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

Objective To design and prototype a self-sufficient miniscale generator To design and prototype a self-sufficient miniscale generator

Goals Sub-5 cm 3 volume Sub-5 cm 3 volume At least 0.1 W/cm 3 At least 0.1 W/cm 3 We can probably exceed these greatly We can probably exceed these greatly Waterwheel with permanent magnets Waterwheel with permanent magnets Salt-water resistant (nautical/sharks) Salt-water resistant (nautical/sharks) Output voltage greater than 7V Output voltage greater than 7V

Design Choices Generator Generator Wheel Wheel Magnets Magnets Windings Windings Electronics Electronics Energy storage Energy storage Energy harvesting circuitry Energy harvesting circuitry Housing Housing

Wheel

Technical Details: Wheel Diameter of wheel: <2.5cm Diameter of wheel: <2.5cm Material: plastic Material: plastic Teflon? Durlen? HDPE? Nylon? Teflon? Durlen? HDPE? Nylon? Magnets mounted on wheel Magnets mounted on wheel

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

Magnet Feasibility Graph Humidity ResistanceField StrengthSalt EnvironmentSmall PiecesCost T1T2T3T4E1sum NdFeB SmCo

We picked NdFeB Dr. Lyshevski told us to Dr. Lyshevski told us to Cheaper Cheaper Stronger Stronger More easily machined into small parts More easily machined into small parts Arcs required for our design Arcs required for our design Corrosion can be dealt with by plastic coating 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” Right now looking at ring magnets with OD = 0.625”, ID = 0.250”, and thickness of either 0.250” or 0.375”

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

Windings Dr. Lyshevski has windings that we can use Dr. Lyshevski has windings that we can use We also found several websites, should we need different windings We also found several websites, should we need different windings Axial motor winding pattern Axial motor winding pattern Pattern will be made of plastic (see below) Pattern will be made of plastic (see below)

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

Batteries vs. Supercapacitors Energy Density Power DensitySize Max VoltageLife Charging Discharging Circuit Operating TempSelf-Discharge H2O SafetyCost T1T2T3T4T5T6T7T8S1E1sum Li-ion Batteries Supercapacitors

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

But which supercapacitor? Capacitance Max Voltage Nom. Voltage Max CurrentSizeESR T1T2T3T4T5T6sum HPSK0G103ZL (flat) FS0H223Z (cyl) FS0H473Z (cyl) FT0H104Z (cyl) FT0H224Z (cyl) FA0H473Z (cyl) FE0H473Z (cyl) FE0H104Z (cyl) PC5 (flat) PC5-5 (flat) GW 2 13D (flat) B49100A1503Q000 (flat) B49100B1104Q000 (flat)

So, which one is it? Further investigation is needed to determine the relative importance of our conditions Further investigation is needed to determine the relative importance of our conditions Size vs. Voltage Size vs. Voltage Size vs. Current Size vs. Current The smaller the size, the better! The smaller the size, the better!

Energy Harvesting: AC-DC Standard bridge rectifier Standard bridge rectifier

Harvesting Circuitry: Voltage Regulation Switched-capacitor DC-DC voltage converter Switched-capacitor DC-DC voltage converter Efficiency: ~90% Efficiency: ~90% Doubles input voltage Doubles input voltage Max output current: 300mA Max output current: 300mA Step-up (boost) converter Step-up (boost) converter Also has an efficiency of ~90% Also has an efficiency of ~90% Depends entirely on ESR values for capacitors and resistors Depends entirely on ESR values for capacitors and resistors But needs more parts (volume, cost) But needs more parts (volume, cost) Adjustable output voltage/current Adjustable output voltage/current Max output current: 1A Max output current: 1A