Decoupled control for internal combustion engines research test beds

Abstract

This article presents a solid and robust automation model which has been developed and implemented in two different research engine test beds which were instrumented, one for diesel and the other one for spark ignition engines. The model, programmed in Matlab, is based on transfer functions with a decoupled (two single input single output systems) independent proportional and integral action controller that allows setting the desired engine speed and torque under stationary operation conditions. It was implemented in a Freescale HC08 family microcontroller external to the PC in order to avoid the risk of losing control during undesirable communication delays on the computer. The model has been validated in a wide range of engine operating modes, from low to high speeds and loads showing a good response. The first order transfer functions with delay have proven to be a good approximation even during the nonlinearities caused by turbocharger and electronic control unit incorporated in the engines. This low cost automation system has been tested for the last three years in a university engine laboratory showing a good performance.