Gain-Scheduling Integrator-Augmented Sliding-Mode Control of Common-Rail Pressure in Diesel-Dual-Fuel Engine

Accurate common-rail pressure control is vital to good engine performance and low emission. Injection strategy of diesel-dual-fuel engine varies more greatly with speed and load than its diesel engine predecessor, and so does the common-rail pressure set point. Along with this swift set point change, other control challenges exist; they are speed-and-load variation, model uncertainty, sensor noise, actuator nonlinearity, and pressure disturbance from injection. Traditional control such as the PID was proved to be only marginally effective because of the swift set point change. We proposed integrating an integrator-augmented sliding-mode control with gain scheduling and feed-forward term. The sliding-mode control has fast action and is low sensitive to model uncertainty and disturbance. The augmented integrator ensures zero steady-state error. The gain scheduling handles the speed-and-load variation. The feed-forward term helps with the actuator nonlinearity. The proposed control system was implemented with four-cylindrical diesel-dual-fuel engines on an engine dynamometer and in a prototype pick-up truck, which runs on a chassis dynamometer and in road test. The common-rail pressure was accurately regulated both during the new European driving cycle test and the set point changes test. The proposed method compared favorably with the best-tuned gain-scheduling PID controller.