US 4,663,536 AGranted

A.C. motor-generator

AssigneePrecise Power Corporation

InventorsJohn F. Roesel, Jr., Ronnie J. Barber

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Abstract

A compact, high efficiency non-interruptive motor generator power system for generating and supplying to a load A.C. of a substantially constant frequency and of a substantially constant voltage, the motor thereof being a synchronous A.C. motor energizable from a source of irregular and interruptible A.C. line power, the generator being capable of converting its rotational energy into the A.C. output for many seconds after interruption of the A.C. line power. The power system comprises a high efficiency, synchronous permanent magnet A.C. motor and an A.C. generator coupled to and driven by the motor. Both the motor and generator have a high rotational enertia common rotor wherein an outer cylindrical shell contains motor and generator rotor elements of high permeability soft magnetic material with a surface layer of magnetizable permanent magnetic material, and in each stator is an excitation coil, energizable with A.C., having a pole piece adjacent a layer of permanent magnetic material whereby to magnetize the layer into a selected pattern of north and south magnetic poles. The motor stator is within and encircled by the common rotor and has power windings producing a rotating magnetic field while the generator stator has windings for generating the A.C. power to the load during rotation of the so-magnetized rotor. Both stators also have feedback windings. In the motor stator, the feedback windings generate A.C. of a selected magnitude and phase which is conveyed by a resonant circuit to the excitation coil and there combined so as to provide energization thereof by A.C. of such strength and phase condition as to magnetize the layer of permanent magnetic material into the selected pattern. In the generator, the A.C. generated in the feedback windings is conveyed by an electrical circuit to the generator excitation coil which will essentially neutralize any A.C. induced therein by the magnetic field as the speed changes through the synchronous speed.

Claims14

Dependent claims

In a relatively compact, quiet running and highly efficient motor-generator NIPS wherein a driving motor is energized from a source of A.C. electrical power which may be subject to voltage irregularities, frequency irregularities and complete power interruptions for varying periods of time, and the generator is capable of supplying to a load A.C. power of a substantially constant frequency and at a substantially constant voltage at all times when the source is delivering usable A.C. to the driving motor and for a substantial period of the order of many seconds during power interruptions, in combination, a supporting base,

(A) a synchronous motor on the supporting base with a stator energized from the source of A.C. power to produce a rotating magnetic field, the motor having a rotor capble of rotating synchronously with the rotating magnetic field for driving the rotor of the A.C. generator, and
(B) the A.C. generator on the supporting base comprising a high rotational inertia rotor comprising (1) a rotatable circular cylindrical shell member mounted for coaxial rotation on bearings on the supporting base, at least one body of soft magnetic material affixed to the inside walls of the shell member, a layer of magnetizable permanent magnetic material attached to the body of soft magnetic material and having an exposed cylindrical surface coaxial with the axis of rotation of the shell, (2) a stator comprising a shaft member fixed to the supporting base and disposed within and along the axis of the rotatable shell member, at least one body of soft magnetic material having a slotted cylinddrical surface affixed to the shaft member and having the slotted surface thereof juxtaposed to and substantially coextensive with the layer of permanent magnetic material with a rotational clearance space therebetween, two of the slots in each body having an intervening pole piece about which an excitation coil is placed, whereby when the excitation coil is energized with single phase A.C. from a control means the pole piece will exert a strong magnetic flux of alternating magnetic polarity whereby the juxtaposed layer of permanent magnetic material will be magnetized during rotation into a selected pattern of north and south magnetic poles, a feedback winding and A.C. power generating windings in other slots in the stator body, and (3) circuit means for connecting the feedback winding to the excitation coil so that during synchronous rotation of the rotor any A.C. potential generated in the excitation coil by the passage of the magnetized poles in the layer is substantially suppressed by the A.C. voltage generated by the poles in the feedback winding.

In an A.C. generator, a rotor comprising a body of soft magnetic material having a surface on which a layer of magnetizable permanent magnetic material is held in place, the layer having an exposed circular cylindrical surface coaxial with the axis of rotation of the rotor, a stator comprising a body of soft magnetic material having a slotted exposed cylindrical surface coaxial with the axis of the rotor juxtaposed and closely adjacent to the exposed cylidrical surface of the layer of magnetic material in the rotor, with a rotational clearance between the surface, at least two adjacent slots in the body of the stator having a pole piece therebetween about which an excitation coil is placed so that when single phase A.C. passes through the excitation coil the pole piece is capable of magnetizing the layer of permanent magnetic material into a selected pattern of no north and south poles during rotation of the rotor, there being A.C. potentials generated in the excitation coil by passage of the magnetized poles during such rotation, and A.C. power generating windings in other slots in the stator in which A.C. output power is generated when the rotor with the magnetized poles in the layer rotates about the stator, the improvement comprising feedback windings placed in selected slots in the slotted stator body to generate an A.C. potential of a selected phase and magnitude and circuit means connecting the feedback windings and the excitation coil so that when the rotor is rotating at synchronous speed, the A.C. potentials from the feedback winding will substantially suppress the A.C. potentials being generated in the excitation coil.

Dependencies are inferred from the claim text.