DETAILED DESIGN REVIEWMSD Project #12441: Thermoelectric Power Pack

Lead Software Engineer: Colin McCune (EE)Project Manager: Andrew Phillips (EE)Test Engineer: Lauren Cummings (EE)Cost Engineer: Xiaolong Zhang (EE)

Goals of Detailed Design Review

1.Communicate detailed design to P12442 and project guides.2.Catch mistakes and overlooked details of the design.3.Display feasibility of the design.

Customer NeedsNeeds 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)Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 -

High Importance

Engineering Specifications 1-10Spec 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 3A system startup is the 20

minute period in which the fan is powered by the battery only.

5 3User interaction to

maintain proper system operation

3 Actions 1 0The 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.

Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Engineering Specifications 11-22

Spec Customer Need Description Importance Units Marginal Target Comments/Status

11 4, 7, 11 Survive a humidity test 2 hours 1 5 Place the unit in an above 90% enclosed area.

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 spec16 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 packs20 10 Enclosure Volume 1 In 5x5x5 3x3x1.5 Include battery packs

21 3 User actions duringoperation cycle 1 # 2 0

22 3 Fuse high cost components 1 Dollars 1 3 Put fuses on lines that supply high

cost components.

Functional Decomposition: Maximum Power Point Tracker (MPPT)

Function Decomposition: Enclosure System

System Architecture

Picking the BatteryLead-Acid Nickle-Metal Hydride Lithium-Ion

Grade Description Grade Description Grade DescriptionCost ($ per pack) + 7.5 - 10 0 9.65 -11.88 waiting on quote

Discharge Capacity (mAh) + 1300 - 4500 0 1500 - 2500 + 2000 - 3000

Charging Complexity 0 Trickle or multi-stage 0 Trickle or multi-stage - Constant current, constant voltage

Robust 0 0 0

Mass (Kg) - .3 - 2 0 .026 - .029 0 .0435 - .0465

Life span (Cycles) - 500 - 800 0 500 - 1000 + 400 - 1200

Charge Time (Hours) - 2 - 20 0 1.5 - 4 0 1.75 - 4.25

Charge/Discharge Efficiency + 50% - 92% 0 66% + 80% - 90%

Volume (Cubic Inches) - ~21 0 ~2 + ~1

Voltage per Cell + 6 - 12 0 1.2 0 3.6 - 4.2

Special Requirement 0 Must be kept vertical to function 0 0 Must be bought in

prebuilt packs

Internal Resistance (mΩ) 0 ~20 0 ~25 - ~2000 - 6000

Change in Charge Voltage (V) - ~2V 0 ~.4V - ~1.5V

Battery

• Battery Selection• Given the high storage requirements, relatively high current

draw (about 700mA), and low cost requirements the Panasonic LC-R064R5P Lead Acid battery was selected.

• The recommended trickle charge current for the battery to achieve a 5 hour charge is 720mA. This is slightly higher than the predicted maximum output current of the MPPT of 670mA. Because of this no current control or disconnect system is needed.

System Power (W) Time (H) Efficiency Required Power (Wh)Fan 1.2 3 0.9 3.96

Microcontroller 0.005 3 0.9 0.02USB 2.5 3 0.9 8.25

Analog Controls 0.3 3 0.9 0.99Total 13.22

Battery Selections Effect on the System• From the figure below it can be seen that at a

discharge rate of 1.125 A the terminal voltage ranges from 5.1V to 6.5V. The power systems will need to be designed to operate across this voltage range.

MPPT Pugh Chart

MPPT Reference Material*

*A maximum power point tracking circuit of thermoelectric generators without digital controllers – Shiho Kim, Sungkyu Cho, Namjae Kim, and Jungyong Park

MPPT Schematic

Maximum Power Equations

Results

MPPT Sawtooth Wave Generator

Sawtooth generator simulation schematic.

Sawtooth generator simulation.

MPPT Simulation Schematic

MPPT TEG Simulation Results

12V Fan Converter

Fan converter schematic

Fan Converter BOMRef Manufacturer Manufacturer PN Description Distributer Distributer PN Quantity Price per

1k

CCOMP Yageo CC0805KRX7R9BB472 CAP CER 4700PF 50V 10% X7R 0805 Digikey 311-1133-2-ND 1 0.010

CIN Murata GRM188R61A335KE15D MLCC SMD/SMT 3.3uF 10Volts X5R 10% Mouser 81-

GRM188R61A335KE5D 1 0.050

COUTUnited Chemi-

Con EMVY160ADA101MF55G CAP ALUM 100UF 16V 20% SMD Digikey 565-2446-2-ND 1 0.093

CSS Murata GRM2195C1H912JA01D MLCC SMD/SMT 0.0091uF 50Volts C0G 0.05 Mouser 81-

GRM2195C1H912JA1D 1 0.082

D1 Toshiba CMS06(TE12L,Q,M) RECT SCHOTTKY 30V 2A 3-4E1A Digikey CMS06QMTR-ND 1 0.186

L1 Bourns Inc. SDR0503-101KL INDUCTOR POWER 100UH 10% SMD Digikey SDR0503-101KLTR-ND 1 0.210

RCOMP Vishay/Dale CRCW080520K0FKEA RES 20.0K OHM 1/8W 1% 0805 SMD Digikey 541-20.0KCTR-ND 1 0.008

RFB1 Vishay/Dale CRCW080510K2FKEA RES 10.2K OHM 1/8W 1% 0805 SMD Digikey 541-10.2KCTR-ND 1 0.008

RFB2 Vishay/Dale CRCW080586K6FKEA RES 86.6K OHM 1/8W 1% 0805 SMD Digikey 541-86.6KCTR-ND 1 0.008

U1Texas

Instruments LM3224MM-ADJ IC BOOST/FLYBCK ADJ 2.45A 8MSOP Digikey LM3224MM-ADJTR-ND 1 1.470

Microcontroller Converter

Ref Manufacturer Manufacturer PN Description Distributer Distributer PN Quantity

Price per 1k

L1 Taiyo Yuden BRC2012T2R2MD INDUCTOR 2.2UH 1.0A 20% SMD Digikey 587-2905-2-ND 1 0.100

R1 Vishay-Dale CRCW1206100KJNEA RES 100K OHM 1/4W 5% 1206 SMD Digikey 541-100KECT-ND 1 0.019

R2 Stackpole Electronics Inc RMCF2512FT16R5 RES TF 1W 16.5 OHM

1% 2512 Digikey RMCF2512FT16R5TR-ND 1 0.041

C1 Taiyo Yuden LMK212BJ106KD-T CAP CER 10UF 10V 10% X5R 0805 Digikey 587-1299-2-ND 1 0.038

C2 Taiyo Yuden JMK212BJ226MG-T CAP CER 22UF 6.3V 20% X5R 0805 Digikey 587-1305-2-ND 1 0.056

U1 Texas Instruments TPS62172 BUCK CONVERTER 3-17V 0.5A 2.5MHZ Mouser 595-TPS62172DSGT 1 1.410

System Converter simulation

Time

0s 50us 100us 150us 200us 250us 300us 350us 400us 450us 500us-I(R2) -I(R4) -I(R6)

0A

100mA

200mA

300mA

(383.648u,200.006m)

I(U1:VIN) I(U2:VIN) I(U3:VIN)0A

0.5A

1.0A

SEL>>

(365.690u,352.662m)

(164.133u,797.787m)

V(U1:VOS)V(U2:VOS)V(U3:VOS)0V

2.0V

4.0V

(391.644u,3.3001)

Steady Input Current(A)

Steady Output Current(A)

Steady Output Voltage(V)

0.352662 0.200006 3.3001

Both input / output current and output voltage become stable after 300 µs.Vary input voltages to 5V, 6V and 7V, output voltages stay the same at 3.3V.

USB Converter

Ref Manufacturer Manufacturer PN Description Distributer Distributer PN Quantity Price per 1kC1 TDK CGJ4J2X7R1C104K CAP CER 0.1UF 16V 10% X7R 0805 Digikey 445-8183-1-ND 1 0.044

C6,7 Kemet C0805C105K4RACTU CAP CER 1UF 16V 10% X7R 0805 Digikey 399-1284-1-ND 2 0.024C3,4,5 TDK C3216X5R1C106M CAP CER 10UF 16V 20% X5R 1206 Digikey 445-1426-1-ND 3 0.078

L1 Vishay-Dale IHLP1212BZER1R0M11 INDUCTOR POWER 1.0UH 5A SMD Digikey 541-1319-1-ND 1 0.648

R1 Vishay-Dale CRCW1206100KJNEA RES 100K OHM 1/4W 5% 1206 SMD Digikey 541-100KECT-ND 1 0.019

U1 TI TPS62133 IC BUCK SYNC 5V 3A 16QFN Digikey 296-29937-1-ND 1 2.85

TPS62133TRANSIENT-MODEL

U 1

TP S 6 2 1 3 3 _ TR A N S

P V I N 1

P V I N 2

A V I N

E N

S S _ TR

DE

F

FS

W

PG

ND

2

PG

ND

1

E TP A D

A G N D

S W 1

S W 2

S W 3

V O S

F B

P G

0

C 1. 1 u F

C 31 0 u F

C 41 0 u F

R 11 0 0 k

L 1

1 u H

V 16 V D C

R 21 0

C 51 0 u F

C 61 u F

R 31 0 m

R 41 0 m

R 51 0 m

R 61 0 m

R 71 0 m

R 8

2 4 m

C 71 u F

R 91 0 m

I

V

Input: 5V to 7V, to account for and voltage fluctuations from the MPPT and the full discharge level of the battery.Output: 5V +/- 5% per USB specifications, the output current will be 700mA max to allow for a maximum draw of 500ma for the USB, and an additional 200mA draw for the analog circuitry.

USB Operation at Nominal Input and 1A Output

Time

0s 20us 40us 60us 80us 100us 120us 140us 160us 180us 200us 220us 240us 260us 280us 300us 320us 340us 360us 380us 400us 420us 440us 460us 480us 500usV(R1:2) -I(R2)

0

2.0

4.0

6.0

SEL>>

I(U1:PVIN1)0A

0.5A

1.0A

The input current (above) and output voltage and current (below) with a 6V input and a load current of 1A.

Output Behavior With A Varying Input

Time

0s 20us 40us 60us 80us 100us 120us 140us 160us 180us 200us 220us 240us 260us 280us 300us 320us 340us 360us 380us 400us 420us 440us 460us 480us 500usV(C5:2) V(R10:2) V(C17:2) -I(R2) -I(R11) -I(R20)

0

1.0

2.0

3.0

4.0

5.0

6.0

The output voltage and current with an input voltage of 5V, 6V, and 7V.

Enclosure Concept

Enclosure Concept

Top View

Side View

Electrical Test Plans System Test Ideal Value Tolerance Test Method

MPPT Output Voltage 6.5V .1V Use multimeter to test output pins of the MPPT circuitry

BatteryCharged Voltage 6.5V 0.1V Use multimeter to test the positive and negative terminal

Discharged Voltage 5.1V 0.1V Use multimeter to test the positive and negative terminal

Fan

Output Voltage 12V 0.5V Use multimeter to test output terminals of the fan

Output Current With a 100Ω Load 0.07A 0.01A Connect multimeter in series with fan to test current

System Converter

Output Voltage 3.3V 0.01V Use multimeter to test output pins of the system converter circuitry

Output Current With a 10Ω Load 0.2A 0.03A Connect multimeter in series with system load to test current

USB

Output Voltage 5V 0.1V Use multimeter to test output terminals of the USB

Output Current With a 10Ω Load 0.7A 0.05A Connect multimeter in series with USB to test current

Mechanical Test Plans

Test Description Ideal Value Marginal Value Equipment Test Method

Drop Completed system will be dropped 20 times from a height of 2 meters onto a

hard surface (pavement) 20 drops 2 drops Completed system, pavement,

meter stick Pass/Fail

Crush

Completed system will be stepped on by a member of the design team,

placing a force of approximately 5 psi on the system. System will be located

on hard surface for this test.

5 psi 2 psi Completed system, pavement, member of design team Pass/Fail

Rain Completed system will be placed in a shower for 2 hours 2 hours 1 hour Completed system, shower,

stopwatch Pass/Fail

Humidity Completed system will be placed in an enclosure with above 90% humidity for

5 hours 5 hours 1 hour

Completed system, enclosed area, humidifier, humidity

measurement system, stopwatch

Pass/Fail

Sample Test Document1.What is being tested and why2.Equipment

1.List of required equipment2.The settings of the required equipment

3.Procedure1.What is being measured?2.How is it being measured?

4.Result table1.Step number2.What is being measured?3.What is the expected value?4.What is the measured value?

5.Pass/Fail and why1.Did the device pass the test? 2.Defend the decision.

Risks 1-6ID Risk Item Effect Cause Likelihood Severity Importance Action to Minimize Risk Owner

1 Exceeding target cost per

unit.

Other features of the end

product may be not included.

Component cost.

Manufacturing cost.

3 3 9

Minimize the amount of components.Increase the

functionality of existing components

Xiaolong

2 P12442 does not provide sufficient

temperature difference

Not enough power, features

must be sacrificed, poor

functionality

Insufficient communication between teams

3 3 9 Effectively communicate with P12442 over

generated temperature difference.

Colin

3 Unable to program

microcontroller

The MPPT will not be able to

provide maximum power

Inexperience, difficulty, hardware

complications.

2 3 6 Community support, professor and professional

assistance

Lauren and Colin

4Device requires

too much power.

Unit will not have full

functionality.Unstable

behavior when operated.

Poor design and component selection.

2 3 6

Design to be as power efficient as possible.

Utilize MPPT functions.Using the uC as much as

possible.

Andrew

5 Device fails to operate.

The project will not be

completed.

Poor designPoor project

planning,2 3 6

Have at least weekly design meetings. Choose

high efficiency parts.Lauren

6Prototype

construction time

Less time for de-bugging, failure

to deliver on time

Poor planning, complex system.

Unforeseen circumstances

2 3 6

Strict scheduling milestones, effective and

reachable deadlines, component delivery time,

ordering parts early enough

Colin

Importance Scale: 1 - Low, 2 - Moderate, 3 - High

Risks 7-11ID Risk Item Effect Cause Likelihood Severity Importance Action to Minimize Risk Owner

7

System cannot power fan

during "warm up"

Stove will take longer to heat up

and longer for the TEG to provide full

power.

Component failure. Bug in the uC code. Poor design.

2 3 6

Design the unit to operate on battery

power. Ensure the uC operates correctly

Andrew

8Going over

development budget.

Difficult to be able to fund

further development.

Poor planning 1 3 3Track spending

Ordering correct partsProper testing.

Xiaolong

9Battery

charging difficulties

Decreased battery lifetime, system does not operate properly

Inexperience in the area, poor

design2 3 6 Professor and

professional assistanceXiaolong and

Andrew

10 Complexity of operation

Sell less unitsImproper use

Reduce system lifetime

Poor Design 1 3 3 Minimize user interaction.Make simple to operate. Colin

11 Decreased reliability

Fewer sales.Unit will get

damaged more often.

Poor part selection.

Poor fabrication.Poor design.

1 3 3

Design the unit to be as robust as possible.

Choose high-lifetime components.

Lauren

Project Plan

Questions or Comments?