Fuzzy logic-based control of cooling valves for energy-efficient hydrogen vehicles with evaluation in a WHVC mode

Precise temperature control in the stack is essential for optimal performance of proton exchange membrane fuel cells, and effective heat dissipation is required to manage temperature fluctuations during power generation. While traditional PID control of cooling systems can yield satisfactory outcomes, there may be better choices for vehicle applications, where the excessive robustness against the performance can result in cost and efficiency concerns. This study involved the design of a vehicle model to assess the cooling system's efficiency and performance using fuzzy control, which adapts actions to specific conditions, enhancing system efficiency. Fuzzy control was applied to regulate the cooling system's valve opening ratio, considering power demand, including parasitic power. In order to observe the improvement by applying fuzzy control, the evaluation protocol used to calculate the fuel economy of actual hydrogen vehicles was adopted, and fuel economy was measured through nine simulations with different initial SOC settings. As a result of simulations of four cases combining PI control and fuzzy control, the case where fuzzy control was applied showed an improvement in fuel economy of about 3.83%, at 18.527 km/kg, compared to 17.844 km/kg, which was the result when only PI control was applied. In addition to the quantitative evaluation of fuel economy, the impact of fuzzy control on improving fuel economy was qualitatively evaluated through analysis of dynamic data such as parasitic power of pumps and fans and valve opening rates.