Research On Biogas Power Air - Fuel Ratio Control Technology

Biogas, a high calorific value, renewable clean energy, aroused people’s great attention, and along with the fast development of biogas technology and the strongly support by the government, biogas has huge social. Economic and environmental value as a driving force fuel with high calorific value. The air-fuel ratio is the key factor, which affects the combustion efficiency and the emission performance of engine power in the processing of biogas combustion. Control the air-fuel ratio in combustion can stable combustion process, speed up the combustion rate, thus improve the combustion efficiency. This paper studies the controlling of the air-fuel ratio in the following three aspects.Firstly, biogas is a complex composition and its concentration changes a lot, in order to realize the effective utilization and precise control of the air-fuel ratio, we need to stable the composition of biogas and improve the content of methane. Based on the mechanisms and technologies of biogas purification, this paper studies the law of the biogas purification by referring the biogas purification technologies at home and abroad. Through controlling the variable factors in purification, such as the inlet pressure, the inlet flow rate, the liquor flow rate, the filler types and amounts etc, studies the purification effect in different conditions, summarizes the law of biogas purification.Secondly, the jet flow characteristics of biogas is the basic data of the air-fuel control of the biogas power engine, the actual amount of injection is related to factors like injection pressure, temperature, injection time and injection size etc, which directly affects the control of air-fuel ratio and performance of engine. Based on the above factors, this paper uses the C8051F340 SCM and 5 phase motor driver board, designs the spraying driving circuit with rapid response and low energy consumption, discusses the injection in different conditions, summarizes the flow characteristics in the spraying processing which can be used to confirm the injector model and the variation range of controlling parameters of biogas power engine.At last, according to the research of controlling characteristics of the air-fuel ratio control of biogas power engine, the paper has proposed a control scheme of biogas power engine. The paper builds a mean value model of biogas power engine, compares, analyzes and compares the theory of the PID control and fuzzy control and has proposed fuzzy PID control strategy at last. While the above have been done, a simulation model of the air-fuel ratio control of biogas power engine has been built. Then the paper can simulate the control the air-fuel ratio of biogas power engine under different load and speed conditions by using the Matlab/Simulink software. The simulation results show that the two control strategies(the fuzzy PID control and the PID control) has good effect on the controlling of the air-fuel ratio of biogas power engine under different load and speed conditions. But compared with the PID control strategy, the fuzzy PID control strategy controls the air-fuel ratio of the biogas power engine more accurately in different operating conditions, the response time is shorter, the fluctuations is smaller and the static and dynamic characteristics of the system is more stable.