US 12,352,212 B2
Electrically starting a gas turbine engine
David R Trainer, Derby (GB); Mark Sweet, Chesterfield (GB); and Matthew S Cartwright, Derby (GB)
Assigned to ROLLS-ROYCE PLC, London (GB)
Filed by ROLLS-ROYCE plc, London (GB)
Filed on May 23, 2024, as Appl. No. 18/672,887.
Claims priority of application No. 2308720 (GB), filed on Jun. 12, 2023.
Prior Publication US 2025/0188870 A1, Jun. 12, 2025
Int. Cl. F02C 7/268 (2006.01)
CPC F02C 7/268 (2013.01) [F05D 2260/85 (2013.01); F05D 2270/52 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An aircraft power and propulsion system, comprising:
a gas turbine engine having a first spool and a second spool, the first spool being a designated starting spool;
one or more electrical networks;
a first electrical machine mechanically coupled with the first spool;
a second electrical machine mechanically coupled with the second spool;
a first power converter having a first side and a second side, wherein the first side of the first power converter is connected to a winding of the first electrical machine, and the second side of the first power converter is connected to one of the one or more electrical networks;
a second power converter having a first side and a second side, wherein the second side of the second power converter is connected to one of the one or more electrical networks; and
a controllable switching arrangement configured so that a connection to the first side of the second power converter is switchable between:
a winding of the second electrical machine, whereby the second electrical machine and the second power converter are configured to extract power from the second spool in a generator mode or drive rotation of the second spool in a motor mode; or
the winding of the first electrical machine, whereby the first and second power converters are connected in parallel to the winding of the first electrical machine for supplying a starting current to the winding of the first electrical machine for starting or restarting the gas turbine engine.
 
19. A method of starting a gas turbine engine of an aircraft power and propulsion system, the power and propulsion system comprising a gas turbine engine having a first spool and a second spool, the first spool being a designated starting spool; one or more electrical networks; a first electrical machine mechanically coupled with the first spool; a second electrical machine mechanically coupled with the second spool; a first power converter having a first side and a second side, wherein the first side of the first power converter is connected to a winding of the first electrical machine, and the second side of the first power converter is connected to one of the one or more electrical networks; a second power converter having a first side and a second side, wherein the second side of the second power converter is connected to one of the one or more electrical networks; and a controllable switching arrangement, the method comprising:
receiving, by a control system of the power and propulsion system, a request to start or restart the gas turbine engine;
controlling the switching arrangement to disconnect the first side of the second power converter from the winding of the second electrical machine and to connect the first side of the second power converter to the winding of the first electrical machine;
supplying electrical power from one or more electrical power sources to the electrical network connected to the second side of the first power converter and to the electrical network connected to the second side of the second power converter; and
supplying electrical power from both the first power converter and the second power converter to the winding of the first electrical machine to produce a starting torque for starting the gas turbine engine.