A MODELICA-Based Object-Centric 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 North American Power Symposium 2002, Arizona State University, Tempe

3. System Area System & Control theory Modeling & Simulation High Power Area Low Power Area Analog Electronics Circuit Theory Signal Processing Electric machines Power Electronics Solid-State Physics Power Systems Digital Electronics Electromagnetics Inter-Disciplinary Nature of Power Electronics Power Electronics North American Power Symposium 2002, Arizona State University, Tempe

4. Power Electronics Simulators • A simulator for power electronic systems should • Haveevent 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 North American Power Symposium 2002, Arizona State University, Tempe

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 North American Power Symposium 2002, Arizona State University, Tempe

6. 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 North American Power Symposium 2002, Arizona State University, Tempe

7. 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 North American Power Symposium 2002, Arizona State University, Tempe

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” North American Power Symposium 2002, Arizona State University, Tempe

9. Modeling of Components in Modelica North American Power Symposium 2002, Arizona State University, Tempe

10. Thyristor Model in Modelica model Thyristor constant Boolean DymolaCompatibility=true; extends Modelica.Electrical.Analog.Interfaces.ThreePin; Real Gate; Real u; Real GOp = 1.E-5; Real RCl = 1.E-5; Real i; Boolean GATE; Boolean Op(start=true); equation cont.v = Gate; u = p.v-n.v; i=p.i; 0=p.i+n.i; GATE = if (Gate < 1.0) then false else true; 0 = if Op then i - GOp*(p.v - n.v) else (p.v - n.v) - RCl*i; when (not (Op) and i < 0) or (Op and u > 0 and GATE) then new(Op) = (not (Op) and i < 0) or (Op and not ((u > 0 and GATE))); end when; end Thyristor; North American Power Symposium 2002, Arizona State University, Tempe

11. Models in the Power Electronics Library North American Power Symposium 2002, Arizona State University, Tempe

12. Architecture of Simulator • Front-end • Pre-processing tool that helps effective understanding and modeling • DYMODRAW • Simulation Engine • For conversion DAE’s 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 North American Power Symposium 2002, Arizona State University, Tempe

13. GraphicalFront-end Object-oriented Modeling Simulation Engine Post-processing Tool Architecture of Simulator North American Power Symposium 2002, Arizona State University, Tempe

14. Step by Step Simulation Procedure Single Thyristor Switch Library Various Libraries North American Power Symposium 2002, Arizona State University, Tempe

15. Step by Step Simulation Procedure Connection of components Entire Circuit & its Translation North American Power Symposium 2002, Arizona State University, Tempe

16. Step by Step Simulation Procedure Simulation Control Plot Window & Output Variables North American Power Symposium 2002, Arizona State University, Tempe

17. Single-Phase Bridge Rectifier North American Power Symposium 2002, Arizona State University, Tempe

18. Single-Phase Bridge Rectifier Firing Angle = 45 degrees Firing Angle = 30 degrees North American Power Symposium 2002, Arizona State University, Tempe

19. Buck Chopper iout Vout North American Power Symposium 2002, Arizona State University, Tempe

20. Buck Chopper Duty Ratio = 0.75 North American Power Symposium 2002, Arizona State University, Tempe

21. 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 North American Power Symposium 2002, Arizona State University, Tempe

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 North American Power Symposium 2002, Arizona State University, Tempe