Power distribution within an electric machine with rectified rotor windings
An electric machine includes a stator defining multiple stator poles with associated stator windings configured to receive a stator current. The electric machine also includes a rotor defining multiple fixed rotor poles with associated rotor windings, wherein the rotor defines a field energizable by magnetic fields produced by the stator windings when receiving the stator current to produce relative motion between the rotor and the stator and wherein the rotor is maintained in synchronicity with the magnetic fields produced by the stator during operation of the electric machine. The electric machine also includes a rectification system configured control against an alternating current being induced in the rotor poles as the field is energized by magnetic fields produced by the stator windings when receiving the stator current.
1. An electric machine comprising:
a stator defining multiple stator poles with associated stator windings configured to receive a stator current; and
a rotor defining multiple fixed rotor poles with associated rotor windings, wherein the rotor defines a field energizable by magnetic fields produced by the stator windings, responsive to the stator windings receiving the stator current, to produce relative motion between the rotor and the stator, wherein the rotor is maintained in synchronicity with the magnetic fields produced by the stator during operation of the electric machine; and
a rectification system configured control against an alternating current being induced in the rotor poles as the field is energized by magnetic fields produced by the stator windings when receiving the stator current.
2. The electric machine of claim 1 , wherein the rectification system includes a rectification component shorting across each of the multiple fixed rotor poles.
3. The electric machine of claim 2 , wherein rectification components in the rectification system are configured to reduce a delay of energization of flux in an air gap between the stator and rotor.
4. The electric machine of claim 1 , wherein the rectification system is configured to produce an asymmetric response to an electric field generated by the stator windings when receiving the stator current to control a rotor torque ripple.
5. The electric machine of claim 1 , wherein the rectification system includes a respective rectifier arranged across each of the multiple fixed rotor poles.
6. The electric machine of claim 1 , wherein the rectification system comprises a passive rectification system or an active rectification system.
7. The electric machine of claim 1 , further comprising a controller configured to:
send the stator current through the stator windings at a current angle measured relative to a closest one of the rotor poles;
determine a desired operational output of the electric machine;
determine a desired rotor motion corresponding to the desired operational output of the electric machine;
calculate a vector control modulation applied to the stator that elicits the desired rotor motion;
adjust the current angle of the stator current based on the vector control modulation to cause the rotor to perform the desired rotor motion; and achieve the desired operational output of the electric machine.
8. The electric machine of claim 7 , wherein the controller is further configured to modulate a magnitude or a frequency of the stator current based on the vector control modulation.
9. The electric machine of claim 7 , wherein the controller is further configured to:
adjust a frequency or an amplitude of the stator current to cause the rotor to perform the desired rotor motion; and
achieve the desired operational output of the electric machine.
10. The electric machine of claim 7 , wherein the controller is further configured to:
adjust a frequency or an amplitude of the stator current to cause the rotor to perform the desired rotor motion; and
control rotor torque ripple when the rotor is performing the desired rotor motion and achieving the desired operational output of the electric machine.
11. The electric machine of claim 10 , wherein the controller is configured to increase a magnitude of the stator current while increasing the current angle of the stator current to control rotor torque ripple.
12. The electric machine of claim 7 , wherein the controller is configured to increase the current angle of the stator current along a winding of the stator ahead of a pole of a rotor to deliver an increased torque.
13. The electric machine of claim 7 , wherein the controller is configured to cause current angle of the stator to be negative to deliver a braking function of the rotor.
14. The electric machine of claim 1 , wherein the stator windings comprise distributed windings and the rotor comprises:
concentrated windings;
salient windings;
non-overlapping windings; or
permanent magnets.
15. The electric machine of claim 14 , wherein the rotor comprises permanent magnets, and the permanent magnets are substantially aligned with the rotor poles.
16. A wound field rotor synchronous machine, comprising:
a stator defining multiple stator poles with associated stator windings;
a rotor defining multiple rotor poles, the rotor configured to rotate synchronously with the stator, the rotor comprising rotor windings associated with each of the rotor poles, the rotor windings configured to be energized by a magnetic field produced by the stator windings to produce a rotor field; and
a rectification system configured to reduce a delay of energizing the rotor windings in response to the magnetic field produced by the stator windings and produce an asymmetric current response in the rotor windings to control rotor torque ripple as at least one of a phase angle of a stator current or a magnitude of the stator current changes.
17. The wound field rotor synchronous machine of claim 16 , wherein the controller is further configured to modulate a frequency of the stator current based on the desired operational output of the wound field rotor synchronous machine.
18. The wound field rotor synchronous machine of claim 16 , wherein to adjust the current angle the controller is further configured to only adjust the current angle on only one axis of the wound field rotor synchronous machine.
19. The wound field rotor synchronous machine of claim 16 , wherein the controller is further configured to select adjustments to at least one of the current angle or the current magnitude to control rotor torque ripple while achieving the desired operational output of the wound field rotor synchronous machine.
20. The wound field rotor synchronous machine of claim 16 , further comprising a controller configured to:
energize the stator windings with a stator current having a current magnitude and a current angle measured relative to a closest one of the rotor poles; and
achieve a desired operational output of the wound field rotor synchronous machine by:
determining a rotor performance that achieves the desired operational output of the wound field rotor synchronous machine;
adjusting a first one of the current angle of the stator current or the current magnitude of the stator current to achieve the desired operational output of the wound field rotor synchronous machine;
receiving a signal indicative of a current operational output of the wound field rotor synchronous machine;
comparing the current operational output of the wound field rotor synchronous machine to the desired operational output of the wound field rotor synchronous machine; and
adjusting a second one of the current angle of the stator current or the current magnitude of the stator current to achieve the desired operational output of the wound field rotor synchronous machine.
21. The wound field rotor synchronous machine of claim 20 , wherein the rectification system comprises rectification components shorting across each of the multiple rotor poles.
22. The wound field rotor synchronous machine of claim 20 , wherein the rectification system includes a respective rectifier arranged across each of the multiple rotor poles.
23. The wound field rotor synchronous machine of claim 20 , wherein the rectification system comprises a passive rectification system or an active rectification system.