Water Content Estimation and Control of PEM Fuel Cell Stack and the Individual Cell in Vehicle (Springer Theses)

This book focuses on water content estimation and control of the PEM fuel cell stack and the individual cell in vehicle. Firstly, the mathematical connection between polarization curve and equivalent circuit model proves importance of MEA and its feasibility to study water content. Optimizing structure of MEA realizes the internal water content recirculation of a fuel cell and improves its performance under middle or lower current density. The influence of water content on performance of MEA is quantified, and variation of equivalent circuit model is an excellent indicator of water content. Secondly, the comprehensive online AC impedance measurement method is put forward, including current excitation method, weak voltage and current signal processing method, and method for analyzing measurement error, and experiment validates measurement accuracy. The high-frequency impedance and statistical characteristic are proposed as indicator of water content. Finally, the dynamic model of the air supply system of a fuel cell engine is established and the closed-loop control of the air supply system and the water content estimation are decoupled. The experiment on a fuel cell system validates the proposed method for searching optimized operating conditions and the water management strategy. Supervisor’s Foreword Abstract Acknowledgements Contents 1 Introduction 1.1 Introduction to Research Background and Research Thesis 1.1.1 Research Background 1.1.2 Research Thesis 1.2 Modeling and Estimation of Water Content in a Fuel Cell 1.2.1 Online AC Impedance Measurement Methods 1.2.2 Water Management Strategy of the Fuel Cell System 1.3 Introduction to Our Research Content 1.4 Organization of This Book References 2 Modeling of Water Content in MEA for the PEM Fuel Cell 2.1 Introduction 2.2 Connection Between Polarization Curve and Equivalent Circuit Model 2.3 Internal Recirculation of Water Content in a Fuel Cell 2.4 Modeling of Water Content Inside the MEA 2.5 Summary References 3 Approach to Online AC Impedance Measurement of the Fuel Cell 3.1 Introduction 3.2 The Specialized DC/DC Converter for the Fuel Cell Stack 3.3 Modeling and Simulation for Feasibility Analysis 3.3.1 Feasibility Analysis for the Specialized DC/DC Converter 3.3.2 Feasibility Analysis for the Second Topology 3.4 Weak Signal Extraction at High Speed and High Precision 3.5 Experiment Based Analysis of Feasibility for System Application 3.6 Summary Reference 4 Water Content Estimation of the PEM Fuel Cell 4.1 Introduction 4.2 Error Analysis and Compensation for the Online AC Impedance 4.3 Sensitivity Analysis of Fuel Cell with Self-humidifying MEA 4.3.1 Analysis Based on High Frequency Resistance 4.3.2 Water Content with Respect to the Fuel Cell Voltage 4.4 Water Content Estimation for a Fuel Cell with External-Humidifying MEA 4.4.1 Average Water Content of MEA 4.4.2 Distribution of Water Content Through the MEA 4.5 Summary Reference 5 Water Management Strategy for the PEM Fuel Cell 5.1 Introduction 5.2 Dynamic Model of the Fuel Cell System 5.2.1 Dynamic Model of the Cathode Chamber 5.2.2 Dynamic Model of the Anode Chamber 5.2.3 Dynamic Model of the Air Supply Subsystem 5.3 Control Algorithm of the Air Supply Subsystem 5.4 Water Management Strategy for the Fuel Cell System 5.4.1 The Fuel Cell System with no External Humidifier 5.4.2 Method for Searching Optimized Operating Condition 5.4.3 Water Management Strategy and Experiment Validation References About the Author