An electrical system having a first dual-wound rotary electric machine mechanically coupled with a first gas turbine spool and having a first three-phase sub-machine and a second three-phase submachine; a second dual-wound rotary electric machine mechanically coupled with a second gas turbine spool and having a third three-phase sub-machine and a fourth three-phase submachine; and a set of N = 4 bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc), each of which has an associated index n = (1, ... , N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine. The dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit.

An electrical system having a first dual-wound rotary electric machine mechanically coupled with a first gas turbine spool and having a first three-phase sub-machine and a second three-phase submachine; a second dual-wound rotary electric machine mechanically coupled with a second gas turbine spool and having a third three-phase sub-machine and a fourth three-phase submachine; and a set of N = 4 bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc), each of which has an associated index n = (1, ... , N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine. The dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit.

A system includes a gas turbine engine of an aircraft, the gas turbine engine having a low speed spool, a high speed spool, and a combustor. The system also includes a low spool motor configured to augment rotational power of the low speed spool and a high spool motor configured to augment rotational power of the high speed spool. The system further includes a controller configured to cause fuel flow. The controller is configured to control a thrust response of the gas turbine engine to a thrust target between zero and a thrust level to move the aircraft during engine start and during engine idle. The controller is also configured to control the low spool motor to drive rotation of the low speed spool responsive to a thrust command while the controller does not command fuel flow to the combustor.

An engine comprises a first power input and a second power input, a main load, and a transmission engaged with the first power input, the second power input, and the main load. An epicyclic gear train is engaged with the first power input and the main load. A brake in a drive condition engages with the epicyclic gear train to transfer power from the first power input to the main load. The brake in a start condition disengages from the epicyclic gear train to decouple the first power input from the main load. A start assist motor is engaged with part of the transmission separate from the epicyclic gear train. The start assist motor in the start condition rotates the main load to initiate start up of the engine, and in the drive condition prevents transferring power to the main load.

For aircraft taxiing, an aircraft is equipped with an electric machine installed in a propulsor gearbox (PGB), in parallel to the gas turbine, working in motor mode during taxi, and in generator mode during flight phases (such as take-off, climb, cruise, descent, approach and landing). Typical current systems which use an electric machine in the PGB do not use the electric machine in motor mode for taxi operations (i.e., it is only an additional generator). An optimized power supply providing a combination of a thermal engine such as an Auxiliary Power Unit (APU) and an electric energy storage system such as a battery provides power to the PGB electric machine even when the gas turbine is off.

A gas turbine engine includes an electrical machine positioned at least partially inward of a core airflow path, the electrical machine including an electrical rotor component and an electrical stator component, a connecting member positioned between the electrical machine and a rotary member, a disconnection device that is positionable between a disengaged position, in which the disconnection device is disengaged from the connecting member, and an engaged position, in which the disconnection device is engaged with the connecting member, and a controller including a processor, where the processor receives a signal from the electrical machine indicative of a fault, and in response to receiving the signal from the electrical machine indicative of the fault, directs the disconnection device to move from the disengaged position to the engaged position.

A bowed rotor prevention system for a gas turbine engine includes a core turning motor operable to drive rotation of an engine core of the gas turbine engine. The bowed rotor prevention system also includes a full authority digital engine control (FADEC) that controls operation of the gas turbine engine in a full-power mode and controls operation of the core turning motor to drive rotation of the engine core using a reduced power draw when the FADEC is partially depowered in a low-power bowed rotor prevention mode.

A method and decoupler for disengaging an output shaft from an engine in a back drive event with a backdrive decoupler. The backdrive decoupler includes a an output shaft, drive shaft, and a retention mechanism selectively coupling the output shaft to the drive shaft. In a backdrive event, the decoupler decouples the output shaft from the drive shaft.

Gas turbine engines and methods of starting gas turbine engines, the gas turbine engine including: an electronic engine controller; one or more spools designated a starting spool for starting the engine, and has a required starting torque τs; a permanent magnet alternator mechanically coupled with the starting spool, the alternator, in a motor mode, provides a peak torque of τa, and, in a generator mode, generates electrical power for the electronic engine controller; and an electrical starter-generator mechanically coupled with the starting spool. The starter-generator in a motor mode, provides a peak torque of τsg, and, in a generator mode, generates electrical power for an external load. τsg+τa≥τs and τsg, τa<τs, and the electronic engine controller, during a start procedure, operates both the permanent magnet alternator and the starter-generator in a motor mode to drive the starting spool.

An air starter for starting a turbine engine that includes a housing, a turbine member, a drive shaft, and at least one bearing assembly. The housing can define an interior where the turbine member rotatably couples to the drive shaft, where the drive shaft or turbine member are rotatably supported by the least one bearing assembly. A scoop wheel located in the interior of the housing provides lubrication to the at least one bearing assembly.