To improve tracking performance of engine speed in the face of nonlinearity and time-varying uncertainty, this article investigates the double closed-loop cascade active disturbance rejection control strategy for automotive engine control system. In this cascade control arrangement, the outer active disturbance rejection speed controller with the extended state observer for the speed error and its integral, and disturbance from load torque and time-varying uncertainty, drives the set-point of the inner loop to keep the engine speed to its set-point; meanwhile, the inner active disturbance rejection pressure controller with the extended state observer for the pressure error and its integral, and disturbance from the air mass flow rate leaving the intake manifold and the pumping fluctuation of air charge, manages the throttle valve to match the pressure with the set-point requested by the outer active disturbance rejection speed controller. The observer gains and controller gains of active disturbance rejection speed controller and active disturbance rejection pressure controller are determined by the linear matrix inequalities ensuring the stability and disturbance attenuation level of the closed-loop system. The effectiveness is validated by implementing the proposed strategy and a series of related control schemes in the simulator of a real V6 engine.
Design of Diesel Engine Adaptive Active Disturbance Rejection Speed Controller