Multiple-output, Variable-output DC Power Supply May03-22 Team Members: Erik Johnson Joel Jorgensen Peter Holm Philip Schulz Clients – Prof. Patterson, Prof. Lamont Faculty Advisor – Dr. Allan Potter April 30 th, 2003

Presentation Overview Problem statement and solutions Problem statement and solutions Summary of activities Summary of activities Resource requirements Resource requirements Summary of progress Summary of progress Questions Questions

General Problem Statement Develop a power supply with the following voltages: +1.5V,  3.0V, +3.2V, +4.5V,  5.0V, +6.0V, +7.5V, +9.0V,  12.0V, +15.0V, +18.0V, +24.0V Develop a power supply with the following voltages: +1.5V,  3.0V, +3.2V, +4.5V,  5.0V, +6.0V, +7.5V, +9.0V,  12.0V, +15.0V, +18.0V, +24.0V Output 2 + voltage outputs and 2 + voltage outputs simultaneously Output 2 + voltage outputs and 2 + voltage outputs simultaneously Produce for a low cost (~$150) Produce for a low cost (~$150) Allow a maximum current of 1A through each set of terminals Allow a maximum current of 1A through each set of terminals

Solution Approach Develop general design Develop general design Simulate and test on CAD program Simulate and test on CAD program Order parts Order parts Assemble Assemble Test Test Modify and re-test if necessary Modify and re-test if necessary

Operating Environment Standard laboratory conditions Standard laboratory conditions –Indoors –Approximately 24 degrees Celsius Standard 120V, 60 Hz wall output Standard 120V, 60 Hz wall output

End Users and Uses Users Users –Research and design students –Faculty Uses Uses –Power and test design projects –Produce a small current at many voltages –Provide several voltages simultaneously

Assumptions and Limitations Assumptions Assumptions –All four outputs will be used simultaneously –Power supply will be used indoors at room temp –Power supply will be powered by 120V, 60 Hz Limitations Limitations –Output current limited to 1A max per output –Total cost must be below $150 –Input must be 120V at 60 Hz

End Product Description 4 selectable output voltage terminal sets 4 selectable output voltage terminal sets Maximum current of 1A per output Maximum current of 1A per output Output voltage selected by rotary knobs Output voltage selected by rotary knobs Digital readout of voltage, current and wattage Digital readout of voltage, current and wattage Fuses for power supply protection Fuses for power supply protection

End Product

Present Accomplishments Schematic simulated and successful Schematic simulated and successful Successfully implemented transformer and bridge rectifiers on circuit board Successfully implemented transformer and bridge rectifiers on circuit board Successfully implemented +/- voltages on circuit board Successfully implemented +/- voltages on circuit board Examined methods of implementing positive only voltages Examined methods of implementing positive only voltages

Approaches to the Design Recycle/modify/incorporate existing insufficient power supplies Recycle/modify/incorporate existing insufficient power supplies Create and design an original power supply Create and design an original power supply –Use store-bought voltage converters –Design and create voltage converters »Flyback converter »Buck converters »LM317T/LM337T voltage regulators

Project Definition Activities The power supply specs were expanded from the original to include the following: The power supply specs were expanded from the original to include the following: –+3.2V, +7.5V, +15V, and +18V –2 + voltage outputs and 2 + voltage outputs –Ammeter and voltmeter

Research Activities The need for more voltage outputs was researched. The need for more voltage outputs was researched. –It was found that the additional voltages of +3.2V, +7.5V, +15V, and +18V would be useful for small home electronics Also researched various power supply designs for ideas to implement in the final product. Also researched various power supply designs for ideas to implement in the final product.

LM317T/LM337T Voltage Regulators Adjustable output down to +1.2v Adjustable output down to +1.2v Adjustable current limiting feature Adjustable current limiting feature Line regulation typically.01%/V Line regulation typically.01%/V Load regulation typically.1% Load regulation typically.1% 80 dB ripple rejection 80 dB ripple rejection

TL494 PWM Control Circuit Up to 200 kHz oscillator frequency Up to 200 kHz oscillator frequency Feedback allows voltage and current regulation Feedback allows voltage and current regulation

Design Activities Different implementation schematics tested Different implementation schematics tested Because the LM317T/LM337T voltage regulators are not in the Workbench/Pspice libraries, the circuits were physically tested Because the LM317T/LM337T voltage regulators are not in the Workbench/Pspice libraries, the circuits were physically tested

Personnel Effort Budget Team MembersPaper WorkResearchDesignConstructionTotals Est.Act.EstAct.Est.Act.Est.Act.Est.Act. Erik Johnson Joel Jorgensen Peter Holm Philip Schulz Totals

Financial Budget ItemOriginal Estimated CostCost to Date Poster$50.00 Case$14.99$0.00 Transformers$35.53$21.94 Resistors/capacitors/diodes$26.80$21.18 Cooling fan$9.99$8.99 Switches, dials, and terminals$25.00$6.21 Meters ($10.25 each)$30.75$0.00 Variable voltage regulator$4.00$3.90 Total $197.07$112.22

Project Schedule

Project Schedule, cont.

Project Evaluation Done on a scale of: incomplete = 0%, to complete = 100% Done on a scale of: incomplete = 0%, to complete = 100% Milestones: Milestones: Overall Status: Prototype Overall Status: Prototype Define problem 100% Determine solution 100% Design power supply 95% Order parts and assemble 75% Test75% Revise and retest if necessary 75% Release0%

Commercialization Estimated cost to produce: $100 - $200 Estimated cost to produce: $100 - $200 Estimated sales price: $400 - $1000 Estimated sales price: $400 - $1000 It is anticipated that this product would have a very large market It is anticipated that this product would have a very large market –Versatile –Financially viable

Recommendations for Additional Work Finish original implementation Finish original implementation Develop a commercial version Develop a commercial version Add power factor correction Add power factor correction Make each set of terminals fully isolated Make each set of terminals fully isolated Make current limitation adjustable Make current limitation adjustable

Lessons Learned What worked What worked –Team worked well at brainstorming, designing –Advisor was helpful when we got stuck –Regular, scheduled meeting What did not work What did not work –Collaborating on reports and poster –Weekly status reports –Ordering parts –Gaining the necessary knowledge –Advisor absence for extended period of time

Lessons Learned (cont) Technical knowledge gained Technical knowledge gained –How power supplies work –How DC-DC converters work –How transformers work –How to use Workbench Things to do differently Things to do differently –Put more time into research early on

Risks and Risk Management Illness Illness –Follow good health practices –Take on some of the sick member’s workload among the other members Accidents such as electrocution or fire Accidents such as electrocution or fire – Follow high voltage safety procedures when assembling –Cut power, use First Aid, call 911, put out fire Losing a team member Losing a team member –Be such a good team that nobody wants to leave –Divide the work among the remaining members, seek assistance from colleagues

Summary Problem: Replace the current power supplies with a single versatile tool Problem: Replace the current power supplies with a single versatile tool Approach: Consider several different alternatives by which multiple voltages can be provided simultaneously by a single power supply Approach: Consider several different alternatives by which multiple voltages can be provided simultaneously by a single power supply Solution: Provide two plus/ground terminals and two plus/minus/ground terminals whose voltage can be set independently of the others. Also provide meters to display the voltage, current, and wattage of the selected set of terminals Solution: Provide two plus/ground terminals and two plus/minus/ground terminals whose voltage can be set independently of the others. Also provide meters to display the voltage, current, and wattage of the selected set of terminals

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