1. Lead Software Engineer: Colin McCune Lead Hardware Engineer: Andrew Phillips Test Engineer: Lauren Cummings Cost Engineer: Xiaolong Zhang

2. 1.Establish customer needs and engineering specifications. 2.Communicate project risks and mitigation plans. 3.Display and defend design decisions made. 4.Receive feedback on design decisions made. 5.Effectively communicate design decisions made to P12442. Goals of this System Design Review

3. NeedsImportanceDescriptionComments/Status 13Cheap cost of systemComponent cost including PCB if applicable 23Plan to couple to team 12442’s stove. 33User-friendly operationMinimal user interaction 42Rugged designSurvive crush and drop test 53Safe to operate 63Fan runs the entire duration of cooking 72Operational in Harsh EnvironmentsExposure to Rain, Moisture, Heat and Salinity 82Fan runs at start-upMultiple start/restart cycles 92Ability to charge USB device 111System must be transportable 1215 year life span (2x use per day) Customer Needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

4. Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 11Component Cost3$1510 Including any PCB, for quantities of 1- 10K. 22, 6, 8Power supplied to fan3W1.21.0 32, 6, 8 Voltage supplied to the fan 3V124Converter needs to be adjustable. 48 Amount of startups that can be performed on battery power. 3Start up13 A system startup is the 20 minute period in which the fan is powered by the battery only. 53 User interaction to maintain proper system operation 3Actions10 The user shouldn’t need to perform adjustments to properly operate electronics. 62 Electrical connections provided to the stove. 3Connections642 input wires, 2 output wires 74, 7, 11Survive drop test2Drops20 Survive 20, 2 meter drops. 84, 7, 11Survive crush test2PSI35 Enclosure must survive being stepped on by Hanzlik 104, 7, 11Survive a rain test2Hours.52Put it in the shower. Engineering Specifications 1-10 Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

5. Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 114, 7, 11 Survive a humidity test 2hours15 Place the unit in an above 90% enclosed area. 125, 10 Enclosure surface temperature 2°C7055 Surface of enclosure should not exceed 55 °C during operation. 133, 5 User interaction to protect system 2Actions10 The user should not need to perform an action to protect the system 149USB output power2W2.5 +/- 5%2.5 Margin derived from specs 15, and 16 159USB output voltage2V5 +/- 5%5From USB spec 169USB output current2A.45 +/-.05.45From USB spec 179 Number of charges from battery 2Charges12 1811Product Life Span2Hours150011,000 Assume 3 hours/use, 2 uses/day, for 5 years 1910System Weight1lbs23Include battery packs 2010Enclosure Volume1In5x5x53x3x1.5Include battery packs Engineering Specifications 10-22 213 User actions during operation cycle 1#20 22 3Fuse high cost components 1Dollars13Put fuses on lines that supply high cost components.

6. Functional Decomposition: Maximum Power Point Tracker (MPPT)

7. Function Decomposition: Enclosure System

8. Circuit Design Pros and Cons of the Circuit Architecture MicrocontrollerPoints Pros Lower power consumption2 Simple to upgrade1 Smart Circuitry possible2 Easier to implement an MPPT3 Cons Higher Cost vs. Analog Circuit-2 More complex-2 Software failure is possible Difficult to repair in the field Result 2 Analog CircuitPoints Pros Lower cost2 Easy to repair1 More robust2 Pre-made schematics available2 Cons Difficult to design-2 High power consumption-2 Difficult to upgrade Result 2

9. Pros and Cons of the MPPT Algorithms Perturb and ObservePoints Pros Very effective2 Easy to implement3 ConsCan oscillate under rapid state changes-3 Result Incremental ConductancePoints ProsMost accurate2 Cons Can oscillate-3 Difficult to implement-3 Result -4 Constant VoltagePoints Pros Very easy to implement3 Easily adjustable1 Simple operation2 Good performance under rapid changes3 Cons Uses an estimate for MPPT tracking Not most efficient-2 Result 6

10. MPPT Design Pros and Cons of the Charging Circuits Smart ChargerPoints Pros Rapid charging(85% in 60 min)3 Adaptable to different chemistries1 Lengthens battery life2 Cons Voltage, temperature, and current monitors needed-3 Difficult to implement-2 Needs a microcontroller-0/-3* Result 1/-2 Trickle ChargerPoints Pros Lengthens battery life2 Minimizes damage to batteries2 Cons Long time to charge-2 Designed to high capacity batteries Microcontroller needed for NiMH-0/-3* Risk of overcharging-2 Result -1/-4 *Dependent on design decisions

11. Batteries Pros and Cons of the Batteries Nickel Cadmium (NiCd) Point s Nickel Metal Hydride (NiMH)Points Pros Cheap3 Pros Cheap cost3 Capable of high rate of discharge2Low memory2 Simple to charge2Robust2 2 Useful in high current drain operation 2 Cons Memory Issues-3Non-toxic1 Lower capacity-3 Cons Fewer life cycles-3 ToxicVery difficult to charge-3 Heavy-2Shorter shelf life-2 Result 0 4 Lead AcidPoints Lithium (Li+) Point s Pros Long service life2 Pros Higher capacity than NiMH3High discharge current possible2 50% lighter than NiCd1High Capacity2 No memory2 Cons Heavy Relatively simple to charge2 Longer to charge compared to batteries -3 Long lifetime2Low power to weight ratio Cons Expensive-3Result 1 Not robust-2 Poor performance in high current situations-2 Toxic Result 2

12. Block Diagram 1

13. Block Diagram 2

14. Power from TEG with a 75 Degree Temperature Difference Current (A)Voltage(V)Power(W) 0.821.6

15. Power from TEG with a 175 Degree Temperature Difference Current (A)Voltage(V)Power(W) 1.1863.2093.807

16. Power from TEG with a 225 Degree Temperature Difference Current(A)Voltage(V)Power(W) 1.3603.7695.124

17. TEG Voltage and Current Model

18. Importance Scale: 1 - Low, 2 - Moderate, 3 - High IDRisk ItemEffectCauseLikelihoodSeverityImportanceAction to Minimize RiskOwner 1 Exceeding target cost per unit. Other features of the end product may be not included. Component cost. Manufacturing cost. 339 Minimize the amount of components. Increase the functionality of existing components (ex: have more tasks run within the uC). Xiaolong 2 P12442 does not provide sufficient temperature difference Not enough power, features must be sacrificed, poor functionality Insufficient communication between teams 339 Effectively communicate with P12442 over generated temperature difference. Colin 3 Unable to program microcontroller The MPPT will not be able to provide maximum power and the batteries will not charge properly. Inexperience, difficulty, hardware complications. 236 Community support, professor and professional assistance Lauren and Colin 4 Device requires too much power. Unit will not have full functionality. Unstable behavior when operated. Poor design and component selection. 236 Design to be as power efficient as possible. Utilize MPPT functions. Using the uC as much as possible. Andrew

19. 5 Device fails to operate. The project will not be completed. Poor design Poor project planning, 236 Have at least weekly design meetings to look over designs. Choose high quality parts that can handle and supply the required power with minimal losses. Lauren 6 Prototype construction time Less time for de- bugging, failure to deliver on time Poor planning, complex system. Unforeseen circumstances 236 Strict scheduling milestones, effective and reachable deadlines, component delivery time, ordering parts early enough Colin 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. 236 Design the unit to operate on battery power. Ensure the uC operates correctly Andrew 8 Going over development budget. Difficult to be able to fund further development. Poor planning133 Track spending Ordering correct parts Proper testing. Xiaolong 9 Battery charging difficulties Decreased battery lifetime, system does not operate properly Inexperience in the area, poor design 236Professor and professional assistance Xiaolong and Andrew 10 Complexity of operation Sell less units Improper use Reduce system lifetime Poor Design133 Minimize user interaction. Make simple to operate. Colin

20. 11 Decreased reliability Fewer sales. Unit will get damaged more often. Poor part selection. Poor fabrication. Poor design. 133 Design the unit to be as robust as possible. Choose high-lifetime components. Lauren 12 Power storage capacity System start-up failure. Cannot charge devices without a fire. Poor system design. Poor system storage capacity. 122 Use high-capacity storage to meet customer specs. Andrew

21. Project Schedule

22. Project Schedule (Continued)