Air-fuel Ratio Fuzzy PID Control for Coal-bed Gas Engine Based on Fuzzy PID Feedforward

摘要

In order to eliminate the adverse effects of coal-bed gas concentration disturbance to coal-bed gas engine air-fuel ratio control and the large pure time-delay existed in signal response of methane transducer, a fuzzy PID feedforward flow control plan was proposed for gas supply system. Fast and efficient flow control was performed in advance according to air-fuel ratio control requirements to eliminate air-fuel ratio control delays caused by the coal bed methane concentration disturbance. Based on the mentioned feedforward flow control plan, considering the premix coal-bed gas engine air-fuel ratio fluctuations arising from engine speed disturbances, a fuzzy PID closed-loop control scheme was proposed. By analyzing different air-fuel ratio control characteristics in transient condition and steady condition, the different closed-loop control of the air-fuel ratio was used to suppress air-fuel ratio fluctuations caused by engine condition changes. Compared to traditional PID control, the simulation results show that the air-fuel ratio fuzzy PID closed control scheme based on fuzzy PID feedforward flow control has ideal control effect, preferable stability and robustness. The air-fuel ratio control delays caused by the coal-bed methane concentration disturbance is well solved, and the problem of air-fuel ratio disturbance is well solved when the engine's working condition changes, meeting the pre-mixed coal-bed gas engine air-fuel ratio control requirements.