Abstract
To a large extent, the efficiency and durability of the proton exchange membrane fuel cell (PEMFC) depend on the effective control of air supply system. However, dynamic load scenarios, internal and external disturbances, and the characteristics of strong nonlinearity make the control of complex air supply systems challenging. This paper mainly studies the modeling of PEMFC air supply system and the design of a nonlinear controller for oxygen excess ratio tracking control. First, we analyze and calibrate the system’s optimal oxygen excess ratio control target and explore how the system temperature and humidity impact it, respectively; second, a second-order affine oriented control model which can represent the static and dynamic characteristics of the air supply system is derived, and a disturbance observer is designed to estimate and compensate the “lumped error” online. Then, aiming at the problem of unmeasurable cathode pressure, a state observer based on Kalman optimal estimation algorithm is proposed to realize the real-time estimation of cathode pressure; finally, a dynamic output feedback control system based on observer and backstepping nonlinear controller is proposed, and the comparison and evaluation of two control strategies based on constant oxygen excess ratio tracking and optimal oxygen excess ratio tracking are carried out. The simulation results show the effectiveness and superiority of the designed control system compared with the reference controller.
Highlights
With the increasingly serious problems of energy crisis and environmental pollution, the development and utilization of new nonpolluting renewable energy sources such as wind energy, solar energy, and hydrogen energy have become an important direction of scientific and technological development
Yang et al [16] provided a novel modeling and control method based on Takagi-Sugeno fuzzy theory and predictive control, which can control the oxygen excess ratio in the ideal range and effectively suppress the fluctuation caused by the load change, and the results proved the proposed method can accurately control the air supply at desire values
Han et al [17] proposed a model reference adaptive control (MRAC) method to deal with various inherent characteristics of the air supply system and the results showed that the presented MRAC strategy performed better than the nominal feedback control method with less wear and less control effort on the compressor
Summary
With the increasingly serious problems of energy crisis and environmental pollution, the development and utilization of new nonpolluting renewable energy sources such as wind energy, solar energy, and hydrogen energy have become an important direction of scientific and technological development. (i) According to the tracking objective of the designed control system, the optimal oxygen excess ratio of the system is calibrated and analyzed, and its sensitivity to different load currents, temperature, and humidity conditions is explored, respectively (ii) A control-oriented model of a second-order affine air supply system is established, and an extended state observer is designed to estimate and compensate the “lumped error” in real time, thereby improving the accuracy of the model (iii) Aiming at the problem that the cathode pressure cannot be measured, a state observer based on Kalman optimal estimation algorithm is designed to estimate the cathode pressure online by using the simplified model (iv) A dynamic output feedback control system based on the observer + backstepping controller architecture is proposed, and the two schemes of fixed-value oxygen excess ratio tracking and optimized oxygen excess ratio tracking are compared and evaluated e main content of this paper is as follows.
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