Airpath Modelling and Control for a Turbocharged Diesel Engine

There is a good advancement of diesel engine technology in recent years mainly because of application of innovative control strategies. The noisy and sluggish diesel engine has become quiet and responsive. This work throws light on the modelling and the control of the airpath for a turbo charged diesel engine to improve its transient response.

The inlet and exhaust manifolds of a diesel engine are coupled through the turbocharger and exhaust gas re-circulation valve. The turbocharger considered is a Variable Geometry Turbocharger (VGT), which has capabilities of controlling the turbine power. Mass flow and pressure are the parameters in the airpath mainly responsible for the transient behavior of a diesel engine. Therefore the main aim for improving transient response is to develop a control law which guarantees tracking of reference inlet manifold pressure (MAP) and inlet manifold air flow (MAF). As mentioned above the MAP and MAF are coupled to the turbocharger and EGR, the control problem can be expressed as a multi-variable problem.

The airpath model is a linear parameter-varying (LPV) model with parameters such as inlet manifold pressure and exhaust manifold pressure. The LPV model needs to be linearized in certain operating points so that its local behavior can be investigated. This Linear model is utilized to develop the open loop system for LPV theory. The LPV theory with linear matrix inequality (LMI) is applied to derive a control law with induced L₂ norm performance.

The parameterization of different matrices is accomplished by testing a prototype engine.