Abstract: A superconducting electrical machine comprises a rotor and a stator. The stator comprises a stator having a plurality of circumferentially spaced radially extending teeth and a plurality of superconducting electric coils. Each superconducting electric coil is positioned around a respective one of the teeth. A thermally conducting member surrounds and contacts the stator. A cooler is arranged to cool the thermally conducting member. A vacuum enclosure encloses the thermally conducting member, the stator and the superconducting electric coils and a pump is arranged to evacuate the vacuum enclosure. The superconducting electrical coils comprise magnesium diboride.

Abstract: Electrical machine arrangements have advantages with regard to providing local electrical power and starting. Embedding such electrical machine arrangements in machinery such as gas turbine engines is advantageous in removing mechanical linkages and reducing aerodynamic drag. However, the components utilised must be able to withstand harsh environmental conditions and therefore the DC link capacitor used for smoothing of voltage fluctuations are limited to relatively low capacitance densities. Low density DC link capacitors require large sizes which render electrical machines less acceptable for embedded usage. By providing offset of electrical current in inductance elements such as stator windings and stator coils of electrical machines in dead periods of the cycle a reduction in DC link capacitor requirements is achieved reducing the size, weight and complexity of installing electrical machines in gas turbine engines.

Abstract: An alternating current system 10 has a primary circuit 11 which forms a primary winding 18 on a core 16. A secondary winding 24 is connected with a current source 26 or, alternatively, with an impedance 60. The core 16 is threaded by a superconducting coil 20 having a current source 22. In normal use, current in the coil 20 provides a DC bias level of flux in the core 16, and the source 26 is varied to maintain substantially constant flux, thereby minimising losses in the primary circuit 11. In fault conditions, current in the coil 20 is reduced or removed to increase voltage losses across the coil 18, thereby limiting fault current. The impedance 60 can also be switched into circuit, creating further current limiting by virtue of the transformer effect of the windings 18, 24.

Abstract: An alternating current system 10 has a primary circuit 11 which forms a primary winding 18 on a core 16. A secondary winding 24 is connected with a current source 26 or, alternatively, with an impedance 60. The core 16 is threaded by a superconducting coil 20 having a current source 22. In normal use, current in the coil 20 provides a DC bias level of flux in the core 16, and the source 26 is varied to maintain substantially constant flux, thereby minimizing losses in the primary circuit 11. In fault conditions, current in the coil 20 is reduced or removed to increase voltage losses across the coil 18, thereby limiting fault current. The impedance 60 can also be switched into circuit, creating further current limiting by virtue of the transformer effect of the windings 18, 24.

Abstract: A jig (10) is used to form a coil (50) for an electrical machine. A plurality of conductive wires (56), each covered in a heat-curable electrically insulated material, are wound around a bobbin (12). Each succeeding winding in contra-wound relative to the previous winding, with the first turn (16) of each succeeding winding overlaying the last turn (5) of the previous winding. Undeformable electrically insulated inserts (54) are inserted into the windings before heating and compressing the coil (50) in the jig (10).

Abstract: A variable reluctance electric machine comprising a rotor and a stator; the stator having two or more electromagnetic windings and the rotor having a plurality of salient poles, the salient poles defining axially extending cooling fluid channels; wherein the salient poles and the cooling fluid channels are circumferentially skewed along at least a part of their length whereby in use the cooling fluid channels impel cooling fluid in a substantially axial direction towards the electromagnetic windings and the stator to facilitate heat transfer and dissipation from the windings.

Abstract: Condition monitoring of an electrical machine is achieved by using electro-magnetic finite element analysis to analyse the machine based on model parameters corresponding with at least one fault condition. This allows the effect of the fault condition to be predicted. Metrology is used to recover live measurements for comparison with the predictions from the electro-magnetic finite element analysis to identify any fault signatures within the live measurements, in principle allowing those faults to be detected or diagnosed before they become catastrophic.

Abstract: An alternating current system 10 has a primary circuit 11 which forms a primary winding 18 on a core 16. A secondary winding 24 is connected with a current source 26 or, alternatively, with an impedance 60. The core 16 is threaded by a superconducting coil 20 having a current source 22. In normal use, current in the coil 20 provides a DC bias level of flux in the core 16, and the source 26 is varied to maintain substantially constant flux, thereby minimising losses in the primary circuit 11. In fault conditions, current in the coil 20 is reduced or removed to increase voltage losses across the coil 18, thereby limiting fault current. The impedance 60 can also be switched into circuit, creating further current limiting by virtue of the transformer effect of the windings 18, 24.

Abstract: A stator coil assembly comprising a stator coil and a mounting platform for the stator coil. The coil has an earth wrap and is bonded to the mounting platform by a resiliently deformable bonding layer. The bonding layer is an electrical insulator formed from silicone rubber and has a thermal conductivity of at least 0.1 W/mK and an electrical resistivity which is at least equal to that of the earth wrap.

Abstract: A jig (10) is used to form a coil (50) for an electrical machine. A plurality of conductive wires (56), each covered in a heat-curable electrically insulated material, are wound around a bobbin (12). Each succeeding winding in contra-wound relative to the previous winding, with the first turn (16) of each succeeding winding overlaying the last turn (5) of the previous winding. Undeformable electrically insulated inserts (54) are inserted into the windings before heating and compressing the coil (50) in the jig (10).