Nonlinear MPC Controller Design for AIR Supply of PEM Fuel Cell Based Power Systems

The air supply system, which provides the oxygen for the fuel cell stack, is one of the most important subsystems of the proton exchange membrane fuel cell (PEMFC). In order to improve the performance of the air supply, a small rechargeable lithium‐ion battery is utilized to start up the PEMFC system and provide buffer power supply for the load demand. With energy consumption of the compressor considered, a power coordinating algorithm utilizing a virtual potential field approach is presented to manage the power demand for the PEMFC and the battery while maintaining the battery's state of charge. A nonlinear observer is designed to estimate the unmeasurable states of the air supply system and its convergence is proven. A nonlinear MPC method is proposed to control the air flow and ensure the adequate oxygen supply. Simulation results are provided to validate the performance of the power management algorithm and the air supply control method. Compared with the results of the MPC algorithm and the nonlinear MPC method for the PEMFC system without an auxiliary battery, the method designed here has better performance.