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

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

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

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

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

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

Turbine Pelton Turbine Francis Turbine

We Picked a Pelton-like wheel

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

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

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

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”

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

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

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)

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

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

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 0.066667 2 3 0.4 0.133333 Sum 7.5

Feasibility for Super Capacitors

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

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

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

Housing Design

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

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

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