Model based control of exhaust gas recirculation valves and estimation of spring torque

Exhaust Gas Recirculation (EGR) valves have been used in diesel engine operation to reduce NOx emissions. In EGR valve operation, the amount of exhaust gas re-circulating back into the intake manifold is controlled through the open position of the valve plate to keep the combustion temperature lower for NOx emission reduction. Most of the control methods do not provide sufficient control accuracy on the valve position and the response time. Here, the model of a motor driven EGR valve is first identified through experiments and then the Generalized Predictive Control (GPC) method is applied to control the plate position of the valve. At the next step, to have a faster and more accurate control of the valve the torque generated by the spring connected inside the valve is estimated. The spring torque is considered as an external disturbance torque and three filters: Kalman, Hinfinity and Hinfinity Gaussian Filters are used to estimated this torque.