Abstract: A controller for a switched reluctance machine is operated to close a switch which would otherwise be open so as to connect a phase winding to the DC link to which the winding is connected during other parts of the electrical cycle. This produces a condition which allows the insulation of the system to be monitored by applying a voltage between the DC link and ground.

Abstract: In an electrical machine which has unidirectional excitation applied to its windings, the mean values of voltage and current can be computed from the instantaneous phase voltage and current by the use of, for example, low-pass filters (in either the analogue or digital domain). The value of winding resistance can then be calculated by dividing the mean voltage by the mean current. This avoids the cost, fragility and potential inaccuracy of conventional temperature sensors, and provides the controller with an ongoing estimate of winding temperature.

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 having salient poles. The poles have one or more holes which are positioned so as to reduce the peak stress experienced by the laminations when the rotor is rotating. The holes are chosen according to a disclosed design procedure which gives a reduction in peak stress for a given limit on the output of the machine.

Abstract: In an electrical machine which has time-varying or position-varying disturbances in its output, signals representing the position and values of machine-related parameters are used to solve a model of the machine to calculate the phase currents which are required to minimize the disturbances. The model is able to provide solutions in the presence of limitations of some of the operating conditions of the machine, for example the supply voltage or the error in the signal representing the position.

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: In an electrical machine which has unidirectional excitation applied to its windings, the mean values of voltage and current can be computed from the instantaneous phase voltage and current by the use of, for example, low-pass filters (in either the analogue or digital domain). The value of winding resistance can then be calculated by dividing the mean voltage by the mean current. This avoids the cost, fragility and potential inaccuracy of conventional temperature sensors, and provides the controller with an ongoing estimate of winding temperature.

Abstract: In an electrical machine which has time-varying or position-varying disturbances in its output, signals representing the position and values of machine-related parameters are used to solve a model of the machine to calculate the phase currents which are required to minimise the disturbances. The model is able to provide solutions in the presence of limitations of some of the operating conditions of the machine, for example the supply voltage or the error in the signal representing the position.

Abstract: A switched reluctance machine has an array of poles attached to a stationary holding member to form a stator. The stator has no back-iron. The machine has two arrays of rotor poles, positioned on either side of the stator poles, and circumferentially aligned with each other. When a pair of rotor poles is aligned with a stator pole, a small airgap is formed at each end of the stator pole, across which flux can be driven to produce torque in a rotary arrangement or force in a linear arrangement. When the poles are in the unaligned position, the phase inductance is very low.

Abstract: A wound core assembly for an electrical machine comprising a stack of laminations defining a core having a plurality of poles, the wound core assembly further comprising at least one slot wedge, wherein the slot wedge comprises a first portion arranged between adjacent poles and at least one second portion protruding from the first portion and abutting an end face of the core in the region of at least one of the poles. The at least one second portion may apply axial pressure to the end face to reduce the tendency of the laminations to splay axially outwards.

Abstract: An electrical drive system includes an electrical machine controlled by an electronic controller and requires control signals representing quantities associated with the operation of the electrical machine. These signals may represent, for example, rotor position and flux or current. A controller includes an estimation routine to use the known magnetic characteristics of the machine and a rotor position signal to provide an estimate of current or of supply voltage.

Abstract: A rotating electrical machine has a rotor composed of laminations having salient poles. The poles have one or more holes which are positioned so as to reduce the peak stress experienced by the lamination when the rotor is rotating. The holes are chosen according to a disclosed design procedure which gives a reduction in peak stress for a given limit on the output of the machine.

Abstract: An electrical drive system includes an electrical machine controlled by an electronic controller, which requires feedback of signals representing quantities associated with the operation of the electrical machine. These signals may represent, for example, flux, current and/or rotor position. The integrity of these signals is validated by setting suitable thresholds for the signals and confirming that both are present at the appropriate time.