Closed-loop Control of SI←→RCCI Mode Transitions in a Multi-Mode Combustion Engine

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Department of Mechanical Engineering-Engineering Mechanics


The primary barrier to implementing the RCCI mode in on-road vehicles is its limited operating range due to excessive pressure rise rates and complexity of combustion control during mode switching. The feasible operating range of the RCCI mode is only a subset of the speed-load range of conventional spark ignition (SI) engines. Therefore, a multi-mode engine concept operating in RCCI and SI modes can cover required engine operating range and can improve engine performance in terms of thermal efficiency and emissions. The goal of this study is to develop a model-based closed loop control of an SI-RCCI multi-mode engine. To this end, a gain scheduled model predictive controller (MPC) is developed for SI-RCCI-SI mode switching. A Kalman filter is designed for state estimations. The control architecture includes; a supervisory controller that determines the optimal operating mode based on the requested engine load and speed, and gain scheduled MPC and a Kalman filter. The controller performance is validated on a 2-liter multi-mode engine for SI-RCCI-SI mode switching at different engine loads (NMEP) and combustion phasings (CA50). The controller is capable of tracking NMEP and CA50 in both modes and during mode transitions while maintaining air-fuel ratio near stoichiometry in SI mode and constraining the maximum pressure rise rate (MPRR) below 8 bar/CAD in the RCCI mode.

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