Abstract:

An effective control strategy for fuel cell hydrogen systems can improve system dynamic performance and extend service life. In this paper， an adaptive sliding mode decoupling control strategy based on gradient optimization is proposed for circulating pump fuel cell hydrogen systems. Firstly， a fuel cell hydrogen system model is built based on Simulink. Based on this model， a decoupled sliding mode controller is designed to compensate for inaccurate model accuracy while achieving decoupling of flow and pressure. The stability of the feedback control rate is demonstrated through Lyapunov principle. However， sliding mode control has the problem of conflicting dynamic response performance and chattering. In response to this， in this study a gradient descent based sliding mode control parameter adaptive optimization method is further designed， and the system stability under variable loads is improved through a feedforward controller. At the same time， the sliding mode optimization parameter MAP self-learning method iss adopted to solve the gradient optimization delay problem under transient conditions while ensuring the stability of the closed-loop system. The results show that the adaptive sliding mode decoupling controller combined with feedforward designed in this paper has small overshoot， short response time， and high robustness. The maximum pressure difference between the anode and cathode is about 0.01 bar， and the maximum flow supply error is 0.015 g/s， which is capable of quickly responding to changes in hydrogen pressure and flow rate during variable load operation within 0.02 seconds. Compared to that before feedforward correction， the pressure fluctuation during the start-up condition of the fuel cell stack has decreased by 0.122 bar. Under disturbance， the system stability remains good， and the maximum fluctuation of hydrogen pressure is 0.01 bar.

Key words: fuel cell, sliding model control, decoupling control, gradient decline, feedforward control