A Hierarchical Predictive Strategy-Based Hydrogen Stoichiometry Control for Automotive Fuel Cell Power System

Fuel cell vehicles which have the advantages of high energy conversion efficiency and no pollution are considered to be an important development direction for new energy vehicles. The output of polymer electrolyte membrane fuel cell (PEMFC), as the main energy source of fuel cell vehicles, is influenced by fuel starvation due to untimely hydrogen supply under frequently changing vehicle operating conditions. Therefore, it is necessary to predict the vehicle speed and regulate the hydrogen stoichiometry to ensure the power of the vehicles and extend the durability of the PEMFC. In this paper, a hydrogen stoichiometry control system for PEMFCs is proposed based on hierarchical predictive strategy. The first layer prediction uses the Markov chain to predict the vehicle speed. The PEMFC current demand as a function of vehicle speed is calculated by the vehicle dynamics model and the PEMFC output characteristic model. The second layer prediction uses the model predictive control (MPC) method to control the fuel cell anode supply system and regulate the hydrogen stoichiometry. The hierarchical predictive control system has a good control effect, which can maintain the hydrogen stoichiometry above 1.4 during the whole operating process of vehicles.