Abstract: A method of detecting faults in a wind turbine generator based on current signature analysis is disclosed herein. The method includes acquiring a set of electrical signals representative of an operating condition of a generator. Further, the electrical signals are processed to generate a normalized spectrum of electrical signals. A fault related to a gearbox or bearing or any other component associated with the generator is detected based on analyzing the current spectrum.

Abstract: A component that includes a longitudinal axle, having a multiple keybars that extend outward from a surface of the axle, such that each of the keybars are disposed axially along and circumferentially around the axle. Also the axis of the keybars is parallel to the axle, such that a profile of all midpoints of the keybars is helicoidal around the axle, also the helicoidal profile is such that they make up one or more helicoidal paths. The profile may be herringbone skewed. The component may be part of a rotor assembly that is part of an electric machine such as an interior permanent magnet (IPM) or Synchronous Reluctance motor.

Abstract: A variable speed electric machine and a method for generating electric energy is provided. The electric machine includes an outer stator with a first set of field windings. Further, the electric machine includes a modulator outer rotor that is concentric and is located proximate to the outer stator. The modulator outer rotor is operatively coupled to an input shaft. Furthermore the electric machine includes a permanent magnet inner rotor concentric to the modulator outer rotor. The electric machine also includes an inner stator with a second set of field windings. The inner stator is concentric to the inner rotor and is operatively coupled to an electric grid. The outer stator, the modulator outer rotor, inner stator and the inner rotor are magnetically coupled with each other so as to maintain a constant electric frequency at the inner stator.

Abstract: A core tube for a transformer is disclosed. The core tube includes a first half portion and a second half portion. The first half portion includes a first side portion, a first joining portion, and a second side portion. The first side portion is coupled to the second side portion via the first joining portion. The first side portion is longer than the second side portion or vice versa. The second half portion includes a third side portion, a second joining portion, and a fourth side portion. The third side portion is coupled to the fourth side portion via the second joining portion. The third side portion is longer than the fourth side portion or vice versa. The first half portion is coupled to the second half portion in an interleaved manner.

Abstract: A current transformer is provided. The current transformer comprises an inner magnetic core having a central opening, an outer sense core circumscribing the inner magnetic core, at least one pair of conductors extending through the central opening and positioned symmetrically with respect to a center point of the inner magnetic core, and one or more coils disposed on the inner magnetic core, the outer sense core, or both, in a magnetically balanced configuration relative to a magnetic neutral axis of the inner magnetic core.

Abstract: An electric motor assembly configured for use in a downhole pumping system includes a number of electrically conductive components that are insulated from fluids, mechanical abrasion, electrical current and electrical grounds using an advanced polyimide film. Preferred polyimide films include poly(4,4?-oxydiphenylene-pyromellitimide) and biphenyl-tetracarboxylic acid dianhydride (BPDA) type polyimide films. Magnet wire, stator laminates, stator coil end turns, motor leads and power cables can all be insulated with the selected polyimide film.

Abstract: An electric motor assembly configured for use in a downhole pumping system includes a number of electrically conductive components that are insulated from fluids, mechanical abrasion, electrical current and electrical grounds using an advanced polyimide film. Preferred polyimide films include poly(4,4?-oxydiphenylene-pyromellitimide) and biphenyl-tetracarboxylic acid dianhydride (BPDA) type polyimide films. Magnet wire, stator laminates, stator coil end turns, motor leads and power cables can all be insulated with the selected polyimide film.

Abstract: An integrated power quality control system includes a transformer with a primary winding, a secondary winding and a compensation winding wound on a magnetic core. A power electronic converter in the system provides a reference voltage to the compensation winding for injecting a series voltage in the secondary winding of the transformer. A controller is utilized to generate the reference voltage for the power electronic converter based on a power quality control requirement.

Abstract: Systems and methods are disclosed for on-line monitoring of the condition of the stator insulation of an AC motor or an electric generator. In certain embodiments, the system includes a transformer surrounding each pair of input and output cables associated with a given phase of power provided to the AC motor or generated by the electric generator. In another embodiment, a transformer surrounds the three input cables (for an AC motor) or the three output cables (for an electric generator) that correspond to phases of the AC motor or electric generator. In both embodiments, the transformers generate voltages that may be used to monitor leakage currents associated with the cables. A microcontroller monitors the voltages generated by the transformers and determines the condition of the stator insulation of the AC motor or the electric generator based on the voltages.

Abstract: An electrical machine includes a stator and a rotor. The stator has a central opening that is configured to receive the rotor. The rotor includes a generally cylindrical first section comprising a first material mounted on an axially extending shaft within the central opening. The rotor further includes a second section having a second material of a predetermined thickness that is coated directly on at least a portion of the first section. The second material has a higher electrical conductivity relative to the first material.

Abstract: A load tap changer includes a mechanical switch, a semiconductor switch and an impedance branch or an uncontrolled semiconductor switch. The mechanical switch is connected to a power terminal of a voltage conversion device to carry an electric current and is activated to switch from a first tap to a second tap of the voltage conversion device when a tap change signal is received. The semiconductor switch is then connected between the first tap and the power terminal of the voltage conversion device when the tap change signal is received and is disconnected before the mechanical switch is connected to the second tap. The impedance branch or the uncontrolled semiconductor switch is connected between the second tap and the power terminal of the voltage conversion device before the mechanical switch is connected to the second tap. The impedance or the uncontrolled semiconductor switch is disconnected after the mechanical switch is connected to the second tap.

Abstract: A system configured to monitor an operating electrical device includes a testing channel coupled to the device. The device is coupled to an electric power source through at least one electric power transmission channel. The power source is configured to transmit electric power at a first frequency. The testing channel is coupled to the power transmission channel. The system also includes a signal generator coupled to the testing channel. The signal generator is configured to inject testing signals into the testing channel at a second frequency that is greater than the first frequency. The system further includes at least one apparatus magnetically coupled to the power transmission channel. The magnetically coupled apparatus is configured to present a first impedance to the electric power at the first frequency and present a second impedance to the test signals at the second frequency. The second impedance is greater than the first impedance.

Abstract: A permanent magnet machine includes a stator having a stator core, a plurality of stator teeth and plurality of stator windings coupled to the stator core. The stator is configured to generate a stator magnetic rotating field when the stator windings are excited with an electric current. The stator magnetic rotating field includes both synchronous sub-harmonic and super-harmonic components. The permanent magnet machine also includes a rotor that is disposed within the stator. The rotor includes a rotor core and a plurality of rotor magnets that are coupled to the rotor core. The rotor magnets are further configured to have a predefined orientation profile such that when the stator windings are excited with an electric current, sub-harmonic and super-harmonic magnetic rotating fields are generated in the rotor magnetic field.

Abstract: An electric machine is presented. The electric machine includes a hollow rotor; and a stator disposed within the hollow rotor, the stator defining a flow channel. The hollow rotor includes a first end portion defining a fluid inlet, a second end portion defining a fluid outlet; the fluid inlet, the fluid outlet, and the flow channel of the stator being configured to allow passage of a fluid from the fluid inlet to the fluid outlet via the flow channel; and wherein the hollow rotor is characterized by a largest cross-sectional area of hollow rotor, and wherein the flow channel is characterized by a smallest cross-sectional area of the flow channel, wherein the smallest cross-sectional area of the flow channel is at least about 25% of the largest cross-sectional area of the hollow rotor. An electric fluid pump and a power generation system are also presented.

Abstract: A transformer tap-changing circuit comprises an apparatus that includes a transformer comprising a secondary winding configured to inductively couple to a primary winding when a current is passed through the primary winding from an energy source, a first rectifier coupled to the secondary winding and configured to rectify a first AC voltage from the secondary winding into a first DC voltage, and a second rectifier coupled to the secondary winding and configured to rectify a second AC voltage from the secondary winding into a second DC voltage. The apparatus also includes a DC bus coupled to the first and second rectifiers and configured to receive the first and second DC voltages therefrom, wherein the first AC voltage is higher than the second AC voltage, and wherein the first DC voltage is higher than the second DC voltage.

Abstract: A flux-switching electric machine includes a rotor having a rotor core that is configured to rotate about a central longitudinal axis. The rotor core has a circumference that includes an approximately constant radius of curvature along an arc length of the rotor core. The rotor core includes magnetic and non-magnetic segments that are arranged in an alternating pattern of magnetic segments and non-magnetic segments along the arc length of the rotor core. The flux-switching electric machine also includes a stator having a stator core that extends a length along the central longitudinal axis. The stator core includes a stator base and stator teeth that extend radially from the stator base relative to the central longitudinal axis. The stator includes a direct current (DC) field coil wound around at least one corresponding stator tooth. The stator includes an alternating current (AC) armature coil wound around at least one corresponding stator tooth.

Abstract: A current transformer is provided.

Abstract: A variable speed electric machine and a method for generating electric energy is provided. The electric machine includes an outer stator with a first set of field windings. Further, the electric machine includes a modulator outer rotor that is concentric and is located proximate to the outer stator. The modulator outer rotor is operatively coupled to an input shaft. Furthermore the electric machine includes a permanent magnet inner rotor concentric to the modulator outer rotor. The electric machine also includes an inner stator with a second set of field windings. The inner stator is concentric to the inner rotor and is operatively coupled to an electric grid. The outer stator, the modulator outer rotor, inner stator and the inner rotor are magnetically coupled with each other so as to maintain a constant electric frequency at the inner stator.

Abstract: In one or more embodiments, the present invention provides electric motors and related systems comprising (a) a motor housing; and (b) a hollow rotor configured to rotate within and be driven by a stator contained within the motor housing; wherein the motor housing is characterized by a largest cross-sectional area of the motor housing, and wherein the hollow rotor defines a flow channel characterized by a smallest cross-sectional area of the flow channel, wherein the smallest cross-sectional area of the flow channel is at least 25% of the largest cross-sectional area of the motor housing, and wherein the hollow rotor has a first end portion defining a fluid inlet, and a second end portion defining a fluid outlet; the fluid inlet, the flow channel and the fluid outlet being configured to allow passage of a fluid from the fluid inlet to the fluid outlet via the flow channel.

Abstract: A current transformer is provided. The current transformer comprises an inner magnetic core having a central opening, an outer sense core circumscribing the inner magnetic core, at least one pair of conductors extending through the central opening and positioned symmetrically with respect to a center point of the inner magnetic core, and one or more coils disposed on the inner magnetic core, the outer sense core, or both, in a magnetically balanced configuration relative to a magnetic neutral axis of the inner magnetic core.