Precision Variable Frequency Drive May 07-13

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Precision Variable Frequency DriveMay 07-13
Client Jim WalkerAdvisor Dr. AjjarapuTeam
MembersMatt ShriverJason KilzerNick
NationDave ReinhardtApril 24, 2007
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Presentation Outline

• Introductory Materials (Nick)
• Project Approach Design (Jason)
• Testing and Implementation (Matt)
• Closing Materials (Dave)

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The Prototype
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List of Definitions

• VFD Variable Frequency Drive
• PWM Pulse Width Modulation
• IGBT Insulated Gate Bipolar Transistor

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Acknowledgements

• Faculty advisor Dr. Ajjarapu
• Client Jim Walker
• Graduate Students
• Ryan Konopinski
• Sheng Yang

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General Problem Statement

• The speed control of an AC synchronous motor.
• The synchronous motor and the subsequent drive
  mechanism do not always keep the correct speed.
• A method is needed to control the frequency that
  is delivered to the synchronous motor.

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Solution

• A precision variable frequency drive will allow
  the user to manually change the operating
  frequency.

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Operating Environment

• Indoors
• No extreme conditions
• Near power outlet

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Intended Use

• As a drive for a low power AC synchronous
  electric motor.
• This drive was not considered to be used on any
  other type of electric motor except for a
  synchronous design.
• This drive shall not be used to power any control
  circuits.

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Intended Users

• Anyone who desires precise control over a small
  AC synchronous motor.
• An owner of a turntable who needs better control
  over the speed of their turntable.
• No technical knowledge will be required to
  operate the Precision VFD.

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Assumptions

• Constant linkage 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 power cord from the record player can
  plug into a standard three pronged outlet.

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Limitations

• Minimum Power Output 75 W
• Output Frequency Range 58-62 Hz
• Frequency Precision 0.001 Hz
• Frequency Stability lt 0.01
• 12 by 12 by 6 size limitation
• Cost less than 350

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Expected End Product

• Precision variable frequency drive
• Portable strobe system
• One-page quick users guide
• Circuit diagrams and parts list

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Project Approach
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Present Accomplishments

• Research technologies (100)
• Simulate entire system (100)
• Purchase components (100)
• Build components (85)
• Test components (70)
• Build entire system (70)

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Approaches Considered
Crystal Oscillator No prior knowledge Frequency range was too high
Reverse Engineer (VPIs Synchronous Drive System) Difficulty getting hands on product Many parts Little understanding of parts
Pulse Width Modulation One group member familiar Prior understanding of parts Could handle low frequencies
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Project Definition Activities

• Develop a VFD that will provide a precise
  frequency that can be changed.
• A strobe light will also be included to measure
  the RPM of the electric motor.

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Research Activities (1 of 2)

• Pulse Width Modulation
• Needs small signal variable frequency sine wave
• Need small signal triangle wave
• Comparator produce pulses from comparison of sine
  and triangle wave
• PWM would create the control signals for the IGBT
  bridge

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Research Activities (2 of 2)

• IGBT Bridge
• Provides power separation between PWM circuits
  and power supply circuitry
• Generates pulses

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Precision Variable Frequency Drive

• Ready to use design
• Delivers precise frequency control for low power
  AC synchronous motors
• Strobe light included to measure RPM of motor

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Design

• Pulse Width Modulation Circuits
• IGBT Bridge and Filter Circuits
• Power Supply Circuits

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Overall Block Diagram (1 of 2)
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Overall Block Diagram (2 of 2)
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Pulse Width Modulation Circuits
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IGBT Bridge and Low Pass Filter
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Power Supply Components

• Astrodyne Power Supply (PT-45C)
• Input 120 VAC
• Outputs /-15V, 5V
• Filament Transformer
• Primary Winding 117V
• Secondary Winding 8V

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Testing and Implementation
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PWM Circuits
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Comparator Input/Output Waveforms
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Inverter Input/Output Waveforms
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IGBT Bridge and Low Pass Filter
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Filter Input/Output Waveforms
Input and Output Waveforms of the Low Pass Filter
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Implementation and Testing

• Function generator chips
• Amplifiers
• Comparator and Inverter
• IGBTs
• Filter
• Strobe light system

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Sine Triangle Generator Chips

• Built and tested on breadboard

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Amplifiers, Comparator, and Inverter Circuits

• Built and tested on breadboard

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Comparator Testing

• Comparator Chips
• UA741 Op Amp
• LM319N High Speed Comparator
• Sources
• Lab Function Generators
• Function Generator Chips

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IGBT Bridge

• build and test on breadboard

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IGBT Bridge Testing

• Design overlooked need for delay circuitry
• Tried multiple timing circuits
• NE555 Timer Circuit
• UA741 Op Amp Circuit

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Strobe Light System
Strobe Light Schematic
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Closing Material
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Resources
Item W/O Labor With Labor
Miscellaneous Parts Materials  20.00  20.00
Device Components 66.90 66.90
Project/Poster Printing 0.00 0.00
Subtotal 86.90 86.90
Labor at 15.00 per hour    
Reinhardt, Dave, 142 hrs   2,130.00
Kilzer, Jason, 166 hrs   2,490.00
Nation, Nick, 148.5 hrs   2,227.50
Shriver, Matt, 245 hrs   3,675.00
Subtotal   10,522.50
Total 86.90 10,609.40
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Schedule
Detailed Gantt Chart
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Deadline Schedule
Deadlines Schedule
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Project Evaluation (1 of 2)
Milestone Degree of Achievement Comments
1. PVFD Project partially met Some milestones were fully achieved while others were not
A. Produce PVFD partially met Some of the items below were attained with others only partially attained or not at all
1) Develop Design for PVFD fully met The design met all technical requirements, when simulation test were complete
2) Simulation of PVFD partially met Full simulation was completed. However two programs were needed to complete simulation
3) Implementation of PVFD partially met The design was completely implemented into a prototype
4) Technical requirements satisfied by prototype partially met See items below.
a) Provide minimum power output of 75 W fully met  
b) Output continuously selectable between 58 and 62 Hz exceeded Output is selectable between 57.5 and 62.5 Hz.
c) Short-term stability less that 0.01 not attempted Client not concerned
d) Frequency display accurate to 0.001 Hz not met PVFD has a frequency display accurate to 0.01 Hz.
B. Portable strobe system partially met  
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Project Evaluation (2 of 2)
Milestones Relative Importance Evaluation Score Resultant Score
Problem Definition 15 100 15.0
Research 10 90 9.0
Technology Selection 5 100 5.0
End Product Design 15 70 10.5
Prototype Implementation 15 60 9.0
End Product Testing 10 50 5.0
End Product Documentation 5 70 3.5
Project Reviews 5 90 4.5
Project Reporting 10 100 10.0
End Product Demonstration 10 50 5.0
Total 100   76.5
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Commercialization

• Not produced for commercialization
• Precision variable frequency drive could be
  implemented for much less than current market
  price (250)

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Additional Work

• Resolve comparator issues
• Resolve IGBT issues
• Combine Precision VFD and strobe light system
  into one product
• Include feedback loop for total autonomy

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Lessons Learned (1 of 2)

• What went well
• Design/Simulation of project
• Testing

• What did not go well
• Problem definition and planning (needed a new
  plan when we started implementing)
• Having everyone on the same page (team members,
  advisor, vendor)

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Lessons Learned (2 of 2)

• Technical
• Implement and test one component at a time
• Keep it simple
• Comparator troubleshooting
• IGBT implementation

• Non-technical
• Should have planned a lot more time for
  implementation
• Everyone must be on the same page
• Have a good plan to start

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Risk and Risk Management
Potential Risks Planned Management
Cost (Over Budget) The group was given 300 (150 - senior design 150 - client). If the cost was less than 75 over budget the group members would chip in some money.
Lazy Group Member E-mails would be sent detailing group members responsibility along with due date.
Design does not meet Clients specifications The client would be contacted and the lack of performance would be discussed. Input for client will determine where the project is to go.
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Unanticipated Risks
Unanticipated Risks Attempts to Manage Risks
Strobe light difficulty The group found a simple "Do It Yourself" strobe light design with complete parts list and schematics.
Comparator not working The group sought advice from advisor, graduate students, and other faculty.
Difficulty of producing output voltage of 120 VAC Planned to use a transformer to step-up the voltage.
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Closing Summary

• An incomplete prototype was produced due to
  difficulties with the comparator and the IGBT
  bridge.
• Estimated final product could be commercialized
  and sold for 250.

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Demonstration and Questions