Experimental validation of passive and active fault-tolerant controls against sensor faults in a proton exchange membrane fuel cell system

A fuel-cell system is interconnected with subsystems such as the stack, thermal/water management systems, air/fuel supply systems, and inverter; if an abnormality occurs, operational efficiency and availability of the entire system can decrease. However, when faults occur in the system, terminating system operations or replacing faulty parts every time can be expensive and inefficient. Instead, appropriate decision-making is required, with fault-tolerant control considered an appropriate solution. This study presents methods and criteria for fault-tolerant control when a fault occurs in a proton exchange membrane fuel cell (PEMFC) system. By configuring a 1 kW residential PEMFC system, a fault occurring in either the thermocouple or mass flow meters – targets for the system control – is diagnosed, and real-time control change is performed instead of immediately repairing the sensor. This approach enables stable and continuous operation of the PEMFC system. The fault-tolerant control method consists of either the feed-back control method, using the real-time predicted value of each control sensor, or the feed-forward method, using the constant control-signal value learned in the normal state; the advantages and limitations of each method are compared. Futhermore, considering the system efficiency, stack durability, and operating control deterioration, a guideline is suggested for applying fault-tolerant control and improving its corresponding effectiveness. For example, fault-tolerant control can resolve a 4.6% decrease in system efficiency caused by a thermocouple fault. This study contributes to improving the system operation rate and reliability by applying fault-tolerant control, thus facilitating efficient decision-making following fault diagnosis.