Transcript Slide 1
Multiple-Output, Variable-Output
DC Power Supply - Phase 2
May 04-08
http://seniord.ee.iastate.edu/may0408/
Multiple-Output, Variable-Output DC Power Supply
Client
Senior Design
Dr. Lamont
Prof Patterson
Advisors
Dr. Potter
Dr. Ajjarapu
Team Members
Benjamin Voetberg, EE
Fares Karadsheh, EE
Trung Nguyen, EE
Darrell Long, EE
Senior Design :: May 04-08
Overview
Project objectives & guidelines
Create low cost dc power supply
Range of voltages
Design Approach
ac to dc
End Result
What the team accomplished
Budget
Price comparison
Layout of cost
Schedule
Project Evaluation
Risk and Risk Management
Senior Design :: May 04-08
Project Objectives & Guidelines
The project is to design a DC power supply that provides
power at various voltages
+/- voltages will include 5V, 6V, 12V, 18V
+/common voltages will include 1.5V, 3.0V, 3.2V, 3.3V,
4.5V, 5V, 6V, 7.5V, 9V, 12V, 15V, 18V, 24V
Voltmeter and Ammeter to display output values
Between 2 to 4 output terminals.
Senior Design :: May 04-08
Project Objectives and
Guidelines Cont.
Operating Environment
Indoor use for senior design projects
Intended users/uses
Students enrolled in EE/CprE senior design
Possibility for use in freshman and sophomore level
labs
Used to test senior design projects that require DC
voltage
Assumptions/Limitations
Powered by a 120V, 60Hz wall outlet
+/- 1% ripple output voltage
Function with +/- 5% of wall outlet voltage
Output current not to exceed 1A on each terminal
Senior Design :: May 04-08
Design Approach Definitions
PWM : Pulse Width Modulation
Duty Ratio (D) : Time ON divided
by the total time
Lm : Magnetizing Inductance of a
transformer
Sample from the
simulation
For the simulation, 2 choice:
Pspice: Available and have a lot of
parts
Electronic Work Bench : Easy and
more visual
Electronic Work Bench was
used to simulate the design
Senior Design :: May 04-08
Design Approach Buck Converter
Convert ac to dc using
bridge rectifier
Buck converter is used to
vary the voltage to get
desired voltage output
Buck converter output
Vo=Vs*D
Simple ac/dc conversion
Buck converter diagram
Design Approach Flyback
Converter
Not able to make 1.5-24
volts directly from 120 V
Use a flyback converter
Flyback converter output
equation
Vo=Vs(D/(1-D)) N2/N1
Senior Design :: May 04-08
Design Approach PWM
Output equations:
Vo=Vs(D/(1-D)) N2/N1
(Flyback)
Vo=Vs*D ( Buck )
PWM : Generate a
square wave. (see figure)
Trig.source
Comparator
The Reason behind using Flyback then a
__buck converter is to create an isolation.
Senior Design :: May 04-08
Design Approach Taken
A commercial power supply to replace
bridge rectifier
flyback converter.
Power supply eliminates problems
Current and the voltage regulation
Difficulty finding transformer
Saved time
Even with changes still functions as the
simulation
Buck converter still used to vary voltage to get
desired output
Senior Design :: May 04-08
The new design
120 VAC
48VDC
Fixed Buck
Converter
High Freq.
Switch
Wall outlet
Power Supply
TL499ACD
25VDC
Variable
Outputs
Variable Buck
Converter
Senior Design :: May 04-08
End Product Options
Client wants for power
# of +/terminals
supply
Low cost system
Useful to senior
design teams
Portable Power
Supply
# of +
terminals
Meters
Option #1
1
1
Ammeter
Voltmeter
Option #2
1
2
Ammeter
Voltmeter
Option #3
2
2
Ammeter
Voltmeter
Senior Design :: May 04-08
Commercial Power Supply
Astrodyne ® Power Supply
Regulated Output
85-265 VAC input
Overload Voltage protection
Short Circuit Protection
EMI Filter
Senior Design :: May 04-08
Fixed Buck Converter
Switch components
Motorola SG3527A Pulse Width Modulator Control Circuit
Fixed duty ratio, 44 VDC to 25 VDC
Sends square wave to MOSFET DRIVER
Maxim MA4428 Dual High-speed 1.5A MOSFET Driver
Drivers both a N-channel and P-channel MOSFET to achieve
the desired switching speed
Texas Instruments TL499A circuit
Wide-Range Power-Supply Controllers
R1, R2, R3 create a
comparison voltage
Voltage varied by changing
potentiometer
Minimum output voltage is
2.5 volts.
Maximum output voltage is
24 volts
Digital Display
Maxim ICL7107 3 1/2
Digit A/D Converter
Connected across the
output
Displays output
voltage to 1/10
accuracy
2 double digit 7
segment LED displays
Future Work Recommendations
A phase to finalize the project
Necessary future work
Negative voltages
Voltage regulation
Circuit protection
Other future work
Variable current
Voltage zero at start up
Auto zeroing voltmeter
Senior Design :: May 04-08
Financial Comparison
Agilent 3631a triple output power supply
80 watts
+ 25 V at 1 A
+6 V at 6 A
$ 1200
Proam universal ac-dc adaptor
9 watts
+ 1.5, 3, 4.5, 6, 7.5, 9, 12 V at .5 A
$ 9.00
Our design now
24 watts
2.5 to 24 V at 1 A
$ 120
Senior Design :: May 04-08
Personal Time Commitment
Paper
work
Research
Design Construction Total
Darrel Long
Fares
Karadsheh
Trung
Nguyen
Benjamin
Voetberg
25
20
41
48
42
47
24
14
134
131
22
41
43
24
132
25
51
45
14
137
Total
90
184
195
65
534
Senior Design :: May 04-08
First Semester Schedule
Senior Design :: May 04-08
Second Semester Schedule
Senior Design :: May 04-08
Project Evaluation
Identify possible designs to implement,
completed
and choose one
Design hardware
completed
Hardware specifications
completed
Circuit simulations
completed
Test hardware
almost complete
Documentation
completed
Senior Design :: May 04-08
Lessons Learned
What went well
Communication
Within the team
With company representatives
Teamwork
What didn’t go well
Unspecific project, time constraint for meeting with
clients
Simulation of the circuit
Hardware implementation
Technical knowledge gained
Simulation experienced gained
Power electronics knowledge
Senior Design :: May 04-08
Risk and Risk Management
Anticipated risks
Team scheduling
Loss of team member, advisor, or clients
Unanticipated risks
Simulation complications
Hardware implementation
Unable to use certain designs because of cost
Senior Design :: May 04-08
Closing Summary
Variable dc output of 2.5 to 24 volts
Meets client specifics
Provides extra voltage values
Digital voltmeter
Accurately provides output voltage
Design is a solid base to further expand
Negative voltages
Circuit protection
Voltage regulation
Senior Design :: May 04-08
Questions?
Senior Design :: May 04-08