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Modelling of displacement compressors using MATLAB/Simulink software
KTH, Superseded Departments, Machine Design.
2004 (English)In: Proceedings of norddesign 2004 - product development in changing environment, TAMPERE: TAMPERE UNIV TECH PRODUCT DEVELOPMENT LABORATORY , 2004, 192-200 p.Conference paper, Published paper (Refereed)
Abstract [en]

Model based development is increasingly used to minimise costly and time consuming testing of physical prototypes during product development. Modelling and concept evaluation by using computer models for performance prediction will then be a substantial part of the PD process synthesis-analysis loop. However, easy-to-use and flexible methods have to be used for modelling, especially during product concept development, to avoid traditional coding and debugging. In this case, a twin-screw compressor has been modelled using the visual programming language MATLAB/Simulink. One of the objectives was to investigate whether it was feasible and appropriate to use MATLAB/Simulink for such a complex task. New developed methods have been used for this. The main difficulty turned out to be how to create a queue-like environment for the chambers. This problem was eventually solved, but it shows how MATLAB/Simulink can be cumbersome to use when dealing with complex problems.

Place, publisher, year, edition, pages
TAMPERE: TAMPERE UNIV TECH PRODUCT DEVELOPMENT LABORATORY , 2004. 192-200 p.
Keyword [en]
twin-screw compressor, simulation, visual programming, MATLAB/Simulink
National Category
Reliability and Maintenance
Identifiers
URN: urn:nbn:se:kth:diva-19441ISI: 000252984000020ISBN: 978-952-15-1227-8 (print)OAI: oai:DiVA.org:kth-19441DiVA: diva2:337923
Conference
5th Biannual NordDesign 2004 Conference Tampere Univ Technol, Tampere, FINLAND, AUG 18-20, 2004
Note
QC 20100810Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2011-11-02Bibliographically approved
In thesis
1. Modeling and Simulation of Physical Systems in a Mechatronic Context
Open this publication in new window or tab >>Modeling and Simulation of Physical Systems in a Mechatronic Context
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis gives different views on the modeling and simulation of physical systems, especially together with embedded systems, forming mechatronic systems. The main considered application domain is automotive. One motivation behind the work is to find suitable representations of physical systems to be used in an architectural description language for automotive embedded systems, EAST-ADL2, which is implemented as a UML2 profile, and uses concepts from both UML and SysML. As a part of the thesis, several languages and tools are investigated, including bond graphs, MATLAB/Simulink, Ptolemy II, Modelica, MATLAB/Simscape and SysML. For SysML, the modeling of continuous-time systems and how it relates to MATLAB/Simulink and Modelica is evaluated. A case study of an electric power assisted steering is modeled to show the differences, the similarities and the usage of the above mentioned languages and tools. To be able to classify the tools and languages, five realization levels were developed:

  • Physical modeling models
  • Constraint models
  • Continuous causal models
  • Discretized models
  • Discretized models with solver and platform implementation

By using these realization levels, models, tools and modeling languages can be classified, and transformations between them can be set up and analyzed. As a result, a method to describe the simulation behavior of a MATLAB/Simulink model has been developed using SysML activity diagrams as an approach to achieve integrated system models. Another result is an evaluation of the parametric diagrams of SysML for continuous-time modeling, which shows that they do not enable “physical modeling”, i.e. modeling the topology of the system and getting the underlying equations out of this topology. By including physical ports and physical connectors to SysML internal block diagrams, this could be solved. The comparison also shows many similarities between the languages. The results led to a more detailed investigation on conjugate variables, such as force and velocity, and electric current and voltage, and how these are treated in various languages. The thesis also includes two industrial case studies: one of a twin-screw compressor, and one of a simulation environment for automotive fuel-cell systems. Conclusions are drawn from these models, referring to the realization levels.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. ix, 85 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2009:12
Keyword
mechatronics, MATLAB/Simulink, SysML, bond graphs, Modelica, Simscape, simulation, modeling, EAST-ADL2, physical modeling
Identifiers
urn:nbn:se:kth:diva-10522 (URN)978-91-7415-361-3 (ISBN)
Public defence
2009-06-09, KTHB, Salongen, Osquars Backe 31, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20100810Available from: 2009-06-03 Created: 2009-05-20 Last updated: 2010-08-10Bibliographically approved
2. On the modular modelling for dynamical simulation with application to fluid systems
Open this publication in new window or tab >>On the modular modelling for dynamical simulation with application to fluid systems
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This licentiate thesis highlights some topics on modular modelling for dynamical simulation with application to fluid systems. The results are based on experience from the development of the fuel cell component simulation environment NFCCPP. The general application is cross-enterprise simulation of technical systems. There are four main topics: component definition including selection of interfaces, lumped modelling of fluid components, the use of dynamical equations to reduce simulation time in large systems and methods of to protect the intellectual property (IP) of a component.

An overview of different dynamical fluid simulation tools such as HOPSAN, MATLAB/Simulink and Easy5 is presented. Special focus is on interfaces, where different approaches for representing interfaces are presented using an illustrative example. Selecting interfaces is however not a separated task from how to set up and solve the underlying equations, which also is shown. Equations to model a lumped component are derived, to get a mathematical background to what problems there are to solve. These equations are derived especially to be applicable in block model software simulation tools such as MATLAB/Simulink. The equations are also compared with the bond-graph approach of representing dynamical systems. A twinscrew compressor is modelled in MATLAB/Simulink as an implementation of these equations. A method to decrease the simulation time in dynamical fluid system is also presented. The technique is to add virtual mass in the force equation to get a slower acceleration of the fluid. Using this slower response, it is possible to use larger time-steps when integrating the equations and thus the total simulation time can be reduced. The error introduced using this method is a modelling error in the time domain, and it is comparable with using unit transmission lines (UTL:s), as does HOPSAN.

The protection of the intellectual property (IP) of a component model is presented. The concept of clamping is thoroughly explained, as it often is overlooked in conventional IPprotection. Three concepts for code protection are presented: “Centralised simulation with remote user control”, “Localised simulation with simulation-time model usage control” and “Parallel distributed simulation”. The NFCCPP implementation of the concept “Localised simulation with simulation-time model usage control” is presented in more detail.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. viii, 20 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2005:30
National Category
Computer Science
Identifiers
urn:nbn:se:kth:diva-566 (URN)
Presentation
2005-12-06, sal A425, KTH, Brinellvägen 83, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101221Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2010-12-21Bibliographically approved

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