Design of cascaded observer of internal oxygen mass for Proton Exchange Membrane Fuel Cell system

Abstract

The Proton Exchange Membrane Fuel Cell (PEMFC) system’s performance and durability are greatly influenced by the oxygen excess rate (OER). However, the accurate measurement of OER can be challenging due to the comprehensive dynamic mechanism of air supply and consumption. To address this issue, a cascaded sliding mode-extended state observer (SM-ESO) was proposed. The pre-stage observer entails reconstructing the full states via a reduced-order sliding mode observer, utilizing compressor speed and supply manifold pressure. Moreover, the sliding mode gains are online updated to accommodate varying operating conditions. The post-stage extended state observer is presented to extract mass flow rate features of oxygen and to obtain OER. Meanwhile, the two-stage cascade provides accurate observation with low cost. The real-time implementation among the proposed method, sliding mode observer, and extended Kalman filter observer demonstrated that SM-ESO gave a more accurate and robust estimate of OER.