MultipleOutput, VariableOutput DC Power Supply Phase 2 May 0408 - PowerPoint PPT Presentation

Title: MultipleOutput, VariableOutput DC Power Supply Phase 2 May 0408


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Multiple-Output, Variable-Output DC Power Supply
- Phase 2 May 04-08
http//seniord.ee.iastate.edu/may0408/
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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
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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

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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.

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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

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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

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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
• VoVsD

Buck converter diagram
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Design Approach Flyback Converter

• Not able to make 1.5-24 volts directly from 120
  V
• Use a flyback converter
• Flyback converter output equation
• VoVs(D/(1-D)) N2/N1

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Design Approach PWM

• Output equations
• VoVs(D/(1-D)) N2/N1 (Flyback)
• VoVsD ( 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.

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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

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The new design
Fixed Buck Converter
TL499ACD
Variable Outputs
120 VAC Wall outlet
48VDC
25VDC
High Freq. Switch
Variable Buck Converter
Power Supply
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End Product Options

• Client wants for power supply
• Low cost system
• Useful to senior design teams
• Portable Power Supply

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Commercial Power Supply

• Astrodyne Power Supply
• Regulated Output
• 85-265 VAC input
• Overload Voltage protection
• Short Circuit Protection
• EMI Filter

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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

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Texas Instruments TL499A circuitWide-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

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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

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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

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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

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Personal Time Commitment
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First Semester Schedule
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Second Semester Schedule
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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

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Lessons Learned

• What went well
• Communication
• Within the team
• With company representatives
• Teamwork
• What didnt 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

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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

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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

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Questions?
Senior Design May 04-08