Electric machine

Patent metadata

Field	Value
Publication number	US-2020091810-A1
Application number	US-201916548032-A
Country	US
Kind code	A1
Filing date	Aug 22, 2019
Priority date	Sep 18, 2018
Publication date	Mar 19, 2020
Grant date	—

Abstract

An electric machine including a stator having a fully non-magnetic core and stator windings formed of a non-superconducting transposed conductor to reduce eddy current losses. It further includes a rotor having a fully non-magnetic core and superconducting windings or superconducting magnets which produce a magnetic field for interaction with the stator windings. A cryogenic cooling system is arranged to cool the stator windings to reduce conduction losses in the stator windings.

First claim

1 . An electric machine comprising:
a stator having a fully non-magnetic core and stator windings formed of a non-superconducting transposed conductor to reduce eddy current losses; a rotor having a fully non-magnetic core and superconducting windings or superconducting magnets which produce a magnetic field for interaction with the stator windings; and a cryogenic cooling system arranged to cool the stator windings to reduce conduction losses in the stator windings.

2 . The electric machine of claim 1 , in which the transposed conductor is a litz conductor.

3 . The electric machine of claim 1 , in which the stator windings are formed from wire strands having a diameter of less than 1 millimetre.

4 . The electric machine of claim 1 , in which the stator windings are formed from one of:
copper; aluminium.

5 . The electric machine of claim 1 , in which the cryogenic cooling system is a high temperature cryogenic cooling system.

6 . The electric machine of claim 5 , in which the cryogenic cooling system is configured to, in operation, maintain the stator windings at a temperature of 223 kelvin or below.

7 . The electric machine of claim 1 , in which the cryogenic cooling system is arranged to cool the superconducting windings or superconducting magnets in the rotor in addition to the stator windings.

8 . The electric machine of claim 1 , in which the fully non-magnetic core in the stator comprises a resin.

9 . The electric machine of claim 1 , comprising one of:
8 poles; 16 poles.

10 . The electric machine of claim 1 , in which the current density in the stator windings is, in operation, one of:
8 amps per square millimetre; 16 amps per square millimetre.

11 . The electric machine of claim 1 , in which, in operation, the stator windings are supplied with an alternating current at a frequency of 800 hertz.

12 . A propulsion system for an aircraft, comprising:
an electrical network for distributing electrical power; a source of electrical power connected with the electrical network; and one or more electric machines according to claim 1 , connected with the electrical network for driving a fan to propel the aircraft.

13 . The propulsion system of claim 12 , in which at least one of the one or more electric machines drives a boundary layer ingestion fan.

14 . A propulsion system for an aircraft, comprising:
an electrical network for distributing electrical power; one or more electric machines according to claim 1 connected with the electrical network for generating said electrical power; and one or more electric propulsion units connected with the electrical network for propelling the aircraft.

15 . The propulsion system of claim 14 , in which the or each electric machine is driven by a respective internal combustion engine.

16 . The propulsion system of claim 15 , in which the or each internal combustion engine is one of:
a piston engine; a turbomachine.

Assignees

• Rolls Royce Plc

Inventors

• Miller Paul R
• Husband Stephen M
• Smith Alexander C
• Manolopoulos Charalampos
• Iacchetti Matteo

Classifications

• H02K7/1823

  structurally associated with turbines or similar engines · CPC title

• H02K3/42

  Means for preventing or reducing eddy-current losses in the winding heads, e.g. by shielding · CPC title

• H02K7/1815

  structurally associated with reciprocating piston engines (general aspects of generating sets, e.g. housing, F02B63/04) · CPC title

• H02K3/02

  Windings characterised by the conductor material · CPC title

• H02K55/00 Primary

  Dynamo-electric machines having windings operating at cryogenic temperatures · CPC title