Switched reluctance generator and a method of controlling such a generator
First Claim
1. A method of controlling the operation of a switched reluctance generator (1) so as to reduce the volt-amp rating of a controller (S1, S2, D1, D2, 88, 90) characterised in that the controller (S1, S2, D1, D2, 88, 90) operates in a first mode for rotational rates below a threshold determined as a function of rotational speed and load, and a second mode for rotational rates at or above said threshold, and in which in the first mode the current supplied to a stator winding (10a, 10b) is modulated to limit the peak value of the current to a limit current value, and in the second mode at least one of the duration, minimum value and maximum value of a supply of current to the stator winding (10a, 10b) is varied in response to demand, the current not returning to zero during a control cycle where a rotor pole approaches and then moves away from the winding.
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Accused Products
Abstract
A switched reluctance generator is provided in association with a controller (86 to 90). The controller is organized to operate in two modes depending on the speed and load of the generator. One mode is a discontinuous conduction mode where the current is a generator winding periodically returns to zero, whereas the other mode is a continuous conduction mode such that current is always flowing. The choice of modes enables a generator to work over a wide speed range while seeking to limit or reduce the volt-amp rating of the generator controller.
41 Citations
37 Claims
- 1. A method of controlling the operation of a switched reluctance generator (1) so as to reduce the volt-amp rating of a controller (S1, S2, D1, D2, 88, 90) characterised in that the controller (S1, S2, D1, D2, 88, 90) operates in a first mode for rotational rates below a threshold determined as a function of rotational speed and load, and a second mode for rotational rates at or above said threshold, and in which in the first mode the current supplied to a stator winding (10a, 10b) is modulated to limit the peak value of the current to a limit current value, and in the second mode at least one of the duration, minimum value and maximum value of a supply of current to the stator winding (10a, 10b) is varied in response to demand, the current not returning to zero during a control cycle where a rotor pole approaches and then moves away from the winding.
- 11. A controller (88, 90) for a switched reluctance generator (1) characterised in that the controller (88, 90) is arranged to control the flow of current in a plurality of stator coils (10a, 10b) in such a way as to reduce the volt-amp rating of the controller, in which the controller operates in a first mode for rotational rates below a mode threshold derived as a function of rotational speed and electrical load supplied by the generator (1), and in a second mode for rotational rates above said mode threshold, and in which in the first mode an excitation current supplied to a a stator coil (10b) is modulated to limit the peak value of current to a limit current value, and in the second mode at least one of the duration, minimum value and maximum value of the supply of the excitation current to the stator coil (10b) is varied in response to a current demand, the current flowing in the stator coil (10b) not returning to zero during a control cycle where a rotor pole approaches and moves away from the stator coil (10b).
- 22. A switched reluctance generator (1) comprising a plurality of stator poles (10a, 10b), wherein at least one of the stator poles is provided with a primary winding (10b) for controlled connection to a supply (20, 22), the generator further comprising variable magnetic biasing means (50) for providing a bias field.
- 34. A controller for a switched reluctance generator, characterised in that the generator has at least one primary coil (10a, 10b) associated with a respective pole and variable magnetic field biasing device (50) in which the controller (60) is arranged to monitor the performance of the generator and to vary the magnetic bias field in order to control the output of the generator.
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36. A method of controlling a switched reluctance generator (1), the generator having a plurality of primary windings (10a, 10b) associated with respective poles, and a magnetic biasing device, the method comprising the steps of exciting the primary windings and delivering energy from the primary windings to a bus, a monitoring the output of the generator and using a measurement of the output or a value derived therefrom to adjust the magnetic field provided by the biasing device (50) or the primary windings (10a, 10b) in order to vary the generator output.
Specification