US 8487459 B2 / Jul 16, 2013

Wave energy converter and power take off system

A wave energy converter (WEC) includes a float tending to move in phase with the waves, a spar tending to move out of phase with the float and power take off device (PTO) coupled between the float and spar for converting their relative motion into useful energy. The PTO includes a rack and pinion mechanism which drives a high-torque, multi-pole, permanent magnet generator (PMG) to produce electrical signals of relatively high frequency relative to the frequency of the waves and the basic motion of the rack and pinion mechanism. In accordance with one aspect of the invention, the rack and pinion mechanism may be located within the spar which may be hermetically sealed by a sealing mechanism which allows a thrust rod coupled between the float and spar to move up and down with little friction to ensure efficient operation. In addition, a braking arrangement is provided for inhibiting relative motion between the float and spar during extreme severe wave conditions. In this way, the pinion gears and generators need only be sized for the operational wave conditions.