Introduction
   
    I've been into mountain biking since High School.  It is a great way to stay in shape and even at speeds of ~30 MPH can satisfy an adrenaline junky.  At one point it was my only means of transportation until I fixed my Honda.  My favorite trails are up and down gravel/dirt rides with occasional steep sections.  I like to work a bit for the descents.  I'm not the type to buy a lift ticket to drag my bike up the mountain.  Occasionally though there are really steep hills that I wish could go by quicker just because it can be boring to pedal up a hill.  It would be really cool, I thought, if some of the energy burned off on the downhill sections could be reused for the ascent later.  This is termed leveling.  I started playing with the idea of a regenerative capable system while finishing High School at BCC.  I wasn't aware back then of any good means of storing a lot of energy at once (and that still is a problem).  I finally settled on the idea of using a flywheel, but I had no means to try it out back then.

    In my senior year at the University of Washington I took a Power Electronics course to satisfy some credits for my BS in EE.  By then I became aware of another device good for quick recharging and high loads - an ultracapacitor.  NessCap (a Korean company) manufactures 10 Farad ultracaps rated at 50 Volts.  This still isn't quite enough energy to be really practical, but it was worth playing around with and I had to do some kind of final project.  The project was actually perfect for the class because the ultra-capacitor drive requires a Buck-Boost controller.  The voltage on the DC motor varies with speed and the voltage on the capacitor drops as it discharges.  Me and my partner, Ben Long, spent half the quarter theorizing and finally building a kind of a prototype.  The final paper goes thru the theory and implementation of the controller.

NessCap 50 V 10 F ultra-capacitor unit

Implementation of a capacitor drive.  The variac is used to simulate a capacitor voltage.

Simulation of controller response (ran by Ben Long)