Adaptive control of oxygen excess ratio in a proton exchange membrane fuel cell system

Abstract

Proton exchange membrane fuel cell (PEMFC) has drawn extensive attention as alternative energy with high power generation efficiency and low pollution. The dynamic performances of the PEMFC air system in a city bus, including oxygen excess ratio (OER) tracking and compressor movement, are essential for its stability and economy. In this paper, the study is concentrated on the control of OER under current disturbance and parameter uncertainty. To this end, a Lyapunov-based model reference adaptive controller (Lyapunov-MRAC) with PD controller is employed. Lyapunov-MRAC adjusts the controller in time to ensure the output of the plant following the desired reference model, and the PD controller further improves the dynamic performance of the controller. The proposed strategy, traditional Lyapunov-MRAC, and proportional–integral (PI) controller are implemented on a widely accepted nonlinear model describing the dynamics of the air supply system. The simulation results indicate that the proposed strategy outperforms traditional methods in OER tracking and overshoot restriction under current disturbance, and improves the robustness under the perturbation of compressor rotational inertia. In addition, the proposed strategy can reduce the control effort of the compressor so as to prolong the lifetime of the compressor.

Keywords

• Proton exchange membrane fuel cell
• System model
• Lyapunov-MRAC
• Adaptive law