Predictive Control in Matrix Converters Marie Curie ECON2 Summer School University of Nottingham,...
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Predictive Control in Matrix Converters Marie Curie ECON2 Summer School University of Nottingham, England July 9-11, 2008 Marco Esteban Rivera Abarca Universidad Técnica Federico Santa María Department of Electronics Engineering Valparaíso, Chile. e-mail: [email protected]
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Transcript of Predictive Control in Matrix Converters Marie Curie ECON2 Summer School University of Nottingham,...
Predictive Control in Matrix Converters
Marie Curie ECON2 Summer SchoolUniversity of Nottingham, England
July 9-11, 2008
Marco Esteban Rivera Abarca
Universidad Técnica Federico Santa MaríaDepartment of Electronics Engineering
Valparaíso, Chile.
e-mail: [email protected]
-2-Marie Curie ECON 2 Summer School, 9 -11 July 2008
1. Introduction
2. Power Circuit and Basic Concepts
3. Control Strategy: Predictive Direct Torque Control (PDTC)
4. Models used to Obtain Predictions
4.1 Matrix Converter
4.2 Induction Machine
4.3 Input Filter
5. Results
6. Improvements
7. Future Work
8. Conclusion
Outline
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
Ready for the next
-3-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Introduction
Matrix Converter is a single-stage power converter and
represents an alternative to back-to-back converters in cases
where size and the absence of large capacitors or inductances
are relevant issues.
Model Predictive Control has been used in applications
related to power converters, generally with modulation
techniques. In this work is presented a control strategy to
control input PF, torque and flux on an IM, based on Predictive
Control: without linear controllers without hysteresis without modulators (PWM)
Ready for the next
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-4-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Power Circuit and Basic Concepts
Matrix Converter
Input Filter
Load : Induction MachineReady for the next
Bidirectional Switch
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-5-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Control Strategy: Predictive Direct Torque Control (PDTC)
An intuitive approach
Ready for the next
PowerSupply
MatrixConverter
InductionMachine
SwitchingState (k)
DigitalController
Time (k+1) Time (k+1)
Time (k+1)
Time (k+1)
Time (k+1)
Time (k+1)Time (k+1)
SwitchingState (k+1)
Time (k+1)
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-6-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Block diagram of the Predictive strategy
Measurements are acquired.
1Predictions of Flux and Torque are computed for each of the 27 switching states by means of a model.
2
The torque reference is generated by a PI controller.
3
The reactive input power is also predicted for each state.
2
A quality function g is evaluated for each prediction.
4
Ready for the next
Control Strategy: Predictive Direct Torque Control (PDTC)
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
The switching state that minimizes g is selected to be applied during the next sampling interval.
5
-7-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Control Strategy: Predictive Torque Control (PTC)
Quality Function g : The Evaluation Criterion
Must reflect the desired objectives, in order to determine the best state.
Considering both objectives (adding):
Objectives related to the load:
Minimize the error on the electric torque and flux magnitude.
Objectives related to input variables:
Controllable input Power Factor (most cases unity PF, no reactive power).
The versatility of the method allows to include other objectivessimply by adding terms to the quality function. Ready for the next
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-8-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Models
Input Filter
Matrix Converter
Induction Machine
Ready for the next
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-9-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Models
Input Filter
Matrix Converter
Induction Machine
Ready for the next
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-10-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Simulation Results
Parameters
B=0 No PF or reactive input power control.
Quality Function:
B=0 No PF or reactive input power control.
High distortion in the input current. THD=68.5%
Low ripple and fast dynamic response.
Sinusoidal output currents, smooth freq. transition.
B=146·10-6 Controlled PF/reactive input power.
Low distortion in the input current. THD=4.7%. PF=1.
Practically identical output variables
B=146·10-6 Controlled PF or reactive input power.
Ready for the next
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-11-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Improvements
Ready for the next
How to reduce the processing
time?
What happens when I don´t have a correct model of
the load?
Perfect Prediction?
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-12-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Improvements
Improve the code of the algorithm.
Ready for the next
Other techniques of predictive control like DMC and GPC.
High computational cost.
Improve the predictive models:
- Kalman Filter to flux estimator.
- Load parameters estimation using LS and RLS methods.
- Correction of Input Currents: Study Input Filter.
- Correction of Input Currents: AC Supply Unbalanced.
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-13-Marie Curie ECON 2 Summer School, 9 -11 July 2008
00.2
0.40.6
0.8
-2
-1
0
1
2-1.5
-1
-0.5
0
0.5
1
1.5
00.2
0.40.6
0.8
-2
-1
0
1
2-1.5
-1
-0.5
0
0.5
1
1.5
Kalman Filter in flux estimator
Stator Flux [Wb]
Rotor Flux [Wb]
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
Improvements
-14-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Load parameters estimation using LS and RLS methods
Load Parameters
Real & Estimated Signal
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
Improvements
-15-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Correction of Input Currents: Study Input Filter
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
Improvements
-16-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Correction of Input Currents in presence of unbalances
Minimization negative sequence of input currents.
To generate a reference of input currents.
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
Improvements
-17-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Future Work
Experimental Implementation Predictive DTC.
Experimental Implementation of Improvements studied in
UCC.
Publications of results respective.
Experimental Strategy using an Indirect Matrix Converter.
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-18-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Conclusion
Simple and effective control for a matrix converter based
induction motor drive.
Controls together input and output variables (PF and motor).
Discrete-time switching - semiconductors switch only at
predefined and equidistant instants (No PWM).
This discrete approach match with the discrete nature of the
matrix converter’s switching states and digital control platforms.
The versatility of the method allows to include additional
objectives. The topic is still open for research.
Outline
Introduction
Power Circuit
Control Strategy: PDTC
Models
Results
Improvements
Future Work
Conclusion
-20-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Selection of the Weighting Factors
Outline
Introduction
Power Circuit
Control Strategy: PTC
Models
Results
Benefits?
Conclusion
Extra
Ready for the next
PF Control
-21-Marie Curie ECON 2 Summer School, 9 -11 July 2008
Selection of the Weighting Factors
Outline
Introduction
Power Circuit
Control Strategy: PTC
Models
Results
Benefits?
Conclusion
Extra
A
Reactive Power
Torque Error
A Flux Error
A
High value Low value
Always B=11
Ready for the next
