Abstract: A method of manufacturing an induction motor rotor assembly, the method includes the steps of: providing a rotor; machining a plurality of re-entrant slots axially along an outer surface of the rotor; positioning a sleeve concentrically over the outer surface of the rotor; applying a friction stir welding process to the sleeve along each re-entrant slot axially along the outer surface of the rotor to cause the sleeve material to plasticise and flow into the axial re-entrant slot to form an axial re-entrant slot bar; and providing an electrical connection at each of the opposing axial ends of the rotor between respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor.

Abstract: An electrical machine including a rotor and a stator, at least one of the rotor and stator being provided with superconducting first electrical windings; and a set of one or more screen electrical windings, provided in the form of one or more further superconducting electrical windings, arranged around and radially outward of the first electrical windings; wherein the set of screen electrical windings is arranged to be supplied with an electrical current for generating a magnetic field of suitable magnitude and phase to reduce the magnitude of the magnetic field, generated at least by the first electrical windings during operation of the electrical machine, radially outwards of the screen electrical windings.

Abstract: This invention concerns a cryo-cooled electrical conduction network. The conduction network has an electrical network divided into two or more conductive sections, each section comprising electrical equipment (24, 28). The conductive network also has a coolant network for maintaining the temperature of a coolant in each section. The electrical equipment (24, 28) and a corresponding portion of the coolant network of each section is housed in a section enclosure (10, 12, 14). The coolant network includes a coolant interface (40) located between each section, wherein the coolant interface (40) is housed in an intermediate enclosure (16, 18, 20, 22) that is isolatable from the section enclosures (10, 12, 14) in the electrical conduction network.

Abstract: A method of manufacturing an induction motor rotor assembly, the method includes the steps of: providing a rotor; machining a plurality of re-entrant slots axially along an outer surface of the rotor; positioning a sleeve concentrically over the outer surface of the rotor; applying a friction stir welding process to the sleeve along each re-entrant slot axially along the outer surface of the rotor to cause the sleeve material to plasticise and flow into the axial re-entrant slot to form an axial re-entrant slot bar; and providing an electrical connection at each of the opposing axial ends of the rotor between respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor.

Abstract: An electrical machine including a rotor and a stator, at least one of the rotor and stator being provided with superconducting first electrical windings; and a set of one or more screen electrical windings, provided in the form of one or more further superconducting electrical windings, arranged around and radially outward of the first electrical windings; wherein the set of screen electrical windings is arranged to be supplied with an electrical current for generating a magnetic field of suitable magnitude and phase to reduce the magnitude of the magnetic field, generated at least by the first electrical windings during operation of the electrical machine, radially outwards of the screen electrical windings.

Abstract: An electrical machine includes a stator including a plurality of electrical phases and a rotor having a plurality of magnets. Each electrical phase includes at least one coil and power electronics. There are means to detect an electrical short circuit in a faulted coil and means to supply an electrical current to the faulted coil when an electrical short circuit is detected in the faulted coil. The means to supply the electrical current to the faulted coil includes one or more un-faulted electrical phases of the electrical machine. The un-faulted electrical phases of the electrical machine are arranged to supply the electrical current to the electrical phase containing the faulted coil. The power electronics of the un-faulted electrical phases are arranged to supply the electrical current from the un-faulted electrical phase to the power electronics of the electrical phase having the faulted coil. This overcomes a problem of a fault in the DC or AC busbar of the electrical machine.

Abstract: An electrical machine system including a permanent magnet assembly having a magnetic field and a plurality of conductive coils, the magnet assembly and coils arranged for relative rotation between the coils and magnetic field in the manner of an electrical generator or motor, the system further comprising a current injector electrically connected to said coils and arranged selectively to supply a current signal thereto, the current signal being asynchronous with the frequency of rotation between the permanent magnet assembly and coils so as to heat and thereby demagnetise one or more magnet within said permanent magnet assembly.

Abstract: A synchronous electrical machine having a plurality of phases, a detecting unit arranged to detect a fault in at least one of the phases of the synchronous electrical machine, an isolating unit arranged to isolate the at least one phase of the synchronous electrical machine with the fault, a phase shift unit arranged to produce a controlled phase shift between the voltage and the current within the remaining phases of the synchronous electrical machine to adjust the phase angle and magnitude of the second harmonic powers produced by the remaining phases of the synchronous electrical machine such that the vector sum of the second harmonic power vectors of the remaining phases of the synchronous electrical machine is zero.

Abstract: A rotary transformer includes a primary core having a primary coil wound thereon, and a secondary core having a secondary coil wound thereon, the cores being mounted for relative rotation about an axis of rotation. The transformer is characterized in that one of the cores includes a plurality of core segments arranged in spaced-apart relation relative to one another in a substantially circular array about the axis, and the other core has a substantially annular configuration. In a particular embodiment, the primary core is fixed and hence remains static during operation, and includes a plurality of spaced apart core segments arranged in a circular array around the axis.

Abstract: A rotor 10 for an electrical machine comprising a rotor body 12, at least one magnet 18 coupled to the rotor body 12 and a retainer 22 for retaining the at least one magnet 18 to the rotor body 12, the retainer 22 comprising at least one elongate fibre in a metal matrix.

Abstract: Generators 12a are for a distributed generation system. A control system 32a receives information about network faults 14a. In normal conditions, the control system 32a controls the field current in the field coils of the generator 12a, to maintain generator output voltage at the rated value. At the onset of fault conditions, the control system 32a changes the manner in which field current is controlled, in order to reduce the fault current put onto the network.

Abstract: Use of a common electrical power bus to which a number of electrical power generators and consumers are coupled is well known. Typically, a high electrical capacitance is provided across the bus in order to provide stabilisation in the switching of generators and consumer devices as well as differences in the operational performances of the electrical power generators. Particularly in aerospace applications provision of high capacity electrical capacitors creates problems. By providing a feedback control and an electrical power converter take primary electrical power from an electro-mechanical converter associated with a rotating component of a prime mover, electrical power stabilisation is achieved by applying torque changes through the electromechanical converter to the rotating component of the prime mover such that stored electrical power can then be drawn as required to accommodate transients in electrical power on the bus.

Abstract: In order to be acceptable for safety critical applications, it is necessary for an electrical machine to allow continued operation despite an electrical short circuit in one of the operational phases of that electrical machine. It will be appreciated that an electrical short circuit creates excessive electrical current through the short circuit with significant heating and other detrimental effects. However, the electrical machine can operate with one operational phase disabled. In such circumstances, the present invention incorporates means for determining an electrical short circuit has occurred and then injects an electrical current approximately equal to or greater than the rated electrical current. In such circumstances, the operational phase or coil 4, 24, 34 is effectively protected despite the electrical short circuit and hence the electrical machine can continue to operate.

Abstract: An electrical conductor winding (70) comprises a plurality of laminates of electrical insulation (72). Each laminate of electrical insulation (72) has a slot (78) on one surface (76). Each laminate of electrical insulation (70) has an electrical conductor (82) arranged in the slot (78). An electrical connector (84) connects the electrical conductor (82) in one laminate of electrical insulation (78) with the electrical conductor (82) in an adjacent laminate of electrical insulation (72). The laminates of electrical insulation (72) are arranged such that the surface (74) of one laminate of electrical insulation (72) abuts and is bonded to the surface (76) of an adjacent laminate of electrical insulation (12). The laminates of electrical insulation (12) comprise a glass-ceramic material. The electrical conductor windings allow active magnetic bearings, electric motors and electric generators to be used at temperatures up to 500° C. for example in gas turbine engines.

Abstract: An electrical machine comprises a combined magnetic gearbox and electrical generator. A first set of permanent magnets (30) are arranged on a rotor (16) to produce a spatially variable first magnetic field. A second set of permanent magnets (32) are arranged on a rotor (40,41,43), stationary pole pieces (36) are positioned between the first set of permanent magnets (30) and the second set of permanent magnets (32) to interfere with the first magnetic field. Rotation of the rotor (16) relative to the pole pieces (36) produces a second magnetic field which rotates the second set of permanent magnets (32). A stator (42) has windings (46) to transduce a changing second magnetic field produced by the rotation of the second set of permanent magnets (32) into an electrical voltage. The electrical machine is useful for a wind turbine generator. Alternatively the arrangement may be modified to produce an electrical motor.

Abstract: An inner rotatable shaft 16 is located within an outer rotatable shaft 18. A stator 52 is provided around the shaft 18. The shaft 18 has a circumferential ring of regions 54a, 54b alternately of relatively high and relatively low magnetic permeability. Flux is therefore transmitted between the stator 52 and the shaft 16 through the regions 54, preferentially through the high permeability regions 54a. Commutation of the stator windings, preferably in synchrony with the speed of rotation of the shaft 18, allows the stator 52 and shaft 16 to interact in the form of an active magnetic bearing. The affect of the presence of the shaft 18 on this interaction is significantly reduced or eliminated.

Abstract: An electrical conductor winding (70) comprises a plurality of laminates of electrical insulation (72). Each laminate of electrical insulation (72) has a slot (78) on one surface (76). Each laminate of electrical insulation (70) has an electrical conductor (82) arranged in the slot (78). An electrical connector (84) connects the electrical conductor (82) in one laminate of electrical insulation (78) with the electrical conductor (82) in an adjacent laminate of electrical insulation (72). The laminates of electrical insulation (72) are arranged such that the surface (74) of one laminate of electrical insulation (72) abuts and is bonded to the surface (76) of an adjacent laminate of electrical insulation (12). The laminates of electrical insulation (12) comprise a glass-ceramic material. The electrical conductor windings allow active magnetic bearings, electric motors and electric generators to be used at temperatures up to 500° C. for example in gas turbine engines.