Systems and methods concerning exciterless synchronous machines
A synchronous machine and related systems include a stator and rotor separated by an air gap. The rotor includes a rotating DC power supply coupled to exciter windings disposed adjacent the air gap. Power from air gap harmonics, including air gap slot harmonics induce current in the exciter windings, which is rectified and supplied to the rotor field windings. In operation, a desired current level in the rotor field windings can be achieved through control of the DC power supply or superposition of harmonics into the stator winding current which induces the prescribed current in exciter windings.
1. A synchronous machine, comprising:
a stator including stator windings;
a rotor operably disposed relative to the stator, a first surface of the rotor and a second surface of the stator separated by an air gap, the rotor including a rotating DC power supply and an exciter winding disposed in the first surface of the rotor adjacent the air gap, the exciter winding electrically coupled to an input of the DC power supply and structured to receive power from the stator windings and provide the received power to the DC power supply, the DC power supply electrically coupled to a rotor winding and structured to output power to the rotor winding; and,
a voltage regulator electrically coupled to the stator windings of the stator and capable of communicating control signals to the DC power supply.
2. The machine of claim 1 , wherein the DC power supply includes a DC to DC converter.
3. The machine of claim 2 , wherein the DC power supply includes a wireless receiver, and the voltage regulator has a wireless transmitter operable to communicate with the receiver.
4. The machine of claim 3 , wherein the receiver and transmitter are wireless control area network (CAN) transceivers.
5. The machine of claim 2 , wherein the DC power supply includes an optical receiver.
6. The machine of claim 5 , wherein the voltage regulator has an optical transmitter operable to communicate with the receiver.
7. The machine of claim 1 , wherein the DC power supply includes a thyristor electrically coupled to the exciter winding, the thyristors configured to provide a DC output.
8. The machine of claim 1 , wherein the rotor includes a plurality of poles including the first surface of the rotor, the exciter winding disposed within at least one exciter winding slot and the stator winding disposed within at least one stator winding slot, wherein the number of exciter winding slots including exciter windings is an integer number between a minimum number of exciter winding slots operable to provide a field rating required power for the machine and about N rs given by:
N
rs
=
k
·
m
·
b
rp
2
π
r
gap
·
N
ss
p
where N rs is a number of exciter winding slots, k is an integer value, m is a number of phases of exciter windings, b rp is an arc width of the rotor pole, r gap is an air gap radius of the machine, N ss is a number of stator slots in the stator and p is a number of rotor poles in the machine.
9. The machine of claim 8 , wherein k has a value of 1, 2, 3, 4 or 5.
10. The machine of claim 9 , wherein k has a value of 1, 2 or 3.
11. The machine of claim wherein the stator winding is disposed within at least one stator winding slot, and the at least one stator winding slot is an open slot.