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 Design Approach Expected End Result Budget 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 simulates battery 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 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 (1) The design was simulated to look like the figure below After searching for the needed parts, it was found out that buying commercial products could save a lot from the budget The design still consist most of the blocks but compacted into one block The Intended design, before substitutes were found Senior Design :: May 04-08

Design Approach (2) A commercial power supply is used to replace the EMI filer, bridge rectifier, flyback converter. The transformer that was planned to be used in the flyback is expensive and hard to find. But those blocks will work in the same methods our simulation worked on

Design Approach (3) A Quick review : Vo=Vs(D/(1-D)) N2/N1 (Flyback) Vo=Vs*D ( Buck ) PWM : Generate a square wave. (see figure) The Reason behind using Flyback then a buck converter is to create an isolation. Comparator Trig.source Senior Design :: May 04-08

Design Approach (4) Electronic Workbench This Figure shows part of the design Transformer Switch Load Duty ration controller Senior Design :: May 04-08

How does it work Figure 1: Buck Converter Figure 2: Flyback converter, it store energy in Lm when closed. When the switch is open the energy transfers from Lm Using commercial power supply have minimized a lot of the problems: like to keep the current and the voltage stable, finding transformer and time. Fig. 1 Fig. 2 Senior Design :: May 04-08

Transformer The transformer is used in the flyback converter to step down the voltage The transformer should be able to hold at least 70-100 KHz Lm should be fairly large, around 1 mh. The Commercial power supply used this transformer, and it is already built in it Senior Design :: May 04-08

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

Summery of Design Approach The DC voltage that the flyback receives from the bridge rectifier is around 105-107. The Flyback brings the voltage down to 30 Vdc. Create isolation ,then we use the buck to get lower voltages (1.5-24 Vdc) Senior Design :: May 04-08

Proposed End Product Features + Voltage Terminals Voltage Controls Digital Display Senior Design :: May 04-08

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

Proposed End Product Cont. Voltage Outputs Output voltages will range from 1.5 volts to 24 voltages. User selects voltages by turning knobs. Display Show output values for all terminals Circuit Protection Resistible breakers on output terminals and input voltage Activation switch for terminals Senior Design :: May 04-08

Future Work Recommendations Voltage starts at zero when power supply is turned on. Further circuit protection Variable Current Senior Design :: May 04-08

Financial Budget Components Estimated Cost Revised Cost Actual Cost Poster $40 Parts Diodes, Resistors, Fuses, Capacitors Free from last year $0 PWM’s Free samples Transformers donated Output terminals Switches Rectifiers Total ~ 20-30 seconds Senior Design :: May 04-08

Personal Budget Person Paper work Research Design Construction Total Darrel Long 15 35 32 20 102 Fares Karadsheh 10 42 37 14 103 Trung Nguyen 12 Benjamin Voetberg 45 105 52 157 139 64 412 Slide time ~20-30 seconds 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 nearly completed Circuit simulations completed Test hardware Started Documentation nearly completed Senior Design :: May 04-08

Lessons Learned What went well What didn’t go well Communication within team Teamwork What didn’t go well Unspecific project, time constraint for meeting with clients Simulation of the circuit 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 Anticipated risks encountered Temporarily lost an advisor Senior Design :: May 04-08

Closing Summary Project objectives & guidelines Design Approach Expected End Result Budget Schedule Project Evaluation Risk and Risk Management Senior Design :: May 04-08

Questions? Senior Design :: May 04-08