초록 ▼

A starter-generator system may be used to supply sufficient starting torque to start an aircraft main engine. The main starter-generator stator winding may be connected to a constant frequency (CF) power source to create a rotating field in the main starter-generator air gap. This rotating field, in

A starter-generator system may be used to supply sufficient starting torque to start an aircraft main engine. The main starter-generator stator winding may be connected to a constant frequency (CF) power source to create a rotating field in the main starter-generator air gap. This rotating field, in turn, may induce current on the main rotor winding, which may be a closed circuit formed by main rotor field winding and exciter armature winding. The interaction between the main rotor current and the air gap flux may give rise to the starting torque to start the main engine. Adjusting the voltage supplied to the exciter stator field winding can modify the induced voltage and current on the rotor circuit to control the rotor current and starting torque. The starter-generator system may also be used to start an aircraft main engine by directly connecting the main stator winding to a power source without powering the exciter stator.

대표청구항 ▼

We claim: 1. An engine starting system comprising: a main starter-generator having a main starter-generator rotor, the main starter-generator rotor having main starter-generator rotor windings wound thereupon; an exciter having an exciter rotor and an exciter stator, the exciter rotor having excite

We claim: 1. An engine starting system comprising: a main starter-generator having a main starter-generator rotor, the main starter-generator rotor having main starter-generator rotor windings wound thereupon; an exciter having an exciter rotor and an exciter stator, the exciter rotor having exciter rotor windings wound thereon; wherein the exciter rotor is configured to provide two phase excitation current to the main starter-generator rotor windings. 2. The engine starting system of claim 1, wherein: the main starter-generator rotor windings are two phase main starter-generator rotor windings that are in quadrature with each other; the exciter rotor windings are two phase exciter rotor windings that are in quadrature with each other; a connection between the main starter-generator rotor windings and the exciter rotor windings is made in an opposite phase sequence or in the same phase sequence. 3. The engine starting system of claim 1, wherein: the main starter-generator rotor and the exciter rotor are configured to rotate in a first direction at a variable rotational speed; the electrical excitation supplied to the exciter stator is multi-phase AC or DC excitation having a phase sequence; and an exciter controller supplies the multi-phase AC or DC electrical excitation to a plurality of exciter stator windings in the phase sequence that is in either the first direction or a second direction opposite the first direction. 4. The engine starting system of claim 3, wherein: the exciter rotor windings have a phase shift in space and time. 5. The engine starting system of claim 4, wherein: the amount of phase shift is a value within a range of about 80 electrical degrees to about 100 electrical degrees. 6. The engine starting system of claim 5, wherein the amount of phase shift is 90 electrical degrees. 7. The engine starting system of claim 6, wherein: the main starter-generator rotor windings have a phase shift in space and time. 8. The engine starting system of claim 7, wherein: the amount of phase shift is a value within a range of about 80 electrical degrees to about 100 electrical degrees. 9. The engine starting system of claim 7, wherein the amount of phase shift is 90 electrical degrees. 10. The engine starting system of claim 6, wherein the exciter controller receives a speed signal from a device that senses the speed of a shaft of the main starter-generator, wherein the device is selected from the group consisting permanent magnet starter-generator, a speed sensor, and the main stator windings. 11. The engine starting system of claim 1, further comprising: a permanent magnet starter-generator mounted on a shaft of the main starter-generator and configured, upon rotation thereof, to provide a speed signal to an exciter controller, the speed signal being representative of the rotational speed of the shaft, wherein the exciter controller provides electrical excitation having a supply amplitude, a frequency, and a phase sequence based at least in part on the speed signal. 12. The engine starting system of claim 8, wherein the main starter-generator stator is supplied from an AC power source. 13. The engine starting system of claim 1, wherein at least one of the exciter rotor windings and the main starter-generator rotor windings are wound around salient poles. 14. The engine starting system of claim 1, wherein at least one of the exciter rotor windings and the main starter-generator rotor windings are wound on a cylindrical core. 15. An engine starting system, comprising: a shaft, wherein sufficient rotation of the shaft starts the engine; a main starter-generator stator with a plurality of main stator windings wound thereon; a main starter-generator rotor mounted on the shaft and disposed at least partially within the main starter-generator stator, the main starter-generator rotor having a plurality of main starter-generator rotor windings wound thereon to generate an air gap flux when they are electrically excited; an exciter rotor mounted on the shaft, the exciter rotor having a plurality of exciter rotor windings wound thereon; an exciter stator surrounding at least a portion of the exciter rotor, the exciter stator having a plurality of exciter stator windings wound thereon; and an exciter controller electrically coupled to the exciter stator windings, the exciter controller configured to provide electrical excitation to the exciter stator windings; and wherein the main starter-generator rotor windings receive a two-phase alternating current; the exciter rotor windings electrically connected to the main starter-generator rotor windings and configured, upon electrical excitation thereof, to supply the two-phase electrical excitation to the main starter-generator rotor windings; and the exciter stator windings configured, upon electrical excitation thereof, to electrically excite the exciter rotor windings. 16. The engine starting system of claim 15, wherein: interaction between current in the main starter-generator stator and the air gap flux creates a starting torque to turn the shaft to start the engine; and voltage supplied to the exciter stator winding controls the current in the main starter-generator rotor and the starting torque. 17. The engine starting system of claim 15, further comprising: a permanent magnet generator mounted on the shaft and configured, upon rotation thereof, to supply a signal to the exciter controller that is representative of the rotational speed of the shaft, wherein the exciter controller determines the rotational speed of the shaft based at least in part on the signal supplied from the permanent magnet generator. 18. An aircraft starter-generator system to start an aircraft gas turbine engine as the prime mover, the system comprising: a housing; a drive shaft rotationally mounted within the housing and transmitting power to the prime mover; a main starter-generator stator mounted within the housing and having a plurality of main starter-generator stator windings wound thereon; a main starter-generator rotor mounted on the drive shaft and disposed within the main starter-generator stator, the main starter-generator rotor having a plurality of main starter-generator rotor windings wound thereon configured to receive a two-phase excitation current, wherein the main starter-generator rotor windings generate an air gap flux upon electrical excitation thereof; an exciter rotor mounted on the drive shaft, the exciter rotor having a plurality of exciter rotor windings wound thereon, the exciter rotor windings electrically connected to the main starter-generator rotor; an exciter stator surrounding the exciter rotor, the exciter stator having a plurality of exciter stator windings wound thereon, the exciter stator windings configured, upon electrical excitation thereof, to electrically excite the exciter rotor windings, wherein interaction between current in the main starter-generator stator and the air gap flux creates a starting torque to turn the shaft to start the engine, and voltage supplied to the exciter stator winding controls the current in the main starter-generator rotor and the starting torque. 19. The aircraft starter-generator system according to claim 18, wherein, after the aircraft gas turbine engine is started, the starter-generator system may act as a generator to generate relatively constant frequency AC power by independently controlling the rotational speed of the air gap flux.