Research And Design Of Nitrogen Oxygen Sensor Control System

In recent years,with the gradual increase in vehicle ownership and the continuous improvement of exhaust emission standards,the detection standards of oxygen sensors have become more and more stringent.At the same time,the demand for oxygen sensors used in automobile exhaust gas treatment is increasing.The new nitrogen-oxygen sensor is widely used in automobile exhaust gas purification systems for its accurate and rapid detection of oxygen concentration and realization of air-fuel ratio and nitrogen-oxygen concentration measurement.However The gap between domestic NOx sensor related technologies and foreign countries is very large.In this thesis,researches are carried out in working characteristics of nitrogen-oxygen sensor,the overall realization of control system,the design of control algorithm and the performance test of control system.A set of nitrogen-oxygen sensor control system is designed to provide a reference scheme for the development of domestic nitrogen-oxygen sensor control system.Firstly,this thesis deeply introduced and analyzed the internal structure,working principle and inherent characteristics of nitrogen-oxygen sensor in aspect of the development of oxygen sensor,combined with electrochemistry,materials science and control theory,and pointed out the requirements for stable operation of nitrogen-oxygen sensor,various performance indicators and the necessary operating conditions,emphasized that the difficulty in the development of the nitrogen oxide sensor control system lies in the accurate measurement of weak electric signals,accurate and rapid temperature control,pump unit control and so on.Secondly,based on the theoretical analysis of the nitrogen oxide sensor and its control system,the design of the key control technology of the nitrogen oxide sensor was completed.Combining the working characteristics of the sensor and the knowledge of the signal conditioning of the hardware circuit,the research and design of each part of the hardware circuit,ideally realize the functions required by the control system.At the same time,according to the working process of nitrogen oxide sensor and the data obtained under different atmospheric conditions,the control process is deeply analyzed,and the control algorithm is designed with temperature control,pump unit control and system fault diagnosis as the core,and simulation tools such as MATLAB are used in modeling and simulation of the relevant controlling methods to verify the feasibility of the control scheme.Finally,combined with the self-developed control system and nitrogen oxide sensor to conduct comprehensive test experiments,verified the performance indexes of the hardware circuit,and the feasibility of hardware design and control by the dynamic and static test analysis of air-fuel ratio and nitrogen oxides on the synchronous atmosphere configuration instrument.The hardware design scheme and the control method are modified according to the test results,and the measurement accuracy and response speed are in line with the automobile exhaust gas detection standard.In addition,a self-developed nitrogen oxide sensor output curve was established,and pointed out the next research direction.