I am designing a three phase permenent magnet generator , and have a question. as a magnet pair passes over a coil , inducing a voltage, that voltage is most dependent on ? 1) the angular velocity ( thats a given) 2) the pole strength 3) flux density 4) energy product. 5) thickness of the magnet ( not the width / length or diameter) Assuming the diameter of the magnet is in the correct proportion to the coil for a three phase generator how is the the thickness of the magnet related to the induced voltage? I have experimented with this , using 7/8" dia x 1/2" and 7/8" dia x 1" NdFeB magnets , with the same air gap , same coil , doubling the thickness only produced a 15 percent increase in voltage . why? I was expecting to double the induced voltage .