Magnetic Suspension System Control Using Position and Current Feedback

1
Magnetic Suspension System Control Using Position
and Current Feedback

• Team Gary Boline and Andrew Michalets
• Advisors Dr. Anakwa and Dr. Schertz

2
Applications of a Magnetic Suspension System
Electromagnetic Suspension Train
Frictionless Magnetic Bearings
3
Summary

• Determine if Current Feedback can be utilized to
  improve performance
• No success with Current Feedback
• Develop New Position Controller
• Design Methods
• Implement xPC Coldfire

4
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

5
System Overview
6
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

7
High Level Block Diagram
8
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

9
Current Modeling

• Experimental
• Simulink
• Transfer Function
• Rate Limiter (nonlinear)

10
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

11
Current Controller Attempts

• State-space
• Current with Lag, Lead, or Lag/Lead
• Noise Problems
• Current Feed-forward
• Current Error Feed-forward
• Based on Proportion to Position
• Position Integrator integrates current term out

12
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

13
Position Controller Development

• Root Locus Attempts
• Block Diagram
• Simulation Data
• Scope Plots
• Performance Data vs. Specs

14
Position Controller Development

• Root Locus
• Open Loop Poles 1.0321, 0.9689
• Closed Loop Poles 0.9704/-0.0077j, 0.8550,
  0.3888

Expanded
15
Position Controller Development

• Block Diagram

16
Position Controller Development

• Step
• Response
• (simulation)
• 28 OS

17
Position Controller Development

• Step
• Response
• (xPC)
• 30 OS

18
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

19
Microcontroller Implementation

• Improvements
• Input/Output Configuration
• System Timing
• Scope Plots
• Performance Data vs. Specs

20
Input/Output Configuration
21
D/A Converter Setup

• Volts (mV) Controller Output
• 2047 FFF
• 0 800
• -1 7FF
• -2047 000

22
Software Flowchart
23
Timing Improvements
24
Step Response
Our Controller Past Controller
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Step Response Results

• Our Controller
• Max Amplitude 0.2Vpp
• Overshoot 47
• Settling Time 240 ms

• Past Controller
• Max Amplitude 0.5Vpp
• Overshoot 36
• Settling Time 560 ms

Advantages Faster System Disadvantages Larger
overshoot, Less input amplitude, Less stability
26
Outline

• Magnetic Suspension System Overview
• High Level Block Diagram
• Current Modeling
• Current Controller Attempts
• Position Controller Development
• Microcontroller Implementation
• Future Suggestions
• References
• Questions

27
Future Suggestions

• Lab bench space
• Modularize Code
• Design to realistic specs
• Anti-aliasing filters
• Design System Bottom Up, Current and Voltage
  Control Independently

28
References

• Jose A Lopez and Winfred K. N. Anakwa,
• Identification and Control of a Magnetic
  Suspension System using Simulink and Dspace
  Tools,
• Proceedings of the ASEE Illinois/Indiana 2003
  Sectional Conference,
• March 27, 2004, Peoria, Illinois, U.S.A.
• Feedback Inc., 437 Dimmocks Mill Road,
  Hillsborough, North Carolina 27278.
  http//www.fbk.com
• Simulink, Version 6.1 (R14SP1), The MathWorks
  Inc., Natick, MA 01760, 2004.
• xPC Target Box, The MathWorks Inc., Natick, MA
  01760, 2003.

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Conclusion

• Determined Current Feedback not viable
• State Space
• Classical
• Designed New Position Controller
• Root Locus
• Simulation and xPC
• Implemented Design on Microcontroller
• Timer Driven
• Faster System
• Bring back focus
• Step back up from lower level
• Project importance at beginning
• Balance additional content

30
Conclusion
31
Questions?