1. Multiple-Output, Variable-Output DC Power Supply - Phase 2 May 04-08

2. 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

3. Overview Project objectives & guidelines Design Approach End Result
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

4. 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

5. 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

6. Design Approach Definitions
PWM : Pulse Width Modulation
Duty Ratio (D) : Time ON divided by the total time
Lm : Magnetizing Inductance of a transformer
For the simulation, 2 choice:
Pspice: Available and have a lot of parts
Electronic Work Bench : Easy and more visual
Sample from the simulation
Electronic Work Bench was used to simulate the design
Senior Design :: May 04-08

7. Design Approach Buck Converter
Simple ac/dc conversion
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
Buck converter diagram

8. Design Approach Flyback Converter
Not able to make 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

9. 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

10. 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

11. Variable Buck Converter
The new design
Fixed Buck Converter
TL499ACD
Variable Outputs
120 VAC
Wall outlet
48VDC
25VDC
High Freq. Switch
Variable Buck Converter
Power Supply
Senior Design :: May 04-08

12. End Product Options Low cost system Useful to senior design teams
Client wants for power supply
Low cost system
Useful to senior design teams
Portable Power Supply
# of +/- terminals
# of + terminals
Meters
Option #1 1
Ammeter
Voltmeter
Option #2 2
Option #3
Senior Design :: May 04-08

13. Commercial Power Supply
Astrodyne ® Power Supply
Regulated Output
VAC input
Overload Voltage protection
Short Circuit Protection
EMI Filter
Senior Design :: May 04-08

14. 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

15. 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

16. 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

17. 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

18. 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
~ seconds
Senior Design :: May 04-08

19. Personal Time Commitment
Paper work
Research
Design
Construction
Total
Darrel Long 25 41 42 24
134
Fares Karadsheh 20 48 47 14
131
Trung Nguyen 22 43
132
Benjamin Voetberg 51 45
137 90
184
195 65
534
Slide time ~20-30 seconds
Senior Design :: May 04-08

20. First Semester Schedule
Senior Design :: May 04-08

21. Second Semester Schedule
Senior Design :: May 04-08

22. 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

23. Lessons Learned What went well What didn’t go 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

24. 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

25. 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

26. Questions?
Senior Design :: May 04-08