Rate-Based Model Predictive Control of Diesel Engines

The paper presents the results of a rate-based model predictive controller development for diesel engine air path control. The objective is to regulate the intake manifold pressure and EGR rate estimate to the specified set-points by coordinated control of the Variable Geometry Turbine (VGT), EGR valve, and EGR throttle. The approach utilizes rate-based reduced order linear models and Model Predictive Control (MPC). Potential benefits of using a rate-based approach versus conventional MPC methods are illustrated. Most notably, it is found that using a rate-based approach greatly extends the operating range of a single linear MPC controller on the nonlinear model. The performance of the rate-based MPC controller versus conventional MPC approaches subject to input and state constraints while following the specified set-points is evaluated using nonlinear model simulations. Strategies to reduce the computational complexity of explicit MPC are exemplified.