Precision Variable Frequency Drive

1
Precision Variable Frequency Drive

• Group May07-13
• Jason Kilzer
• Nick Nation
• Dave Reinhardt
• Matt Shriver
• Client Jim Walker
• Faculty Advisor Professor Ajjarapu

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Precision Variable Frequency Drive

• Nick Uses and Constraints
• Jason Technology and Overall Design
• Matt Detailed Design
• Dave Requirements, Schedules, Conclusions

3
Problem Statement

• The problem is the ability of a record player to
  keep a specific speed. The synchronous motor used
  on a record player is supposed to play the record
  at a specific speed. However, the motor does not
  always run at the specified speed which causes
  the record to sound out of pitch. A precision
  variable frequency drive will provide a constant
  frequency to the synchronous motor which in turn
  will maintain a constant speed of the record
  table.

4
Executive Summary

• Synchronous motors are motors that run at a
  specific speed. A customer may want to run the
  motor at different speeds, like for a record
  player that needs to operate at 45 and 33 1/3
  rpm. A precision variable frequency drive is a
  way to speed up or slow down the motor by
  changing the frequency of the input voltage.
•  
• This product will be designed to adjust the
  frequency between 58 to 62 hertz by the turning
  of a dial. The digital display will be accurate
  up to the thousandth of a hertz. In addition, a
  strobe light will allow the user to observe the
  rpm of the motor. The precision variable
  frequency drive will have a long term drift that
  requires a gradual decrease/increase of speed
  that allows for more accurate tuning.

5
Operating Environment

• Indoors
• No extreme dust
• No extreme temperatures

6
Intended Users and Uses

• Users
• Avid music listener
• Lay person
• Uses
• Adjust the frequency of the turn-table
• With other synchronous motors

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Assumptions

• Constant linkage the belt connecting the motor
  to the turntable is constant over a short time
  period. Basically, an increase in motor speed by
  a certain factor will result in an increase in
  the speed of the turntable by the same factor.
• Plug the plug from the record player can plug
  into a standard three pronged outlet.

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Limitations

• Precision the precision variable frequency
  drive will be accurate to .1 Hertz.
• Price the total end product cost must be less
  than 1,000.
• Frequency Range 58 to 62 Hertz with step of 0.1
  Hertz.
• Nominal Voltage 120 VAC.
• Stability the precision variable frequency
  drive must be stable. Short term stability of
  less that /- 0.01. It shall not be affected by
  fluctuations in incoming voltage or frequency.
• Power Output 75 W minimum.
• Input Voltage the input voltage will be a
  standard household outlet of 120 V at 60 Hz.
  single phase

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Design Considerations

• Maximum weight and size
• Minimum power output
• Minimum operating frequency

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Functional Requirements

• Synchronous motor frequency controller
• Knob controller to adjust frequency
• Digital read-out of frequency
• Portable strobe system

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Technology Considerations

• Pulse Width Modulation
• Crystal Oscillator

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Technology Approach Considerations

•  An AC/DC converter was needed to change the
  input of AC voltage to DC voltage.
•  The pulse width modulator will allow the user to
  change the frequency of the voltage.
• 3.  A low pass filter would change the DC signal
  back into an AC signal at the desired frequency.
• 4. A amplifier would be needed to step the
  voltage up to an appropriate level to feed the
  turn-table.
• 5. A frequency counter would be used to display
  the frequency output of the low pass filter.
• 6. A strobe light system would be used to
  measure the RPM of the motor.

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Testing Considerations

• Pulse-width modulator
• Strobe system
• Complete system

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Product Design
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Power Source

• 110-120 VAC
• 60 Hz nominal frequency
• Standard wall outlet

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AC to DC Converter

• The AC to DC converter will take in 120 VAC and
  produce 25 Volt DC. The project team will
  purchase this component. The group is going to
  purchase a converter of the same type that a cell
  phone charger would use. The converter is around
  20 to purchase. After the power has been
  changed into DC pulse width modulation can take
  place.

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Circuit Simulation via Simulink
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Pulse Width Modulator (PWM)
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Circuit Design of PWM
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Triangle Waveform Generator Circuit
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Triangle Waveform
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Comparator Circuit
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Waveform after PWM
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Low Pass Filter
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Waveform After Low-Pass Filter
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Transformer
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Waveform After Transformer
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Frequency Counter

• A frequency counter will connect to the circuit
  after the low pass filter and measure the
  frequency of the AC signal being outputted to the
  voltage amplifier. This device will display the
  frequency of the power it is sampling on a LCD
  screen. Figure 8 shows a picture of the frequency
  counter that will be purchased.

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Product Design
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Strobe Light System
The strobe system will be used to measure the the
RPM of the turn-table. As the picture shows,
there are three different circles for the three
rates, 33 1/3, 45, and 78.
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Personal Requirements
Name Task 1 Task 2 Task 3 Task 4 Task 5 Task 6 Task 7 Task 8 Totals
Reinhardt, Dave 1 7 40 6 5 4 5 24 92
Kilzer, Jason 1 10 42 3 5 2 5 18 86
Nation, Nick 1 7 40 3 5 6 5 18 85
Shriver, Matt 1.5 6 40 3 5 6 5 20 86.5
Total (hours) 4.5 30 162 15 20 18 20 80 349.5
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Other Resource Requirements
Item Team Hours Other Hours Cost
Miscellaneous Parts Materials  0  0 20.00 
Device Components 2 0 65.94
Project/Poster Printing 5 0 0.00
Total 7 0 85.94
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Financial Requirements
Item   W/O Labor With Labor
Miscellaneous Parts Materials    20.00  20.00
Device Components   65.94 65.94
Project/Poster Printing   0.00 40.00
  Subtotal 85.94 125.94
Labor at 15.00 per hour Labor at 15.00 per hour    
Reinhardt, Dave     1,380.00
Kilzer, Jason     1,290.00
Nation, Nick     1,275.00
Shriver, Matt     1,297.50
  Subtotal   5,242.50
  Total 85.94 5,368.44
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Schedule
35
Deadline Chart
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Design Evaluation
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Summary

• Upon review of the detailed project design, it
  has been decided to continue the project as
  planned. It will be continued as scheduled
  because the detailed design has meet the
  functional requirements of the precision variable
  frequency drive.

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Questions?