1997-02-24

A High Resolution Real-Time Model of a Diesel Engine 970614

Today diesel engines are controlled by electronic control units (ECU's), performing complex functions. New developed control algorithms should already be tested under real-time conditions in the laboratory before they are applied to the real engine. Hardware-in-the-loop simulation (HIL) is a powerful tool for development and test of the control algorithms implemented in the ECU's. Modern diesel ECU's are able to react to rotary oscillations of the crankshaft within a work cycle in order to control idling and running smoothness by a cylinder-individual variation of the start of delivery and the injection time. As a consequence also the simulator has to be able to generate torque oscillations with a resolution adapted to the sample rate of the ECU. The paper describes a high resolution real-time model which was designed by expanding a steady state model by a parallel thermodynamic model with a simplified structure. Comparing the mean values of the two model types, the parameters of the dynamic model can be adapted. This results in a reliable approximation of the dynamic characteristic within a work cycle. The theoretical deduction is completed by simulation results using a real-time simulator (Figure 1) connected to a diesel-ECU.

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