Hybrid gas turbine engine starter-generator
A rotating electrical machine, such as an aircraft starter-generator, that may be operated in either a DC motor mode or an AC generator mode. The machine includes a conventionally wound main stator that is selectively configurable as a multi-pole AC stator and a multi-pole DC stator. The machine also includes rotor windings that are configured to be selectively coupled to either an exciter or a plurality of commutator segments, and DC brushes that are selectively moveable into, and out of, electrical contact with the commutator segments, to thereby electrically couple and decouple a DC power source to and from, respectively, the rotor windings.
1. A gas turbine engine starter-generator, comprising:
a housing;
a main rotor rotationally mounted within the housing; and
a main stator mounted within the housing and at least partially surrounding at least a portion of the main rotor, the main stator selectively configurable as an M-pole AC stator or an N-pole DC stator, M and N each integers greater than one,
wherein:
when the main stator is configured as the M-pole, multi-phase AC stator, each phase consists of two or more stator winding circuits electrically coupled in parallel with one another, and
when the main stator is configured as the N-pole DC stator, the stator winding circuits associated with each phase are directly connected in series with one another.
2. The starter-generator of claim 1 , further comprising:
a control circuit electrically coupled to at least the main stator and operable to selectively configure the main stator as the M-pole AC stator or the N-pole DC stator.
3. The starter-generator of claim 2 , further comprising:
a plurality of windings wound on at least a portion of the main stator; and
a plurality of stator switches electrically coupled between selected ones of the main stator windings, each of the stator switches having at least a first position and a second position,
wherein the main stator is configured as the M-pole AC stator with the plurality of switches in the first position, and is configured as the N-pole DC stator with plurality of switches in the second position.
4. The starter-generator of claim 3 , wherein the control circuit comprises:
switch control circuitry operable to move the plurality of switches between at least the first position and the second position.
5. The starter-generator of claim 1 , further comprising:
an exciter rotor rotationally mounted in the housing, the exciter rotor having a plurality of windings wound thereon;
an exciter stator having a plurality of windings wound thereon, the exciter stator mounted within the housing and located at least partially around at least a portion of the exciter rotor; and
one or more rectifier assemblies electrically coupled in series between the exciter rotor windings and the main rotor windings.
6. The starter-generator of claim 5 , further comprising:
a plurality of main rotor windings wound on at least a portion of the main rotor, each of the main rotor windings adapted to selectively receive DC current from either the rectifier assemblies or a DC power source.
7. The starter-generator of claim 6 , further comprising:
at least two brushes adapted to electrically couple to the DC power source and selectively moveable into, and out of, electrical contact with at least a portion of the main rotor, whereby the brushes are electrically coupled to, and decoupled from, respectively, the main rotor windings.
8. The starter generator of claim 1 , further comprising:
a DC power source electrically coupled in series with the main stator when the main stator is configured as an N-pole DC stator.
9. The starter-generator of claim 1 , wherein M is unequal to N.
10. The starter-generator of claim 9 , wherein N=(M/2).
11. A stator, comprising:
a main stator body;
a plurality of stator coils wound around at least a portion of the main body in a configuration that allows the stator to be selectively configured as an M-pole AC stator or an N-pole DC stator, M and N each integers greater than one,
wherein:
when the stator is configured as the M-pole AC stator, each phase consists of two or more stator winding circuits electrically coupled in parallel with one another, and
when the stator is configured as the N-pole DC stator, the stator winding circuits associated with each phase are directly connected in series with one another.
12. The stator of claim 11 , further comprising:
a plurality of stator switches electrically coupled between selected ones of the stator coils, each of the stator switches having at least a first position and a second position.
13. The stator of claim 12 , wherein the stator is configured as the M-pole AC stator with the stator switches in the first position, and is configured as the N-pole DC stator with the stator switches in the second position.
14. The stator of claim 11 , wherein M is unequal to N.
15. The stator of claim 14 , wherein N=(M/2).