Performance Evaluation of Model-Based Controller with On-board Polytropic Index Prediction Model for Compression Stroke under Steady Driving Condition of CI Engine

Abstract

In the conventional map control, the number of adaptations becomes large to make the map for transient driving conditions, which leads to extend the development period and increase the development cost. To overcome these shortcomings, the development of the model-based control is required. The previous modelbased feedforward (FF) controller for diesel engines used several empirical equations based on experiments to predict the polytropic index for the compression stroke considering heat losses. To reduce the number of experiments, the authors developed the physical model for predicting the polytropic index (referred to as the present model) and implemented on the above FF controller. For the verification of the sensitivity of the polytropic index to the control results, we compared between the FF controller with the empirical equation and that with the present model. Under the steady driving conditions, it was found that the FF controller with the present model could predict the polytropic index with an average error of 0.22% and the IMEP with the difference of 8.56 kPa, which shows that the present model can be used in place of the empirical equation.