VIP Handle Team: Energy Harvesting Unit Mark Tubergen

1. VIP Handle Team: Energy Harvesting UnitMark Tubergen Supervised by: Professor Peroulis AbbasSemnami • Design: • Inspired by ankle monitoring unit • Simple application of Faraday’s law of induction • Challenges: • Keep weight down • Obtain appropriate power generation • Model changing B-field accurately • Concept: • 10s of mW power scale • Wearable Device • Power a 50Ω medical device • Inspired by energy harvesting backpack • Backpack was able to create 6-7W of power http://www-personal.umich.edu/~kzelik/Energy_Harvesting_Backpack.html • Step 2: The Model • Make basic assumptions about core size • Create position data to reflect appropriate curve • Apply formula for B field at a distance from a cylindrical magnet: B=Bo*(L^2+R^2)^(1/2)/L*[(x+L)(R^2+(x+L)^2)^(-1/2)-x(R^2+x^2)^(-1/2)] • Apply faraday’s laws and fit polynomial to data • Calculate effective voltage • Step 1: The Magnet • Find appropriate scale and strength • 1” diameter x1” thickness • Cylinder • Surface Field= .6619 T • “Neodymium magnets are the strongest and most permanent magnets known to man” • Step 3: The Coil • Designed power to load 50mW • Will require source voltage of 1.58V • Veff/turn = 1mV • Inductor needs >= 1580 turns • Account for coil resistance to get actual power delivered • ID = 1.5”, OD = 2.3”, L = 3” • 24AWG copper wire • d = .0201” • R = 84.22mΩ/m • 240m of wire • DC resistance = 20.2Ω • Actual power output ~ 25mW