Abstract: A vehicle propulsion system comprises a first propulsor and a second propulsor. The first and second propulsors are coupled to an electric machine comprising a stator and first and second rotors. Each of the first and second rotors are electromagnetically coupled to the stator. The first rotor is coupled to the first propulsor and the second rotor is coupled to the second propulsor.

Abstract: The present disclosure relates to an electromechanical system comprising a toothed rotor and a stator segment. The stator segment comprises an armature coil defining a coil interior. The stator segment further comprises first and second stator portions, each stator portion comprising connected inner and outer radially extending poles. Each of the inner poles passes through the coil interior and each of the outer poles is provided outside of the coil interior. The stator segment further comprises a bridge spacing the stator portions and the bridge comprises a magnetic field generator arranged to generate a magnetic field between the stator portions.

Abstract: An electromechanical system comprising: a rotor comprising a plurality of teeth spaced about a circumference of the rotor, wherein the teeth of the rotor are equally spaced about the rotor according to a tooth spacing angle, and are skewed in an axial direction such that the circumferential positions of the teeth of the rotor vary along the axial length of the rotor, and first and second stator segments, each extending partway about the rotor and comprising a field winding and poles arranged to magnetically interact with the teeth of the rotor such that an alternating current (AC) back-emf is induced in the field winding upon rotation of the rotor. The poles of the first stator segment are angularly displaced about the rotor from the poles of the second stator segment such that the back-emf induced in the field winding of the first stator segment is phase shifted with respect to the back-emf induced in the field winding of the second stator segment.

Abstract: The dual rotor electric machine comprises: a stator having one or more slots and one or more stator windings. The dual rotor electric machine further comprises a first rotor arranged to rotate relative to the stator with an airgap therebetween. The first rotor comprises a first rotor excitation element having one or more magnetic pole pairs arranged to interact with the stator windings, the first rotor configured to rotate about an axis (X). The dual rotor electric machine further comprises a second rotor arranged to rotate relative to the stator with an airgap therebetween. The second rotor comprises a second rotor excitation element having one or more magnetic pole pairs arranged to interact with the stator windings, the second rotor being configured to rotate about the axis (X).

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 including a moveable permanent magnet configured to generate a first magnetic field. A stator including windings configured to excite a second magnetic field. A moveable inter-pole component located between the permanent magnet component and the stator, the inter-pole component comprising an array of magnetic inter-pole pieces. The speed of movement of the inter-pole component is controlled to set a magnetic gear ratio between the first and second magnetic fields. Also a gas turbine engine, propulsor or thruster incorporating the electrical machine.

Abstract: An electrical converter (203) having an active diode-clamped multilevel topology is shown. Each clamping diode is connected in antiparallel with a switch (S5A, S5B). The converter comprises polyphase supply phases (A, B, C) each of which are connected via a respective phase leg (401, 402, 403) to dc rails (301, 302) and a dc-link capacitor. The dc-link capacitor includes a plurality of series-connected capacitors (404, 405). A controller is configured to, in response to an event signal, for each phase leg, activate a combination of switches therein to form a pair of parallel conduction paths to a midpoint (406) between two capacitors in the dc-link capacitor, thereby connecting each phase to the same node.

Abstract: A switched reluctance machine is provided, the machine includes a stator having a circumferential row of magnetically energizable teeth carrying coil windings. The machine further includes a coaxial variable reluctance rotor having a circumferential row of magnetisable poles, the reluctance of the rotor-to-stator magnetic flux path varying with rotor position. Each pole has first and second side flanks and a tip surface, one of the side flanks forming a leading edge surface of the pole, the other side flank forming an opposite, trailing edge surface of the pole, and the tip surface arcing from the leading edge surface to the trailing edge surface and facing the stator to form an air gap to the teeth of the stator. Also each pole contains one or more cavities.

Abstract: A synchronous electrical machine includes a stator having a circumferential row of teeth carrying stator windings. The electrical machine further includes a coaxial rotor having a circumferential row of poles carrying field windings. Each pole has first and second side flanks and a tip surface which extends continuously there between to form an air gap to the teeth of the stator. On a transverse cross-section through the machine, one of the side flanks forms a leading edge of the pole, and the other side flank forms an opposite, trailing edge of the pole. Each pole carries a row of permanent magnets which extends across the tip surface from one of the side flanks to the other side flank, the permanent magnets compensating for armature magnetic reaction. The radial thickness of the permanent magnets increases smoothly with progressive distance across the tip surface from one of the side flanks to the other side flank.

Abstract: A sleeve for retaining magnets around a rotor of an electrical machine. The sleeve is cylindrical and hollow, having axial length and having radial thickness between its inner surface and outer surface. The sleeve defines a plurality of axially spaced, circumferentially extending grooves. Each groove has radial depth which is less than the radial thickness of the sleeve.

Abstract: An electrical machine is disclosed comprising a stator cavity. The stator cavity is axially divided by a distribution plate into a winding chamber containing stator windings of the electrical machine and a handling chamber. The handling chamber has one of a fluid inlet and a fluid outlet and the winding chamber has the other of the fluid inlet and fluid outlet. In use fluid is passed from the fluid inlet to the fluid outlet via the handling chamber, the winding chamber and an array of fluid passages in the distribution plate providing fluid communication between the handling chamber and winding chamber. The array of fluid passages comprises passages of at least two different cross-sectional areas.

Abstract: An axial flux permanent magnet machine including a pair of axially spaced first components. A second component positioned axially between and equidistant from the first components. Either the pair of first components or the second component is arranged to rotate about a shaft. A translation mechanism coupled to each of the first components. The translation mechanism configured to translate the first components axially away from the second component. Also a method of controlling an axial flux permanent magnet machine.

Abstract: An electrical machine comprising a two-part rotor formed of a first rotor part and a second rotor part. The first rotor part includes a conical section and is mounted to a shaft of the machine. The second rotor part has a bore including a complementary conical section. The second rotor part is configured to displace axially between a first state, in which it is engaged with the first rotor part to form the rotor of the electrical machine, and a second state, in which it is axially disengaged from the first rotor part. Also a clutch having an engaged state and a disengaged state. When the clutch is in one of its states the second rotor part is in its first state and switching the clutch to the other of its states axially displaces the second rotor part to its second state.

Abstract: An electrical machine including a moveable permanent magnet configured to generate a first magnetic field. A stator including windings configured to excite a second magnetic field. A moveable inter-pole component located between the permanent magnet component and the stator, the inter-pole component comprising an array of magnetic inter-pole pieces. The speed of movement of the inter-pole component is controlled to set a magnetic gear ratio between the first and second magnetic fields. Also a gas turbine engine, propulsor or thruster incorporating the electrical machine.

Abstract: A variable speed generator for producing AC electrical power includes an alternator powerable by rotational action to generate a first AC current, and a first rectifier which rectifies the first AC current from the alternator. The generator further includes a main exciter having a first field winding which receives the rectified first AC current, and having a first armature which produces in response a second AC current. The generator further includes a second rectifier which rectifies the second AC current from the first armature. The generator further includes a main generator having a second field winding which receives the rectified second AC current, and having a second armature which produces in response an output AC current. The second field winding is configured to provide a plurality of selectively activatable pole configurations which differ in the number of their poles, such that the frequency of the output AC current can be varied by switching between the pole configurations.

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 electromagnetic machine, comprising: a first stator winding having a first number of pole pairs; a second stator winding having a second number of pole pairs which is different to the first number of pole pairs; and, a modulator having a plurality of pole pieces arranged relative to the first and second stator windings so as to modulate the electromagnetic fields produced by the first and second stator windings, thereby matching harmonic spectra of the first and second stator windings.

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 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.