Anode Pressure Control with Fuzzy Compensator in PEMFC System

Hydrogen safety is of great importance in proton exchange membrane fuel cell (PEMFC) systems. Anode pressure control has become a focus point in recent years. The differential pressure between anode and cathode in PEMFC system needs to be carefully controlled under a suitable threshold. In practice, the anode pressure is usually controlled about 20–30kPa higher than the cathode pressure to minimize nitrogen crossover and improve cell stability. High differential pressure could lead to irreversible damage in proton exchange membrane. PID control was the dominant method to control the anode pressure in the past. However, the anode pressure’s fluctuation when hydrogen mass flow suddenly changes is a long-term challenge. As the requirements of control precision are increasingly high, the traditional PID control needs to be improved. Several new control algorithms are presented in recent researches, however, mostly are theoretical and experimental. In order to achieve the goal of precise control of anode gas pressure in PEMFC system, a control algorithm for proportional valve as hydrogen supply equipment is introduced. This algorithm is based on a zero-order Takagi-Sugeno (T-S) controller and a compensator using Mamdani fuzzy model to solve the pressure fluctuation problem when hydrogen mass flow suddenly changes. This controller has succinct structure and simple calibration variables. This control algorithm is tested with comparison to the traditional PID controller and then tested on three different power level fuel cell systems with varying proportional valve calibers. The control performance is analyzed in detail, and the control error of anode pressure is acceptable. The results show that this control algorithm could be a universal method for anode pressure control in PEMFC system.