A Transient Diesel EMS Strategy for Online Implementation

Abstract

A recently developed strategy for diesel engine management systems is modified to reduce the implementation complexity. The strategy calculates set points for engine management system controllable quantities with an aim to minimize fuel consumption for a given engine speed and requested torque profile, while keeping accumulated emissions below given limits. The strategy is based on the methodology for steady-state engine operation, but extended to handle transient effects in the engine caused by dynamics in the air system. The strategy leads to the parametrization of mappings with two, three and four input dimensions respectively. In this paper, a modification of the strategy is proposed such that the memory demanding multidimensional mappings can be approximated in an engine management system using only two-dimensional grid maps. The modified strategy has been evaluated using a complete diesel engine vehicle system model simulating the NEDC driving cycle. The performance of the modified strategy has been compared with the original performance of the strategy. It is demonstrated that the modification of the strategy has very little impact on resulting performance of a vehicle but requires considerably less memory for implementation.

Model-based diesel Engine Management System optimization for transient engine operation

“…The calculation of the set points using the transient extension is more complex, and two-, three-, and four-dimensional grid maps are needed for online implementation for boost pressure set points, oxygen fraction set points, and injection timing respectively. In a recent study presented in Grahn, Johansson, and McKelvey (2014a), it is demonstrated that the strategy can be modified such that it can be implemented using only twodimensional grid maps, without significantly decreasing the performance.…”