Method and apparatus for controlling an electric machine
AssigneePratt & Whitney Canada Corp.
InventorsKevin Dooley, Michael Dowhan
Life of this patent
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Abstract
The invention provides a method and apparatus for controlling a machine in which the magnetic flux emanating from a rotor is selectively diverted to a second path in the stator which bypasses the winding or windings so as to magnetically de-couple the winding or windings from the rotor.
Claims21
A method of operating an electricity generating machine, the machine having a rotor, stator and at least one winding disposed in at least one slot in the stator, the method comprising the steps of:
- circulating magnetic flux along a first magnetic path through the stator to thereby induce an output voltage and current in the at least one winding;
- and then,
- upon the occurrence of an internal fault in the machine, interposing a member across the at least one slot to provide a second magnetic path through the stator, the second path bypassing the at least one winding such that magnetic flux circulating along the second magnetic path induces substantially no voltage in the at least one winding;
- and
- diverting said magnetic flux from the first path to the second path.
A method of operating an electric machine, the machine having a rotor, a stator and at least one winding disposed in the stator, the method comprising the steps of:
- circulating magnetic flux along a first path in the stator, the first path at least partially encircling the at least one winding such that, when magnetic flux is circulated along the first path, the at least one winding is magnetically coupled to the rotor;
- sensing a temperature in the machine;
- and then
- upon the occurrence of an internal fault in the machine detected when the sensed temperature exceeds a selected threshold, selectively diverting the magnetic flux to a second path in the stator, the second path bypassing the at least one winding such that, when magnetic flux is circulated along the second path, the at least one winding become magnetically de-coupled from the rotor.
A method of operating an electric machine, the machine having a rotor, a stator and at least one winding disposed in the stator, the method comprising the steps of:
- circulating magnetic flux along a first path in the stator, the first path at least partially encircling the at least one winding such that, when magnetic flux is circulated along the first path, the at least one winding is magnetically coupled to the rotor and then
- upon the occurrence of an internal fault in the machine, lowering the reluctance of a second path in the stator to selectively divert the magnetic flux to the second path, the second path bypassing the at least one winding such that, when magnetic flux is circulated along the second path, the at least one winding become magnetically de-coupled from the rotor.
A method of operating an electric machine, the machine having a rotor, a stator and at least one winding disposed in the stator, the method comprising the steps of:
- circulating magnetic flux along a first path in the stator, the first path at least partially encircling the at least one winding such that, when magnetic flux is circulated along the first path, the at least one winding is magnetically coupled to the rotor;
- and then
- upon the occurrence of an internal fault in the machine, moving a stator member to selectively divert the magnetic flux to a second path in the stator, the second path bypassing the at least one winding such that, when magnetic flux is circulated along the second path, the at least one winding become magnetically de-coupled from the rotor.
A method of operating an electric machine, the machine having a rotor adjacent a stator assembly, the stator assembly having at least one slot and at least one winding in the slot, the slot defining a slot gap, the method comprising the steps of:
- moving the rotor to generate electricity in the at least one winding, and then
- upon the occurrence of an internal short circuit in at least one of the machine and its associated control circuitry, moving at least a piece of the stator assembly to substantially close the slot gap and thereby provide a low reluctance path for guiding rotor magnetic flux away from the at least one winding and thereby substantially deactivating the at least one winding.
Dependencies are inferred from the claim text.