Quadrature axis field brushless exciter

A dynamoelectric machine comprising, in combination:

• a shaft;
• a rotatable armature member disposed on said shaft, said armature member carrying an armature winding;
• a stator member having a plurality of salient poles thereon concentrically disposed about and spaced apart from said armature;
• a stator field coil disposed on selected ones of said salient poles, said stator field coils being connected together to constitute a stator field winding;
• and,
• a plurality of alternating current induction coils interposed between adjacent ones of said salient poles, the magnetic axes of said induction coils being disposed substantially in space quadrature relation with respect to the magnetic axes of said field coils, said induction coils being connected together to constitute a single phase an alternating current starting winding.

In a synchronous dynamoelectric machine, a rotor member having field coils connected together to form a rotor field winding, an alternating current exciter having a stator member and a plurality of salient stator poles thereon, stator field coils disposed on said salient poles and connected together to form a stator exciter field winding and at least one starting coil interposed between salient poles, the magnetic axis of said starting coil being disposed substantially in space-quadrature relation with respect to the magnetic axes of adjacent field coils, an exciter armature member rotatable with said rotor field winding and having an armature winding thereon, said exciter armature winding being coupled magnetically with said exciter stator field winding for developing an alternating current excitation signal within said armature winding, rectifier means interconnecting said armature winding and said rotor field winding to provide direct current excitation to said rotor field winding;

• the combination with said synchronous dynamoelectric machine of means connected to a supplemental source of single phase alternating current to induce by magnet induction an alternating current excitation signal within said exciter armature winding when said rotor is at standstill, whereby direct current excitation is provided to said rotor field winding by said rectifier means independently of rotor rotation to permit acceleration of said rotor from rest to a predetermined operating speed by the interaction of the static magnetic field established by the rotor field winding with the rotating magnetic field established by the dynamoelectric machine stator winding in response to polyphase alternating current excitation applied thereto, the frequency of said polyphase excitation being variable in frequency from substantially zero cycles per second to a higher frequency which corresponds with the rotation of said rotor at a speed substantially equal to said predetermined operating speed.

A method of accelerating the rotor member of a synchronous dynamoelectric machine from rest to a predetermined speed of rotation, said dynamoelectric machine having a brushless exciter with a quadrature axis winding around the stator of said exciter, said dynamoelectric machine having a polyphase alternating current stator winding and a direct current rotor field winding, said method comprising:

• exciting the rotor field winding of said rotor member with direct current to establish a static magnetic field by connecting said rotor field winding to receive direct current excitation from the rotatable rectifier assembly of a brushless exciter, said brushless exciter including an alternator having a direct-axis, direct current stator winding and an alternating current quadrature-axis winding, the step of exciting the field winding of said synchronous dynamoelectric machine being accomplished by:
• exciting said quadrature axis winding of the stator of said exciter with single phase alternating current, whereby alternating current is induced within the rotor armature winding of said exciter and direct current excitation is applied to said rotor field winding through said rotatable rectifier independently of the rotation of said rotor member;
• exciting the stator winding of said dynamolelectric machine with polyphase alternating current to establish a dynamic magnetic field which rotates at a speed proportional to the frequency of the applied polyphase alternating current excitation;
• and,
• increasing the frequency of the applied polyphase alternating current excitation from substantially zero cycles per second to a higher frequency until said rotor member has accelerated to said predetermined speed of rotation.