Patent ID: 7737591

Claim:
A coaxial twin variable field permanent magnetic dynamoelectric machine that comprises: a first stator that comprises a first stator inner surface with a first stator axis; a first permanent magnet rotor that comprises a first rotor outer surface that is smaller than the first stator inner surface with a first rotor axis that is substantially coincident with the first stator axis and with the first rotor outer surface adjacent the first stator inner surface; at least one first axial hydraulic actuator mounted within the first rotor for axially displacing the first rotor outer surface along the first rotor axis relative to the first stator inner surface in a first axial direction to change magnetic flux interaction between the first stator the first rotor; a first magnetic shield that covers an outer surface of the first stator; a second stator displaced from the first stator in the first axial direction that comprises a second stator outer surface with a second stator axis that is substantially coincident with the first stator axis; a second permanent magnet rotor that comprises a second rotor inner surface that is larger than the second stator outer surface with a second rotor axis for the second rotor inner surface that is substantially coincident with the second stator axis and with the second rotor inner surface adjacent the second stator outer surface; at least one second axial hydraulic actuator mounted within the second rotor for axially displacing the second rotor inner surface along the second rotor axis relative to the second stator outer surface in a second axial direction opposite the first axial direction to change magnetic flux interaction between the second stator and the second rotor; a second magnetic shield that covers an inner surface of the second stator; and a drive shaft with a drive shaft axis of rotation that is substantially coincident with the first and second stator axes of rotation that couples to the first and second rotors; wherein the first axial hydraulic actuator may displace the first rotor outer surface within the second magnetic shield and the second axial hydraulic actuator may displace the second rotor inner surface over the first magnetic shield with reduced first rotor-second stator and second rotor-first stator magnetic flux interaction.