuel Cells and Lithium Batteries

This paper presents the simulation of a hybrid power system combining a fuel cell and a lithium-ion battery. The main power system architecture consists of a 70 kW proton exchange membrane fuel cell (PEMFC) integrated with a buck/boost converter. Additionally, a 175 kW lithium-ion battery is used as an auxiliary power source at the output stage, providing energy support during high-load conditions. The system is constructed using MATLAB Simulink, simulating the power system architecture of commercially available high-power hydrogen energy hybrid buses. Fuzzy control logic is incorporated to enhance overall system controllability, ensuring stable charging and discharging control of the lithium-ion battery’s State of Charge (SOC) to extend its lifespan. The simulation investigates the fuel cell’s output voltage, current, and power under conditions where the lithium battery’s SOC is regulated.To validate the SOC control method, a series of tests are conducted to assess its effectiveness and feasibility in maintaining optimal SOC levels, demonstrating that the proposed control strategy successfully prevents overcharging and extends battery life under varying load conditions.