Download Precision Variable Frequency Drive May 07-13

Precision Variable Frequency Drive
May 07-13
Client: Jim Walker
Advisor: Dr. Ajjarapu
Team Members:
Matt Shriver
Jason Kilzer
Nick Nation
Dave Reinhardt
April 24, 2007
Presentation Outline




Introductory Materials (Nick)
Project Approach & Design (Jason)
Testing and Implementation (Matt)
Closing Materials (Dave)
The Prototype
List of Definitions



VFD: Variable Frequency Drive
PWM: Pulse Width Modulation
IGBT: Insulated Gate Bipolar Transistor
Acknowledgements



Faculty advisor Dr. Ajjarapu
Client Jim Walker
Graduate Students


Ryan Konopinski
Sheng Yang
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.
Solution

A precision variable frequency drive
will allow the user to manually
change the operating frequency.
Operating Environment



Indoors
No extreme conditions
Near power outlet
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.
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.
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.
Limitations






Minimum Power Output: 75 W
Output Frequency Range: 58-62 Hz
Frequency Precision: 0.001 Hz
Frequency Stability: < ± 0.01 %
12” by 12” by 6” size limitation
Cost less than $350
Expected End Product




Precision variable frequency drive
Portable strobe system
One-page quick users guide
Circuit diagrams and parts list
Project Approach
Present Accomplishments






Research technologies (100%)
Simulate entire system (100%)
Purchase components (100%)
Build components (85%)
Test components (70%)
Build entire system (70%)
Approaches Considered
Crystal Oscillator
No
prior knowledge
Frequency range was too high
Difficulty getting hands on
Reverse Engineer
product
(VPI’s Synchronous Many parts
Drive System)
Little understanding of parts
Pulse Width
Modulation
One
group member familiar
Prior understanding of parts
Could handle low frequencies
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.
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
Research Activities (2 of 2)

IGBT Bridge


Provides power separation between
PWM circuits and power supply circuitry
Generates pulses
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
Design
Pulse Width Modulation Circuits
 IGBT Bridge and Filter Circuits
 Power Supply Circuits

Overall Block Diagram (1 of 2)
Sine Wave
Comparator
IGBT Bridge
Triangle Wave
Inverter
Overall Block Diagram (2 of 2)
Low Pass
Filter
Frequency
Counter
Transformer
Output
IGBT Bridge
Pulse Width Modulation Circuits
Sine
Waveform
(Variable
Frequency)
Comparator
Triangle
Waveform
Inverter
IGBT Bridge and Low Pass Filter
IGBT
Bridge
Low
Pass
Filter
Power Supply Components

Astrodyne Power
Supply (PT-45C)



Input: 120 VAC
Outputs: +/-15V, +5V
Filament Transformer


Primary Winding: 117V
Secondary Winding: 8V
Testing and Implementation
PWM Circuits
Inverter
+
7
OS2
2
-
V-
OUT
OS1
5
Gate Signal
6
2
1
uA741
-
OS1
uA741
4
0
+Vcc
Triangle Wave
-V cc
VOFF = 0
VA MPL = .375
FREQ = 60
5Vdc
0
-V cc
V3
V2
Sine Wave
OS2
OUT
V-
V1
+
4
3
V1 = .5
V2 = -.5
TD = 1p
TR = 249.99999u
TF = 249.99999u
PW = 1p
PER = .5m
0
V+
U2
U3
3
V+
+Vcc
7
+Vcc
Comparator
V4
-5Vdc
0
0
-V cc
5
6
1
Inverted
Gate Signal
Comparator Input/Output Waveforms
Inverter Input/Output Waveforms
IGBT Bridge and Low Pass Filter
Filter Input/Output Waveforms
Input and Output Waveforms of the Low Pass Filter
Implementation and Testing
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Function generator chips
Amplifiers
Comparator and Inverter
IGBT’s
Filter
Strobe light system
Sine & Triangle Generator Chips

Built and tested on breadboard
Amplifiers, Comparator, and Inverter
Circuits

Built and tested on breadboard
Comparator Testing
Comparator Chips
 UA741 Op Amp
 LM319N High Speed Comparator
Sources
 Lab Function Generators
 Function Generator Chips
IGBT Bridge

build and test on breadboard
IGBT Bridge Testing
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
Design overlooked need for delay
circuitry
Tried multiple timing circuits


NE555 Timer Circuit
UA741 Op Amp Circuit
Strobe Light System
Strobe Light Schematic
Closing Material
Resources
Item
W/O Labor
With Labor
Miscellaneous Parts & Materials
$20.00
$20.00
Device Components
$66.90
$66.90
$0.00
$0.00
$86.90
$86.90
Project/Poster Printing
Subtotal
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
Total
$10,522.50
$86.90
$ 10,609.40
Schedule
Detailed Gantt Chart
Deadline Schedule
Deadlines Schedule
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
b) Output continuously selectable between 58
and 62 Hz
c) Short-term stability less that 0.01%
d) Frequency display accurate to 0.001 Hz
B. Portable strobe system
fully met
exceeded
not attempted
not met
partially met
Output is selectable between 57.5 and 62.5 Hz.
Client not concerned
PVFD has a frequency display accurate to 0.01 Hz.
Project Evaluation (2 of 2)
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
Milestones
Total
100%
76.5
Commercialization
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Not produced for commercialization
Precision variable frequency drive
could be implemented for much less
than current market price (~$250)
Additional Work
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Resolve comparator issues
Resolve IGBT issues
Combine Precision VFD and strobe
light system into one product
Include feedback loop for total
autonomy
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)
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
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 Client’s
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.
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.
Closing Summary
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
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.
Demonstration and Questions