Development of a model based combined Fuzzy-PID controller for idle speed control of internal combustion engine

In this paper a combined fuzzy-PID controller for idle speed control of internal combustion engine has been developed. The main purpose of this controller is appropriate engine operating under normal and transient loads and reduction of emission and fuel consumption. Using the approach of model based controller design, first, an engine model for the idle state has been developed. In this model idle air valve command and ignition angle are used as inputs and engine speed has been calculated as output. In order to evaluate the behavior of the model, XU7-1761cc gasoline engine data has been used within the idle state. Average error for developed model is 2.33% and maximum error is 8%. Speed control is performed by two new Fuzzy and Fuzzy-PID controllers. Ignition angle and idle air valve opening rate are two outputs of the controlled transient conditions under applying external load such as air condition, power steering and alternator have been simulated. Simulation results show that designed controller has stable and acceptable behavior under transient load condition and reduces fuel consumption up to 14.4% compared to the feedback-feedforward controller implemented in electronic control unit of the vehicle.