Robust Switching MIMO Control of Turbocharged Lean-Burn Natural Gas Engines

Abstract

This paper illustrates a multiple-input multiple-output (MIMO) controller design framework and a controller switching algorithm for MIMO controllers to achieve robust coordinated control of turbocharged lean-burn engines. The control problem tracks engine speed, diferential pressure across the throttle valve and the air-to-fuel ratio simultaneously to achieve satisfactory engine performance while avoiding compressor surge. The controller design approach is applied to a high-fidelity GT-Power engine model for a lean-burn natural gas engine to assess the closed-loop controller performance. The engine performance with the robust MIMO controller is compared with that using a benchmark production controller to evaluate the additional benefits of the MIMO controller. In a large step increase in desired engine speed and corresponding engine torque, it is observed that the MIMO controller leads to a slightly faster engine speed response. Furthermore, during transience, the minimum air-to-fuel ratio is 20% higher and the peak in differential pressure across the throttle is reduced by 59% when using the MIMO controller.