Research On Nonlinear Control Method Of Fuel Cell Hybrid Power System

As a clean, efficient power appliance, proton exchange membrane fuel cell (PEMFC) is considered to be one of the important sources of electric energy in the future. But compared with the traditional power supply, its inherent problems such as slow dynamic response affect its application in many fields. A hybrid power system that uses battery or supercapacitor as auxiliary energy storage device combined with a fuel cell can improve the dynamic response and expand the scope of application of the fuel cell. For hybrid power systems, energy management controller is crucial, largely determines the performance of the whole hybrid system.With the fuel cell/supercapacitor hybrid system as the research object, this thesis uses nonlinear control method to design the energy management controller. The main content of this thesis includes three parts:1) A fuel cell indirect hybrid system model is established in the MATLAB/Simulink simulation software, including a fuel cell model, a supercapacitor model and a Boost DC/DC converter model. It provides the simulation platform for the energy management controller design and validation.2) A nonlinear control based on the flatness method is applied to analyze the fuel cell/supercapacitor hybrid system. The Boost DC/DC converter and the hybrid power system are proved to be flat. Furthermore, a DC/DC converter controller is designed to control the fuel cell output power change with its reference, and an energy management controller designed for control energy and power distribution. Reference value of control target is set by power following energy management strategy and simulations are carried out.3) In order to meet accuracy requirement of flatness control, variable structure sliding mode controller is designed to improve the original controller. The sensitivity of the model parameter error can be reduced and the robustness of the system can be enhanced. Relevant simulations are implemented.