Study On The CNG Engine Torque Control Based On Model

In this paper, the torque control system for compressed natural gas (CNG) engine is studied based on the system model. Firstly, the CNG engine torque control theory is introduced, and the relationship between the engine output torque and the three control parameters: the spark advance angle, the air-fuel ratio and the throttle opening, is derivated. Then for different engine working states, the regulation methods for the above three control parameters are analyzed. The relationship among them is used as the basis for establishing control strategy.With Matlab/Curve Fitting Toolbox and sensor calibration data, the temperature and the pressure sensor models are built. For position sensor, the working principles of them are analyzed to establish the models and transform the sensor voltage signal to physical signal. The CNG engine control system model is consists of three functional modules, which are operation intentions, torque control and hardware drivers. Using Matlab/Simulink/Stateflow, the control system model is built. The validity of the sensor singals is completed with condition detecting algorithm. The validated signals are used to identify engine state and calculate control parameters. The control strategy model is established for different engine working states.CNG engine model is used to verify and validate the correctness of control strategy model. Off-line simulation results show that the model with the control system requirement. With Matlab/RTW, the model is transformed to code and downloaded into the MACS565 atuomotive rapid control prototyping system. Some in-the-loop simulation tests are carried out to verify system model. At last, the initial calibration MAPs are established.