Patent ID: 7453180

Claim:
A system for generating an electrical current in a circuit which comprises: a base; a rotor mounted on the base for rotation about an axis; a stator rigidly attached to the base; a first plurality of permanent magnets mounted in an annular groove on the rotor at a first radial distance from the axis; a polyphase winding mounted on the stator; a current source connected to the polyphase winding for interaction of the polyphase winding with the first plurality of magnets to rotate the rotor; a second plurality of permanent magnets mounted in an annular groove on the rotor at a second radial distance from the axis to establish a time-varying magnetic field during rotation of the rotor, and to establish a radial gap between the first plurality of permanent magnets and the second plurality of permanent magnets; a generator winding mounted on the stator for generating an electrical current in response to the time-varying magnetic field; a switch for reconfiguring the circuit between a first, open-circuit configuration and a second closed-circuit configuration wherein the current generated at the generator winding flows through the circuit; and a conductive shield mounted on said rotor for rotation therewith, said conductive shield being positioned between said second plurality of permanent magnets and the generator winding on said stator to prevent de-magnetization of said second plurality of permanent magnets when said switch is closed, wherein said conductive shield terminates adjacent the radial gap between the first plurality of permanent magnets and the second plurality of permanent magnets.