Surge analysis and optimization control of air supply system of fuel cell engine based on virtual flow sensor

Abstract

Due to rapid load fluctuations and high altitudes operation, the air supply system of a fuel cell engine is prone to surge, which compromises environmental adaptability and system reliability. To address this issue, this study introduces a surge control strategy by incorporating a bypass valve into the air supply system. A key innovation lies in estimating the bypass flow using a virtual flow sensor, thereby eliminating the need for physical flow measurement. However, when the bypass valve opens, the bypass flow tends to fluctuate significantly, leading to overshoot and oscillation in both flow and pressure. To mitigate these effects, an optimal control strategy based on a decoupling algorithm is developed. Experimental results demonstrate that the virtual flow sensor is both feasible and accurate. When the bypass valve opening ranges from 2° to 42°, the average relative error rate of the estimated flow remains below 3.35 %. Furthermore, the surge control strategy effectively maintains the flow-pressure ratio curve outside the surge region. This approach enhances the reliability and energy conversion efficiency of fuel cell air supply systems, offering a novel solution for surge suppression for dynamic and high-altitude conditions.