Multi-inverter system for electric machine
An electric motor may comprise a rotor and a stator. One or more first cables connected to a first power converter circuit of are wrapped adjacent to at least some stator teeth of a stator core to form at least a first portion of one or more coil windings. One or more second cables connected to a second power converter circuit of the plurality of power converter circuit also may be wrapped adjacent to at least some of the stator teeth to form at least a second portion of the one or more coil windings.
1. A device comprising:
a power bus;
a motor, the motor comprising a rotor and a stator;
a plurality of power converter circuits coupled to the power bus,
the plurality of power converter circuits in combination with the stator to provide a plurality of independently operating segments of an electric machine, each segment of the plurality of independently operating segments comprised of a set of coil windings wrapped over offset angular sectors of a stator core of the stator, wherein:
a first power converter circuit is coupled to cables of a first set of coil windings to provide a plurality of first voltage waveform signals;
a second power converter circuit is coupled to cables of a second set of coil windings to provide a plurality of second voltage waveform signals; and
a controller that independently controls the first power converter circuit and the second power converter circuit to supply portions of an overall torque applied to the rotor.
2. The device of claim 1 , wherein the controller is further configured so that the first voltage waveform signals and the second voltage waveform signals produced by the plurality of power converter circuits are generated according to and/or synchronized with a single clock signal.
3. The device of claim 1 , wherein the controller is further to synchronize a first one of the first voltage waveform signals with a first one of the second voltage waveform signals.
4. The device of claim 1 , wherein the first voltage waveform signals and the second voltage waveform signals are substantially identical.
5. The device of claim 1 , and further comprising:
a third power converter circuit is coupled to cables of a third set of coil windings to provide a plurality of third voltage waveform signals; and
wherein the controller is further to independently control the third power converter circuit to supply portions of the overall torque applied to the rotor.
6. The device of claim 5 , and further comprising:
a fourth power converter circuit is coupled to cables of a fourth set of coil windings to provide a plurality of fourth voltage waveform signals; and
wherein the controller is further to independently control the fourth power converter circuit.
7. The device of claim 6 , wherein the controller is further to synchronize at a first one of the fourth voltage waveform signals with a second one of the first voltage waveform signals.
8. The device of claim 5 , wherein the motor is operable in a degraded mode if the first power converter circuit is inoperable while the second power converter circuit and the third power converter circuit are operable.
9. The device of claim 8 , wherein operable power converter circuits of the plurality of power converter circuits operate to provide a voltage waveform to coil windings previously energized by the inoperable first power converter circuit.
10. The device of claim 8 , wherein the motor propels an aircraft such that the degraded mode enables the aircraft to safely land.
11. The device of claim 5 , wherein the first set of windings at least partially overlaps the second set of windings for at least an angular portion of the stator.
12. The device of claim 5 , wherein:
the first set of coil windings comprises a plurality of first cables;
the second set of coil windings comprises a plurality of second cables;
the third set of coil windings comprises a plurality of third cables;
the stator core comprises a plurality of stator teeth;
at least one of the first cables and at least one of the second cables are wrapped adjacently together to at least some slots between stator teeth in a winding path over a first overlapped portion of the stator core;
at least one of the second cables and the at least one of the third cables are wrapped adjacently together to at least some slots between stator teeth over a second overlapped portion of the stator core; and
at least one of the first cables and at least one of the third cables are wrapped adjacently together to at least some slots between stator teeth over a third overlapped portion of the stator core.
13. The device of claim 5 , further wherein the at least one of the cables connected to the second power converter circuit and one of the cables connected to the third power converter circuit are disposed between at least one pair of adjacent stator teeth, and wherein at least one of the cables connected to the first power converter circuit and at least one of the cables connected to the third power converter circuit are disposed between at least one pair of adjacent stator teeth.
14. The device of claim 1 , wherein:
the first one of the first voltage waveform signals is applied to energize a first cable in the first set of coil windings; and
the first one of the second voltage waveform signals is applied to energize a first cable in the second set of coil windings.
15. The device of claim 1 , wherein:
the first one of the first voltage waveform signals is applied to energize a first cable in the first set of coil windings; and
the first one of the second voltage waveform signals is applied to energize a first cable in the second set of coil windings.
16. The device of claim 15 , wherein the independently controlled first and second power converter circuits apply substantially identical voltage waveform signals to the overlapping windings such that a switching current in the first cable in the first set of coil windings is fully out of phase with a switching current in the first cable in the second set of coil windings.
17. The device of claim 15 , wherein no filter to remove high frequency switching current is disposed between the independently controlled first and second power converter circuits.
18. The device of claim 1 , and further comprising:
one or more current sensors to measure a first current signal in a first winding of the first set of windings responsive to the first one of the first voltage waveform signals and a second current signal in a first cable of the second set of windings responsive to the first one of the second voltage waveform signals, and
wherein the controller is further to affect timing of the first one of the first voltage waveform signals based on measurements of the first current signal and the second current signal.
19. The device of claim 18 , and further comprising:
wherein timing of the first one of the first voltage waveform signals is affected in order to synchronize the first current signal and the second current signal.
20. The device of claim 18 , and further comprising:
wherein timing of the first one of the first voltage waveform signals is affected such that a phase difference between or among fundamental periods of the first current signal and the second current signal is reduced or minimized.
21. The device of claim 1 , wherein the rotor comprises a plurality of permanent magnets mounted on a rotor hub surface.
22. The device of claim 1 , wherein the power bus provides a voltage waveform less than 700V DC.
23. The device of claim 1 , wherein each of the cables of the first set of coil windings and each of the cables of the second set of coil windings comprise a plurality of electrically isolated 20 AWG conductors.
24. The device of claim 1 , further wherein the stator core comprises a plurality of stator teeth, wherein at least one cable coupled to the first power converter circuit and at least one cable coupled to the second power converter circuit are disposed between at least one pair of adjacent stator teeth.