Constant frequency variable rpm generator

Abstract

A prime mover delivers rotational torque to a generator having an exciter and a main unit connected sequentially along the prime mover output shaft. A voltage sensor is connected to the generator output and supplies a signal reflective of the output voltage to a frequency source. The frequency source is connected to receive power from a secondary energy source associated with the prime mover. The frequency source supplies an output signal at a preselected frequency at variable power levels related to the magnitude of the generator output voltage. The frequency source output is connected to the stator of the exciter to generate the magnetic field therein which rotates directionally with respect to the rotational direction of the prime mover output shaft to generate an output of preselected frequency. The rotor of the exciter has an output which is connected to the rotor of the main unit of the generator to generate in the main unit a magnetic field which rotates directionally relative to the direction of rotation of the prime mover output shaft to generate an output signal at a frequency independent of prime mover shaft rotational rate. The frequency source may be an alternator powered mechanically from the secondary energy source of the prime mover or a circuit powered from a battery associated with the prime mover. In operation, the prime mover output shaft rotational rate may vary below, but preferably above and not at electrical synchronous speed, as desired by the user and in relation to the output power required from the generator. Switching and wiring are also adapted to provide for conventional isochronous prime mover operation. A plurality of electrical machines may be ganged to the prime mover output shaft to provide desired gain and output power at the output of the generating system.