Rolls-royce Corporation

Rolls-royce Power Engineering Plc

Alan J Mitcham

David Reginald Trainer

Anthony G Razzell

John J A Cullen

Jason E Hill

Andrew John Forsyth

Andrew M Cross

John Rickman

Ahmed A-m Abdel-Hafez

Colin J Grime

Steven J Mountain

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.

Synchronous electrical machine

A magnetic coilfor an electrical machine is constructed from two sub-conductorsA,B, each in the form of laminae of conducting material such as copper sheet, coated with an insulating material. At one end of the coil, the sub-conductors extend by different distances, to provide space atfor a transposition of the sub-conductors.

Magnetic coils for electrical machines

An electrical machine incorporates a rotor core assembly () wherein the core () has rotor bars () extending into and secured within slots of end rings () either side of the core (). The core () is secured in axial compression upon a shaft () by at least inner clamp rings (). These inner clamp rings () include a recess, which in association with a recess in an outer clamp ring () forms a cavity to retain a clamp section () of the respective end rings (). The outer clamp ring () is secured to the inner clamp ring () typically using bolts. Thus, the structural strength of the clamp rings () inhibits differential radial growth between the core () and the end rings () due to thermal, rotational and centrifrugal expansion.

Electrical machine

A stator corecomprises laminations () of low loss stator iron forming a body of magnetic nature and lamination components () of high thermal conductivity material regularly arranged within that body. The high thermal conductivity components () increasing the effective radial thermal conductivity rate of the corewhereby temperature gradients are reduced in comparison with previous stator cores. Thus, there is a reduction in operational temperature of the electrical insulation on the stator windings.

Stator core

A permanent magnet fault tolerant generator is driven by a variable speed shaft to create AC power at terminals , converted at to DC power before being applied to a load . The converter is a bi-directional device which rectifies AC to DC and also acts as an inverter to synthesize AC from the DC. This synthesized AC waveform is imposed on the terminals to maintain a constant magnitude generator output voltage, regardless of the speed of the shaft , and thus regardless of the EMF of the generator. This results in reactive currents flowing between the generator and the converter , but allows the generator design have a reduced current rating, resulting in improved generator size and weight.

Generator arrangements

An electrical machine has a rotor shaft (12) which carries a plurality of rotor discs (14) for rotation therewith. Each rotor disc (14) has pairs of rotor rims (16) secured thereto. Each rotor rim (16) consists of a single row of alternate magnets (20) and laminated pole pieces (18) and is opposed by a series of stator cores (22) which straddle the rotor rim (16). Armature windings (24) are disposed within the stator cores (22) for operably exciting said stator. The phase relationship between the currents through the armature windings (24) and the orientation of the stator cores (22) or the magnets (20) in opposing rims (16) are such that the effects of electromagnetic coupling, long path fluxes and torque ripple is reduced.

An electrical machine has a rotor shaft which carries a plurality of rotor discs for rotation therewith. Each rotor disc has two pairs of rotor rims secured thereto. Each rotor rim consists of a single row of alternate magnets and pole pieces and is opposed by a series of stator cores which straddle the rotor rim. The stator cores are `c` shaped so that they receive flux from two adjacent magnets and close around two opposite rotor poles on either side of the rotor rim. The stator cores, formed by winding electrical steel around a former, reduce the losses caused by eddy currents generated when flux impinges on the side faces of the stator core.

A rotor disc for use in an electrical machine has circumferential rotor rims mounted thereon. The rotor rim comprises a row of alternate magnets and pole pieces. The magnets are tapered at their radially inner and outer extents and engage with correspondingly tapered surfaces on adjacent pole pieces to prevent relative physical movement therebetween. Each side of the radially inner and outer extents of the magnets may be tapered by a different amount to ensure correct orientation of the magnet polarity.

Growing community of inventors

Ponteland, United Kingdom

Alan J Mitcham