Air/Fuel Control System Design For 30kW Biomass Gas Engine-generator

With the development of society, we are needing more and more energy. the energy shortage has become a bottleneck restricting the development of society. On the other hand, China’s environmental pollution has become more serious. The use of clean energy has become an inevitable trend.Biomass is a clean energy source. Biomass gas engine generator set is a key to achieve efficient conversion and utilization of biomass energy. However, biomass gas low calorific value combustible gas content of large fluctuations, likely to cause instability in plant operation, difficulty in starting, inefficiencies and many other issues, but the key to solving these problems lies in the effective control of the air-fuel ratio.This topic originates from the national "863" project "new efficient biomass gas generator development and CCHP demonstration application". In this paper, the design of the structure and method of controlling air-fuel ratio control system. By working condition control, cylinder temperature correction method, feedforward and feedback control to achieve rapid and effective air-fuel ratio. I developed an air-fuel ratio controller, including hardware and software, and tested controller performance by HILS. The main work is as follows:Firstly, analyzing the air-fuel ratio control system at home and abroad. According to its shortcomings design the structure of the air-fuel ratio control system, and on this basis, devised a step method to control air-fuel ratio. By determining working conditions, the cylinder temperature correction, feedback and feedforward combined control to achieve rapid and effective control of air-fuel ratio.Second, according to the structure and method of control method of the air-fuel ratio control system, design the air-fuel ratio controller hardware, including minimum system board, the bottom board, and peripheral interface circuits. Wherein, peripherals and interface circuitry including speed measurement module, the cylinder temperature measurement module, exhaust oxygen content measurement module, methane concentration measurement module, fuel inflow control module and mixture inflow control module.Third, based on the hardware, design the software of the controller. It includes the main program, UEGO program, open ratio of fuel valve program, acquisition of signal program, display program, button program and communication program.Finally, tested controller performance by HILS. build internal combustion engine model and verified the feedforward and feedback control method.