1. Miniscale Energy Generation
Peter C. Gravelle, Borce Gorevski, Nick Ieva
Sponsor/Advisor: Dr. S. Lyshevski, Electrical Engineering Department

2. The Team Left to Right: Nick Ieva, Peter C. Gravelle , Borce Gorevski
Advisor/Sponsor: Dr. S Lyshevski

3. Objective
To design and prototype a self-sufficient mini-scale generator.

4. Block Diagram/Roadmap
Velocity of Water
Angular velocity of turbine
Velocity of magnets over windings
Current in windings (AC)
Rectifier (AC-DC)
Is voltage too high?
Zener diode burns excess energy
Yes
Store in supercapacitor No
DC-DC conversion (increase voltage)
Load

5. Goals Sub-20 cm3 volume At least 0.1 W/cm3
We want to exceed these
Turbine (Runner) with permanent magnets
Salt-water resistant (nautical/sharks)
Output voltage greater than 7V

6. Design Choices Generator Electronics Housing Turbine Magnets Windings
Energy storage
Energy harvesting circuitry
Housing

7. Turbine
Pelton Turbine
Francis Turbine

8. We Picked a Pelton-like wheel

9. Technical Details: Turbine
Diameter of turbine: <2.5cm
Material: plastic
Nylon (reinforced or not?)
Magnets mounted on wheel using water-proof epoxy.

10. Magnets SmCo NdFeB Corrosion resistant More expensive Weaker
Very highly magnetic
Low cost
Very corrodible

11. Magnet Feasibility Graph
Feasibility Chart: Magnets 1 2 3 T1 T2 T3 T4 E1
NdFeB
SmCo
Humidity Resistance
Field Strength
Salt Environment
Small Pieces
Cost T1 T2 T T4 E1 sm
NdFeB 1 3 11
SmCo 2 10

12. We’re using NdFeB Dr. Lyshevski recommended it Cheaper Stronger
More easily machined into small parts
Small arcs required for our design
Corrosion can be dealt with by plastic coating
Right now looking at ring magnets with OD = 0.625”, ID = 0.250”, and thickness of either 0.250” or 0.375”

13. Field Simulation for N35 grade NdFeB (3mm dia, 1mm thick disc)

14. Windings Winding wire will be supplied by Dr. Lyshevski
Axial motor winding pattern
Pattern will be made of plastic (see below)

15. Energy Storage Batteries Supercapacitors High energy density
Limited charge cycles
Lower voltage
Temperature sensitivity
Supercapacitors
High (but lower than batteries) energy density
Unlimited charge cycles
Higher voltage
Temperature insensitive ( -40C to 70C)

16. Batteries vs. Supercapacitors
Energy
Density
Power
Size
Max
Voltage
Life
Charging
Discharging
Circuit
Operating
Temp
Self-Discharge
H2O
Safety
Cost T1 T2 T3 T4 T5 T6 T7 T8 S1 E1
sum
Li-ion Batteries 3 1 2 15
Supercapacitors 25

17. We picked Supercapacitors
Smaller size
Greater cycle life
Will not ignite in water
Greater power density
High voltage density

18. Feasibility for Supercapacitors
Capacitance
Nom. Voltage
Max Current
Size
ESR
Row Total
Column Total
Row + Column
Relative Weights \ -
1.5
0.2 | 1
0.5 2 3
0.4
Sum
7.5

19. Feasibility for Super Capacitors

20. Energy Harvesting: AC-DC
Standard bridge rectifier
Takes AC input and turns it into DC output
We will be using a capacitor for additional smoothing

21. Harvesting Circuitry: Voltage Regulation
Switched-capacitor DC-DC voltage converter
Efficiency: 88-96%
Doubles input voltage
Max output current: 200mA
Step-up (boost) converter
Has an efficiency of 60-90%
But needs more parts (volume, cost)
Adjustable output voltage/current
More robust
Voltage/thermal/current protections
Max output current: 1A

22. Ease Of
Design
Efficiency
Tunable
Robust
Max
Current
Operating
temperature
EMI
Volume T1 T2 T3 T4 T5 T6 T7 T8
sum
Switched
Capacitor 3 1 2 17
Boost
Conversion 16

23. Housing Design

24. House Design
This cylindrical casing was designed so we can save on volume

25. Housing Design
Our final design has the codename: Windmill -please note the extended shaft
The idea came from a meeting with Dr. Lyshevski

26. Questions and Comments