Electric Motor for Challenge X

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Electric Motor for Challenge X
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Members

• Faculty Advisor
• Dr. Marshall Molen
• Team Members
• Michael Robertson Craig Ross Dustin Ott
  Jeff Smith
• (Team leader)
• Hardware, testing, Website, simulation
  Hardware, testing, Hardware, testing,
• and research and research
  and research and
  research

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Motivation

• Become involved in an effort to make vehicles
  cleaner and more efficient
• Gain experience in a large-scale engineering
  effort
• Help MSU win

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Overview

• Many alternatives to a gasoline engine exist.
  In several lies a common thread
• Electrical energy storage device
• Electric motor
• The motor provides extra efficiency, high
  starting torque, and the ability to recapture
  energy from the wheels.

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Design Constraints
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Configuration

• Originally, we considered 3 options
• 1 AC induction motor
• 2 AC induction motors
• 1 AC induction 1 DC permanent magnet motor
• 1 AC induction motor seemed the best compromise
  between performance and size / weight

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Configuration

• Another option 1 DC permanent magnet motor
• High energy density
• Better speed control
• gt 90 efficient as both a motor and a generator
• Brushed or brushless?
• Brushless DC motors have longer lives, require
  less maintenance, and have better thermal /
  electrical / mechanical characteristics

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Testing

• To test the accuracy of the efficiency numbers,
  we decided to measure the characteristics of a
  smaller brushless DC motor.
• Motor Bosch Rexroth MKD-112C-058
• Controller Bosch Rexroth DKC01.3-100
• Motor was operated via DriveTop
• Motoring characteristics were measured by placing
  various loads on the motor

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Testing

• Results
• Motoring
• More testingneeded
• Generating
• Were not able to couple the MKD-112C with another
  motor to test the generation capabilities

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Motor Design

• Dimensions
• Power is proportional to l x r2
• However, small r is essential for fitting under
  the vehicle
• Also, a long, thin motor would work better,
  mechanically

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Motor Design

• Materials
• Electrically magnetized components
• Simple field-weakening 1
• Permanent magnet
• Higher torque, more compact 1
• Magnetic composites
• Increase torque/weight ratio, decrease axial
  length 2

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Motor Design

• Feedback 3
• Hall sensors
• Simple control
• More elaborate motor
• Back EMF sensing
• More complex control
• Less maintenance
• Less motor components

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Motor Design

• Possible modification
• Multiple windings 4
• Two sets of windings with different numbers of
  turns can act as an electric gear system
• Useful for providing high starting torque
  while retaining a large region of operation

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Controller Design

• Concept 3
• Two switches are closed at a time
• The rotor position sensors are used to
  determine which two to activate
• Pulse widths determine the desired speed of the
  motor
• Back EMF zero-crossing can be translated to look
  like Hall sensor data

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Controller Design

• Commutation Algorithm 3
• // If the state has not changed, do nothing
  if (sensor_port sensor_old) return //
  Update the PWM outputs and retain the new state
  sensor_old ? sensor_port if(direction 0)
  pwm_port ??comm_table0-5 else pwm_port
  ??comm_table1-0,3-2,5-4 duty_cycle ? vm /
  vdc spd_fraction return

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Future Work

• Continue to become acquainted with the state of
  the art in motors
• Order the actual motor
• Fit the motor and controller into the car

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Acknowledgements

• Dr. Marshall Molen
• Philip Conley
• Dr. Joseph Picone
• Dr. Wenzhong  Gao

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References

• 1 D. Martinez-Mufioz and M. Alakiila,
  Comparison between a novel claw-pole
  electrically magnetized synchronous machine
  without slip-rings and a permanent magnet
  machine
• 2 P. Viarouge, J. Cros, Y. Chalifour, and C.
  Gélinas, New Structures of Brush and Brushless
  DC Motors using Soft Magnetic Composites for
  Automotive Applications
• 3 P. Yedamale, Brushless DC (BLDC) Motor
  Fundamentals
• 4 J. Cros, J.R. Figueroa, P.Viarouge, BLDC
  Motors with surface mounted PM rotor for wide
  constant power operation

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Questions??