Model Based Control of Refrigeration Containers Kresten Kjær Sørensen Lodam electronics a/s and Aalborg University

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Outline Developmental, commercial and scientific objectives System overview Project status Issues that should be addressed Research

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Developmental Objectives “A set of methods that enable optimal, adaptive, constrained control of a refrigeration container that is also applicable to other thermodynamical systems”

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Commercial Objectives Better competitiveness through: –Reduced energy consumption –Reduced mechanical wear and tear –Improved adaptiveness of the controller

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Scientific Objectives To use MPC for refrigeration by: –Finding a suitable method for modeling nonlinear dynamics of the refrigeration system that may be used by an MPC. –Finding a method to cope with changes in system dynamics in the event of failure.

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · System overview Known refrigeration system dynamics Unknown cargo dynamics Known constraints on cargo temperature Economizer gives an additional degree of freedom

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Log(p)-h Diagram

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Project Status A library of nonlinear refrigeration component models has been developed. A composite simulation model has been developed. A framework that allows to test a controller, working within Matlab, with real hardware is ready.

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Simulation Model 1/2 Nonlinear simulation model of the refrigeration system. Composed of smaller component models from a library. Simulation is done in Matlab by a set of custom functions.

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Simulation Model 2/2 The simulation model is described by a number of files Each component are simulated separately for a short time step All outputs at the end of the simulation is propagated to the relevant inputs Simulation run again for another time step Equivalent of simulating a large, combined function with ZOH’s inserted between components

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Issues that must be addressed The system is nonlinear and has a large area of operation for both hot and cold temperatures. There are discrete actuators with strong influence on the dynamics that cannot be neglected. In case of partial system malfunction it is very important to continue cooling.

Lodam electronics a/s · Kærvej 77 · DK-6400 Sønderborg · Tlf · Fax · Research Adaptive MPC for increased robustness in the event of failure. Auto-generation of a model usable with MPC, based on the simulation model.