Magnetic Suspension System Control Using Position and Current

Applications of a Magnetic Suspension System Electromagnetic Suspension Train Frictionless Magnetic Bearings

Summary n Determine if Current Feedback can be utilized to improve performance n n

Outline n n n n n Magnetic Suspension System Overview High Level Block Diagram

Current Modeling n n Experimental Simulink n n Transfer Function Rate Limiter (nonlinear)

Current Controller Attempts n n State-space Current with Lag, Lead, or Lag/Lead n n

Position Controller Development n n n Root Locus Attempts Block Diagram Simulation Data Scope

Position Controller Development n Root Locus n n Open Loop Poles: 1. 0321, 0.

Position Controller Development n Block Diagram

Position Controller Development Step Response (simulation) n 28% OS n

Position Controller Development Step Response (x. PC) n ~30% OS n

Microcontroller Implementation n Improvements n n Input/Output Configuration System Timing Scope Plots Performance Data

D/A Converter Setup Volts (m. V) +2047 : 0 -1 : -2047 Controller Output

Step Response Our Controller Past Controller

Step Response Results n Our Controller Max Amplitude : 0. 2 Vpp Overshoot :

Future Suggestions n n n Lab bench space Modularize Code Design to realistic specs

References Jose A Lopez and Winfred K. N. Anakwa, “Identification and Control of a

Conclusion n Determined Current Feedback not viable n n n Designed New Position Controller

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Magnetic Suspension System Control Using Position and Current Feedback Team: Gary Boline and Andrew Michalets Advisors: Dr. Anakwa and Dr. Schertz

Applications of a Magnetic Suspension System Electromagnetic Suspension Train Frictionless Magnetic Bearings

Summary n Determine if Current Feedback can be utilized to improve performance n n No success with Current Feedback Develop New Position Controller n n Design Methods Implement: x. PC & Coldfire

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

System Overview

High Level Block Diagram

Current Modeling n n Experimental Simulink n n Transfer Function Rate Limiter (nonlinear)

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

Position Controller Development n n n Root Locus Attempts Block Diagram Simulation Data Scope Plots Performance Data vs. Specs

Position Controller Development n Root Locus n n Open Loop Poles: 1. 0321, 0. 9689 Closed Loop Poles: 0. 9704+/-0. 0077 j, 0. 8550, 0. 3888 Expanded

Position Controller Development n Block Diagram

Position Controller Development Step Response (simulation) n 28% OS n

Position Controller Development Step Response (x. PC) n ~30% OS n

Microcontroller Implementation n Improvements n n Input/Output Configuration System Timing Scope Plots Performance Data vs. Specs

Input/Output Configuration

D/A Converter Setup Volts (m. V) +2047 : 0 -1 : -2047 Controller Output FFF : 800 7 FF : 000

Software Flowchart

Timing Improvements

Step Response Our Controller Past Controller

Step Response Results n Our Controller Max Amplitude : 0. 2 Vpp Overshoot : 47% Settling Time : 240 ms n Past Controller Max Amplitude : 0. 5 Vpp Overshoot : 36% Settling Time : 560 ms Advantages: Faster System Disadvantages: Larger overshoot, Less input amplitude, Less stability

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

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. n n Feedback Inc. , 437 Dimmocks Mill Road, Hillsborough, North Carolina 27278. http: //www. fbk. com n Simulink, Version 6. 1 (R 14 SP 1), The Math. Works Inc. , Natick, MA 01760, 2004. n x. PC Target Box, The Math. Works Inc. , Natick, MA 01760, 2003.

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

Conclusion

Questions?