On Decoupling Control of the VGT-EGR System in Diesel Engines: A New Framework

In this brief, a novel decoupling solution is proposed for the variable-geometry turbine (VGT) and exhaust gas recirculation (EGR) system of diesel engines based on the principle of active disturbance rejection control. This complex, double-input, double-output, VGT-EGR system is treated as two ideal, decoupled integrators for the purpose of control design, while all other dynamics that deviate from the ideal model, including cross coupling and dynamic variations due to operating point changes, and all other uncertainties are treated as the total disturbance to be estimated and canceled. Since the estimation of the total disturbance is bandwidth limited in the VGT-EGR system, feedforward controllers, one static and one dynamic, are used to speed up the response. The proposed controller is simple to implement, easy to tune, and able to handle a wide range of uncertainties without retuning or gain-scheduling. Its effectiveness has been validated in simulation, experimental tests, as well as in mathematical analysis, proving the inverse relationship between the tracking error and the controller bandwidth.