Abstract: A power generator that operates at a reduced keybar voltages and currents, flange currents, and keybar voltage differentials includes a keybar shield that reduces the amount of magnetic flux coupling into a keybar of multiple keybars during operation of the generator. By reducing the amount of coupled flux, the keybar shield reduces a keybar voltage and a keybar current in a keybar, reduces keybar current flowing into a flange, and reduces a voltage differential between voltages induced by the flux in the multiple keybars.

Abstract: An axial flux machine includes a rotatable shaft; at least one rotor disk coupled to the rotatable shaft; at least one permanent magnet supported by the at least one rotor disk; at least one stator extension positioned in parallel with the at least one rotor disk; at least two molded iron pole elements attached to the at least one stator extension and facing the at least one permanent magnet; and at least two electrical coils, each wrapped around a respective one of the at least two molded iron pole elements.

Abstract: A salient pole synchronous machine rotor includes a rotor shaft; a plurality of salient poles concentric to the rotor shaft; and end plates facing opposing ends of the salient poles, each end plate extending continuously around the rotor shaft.

Abstract: A hybrid synchronous machine (10) includes a cylindrical element (12 or 14) having slots (22 and/or 28); excitation windings (24 or 26) situated in at least some of the slots; and permanent magnets (30) situated in at least some of the slots. For a hybrid salient pole machine 16 a cylindrical element (112) has salient poles (36) with excitation windings (224) situated around the salient poles and permanent magnets (530, 630, 730, or 830) supported by the salient poles.

Abstract: An X-ray unit includes an X-ray tube including a rotating anode coupled to a rotor and a metal frame enclosing the rotating anode and the rotor. A motor, including the rotor of the X-ray tube, and a stator are situated outside the metal frame while an electromagnetic shield is situated between the stator and the rotor to minimize coupling to the stator of magnetic fields resulting from X-ray tube arcing. In one optional embodiment the electromagnetic shield includes an electrically conductive film situated on an outer diameter of the metal frame, and in another optional embodiment the electromagnetic shield includes an insulating film metallized on one surface with an electrically conductive film.

Abstract: An induction motor rotor comprises a rotor shaft, a rotor core, which may be solid or may include a plurality of rotor laminations, having rotor bar slots, a plurality of rotor bars extending through the rotor bar slots, and two rotor end rings brazed to the rotor bars and extending to the rotor shaft, the rotor bars and rotor end rings pre-stressing the rotor core.

Abstract: An induction machine asymmetry detection instrument includes an interconnector and a voltmeter. The interconnector is configured to connect an electric source across a first terminal and a second terminal of a stator of an induction machine. The induction machine includes a rotor disposed for magnetic coupling with the stator. The interconnector is further configured to cause a flow of direct current between the first terminal and the second terminal of the stator during a rotation of the rotor when the induction machine is substantially unloaded. The voltmeter is connectable across the second terminal and a third terminal of the stator. A detection by the voltmeter of a meaningful voltage across the second terminal and the third terminal of the stator concurrent with the flow of direct current between the first terminal and the second terminal and concurrent with the rotation of the rotor serves to indicate an asymmetry of a portion of the induction machine.

Abstract: A multipole brushless DC motor stator is formed with a pair of complementary opposable claw pole stator structures in which each of the stator structures comprises a stator base formed of a plurality of stacked sheet metal laminations. A plurality of stator pole members extend from the stator base and are formed by compression molding of a ferromagnetic material. In one form, the ferromagnetic material is molded in situ on the stator base by positioning the stator base in a compression mold having the slots in which a powdered or flaked ferromagnetic material can be positioned and compressed by a die. In another form, the ferromagnetic pole members may be independently compression molded of powdered or flaked ferromagnetic material and then adhesively bonded to the stacked laminations forming the stator base. In either method, the stacked laminations are formed with a plurality of receptacles for receiving one end of each of the stator poles and holding the stator poles to the stator base.

Abstract: A dynamoelectric machine includes a stator having teeth fabricated from a non-magnetic material and containing at least one embedded conductor. The teeth are unitary with a back portion that is mounted to a stator back iron. Permeance variations induced by a stator winding mounted on the non-magnetic stator teeth are low which facilitates a reduction of motor noise. Specifically, since the non-magnetic teeth reduce production of permeance variations, changes in air gap forces between the rotor and the stator are decreased.

Abstract: A seal-less pump and electric motor assembly includes a motor rotor fixed to a driving shaft connected to an impeller in the pump assembly. The rotor and impeller are enclosed in a common housing such that the rotor rotates within any fluid being pumped by the impeller. The portion of the housing circumscribing the rotor includes a plurality of axially extending, circumferentially spaced strips of magnetic material penetrating through plastic material of the housing. Each of the strips coincide with corresponding ones of the pole teeth of a motor stator circumscribing the outer portion of the housing such that the strips in the housing act as extensions of the pole teeth. In one embodiment, the strips of magnetic material in the housing are formed by molding powdered iron in a plastic binder material. The strips are then placed in a mold in which the housing is formed by injecting plastic. The plastic binder in the strips melds with the injected plastic to form a continuous housing for enclosing the rotor.

Abstract: A radio frequency (RF) or other form of detector detects discharges of an insulated system which can occur when electrical insulation becomes wet, for subsequent analysis and decision processes. Additionally, for RF detection, a frequency selector can be used to select a “quiet” region of the discharge spectrum before demodulation and further analysis and decision. Finally, redundant sets of such filters avoid the need to continuously reconfigure the detection system.

Abstract: An assembly for transferring current comprises at least one electrically conductive slip ring; at least one electrically conductive brush for supplying current to the at least one slip ring; and an electric or pressure actuator driven vibration source for changing the position of the brush with respect to the slip ring. If desired, brush current can shared by using inductance variations or by selective coupling of rotor windings to the slip rings.

Abstract: An assembly for transferring current comprises at least one electrically conductive slip ring; at least one electrically conductive brush for supplying current to the at least one slip ring; and an electric or pressure actuator driven vibration source for changing the position of the brush with respect to the slip ring. If desired, brush current can shared by using inductance variations or by selective coupling of rotor windings to the slip rings.

Abstract: An induction machine asymmetry detection instrument includes an interconnector and a voltmeter. The interconnector is configured to connect an electric source across a first terminal and a second terminal of a stator of an induction machine. The induction machine includes a rotor disposed for magnetic coupling with the stator. The interconnector is further configured to cause a flow of direct current between the first terminal and the second terminal of the stator during a rotation of the rotor when the induction machine is substantially unloaded. The voltmeter is connectable across the second terminal and a third terminal of the stator. A detection by the voltmeter of a meaningful voltage across the second terminal and the third terminal of the stator concurrent with the flow of direct current between the first terminal and the second terminal and concurrent with the rotation of the rotor serves to indicate an asymmetry of a portion of the induction machine.

Abstract: A seal-less pump and electric motor assembly includes a motor rotor fixed to a driving shaft connected to an impeller in the pump assembly. The rotor and impeller are enclosed in a common housing such that the rotor rotates within any fluid being pumped by the impeller. The portion of the housing circumscribing the rotor includes a plurality of axially extending, circumferentially spaced strips of magnetic material penetrating through plastic material of the housing. Each of the strips coincide with corresponding ones of the pole teeth of a motor stator circumscribing the outer portion of the housing such that the strips in the housing act as extensions of the pole teeth. In one embodiment, the strips of magnetic material in the housing are formed by molding powdered iron in a plastic binder material. The strips are then placed in a mold in which the housing is formed by injecting plastic. The plastic binder in the strips melds with the injected plastic to form a continuous housing for enclosing the rotor.

Abstract: A method for turn fault detection in a multi-phase alternating current machine includes obtaining instantaneous line-to-neutral voltages from each phase of the machine, calculating the sum of the line-to-neutral voltages, and using the sum to determine whether a turn fault exists. The line-to-neutral voltages can be filtered to reduce harmonics. In one embodiment, deviations in a time-averaged function of the sum are examined. The time-averaged function can be exponentially weighted. Each of the line-to-neutral voltages can be calibrated to remove inherent machine phase impedance imbalance prior to calculating the sum of the line-to-neutral voltages.

Abstract: A method for fabricating an induction motor rotor lamination includes using an indexed notching die to punch a plurality of closed rotor slots at different distances from a center point of rotation by punching a first rotor slot, changing the position of a center point of the rotor lamination with respect to the notching die, and punching a second rotor slot. In another embodiment, a plurality of rotor slit patterns are punched using a variable depth indexed notching die including at least two rotor slit punching portions, one being deeper than another, by punching a first rotor slit pattern, changing the depth of closure of the notching die, and punching a second rotor slit pattern with the second rotor slit pattern having a different number of rotor slits than the first.

Abstract: A sensing coil affixed to the outside of an induction motor housing uses flux signals from the motor to measure motor speed. In particular, components of the rotor current are measured and compared to analysis from stator fundamentals and sidebands to determine the true rotor frequency which can then be used to determine the motor speed. A shield and/or a compensating coil can optionally be used to filter out extraneous signal noise.

Abstract: A method for removing spurious signals in a process of motor current signature analysis of an electric motor (24 or 33) includes creating an electronic model of the motor, acquiring simultaneous measurements of voltage and current at the motor, applying the voltage measurement to the motor model and determining an equivalent current produced in the motor model by the applied voltage, subtracting the equivalent current from the current measurement to produce a corrected motor current, and processing the corrected motor current through motor current signature analysis. For an ac motor (33), the method includes extracting signals corresponding to the fundamental excitation frequency from the voltage measurement to produce an interfering voltage, processing the interfering voltage through the motor model to produce a corresponding spurious current signal, and subtracting the spurious current signal from the measured current to produce the corrected motor current signal for analysis.

Abstract: A bearing assembly includes: an axial rotatable structure including a cylindrical rotor assembly (including a motor rotor and a plurality of magnetic bearing rotors); a cylindrical stationary shaft; rotating element bearings mechanically coupling the rotatable structure and the stationary shaft; and a cylindrical stator assembly including a motor stator and a plurality of magnetic bearing stators. The magnetic bearing stators and the magnetic bearing rotors forming magnetic bearings magnetically coupling the rotor and stator assemblies. Command feedforward of electrical current can be provided to at least some of the bearings to achieve appropriate radial forces for respective operating trajectories.