Kinetic energy of a rotor is substantially prevented from exceeding a predetermined amount of kinetic energy by determining a first kinetic energy of the rotor spinning at a first rotational velocity and determining whether the first kinetic energy exceeds the predetermined amount of kinetic energy....http://www.google.es/patents/US6943509?utm_source=gb-gplus-sharePatente US6943509 - Rotor speed control device and method
