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Outdoors Power Supply

Outdoors Power Supply. Team 2 ECE 445 Senior Design Saad Baig Arturo Guillen. Table of Contents. Introduction Features Design Overview Testing Successes and Challenges Recommendations Potential Improvements Acknowledgments Questions. Introduction. The outdoor power supply

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Outdoors Power Supply

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  1. Outdoors Power Supply Team 2 ECE 445 Senior Design SaadBaig Arturo Guillen

  2. Table of Contents • Introduction • Features • Design Overview • Testing • Successes and Challenges • Recommendations • Potential Improvements • Acknowledgments • Questions

  3. Introduction • The outdoor power supply • Purpose • Implementation • Two stages • Power generation • DC-DC conversion

  4. Features • Multiple outputs (12 V, 5V, Universal) • Portable • Runs on conventional fuel • Ease of use

  5. Design Overview • Basic block diagram

  6. Thermoelectric Generation • What is a TEG? • No moving parts • Completely silent • Highly reliable

  7. Initial TEG Housing Structure • Design parameters • 200 psi Compressive Loading • Uniform Load • Insulation

  8. Final Structure • Fan • Water pot heatsink • Compression at the edges • Insulation at the base

  9. Initial Converter Design • Comparison of different topologies • Flyback and Boost have high efficiencies

  10. IV Characteristic of HZ 14

  11. Flyback Advantages • Flyback Topology • Dielectric isolation • Minimal parts required • Easily derive multiple outputs

  12. Flyback Design Issues • Low input voltage from TEG • Very high peak currents on the primary • Challenging inductor design • Availability of materials

  13. Final Converter Design • Boost topology • Main components • Inductor • MOSFET • Diode • Output Capacitor

  14. Two-Stage Boost

  15. Boost Schematic (PCB Design)

  16. Controller • TPS 43000 • Under-voltage lockout at 1.65 V • Hiccup over-current protection • Imax(hu) = .25 / RDS(ON) = 11.36 A • Low power mode

  17. Inductor Calculations • Minimum inductance needed to avoid operating in DCM • 5 V • Lcrit = 1.908 uH • 12 V • Lcrit = 11.27 uH Lcrit = (Rmin / 2) * Tsw(1-D)2*D

  18. Output Filter • Moderate voltage ripple at the output • 5 V • C0 min = 3.6 uF • 12 V • C0 min = 16.8 uF Coutmin = I0max * Dmax / ( fin * vripple )

  19. Feedback Network • Vr = [Rbias/(Rbias+R1)]* Vout • Vout = [1/(1-D)]* Vin FB pin Vr R1 Vout To PWM Comparator Rbias Vref

  20. Testing: TEG • Approximate module Δ T • Verify power output • Verify module integrity • Calculate temperature differences across interfaces

  21. Approximate Module ΔT • Measured temperatures • Th = 2740 C • Tc = 1250 C • Measured open circuit voltage • Voc = 1.93 V ΔT = 1100 C

  22. Verify Power Output P0 = 4.9 Watts

  23. Verifying Module Integrity • Voltage across .3Ω load • VR = 1.427 V • Module current • I = VR / RL = 4.76 A • Internal resistance • Ri = ( VL-Voc )/ I = .126 Ω

  24. Calculating ΔTi • Interface temperature drop • ΔTi = (Th - Tc) – ΔT = 390 C • Values in the range of 300 C to 500 C are acceptable

  25. Testing: Boost Converter • Vds, Vgs, output voltages and ripple voltages • Efficiencies at different loads • Testing in conjunction with the TEG • Line and load regulation

  26. Converter Waveforms 5 V 12 V Drain Voltage Gate Voltage

  27. 5 V Converter Efficiency 𝜼 = 1 – Ploss/Pin

  28. 12 V Converter Efficiency

  29. 5 V TEG/Supply Testing

  30. 12V TEG/Supply Testing

  31. Line And Load Regulation • 5 V • % Load reg = 2.2 (.11 V) • % Line reg = 1.2 (.06 V) • 12 V • % Load reg = 5.0 (.6 V) • % Line reg = 2.2 (.264 V) % Line regulation = [Vout (highest input) – Vout (lowest input)]/ Vout nominal % Load regulation = [Vout (no load) – Vout (max load)]/ Vout nominal

  32. Successes • Both converters worked • Good efficiencies on the converter • TEG was able to provide sufficient power

  33. Challenges • Lead time on parts • Low input voltage controllers uncommon • Time constraints • Magnetics design can be complex

  34. Recommendation • Importance of documentation • Maintain a well organized lab journal • Record ideas, implementation, test data, etc • Explore multiple sources • Verify design equations against different sources • Utilize design tools provided by manufacturer

  35. Potential Improvements • Circuitry for low-power temperature controlled heat sink fan • Better TEG structure • Compression/Thermal expansion • Uniform Load • Smaller and lighter design • Safety

  36. Acknowledgments • Professor Paul S. Carney • Professor Patrick L. Chapman • Professor Philip T. Krein • Paul Rancuret • ECE machine shop • Scott McDonald • David Switzer • Greg Bennett • ECE parts shop • Mark Smart • Power Lab • Andy Friedl • Kevin Colravy • Ben Niemoeller

  37. Q & A QUESTIONS ?

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