Abstract: An electric machine comprising a stator (50), a rotor (29) radially inward of the stator and comprising a plurality of surface permanent magnets (44) and a rotor sleeve (46) surrounding the rotor. The rotor sleeve comprises a plurality of layers of fibre reinforced matrix material (56, 60). The rotor sleeve defines a rotor sleeve radius to radial thickness ratio (r:t) between 20 and 40, and the electric machine has a maximum rotor rotational speed greater than 15000 RPM.

Abstract: A turbo-generator system for generating propulsive electrical power for an aircraft includes an electric machine comprising: a rotor configured to be rotated by a gas-turbine of the turbo-generator system; a stator comprising: a first active section comprising first windings surrounding a first portion of the rotor, and a second active section comprising second windings surrounding a second portion of the rotor.

Abstract: An example stator tube assembly includes a hollow body defining a cavity and having a longitudinal length and a radial thickness. The hollow body is configured to be disposed within a stator housing and to separate the cavity from a stator cavity within the stator housing. The hollow body comprises a first radial thickness along a first portion of its longitudinal length and a second radial thickness along a second portion of its longitudinal length, the second radial thickness being greater than the first radial thickness.

Abstract: An example system comprises an electric machine including a stator and a rotor, a cooling system configured to supply a cooling fluid to cool the electric machine, and a stator tube configured to contain the cooling fluid within a stator portion of the electric machine and prevent the cooling fluid from contacting the rotor.

Abstract: An example rotor assembly includes a rotor core having an axial length and configured to rotate about a longitudinal axis. The rotor core includes a first wall and a second wall radially within the first wall and defining a fluid flow path configured to guide a fluid along an inner surface of the first wall.

Abstract: A rotor sleeve (46) for a rotor (29) of an electric machine (28). The sleeve comprises a plurality of layers (66a, 66b) of carbon fibre reinforced polymer, each layer (66a, 66b) comprising fibres (68) oriented substantially 90° to a rotational axis (X) and at least one layer (72a) of fibres (74) having a lower modulus of elasticity provided between layers (66a, 66b) of carbon fibre reinforced polymer. The lower modulus of elasticity fibres (74) are oriented between 50° and 75° relative to the rotational axis (X).

Abstract: A rotor sleeve (46) for a rotor (29) of an electric machine (28), the rotor sleeve (46) comprising: an inner layer (52) of wound filaments (56) comprising a first material having a first modulus of elasticity; and an outer layer (54) of wound filaments (60) wound around the inner layer (52), the outer layer (54) comprising a second material having a second modulus of elasticity higher than the first modulus.

Abstract: A system includes a first generator configured to output a first plurality of AC signals; a second generator configured to output a second plurality of AC signals; a first set of rectifiers configured to convert the first plurality of AC signals into a first plurality of DC signals for output onto a first DC bus, wherein each of the first set of rectifiers includes a respective contactor configured to de-couple a DC output of the respective rectifier from the first DC electrical bus; and a second set of rectifiers configured to convert the second plurality of AC signals into a second plurality of DC signals for output onto a second DC bus, wherein each of the second set of rectifiers includes a respective contactor configured to de-couple a DC output of the respective rectifier from the second DC bus.

Abstract: A rotor sleeve (46) for a rotor (29) of an electric machine (28). The sleeve comprises a plurality of layers (66a, 66b) of carbon fibre reinforced polymer, each layer (66a, 66b) comprising fibres (68) oriented substantially 90° to a rotational axis (X) and at least one layer (72a) of fibres (74) having a lower modulus of elasticity provided between layers (66a, 66b) of carbon fibre reinforced polymer. The lower modulus of elasticity fibres (74) are oriented between 50° and 75° relative to the rotational axis (X).

Abstract: A rotor sleeve (46) for a rotor (29) of an electric machine (28), the rotor sleeve (46) comprising: an inner layer (52) of wound filaments (56) comprising a first material having a first modulus of elasticity; and an outer layer (54) of wound filaments (60) wound around the inner layer (52), the outer layer (54) comprising a second material having a second modulus of elasticity higher than the first modulus.

Abstract: An electric machine comprising a stator (50), a rotor (29) radially inward of the stator and comprising a plurality of surface permanent magnets (44) and a rotor sleeve (46) surrounding the rotor. The rotor sleeve comprises a plurality of layers of fibre reinforced matrix material (56, 60). The rotor sleeve defines a rotor sleeve radius to radial thickness ratio (r:t) between 20 and 40, and the electric machine has a maximum rotor rotational speed greater than 15000 RPM.