p12441: thermoelectric power pack for next generation stove andrew phillips – project manager...
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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 interaction
5 3 Safe to operate
6 2 Fan runs at start-up Multiple start/restart cycles
7 2 Rugged design Survive crush and drop test
8 2 Operational in Harsh Environments Exposure to Rain, Moisture, Heat and Salinity
9 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 tomaintain 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 temperature
2 °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
system
13 9 USB output power 2 W 2.375 2.5 Margin derived from specs 15, and 16
14 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
years
18 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
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)
Vo
ltag
e (
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.
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 interaction
5 3 Safe to operate
6 2 Fan runs at start-up Multiple start/restart cycles
7 2 Rugged design Survive crush and drop test
8 2 Operational in Harsh Environments Exposure to Rain, Moisture, Heat and Salinity
9 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 tomaintain 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 16
15 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