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: 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: 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: A machine such as a ship's engine has a superconducting component requiring cooling for its operation, and includes a cooling system. The cooling system is operable in first and second modes. In a cool-down phase the cooling system is run in the first mode providing relatively high heat transfer from the superconducting component. On attainment of a desired operating temperature the cooling system is run in the second mode, providing lower heat transfer. This enables a reduced cool-down time of the machine, while allowing economical operation in normal service. The higher level of cooling in the first mode used during the start-up procedure can involve a colder cryogen, or a greater flow of coolant. One way of achieving the latter is to circulate the coolant in normally evacuated regions during the cool-down phase, and then re-establishing the vacuum in these regions for normal service operation.

Abstract: A synchronous electrical machine comprises a plurality of phases and detecting means arranged to detect an open-circuit fault in at least one of the phases of the synchronous electrical machine. Isolating means is arranged to isolate the at least one phase of the synchronous electrical machine with the fault. Phase shift means are arranged to produce a controlled phase shift between the voltage and the current within the remaining phases of the synchronous electrical machine so as to adjust the phase angle 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 to eliminate torque ripple. The phase shift means is arranged to adjust the phase angle of all the remaining phases by the same predetermined angle to maximize the torque ripple-free power output of the synchronous 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 machine such as a ship's engine has a superconducting component 15 requiring cooling for its operation, and includes a cooling system 40. The cooling system is operable in first and second modes. In a cool-down phase the cooling system is run in the first mode providing relatively high heat transfer from the superconducting component. On attainment of a desired operating temperature the cooling system is run in the second mode, providing lower heat transfer. This enables a reduced cool-down time of the machine, while allowing economical operation in normal service. The higher level of cooling in the first mode used during the start-up procedure can involve a colder cryogen, or a greater flow of coolant. One way of achieving the latter is to circulate the coolant in normally evacuated regions 16 during the cool-down phase, and then re-establishing the vacuum in these regions for normal service operation.

Abstract: A rotary transformer is disclosed which includes a primary core having a primary coil wound thereon, and a secondary core having a secondary coil wound thereon, wherein said cores are mounted for relative rotation about an axis of rotation. One of said cores includes a plurality of core segments arranged in spaced-apart relation relative to one another in a substantially circular array about said axis, the other core having a substantially annular configuration. In a particular embodiment, said 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 said axis.

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 comprises a plurality of phases and detecting means arranged to detect an open-circuit fault in at least one of the phases of the synchronous electrical machine. Isolating means is arranged to isolate the at least one phase of the synchronous electrical machine with the fault. Phase shift means are arranged to produce a controlled phase shift between the voltage and the current within the remaining phases of the synchronous electrical machine so as to adjust the phase angle 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 to eliminate torque ripple. The phase shift means is arranged to adjust the phase angle of all the remaining phases by the same predetermined angle to maximise the torque ripple-free power output of the synchronous electrical machine.

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: A component of an electric machine 46, the component comprising a core 10; two or more teeth 14 extending radially therefrom; at least one electromagnetic winding 12, each winding 12 around at least one of the teeth 14; wherein the core 10 having a cooling arrangement including at least one cooling insert 48 located between adjacent windings 12 and whereby in use a cooling fluid being arranged to flow through the at least one cooling insert 48 to facilitate heat transfer and dissipation from the electromagnetic windings 12. The cooling inserts providing improved cooling, structural support to the windings, and electrical insulation between the windings and the core.