P12441: Thermoelectric Power Pack for Next Generation Stove
Andrew Phillips – Project ManagerColin McCune – Lead EngineerLauren Cummings – Electrical EngineerXiaolong Zhang – Cost Engineer
Background• 3 billion people use open fires and inefficient stoves
regularly• Requires large amounts of fuel
• Damage to ecosystem
Haiti• Deforestation
• Soil erosion• Decrease in agricultural yields• Landslides• Running out of fuel
• Need for more fuel-efficient stoves• Add oxygen to combustion
process
Haiti
Dominican Republic
Need for Power
• Haiti has a history of destructive earthquakes• No power grid and no landlines• Cell phones and radios for
communication• Difficult to charge
Needs Importance
Description Comments/Status
1 3* Fan runs the entire duration of cooking
2 3* Plan to couple to team 12442’s stove.
3 3 Cheap cost of system Component cost including PCB if applicable
4 3 User-friendly operation Minimal user interaction5 3 Safe to operate 6 2 Fan runs at start-up Multiple start/restart cycles7 2 Rugged design Survive crush and drop test8 2 Operational in Harsh Environments Exposure to Rain, Moisture, Heat
and Salinity9 2 Ability to charge USB device
10 1 System must be transportable 11 1 5 year life span (3x use per day)
Customer Needs
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
Spec Customer Need
Description Importance
Units Marginal
Target Comments/Status
1 1 Component Cost 3 $ 15 10 Including any PCB, for quantities of 1-10K.
2 2, 6, 8 Power supplied to fan
3 W .7 1.2
3 2, 6, 8 Voltage supplied to the fan
3 V 11 12 Converter needs to be adjustable.
4 8 Amount of startups that can be performed on battery power.
3 Start up 1 3 A system startup is the 20 minute period in
which the fan is powered by the battery
only.5 3 User interaction to
maintain proper system operation
3 Actions 1 0 The user shouldn’t need to perform
adjustments to properly operate electronics.
6 2 Electrical connections
provided to the stove.
3 Connections 6 4 2 input wires, 2 output wires
7 4, 7, 11 Survive drop test 2 Drops 2 20 Survive 20, 2 meter drops.
8 4, 7, 11 Survive crush test 2 PSI 2 5 Enclosure must survive being stepped on
9 4, 7, 11 Survive a rain test 2 hours 1 2 Put it in the shower.
Engineering Specifications
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
Spec Customer Need
Description Importance Units Marginal Target Comments/Status
10 4, 7, 11 Survive a humidity test
2 hours 1 5 Place the unit in an above 90% enclosed
area.11 5, 10 Enclosure surface
temperature2 °C 10 55 Surface of enclosure
may not exceed 55 °C during operation.
12 3, 5 User interaction to protect system
2 Actions 1 0 The user should not need to perform an action to protect the
system13 9 USB output power 2 W 2.375 2.5 Margin derived from
specs 15, and 1614 9 USB output voltage 2 V 4.75 5 From USB spec
15 9 USB output current 2 A .475 .5 From USB spec
16 9 Number of charges from battery
2 Charges 1 2
17 11 Product Life Span 2 Hours 1500 11,000 Assume 3 hours/use, 2 uses/day, for 5
years18 10 System Weight 1 lbs 6 3 Include battery packs
Engineering Specifications cont.
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
Spec Customer Need
Description Importance
Units Marginal
Target Comments/Status
19 10 Enclosure Volume 1 In 5x5x5 3x3x1.5 Include battery packs
20 3 User actions duringoperation cycle
1 # 2 0
Engineering Specifications cont.
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
System Architecture
Maximum Power Point Tracker (MPPT)
Network Power Storage and
Distribution
MPPT
Maximum Power Point Tracker (MPPT)
Network
Maximum Power Point Tracker (MPPT)o Allows efficient power transfer from TEG to
system
Power Distribution
Power Storage and Distribution
0 50 100 150 200 250 3005
5.2
5.4
5.6
5.8
6
6.2
6.4
6.6
Battery Discharge Test
Battery B (Connected)
Battery B (Disconnected)
Battery A
Time (Minutes)
Volt
age
(V)
• The battery must always have enough power to run the system during start-up
• To prevent overdraw• First USB is disabled• Then fan is disconnected
• To prevent overcharging• System will stop charging
battery
Battery Management
Battery Protection SystemBattery disconnect from MPPT and TEG when terminal voltage reaches 6.4 V
USB and Fan disconnect from battery when terminal voltage reaches 5.8 V
The voltage at the terminal of the switch (yellow) and the voltage at the input to the switch (blue)
CAT ProcedureStep 1: Connect battery and power on circuit.
Step 2: Run system until USB is disabled.
Step 3: Run system until fan is disconnected.
Step 4: Attach power pack to TEG.
Step 5: Run system until powered by TEG,
Step 6: Run system until fan is reconnected.
Step 7: Run system until USB is re-enabled.
Step 8: Run system until battery is disconnected.
Step 9: Disconnect power pack from TEG.
Step 10: Connect cell phone to USB output.
Step 11: Charge cell phones until USB is disconnected.
Step 12: Power off power pack.
Customer Acceptance Test (CAT)Bench Setup
A A
A A
The output power of the various systems sinks and sources.
The voltages at the various voltage sources of the system
The currents of the various systems
Needs Importance
Description Comments/Status
1 3* Fan runs the entire duration of cooking
2 3* Plan to couple to team 12442’s stove.
3 3 Cheap cost of system Component cost including PCB if applicable
4 3 User-friendly operation Minimal user interaction5 3 Safe to operate 6 2 Fan runs at start-up Multiple start/restart cycles7 2 Rugged design Survive crush and drop test8 2 Operational in Harsh Environments Exposure to Rain, Moisture, Heat
and Salinity9 2 Ability to charge USB device
10 1 System must be transportable 11 1 5 year life span (3x use per day)
Project Status
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
Spec Customer Need
Description Importance
Units Marginal
Target Comments/Status
1 1 Component Cost 3 $ 15 10 Including any PCB, for quantities of 1-10K.
2 2, 6, 8 Power supplied to fan
3 W .7 1.2
3 2, 6, 8 Voltage supplied to the fan
3 V 11 12 Converter needs to be adjustable.
4 8 Amount of startups that can be performed on battery power.
3 Start up 1 3 A system startup is the 20 minute period in
which the fan is powered by the battery
only.5 3 User interaction to
maintain proper system operation
3 Actions 1 0 The user shouldn’t need to perform
adjustments to properly operate electronics.
6 2 Electrical connections
provided to the stove.
3 Connections 6 4 2 input wires, 2 output wires
7 4, 7, 11 Survive drop test 2 Drops 2 20 Survive 20, 2 meter drops.
8 4, 7, 11 Survive crush test 2 PSI 2 5 Enclosure must survive being stepped on
10 4, 7, 11 Survive a rain test 2 hours 1 2 Put it in the shower.
Project Status cont.
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
Spec Customer Need
Description Importance Units Marginal Target Comments/Status
12 5, 10 Enclosure surface temperature
2 °C 10 55 Surface of enclosure may
not exceed 55 °C during operation.
13 3, 5 User interaction to protect system
2 Actions 1 0 The user should not need to perform an
action to protect the system
14 9 USB output power 2 W 2.375 2.5 Margin derived from specs 15,
and 1615 9 USB output voltage 2 V 4.75 5 From USB spec
16 9 USB output current 2 A .475 .5 From USB spec
17 9 Number of charges from battery
2 Charges 1 2
18 11 Product Life Span 2 Hours 1500 11,000 Assume 3 hours/use, 2
uses/day, for 5 years
19 10 System Weight 1 lbs 6 3 Include battery packs
20 10 Enclosure Volume 1 In 5x5x5 3x3x1.5 Include battery packs
Project Status cont.
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
Spec Customer Need
Description Importance
Units Marginal
Target Comments/Status
19 10 Enclosure Volume 1 In 5x5x5 3x3x1.5 Include battery packs
20 3 User actions duringoperation cycle
1 # 2 0
Project Status cont.
*Most important needsImportance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance
• Complete design and implementation of the MPPT.
• Decrease system cost.• Increase the efficiency of
the DC-DC converters.• Complete system PCB
layout, and have PCB layout.
• Manufacture and test enclosure.
• Send system to Haiti for field testing.
Future Work
Questions?