Outdoors Power Supply

1
Outdoors Power Supply

• Team 2
• ECE 445 Senior Design
• Saad Baig
• 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)2D
18
Output Filter

• Moderate voltage ripple at the output
• 5 V
• C0 min 3.6 uF
• 12 V
• C0 min 16.8 uF

Cout min I0 max Dmax / ( fin vripple )
19
Feedback Network

• Vr Rbias/(RbiasR1) Vout
• Vout 1/(1-D) Vin

20
Testing TEG

• Approximate module ? T
• Verify power output
• Verify module integrity
• Calculate temperature differences across
  interfaces

21
Approximate Module ?T

• Measured temperatures
• Th 2740 C
• Tc 1250 C
• Measured open circuit voltage
• Voc 1.93 V

?T 1100 C
22
Verify Power Output
P0 4.9 Watts
23
Verifying Module Integrity

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

24
Calculating ?Ti

• Interface temperature drop
• ?Ti (Th - Tc) ?T 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
?? 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 ?