A MODELICABased ObjectCentric Virtual Power Electronics Laboratory

1
A MODELICA-Based Object-Centric Virtual Power
Electronics Laboratory

• Janhavi Agashe
• V.V.Sastry
• V.Ajjarapu
• S.S.Venkata

Dept. Of Electrical Computer Engineering Iowa
State University
2
Outline

• Power Electronics Simulators
• Object-Oriented Modeling Language Modelica
• Modeling of Components in Modelica
• Various Models Developed
• Simulation Results
• Conclusions

3
Inter-Disciplinary Nature of Power Electronics
Power Electronics
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Power Electronics Simulators

• A simulator for power electronic systems should
• Have event handling capabilities.
• Handle hybrid/ mixed-mode systems.
• Support multi-domain modeling.
• Widely used simulators SABER, PSPICE,
  MATLAB/SIMULINK etc.
• Lack of Object-oriented features
• Closed modeling environment

5
Object-oriented Modeling Language - Modelica

• Developed by the Modelica Association, Germany
• Key Features
• Object-oriented modeling language
• Hierarchical structuring
• Reuse
• Effective in solving large and complex models
• Open Modeling Environment

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Object-oriented Modeling Language - Modelica

• Additional Features
• Acausal modeling
• Ports are not committed to input and output
  early in the modeling/design process
• Simpler models
• More efficient simulation
• Multi-domain
• Electrical circuits, multi-body systems, drive
  trains, hydraulics, thermodynamic systems

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Object-oriented Modeling Language Modelica

• Additional Features (contd.)
• Several formalisms
• ODE, DAE, bond graphs, finite state automata,
  state charts
• Graphical user interfaces
• Icons representing model components
• Menu driven interface for modeling and simulation
  
• Standardization effort
• Group of internationally recognized and
  experienced researchers and companies worked for
  language and model development

8
Modeling of Components in Modelica

• Model is derived as an extension of some base
  class using the extends statement
• Required variables are declared
• Necessary equations are defined in the equation
  section
• The annotation section defines the graphical
  symbol i.e. icon for the model
• The file is saved as .mo

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Modeling of Components in Modelica
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Thyristor Model in Modelica

• model Thyristor
• constant Boolean DymolaCompatibilitytrue
• extends Modelica.Electrical.Analog.Interfaces.Th
  reePin
• Real Gate
• Real u
• Real GOp 1.E-5
• Real RCl 1.E-5
• Real i
• Boolean GATE
• Boolean Op(starttrue)
• equation
• cont.v Gate
• u p.v-n.v
• ip.i
• 0p.in.i
• GATE if (Gate lt 1.0) then false else true
• 0 if Op then i - GOp(p.v - n.v) else (p.v -
  n.v) - RCli
• when (not (Op) and i lt 0) or (Op and u gt 0 and
  GATE) then
• new(Op) (not (Op) and i lt 0) or (Op and not
  ((u gt 0 and GATE)))

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Models in the Power Electronics Library
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Architecture of Simulator

• Front-end
• Pre-processing tool that helps effective
  understanding and modeling
• DYMODRAW
• Simulation Engine
• For conversion DAEs into state space form and
  solving them symbolically or with efficient
  numerical techniques.
• DYMOSIM. Any other simulator like ACSL, SIMULINK,
  etc. can also be used.
• Post-processing tool
• Visualization of dynamic behavior, 2-D or 3-D
  graphical view or animation.
• DYMOVIEW

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Architecture of Simulator
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Step by Step Simulation Procedure
Single Thyristor
Switch Library
Various Libraries
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Step by Step Simulation Procedure
Connection of components
Entire Circuit its Translation
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Step by Step Simulation Procedure
Simulation Control
Plot Window Output Variables
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Single-Phase Bridge Rectifier
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Single-Phase Bridge Rectifier
Firing Angle 45 degrees
Firing Angle 30 degrees
19
Buck Chopper
iout
Vout
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Buck Chopper
Duty Ratio 0.75
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MODELICA Based EE 452 Laboratory Experiments

• Single Phase Thyristor Rectifier
• Three Phase Thyristor Rectifier
• Buck Chopper
• Boost Chopper
• Single Phase Square-Wave Inverter
• Three Phase Square-Wave Inverter
• Chopper-fed DC Motor Drive
• V/F control of Induction Motor

22
Conclusions

• Object-oriented modeling language enabled reuse
  of models, hierarchical structuring and easy
  maintenance of models
• The power electronics library using MODELICA has
  been developed at Iowa State University
• EE 452 experiments earlier written in DYMOLA have
  been designed around the new MODELICA library