Oxygen excess ratio control of PEM fuel cell systems with prescribed regulation time.

In this paper, we focus on addressing the air supply problem for fuel cells. The air supply system faces a challenge: operating at maximum load consumes a significant amount of power, while insufficient air can lead to oxygen starvation problems in fuel cells. An important metric, the oxygen excess ratio, indicates whether the fuel cell is receiving the appropriate amount of air. Unfortunately, directly measuring this ratio is generally impractical. To overcome this limitation, we propose a fixed-time observer that reconstructs the oxygen excess ratio within a short predetermined period. By utilizing this reconstructed index, we introduce a cascaded double-loop controller. Specifically, both the external and internal loops are regulated using a modified prescribed time control strategy. This approach enables the regulation of the oxygen excess ratio to the optimal value within a prescribed short time. The advantages of our proposed method are validated through hardware in-loop experiments, showcasing its superiority over conventional finite-time control techniques.

Adaptive generalized super twisting sliding mode control for PMSMs with filtered high-gain observer.

This paper proposes a novel adaptive-gain generalized super twisting algorithm for permanent magnet synchronous motors. The stability of this algorithm is strict proof using the Lyapunov method. Both controllers of the speed-tracking loop and the current regulation loop are designed according to the proposed adaptive-gain generalized super twisting algorithm. Dynamically adjusted gains in the controllers can improve the transient performance and system's robustness while reducing chattering. A filtered high-gain observer is applied in the speed-tracking loop to estimate the lumped disturbances, including parameter uncertainties and external load torque disturbances. The estimates feeding forward to the controller further improve the robustness of the system. Meanwhile, the linear filtering subsystem reduces the sensitivity of the observer to the measurement noise. Finally, experiments are constructed using the adaptive gain generalized super twisting sliding mode algorithm and the fixed gain one, showing the effectiveness and advantages of the proposed control scheme.