Abstract: An electrical machine is controlled without using a physical rotor position detector. When the demanded torque output is low, a control method causes the machine to operate on fewer than all the phases, thus increasing the phase current and improving the resolution of the position detection algorithm. The method can include sampling the phase current of the machine, determining whether the phase current is above a predetermined threshold, reducing the number of active phases, and then deriving the value of rotor position from the increased phase current in the remaining phases.

Abstract: A switched reluctance drive is controlled without using a physical rotor position detector. The control method estimates the standing flux-linkage associated with the phase and uses this estimate to improve its estimate of rotor position. The method works robustly regardless of whether the current is continuous or discontinuous.

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: An electrical machine includes a rotor, a stator operably coupled with the rotor, at least one phase winding operably coupled with the rotor and stator and arranged to establish flux in a magnetic circuit in the machine, and a flux observer adapted to produce a signal indicative of flux-causing voltage across the at least one phase winding. A flux control system includes a flux controller adapted to receive a flux command as an input and to provide a phase coil energization signal as an output. The system also includes an electromagnetic system adapted to receive the phase coil energization signal, the electromagnetic system including at least one phase coil, and a flux observer adapted to provide a feedback signal to the flux controller. The feedback signal corresponds to flux in the electromagnetic system, and the phase coil energization signal provided by the flux controller energizes the electromagnetic system such that flux in the electromagnetic system follows the flux command.

Abstract: A switched reluctance drive is supplied from a power source and has a DC link capacitor. The phases of the machine are controlled by a current chopping controller which, during phase conduction overlap, controls the initiation of chopping in a second phase so as to minimize the current drawn from the capacitor, thereby allowing a reduction in the capacitor rating.

Abstract: A switched reluctance drive is supplied from a first voltage source (V1) during an idle period, in which it transfers energy to a second voltage source (V2). The machine is subsequently run at high power from the second source (V2), so that the first source (V1) does not have to supply the current required when the machine is operating at high power. The drive is able to regulate the amount of energy transferred to the second source (V2).

Abstract: A switched reluctance machine is controlled without using a physical rotor position detector. The rotor position at start-up is determined by simultaneously injecting a current of known magnitude into two phases. The rise times of the currents are measured and used to interrogate a stored table of rise time against rotor angle for the known current level. This produces two possible rotor positions from each rise time. Comparisons of the pairs of angles yield the actual position.

Abstract: A reluctance drive includes a stator, a phase winding (16) on the stator, a rotor (12) that is movable relative to the stator, a controller for applying a current to the phase winding (13), and a sensor for measuring the phase current in the winding (16). Aspects of the invention detect when the phase current has passed its peak, compute when the peak phase current occurred using information on when the phase current passed its peak, determine rotor position using the computed position of the peak phase current.

Abstract: A switched reluctance drive is supplied from a voltage source which varies from the voltage at which the control laws for the drive were determined. The control system compensates for this by modifying both the speed and torque values used to determine the correct firing angles for the demanded load. The system works over a very wide range of voltage variation and is independent of the shape of the torque/speed curve of the drive.

Abstract: A controller for an electronically commutated electrical machine receives a feedback signal indicative of a parameter which it is desired to minimize, e.g. torque ripple, current, voltage, vibration or acoustic noise. The controller computes the amplitude and phase of a set of harmonics in the parameter and sequentially injects harmonics of the correct amplitude and phase to minimize the parameter. An optimizing routine iterates through the set of harmonics to further reduce the parameter.

Abstract: A switched reluctance machine is supplied from two voltage sources during a cycle of excitation. The higher voltage is a conventional bus voltage obtained, e.g., from a low-voltage storage battery and an up-converter. The lower voltage is supplied directly from the battery. The higher voltage supplies the machine during only part of an excitation cycle, the lower voltage supply supplying the energy directly to the machine during the remainder of the excitation cycle. This reduces the duty of the up-converter and increases the efficiency of the overall drive. One method of operation of the circuit allows the elimination of the up-converter.

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: A switched reluctance machine uses a Hall-effect device to detect the flux in the flux path for each machine phase. The flux signal from the Hall-effect device is fed back to a controller which compares the flux feedback with a demand signal to produce an error signal. The error signal is used to control the machine flux using a control law function actuating timed switches for each phase.

Abstract: A transducer circuit, particularly for monitoring current, compensates for offset in the transducer output by sampling the output periodically at a moment at which the output is known, and storing the sampled value as an offset. The offset is compared with subsequent outputs from the transducer to provide a difference signal which is the compensated output of the transducer. When the calibrated output of the transducer is non-zero at the said moment, the non-zero value is added as a reference to the compensated value to correct the magnitude of the transducer output.

Abstract: A switched reluctance drive includes a reluctance machine, a controller, power switches actuated by the controller and a current transducer for monitoring the current in each phase winding. The controller employs a sensorless rotor position detection technique by injecting voltage pulses into the idle period of each phase winding in a chopping mode. Acoustic noise associated with the injected pulses is concealed by varying the frequency at which the pulses are injected according to rotor speed. In an alternative embodiment the frequency is varied pseudo-randomly.

Abstract: A method and apparatus for reducing winding failures in electric machines resulting from the application of high frequency or high dV/dt voltage pulses or voltage signals to the phase windings of the machine in which an inductive element is provided between the source of the high-frequency or high dV/dt pulses and the phase winding to absorb a portion of the voltage stresses on the phase windings that result from the application of the high-frequency or high dV/dt pulses to the machine.

Abstract: A method and apparatus for reducing winding failures in reluctance machines wherein winding coils for the switched reluctance motor are formed and positioned such that the turn-to-ground capacitance of the portion of the winding coil coupled to an electronic motor controller is reduced. Alternate embodiments are disclosed wherein additional insulation, and capacitive voltage distributors are provided to enable a switched reluctance motor to better handle the voltage stresses produced when high frequency or high dV/dt voltage pulses are provided to the motor.

Abstract: A current control circuit for a switched reluctance machine provides corner shaping at the end of the active conduction period of a phase in which the phase winding is energized. The pulse width modulated firing pulses are gradually reduced in duty cycle so that the transition between the current in the winding in the active period and the decay of current in a ramp down period is smoothed to reduce the forces leading to vibration and acoustic noise.

Abstract: A normalization circuit for a phase energization controller receives a rotor position value from a position encoder, and the normalization circuit obtains a normalized rotor position for each phase of a switched reluctance machine. Accordingly, the normalization circuit simplifies the detection of commutation positions for all the machine phases by reducing the commutation position determination to that of a single phase. Also, an initialization circuit for the phase energization controller energizes one or more phases of the switched reluctance motor to set the rotor of the switched reluctance motor to a preferred position to determine an offset value.

Abstract: An apparatus and method for starting a single-phase variable reluctance motor defined by a stator having one or more pairs of projecting poles defining a principal axis and a rotor mounted on a rotatable shaft co-axial with the principal axis of the stator is provided. The apparatus includes a device for preventing the rotor from being halted in a position of zero-developed torque thereby enabling reliable starting of the motor. The device includes a vane defined by a ferromagnetic disk having alternating mark regions and space regions which is mounted to the rotatable shaft and may form part of a rotor position transducer. A permanent magnet is positioned so as to move the vane into a position at which starting torque of the desired direction will be developed when the motor is energized. A further embodiment combines the magnet with a Hall-effect sensor so that, in conjunction with the vane, a rotor position transducer is formed.