Nonlinear model-predictive control for an engine cooling system with smart valve and pump

In this paper, a nonlinear control approach based on a control-oriented model of an engine cooling system for vehicles is presented. An electrically driven coolant pump and a servo-controlled bypass valve act as control inputs. Due to physical limitations regarding the volume flow provided by the coolant pump as well as the opening section of the servo-controlled bypass valve, a constrained control problem arises. Therefore, a nonlinear model-predictive controller is employed, which explicitly takes the actuator limitations into account. A reduced-order disturbance observer is used to estimate unmeasured heat flows within the system in order to obtain a reliable prediction. An experimental analysis highlights the effectiveness of the nonlinear model-predictive control strategy in combination with a reduced-order observer.