Abstract: A brushless electrical machine has at least one phase winding which produces torque to drive a load. The control system for the machine is able to vary the flux and current supplied to a phase so as to vary the torque output as a function of the rotor position. The energization is reduced at particular angles to produce a dip in the torque profile, thus ensuring that, if the drive stalls, it does so at a predetermined position, for example where the losses in the drive are minimized.

Abstract: A rotating electrical machine has a rotor composed of laminations which are mounted on a shaft in an embodiment. The portion of the laminations adjacent the shaft has one or more slots, so designed as to increase the contact force between the lamination and the shaft as the speed of the rotor rises. This allows the laminations to be assembled to the shaft with a smaller interference fit yet retain a contact force at high speeds. The laminations may be assembled to the shaft with a suitable adhesive.

Abstract: A brushless electrical machine has at least one phase winding which produces torque to drive a load. The control system for the machine is able to vary the flux and current supplied to a phase so as to vary the torque output as a function of the rotor position. The energisation is reduced at particular angles to produce a dip in the torque profile, thus ensuring that, if the drive stalls, it does so at a predetermined position, for example where the losses in the drive are minimised.

Abstract: The windings of a switched reluctance machine are supplied from a converter which is capable of providing bipolar energization. The energization pattern supplied to the windings is dependent on the number of stator and rotor poles in the machine and is selected to produce unipolar energization in the rotor poles. This in turn reduces the losses in the rotor which would otherwise result from bipolar energization. The machine may also be operated to provide energization patterns which are adapted to provide optimum performance in different parts of its operating speed range.

Abstract: A switched reluctance machine has salient poles on the stator and rotor. The windings of the machine are supplied from a converter which provides energization at a chosen rate. The windings of the machine may be energized at the rate at which the rotor poles pass the stator poles, or it may be operated at a fraction of that rate by energizing the windings to cooperate with every second, third or fourth rotor pole. This can extend the output of the machine.

Abstract: A switched reluctance machine has salient poles on the stator and rotor. The windings of the machine are supplied from a converter which provides energisation at a chosen rate. The windings of the machine may be energised at the rate at which the rotor poles pass the stator poles, or it may be operated at a fraction of that rate by energising the windings to cooperate with every second, third or fourth rotor pole. This can extend the output of the machine.

Abstract: The windings of a switched reluctance machine are supplied from a converter which is capable of providing bipolar energisation. The energisation pattern supplied to the windings is dependent on the number of stator and rotor poles in the machine and is selected to produce unipolar energisation in the rotor poles. This in turn reduces the losses in the rotor which would otherwise result from bipolar energisation. The machine may also be operated to provide energisation patterns which are adapted to provide optimum performance in different parts of its operating speed range.

Abstract: A variable reluctance generator has phase windings and a bias winding. By controlling the excitation produced by the bias winding, the speed of the machine or the DC link, a power converter using only diodes can supply power to a DC bus. A method of operating a variable reluctance machine as a generator, the machine having at least one phase winding, includes creating a bias flux linking the or at least one phase winding, and limiting the phase voltage to a magnitude below that otherwise induced in the phase winding by the bias flux.

Abstract: An electro-mechanical transmission system, driven by a prime mover, includes two epicyclic gearsets connected between input and output shafts, and two electrical machines having their rotors connected to respective elements of the two gearsets. The torque on the output shaft is boosted by a controller, which dumps energy from the system when one of the machines is acting as a generator and the other as a motor.

Abstract: A cooling system for an electrical machine includes at least one set of heat-conducting inserts positioned so as to transmit heat from at least one part of the winding in the stator to a heatsink. The heatsink may be the frame of the machine itself, but could also be a coolant pipe mounted at one or both ends of the stator. One form of insert is arranged between windings to draw heat away from the sides of the poles. Another form of insert is arranged on the ends of the poles to draw heat from that region.

Abstract: A variable reluctance generator has phase windings and a bias winding. By controlling the excitation produced by the bias winding, the speed of the machine or the DC link, a power converter using only diodes can supply power to a DC bus. A method of operating a variable reluctance machine as a generator, the machine having at least one phase winding, includes creating a bias flux linking the or at least one phase winding, and limiting the phase voltage to a magnitude below that otherwise induced in the phase winding by the bias flux.

Abstract: An electro-mechanical transmission system, driven by a prime mover, includes two epicyclic gearsets connected between input and output shafts, and two electrical machines having their rotors connected to respective elements of the two gearsets. The torque on the output shaft is boosted by a controller, which dumps energy from the system when one of the machines is acting as a generator and the other as a motor.

Abstract: A cooling system for an electrical machine includes at least one set of heat-conducting inserts positioned so as to transmit heat from at least one part of the winding in the stator to a heatsink. The heatsink may be the frame of the machine itself, but could also be a coolant pipe mounted at one or both ends of the stator. One form of insert is arranged between windings to draw heat away from the sides of the poles. Another form of insert is arranged on the ends of the poles to draw heat from that region.

Abstract: A novel coil shape, particularly suitable for 1-phase switched reluctance machines, is disclosed. The coil may be wound on a bobbin which is then inserted into the stator or it may be free standing. The shape is such that it can be inserted into the stator without further deformation of its shape to allow subsequent components of the machine to be assembled.

Abstract: In a switched reluctance machine, the air gap between aligned rotor and stator poles is defined to have an inner region of substantially uniform length and outer regions of increasing length. The outer regions are flanked by extension portions on one or both of the poles that form a radiussed transition region on the pole between each outer region and a side wall of the pole. The at least one of the poles has a waist portion between the extension portions and the body of the lamination. As the rotor rotates with respect to the stator, alignment of the poles more gradually modifies the flux path such that radial forces tending to distort the stator and give rise to vibration and acoustic noise are reduced. The waist portion decreases the inductance of the stator winding in the minimum inductance position of the rotor.

Abstract: A reduced vibration and reduced noise controller for a switched reluctance machine system and a method for reducing unwanted vibration and noise produced by a switched reluctance machine system. The energization of the voltage across a phase winding in the switched reluctance machine is controlled such that the voltage across the phase winding varies over time in a controlled manner from a first voltage level to a second voltage level following a predefined switching event. The control of the transition of the voltage across the phase winding from the first voltage level to the second voltage level is accomplished through application of a succession of timed voltage pulses to the phase winding at a fixed point in time after the predefined switching event or through use of a capacitor smoothing circuit.

Abstract: A reduced vibration and reduced noise controller for a switched reluctance machine system. A decoder circuit monitors firing signals which are used to energize a phase winding in the switched reluctance machine over an angular period of rotor rotation. When the firing signals indicate that a predefined switching event has occurred, one or more timed voltage pulses are applied to the phase winding at fixed points in time following the predefined switching event. The timed voltage pulses induce vibration forces in the motor which actively cancel unwanted vibrations in the motor system, thus reducing unwanted vibrations and acoustic noise.

Abstract: A method of controlling a switched reluctance machine having a rotor and a stator with at least one phase winding to reduce iron loss whereby the phase winding is energized over a first angular period of the rotation of the rotor and then current in the phase winding is allowed to freewheel through the phase winding for a second angular period of rotor rotation where, in a first method, the second angular period is greater than the first angular period. Also a method of using freewheeling in high speed applications to reduce iron loss.