Abstract:
An apparatus for estimating rotor position of a rotating machine having an even number of phase windings selects first and second phase position estimates developed in response to pulses applied to phase windings having associated phase profiles that are displaced at other than 180 electrical degrees and determines a rotor position estimate from the first and second phase position estimates.
Abstract:
A sensorless control for operating an inverter coupled to a switched reluctance machine includes an instantaneous position generation circuit that develops a signal for controlling commutation of the switched reluctance machine. The instantaneous position generation circuit includes a digitally controlled counter which provides a direct interface between a position estimation circuit and commutation logic for the inverter.
Abstract:
A method for powering an electronically switched variable-reluctance polyphase electric motor from a rectified voltage source, including, for each phase, magnetising sequences (M1-3) during which the rectified voltage is applied to said phase, and demagnetising sequences (DM1-3) during which the inverse of the rectified voltage is applied to said phase. The method further comprises sensing disturbance in the current from the rectified voltage source, and, in response thereto, free-wheel sequences (RL1-3) during which the magnetic energy currently stored in at least one of the phases is substantially maintained therein. The method is useful for powering domestic appliances.
Abstract:
A switched reluctance electric machine system has an electric machine, a rechargeable DC energy store (7), principal voltage terminals (5, 6) and a controller. Where the machine is an electric motor, it is advantageous to be able to drive the motor from the DC energy store (7) as well as from an AC supply, and to recharge the energy store (7) from the AC supply. The charger which is needed for recharging is formed by a pair of closely-coupled coils (2, 3) forming windings for the machine, and a power converter (4) having a first circuit (9) containing a coil (2) and the principal voltage terminals (5, 6) and a second circuit (14) having a coil (3) and the DC energy store (7), each circuit (9, 14) including an electronic switching arrangement of a switch (12, 12') and a diode (13, 13') arranged in anti-parallel and connected in series with the coil (2, 3) to enable current to flow through each coil in either direction. The controller operates the switches (12, 12') of the converter (4) to provide a required operational mode, without needing manual re-configuration of the system. The charger is therefore formed from existing components, and the system as a whole has a flexibility, enabling the machine to act as a generator as well.
Abstract:
A pulse width modulation controller for a variable speed variable torque electric motor. Inputs to the controller are a desired RPM signal, a motor electrical signal which is a function of the RPM of the rotor of the motor and its angular position relative to the stator, and a torque feed back signal derived from the power phase winding circuits of the motor. The controller produces pulse width modulated power drive signals which are applied to power switches of the power phase winding circuits of the motor to allow electric current to flow through the power phase winding circuits when power phase enables signals produced by the controller sequentially enabling the power switch of a power phase winding circuit to do so. The duty cycle of the power drive signals is a function of the difference between the desired and actual RPM of the motor and the torque of the motor. The frequency of the power drive signals is a fixed integral multiple of the frequency of the power phase enable signals over the full operating range of RPMs of the motor.
Abstract:
A control for operating an inverter coupled to a switched reluctance machine includes a relative angle estimation circuit for estimating rotor angle for a phase in the switched reluctance machine. The relative angle estimation circuit estimates a phase voltage and thereby calculates phase flux linkage to estimate the rotor angle.
Abstract:
A device for controlling a 4-phase 8-stator pole/6 rotor pole switched reluctance machine includes a microcontroller, a converter circuit for energizing the stator windings of the switched reluctance machine, four Hall sensors adapted to detect rotor position to a resolution of 15 mechanical degrees, a phase current sensor, and a phase voltage sensor. The controller is programmed to implement a rotor position estimator for generating an estimated rotor position signal corresponding to the position of the rotor. The estimator is implemented using an observer-based state variable motor model, and is responsive to the measured phase voltage, the measured phase current, and the transitions generated by the Hall sensors. The estimated rotor position signal is determined by running the observer model in parallel with the physical motor. The observer uses a phase current error signal, and a position error signal generated using the low resolution position transitions, to force the estimated rotor position state variable to converge. The generated estimated rotor position signal is substantially continuously-valued and is used by a commutation means programmed in the controller for controlling commutation of the machine phases.
Abstract:
A process is disclosed for controlling the switching-off process of the branches of a reluctance engine whose stator is provided with windings to which are transmitted current pulses calculated as a function of angular position and speed of rotation of the rotor according to a predetermined algorithm. The excited branch is switched off when a switching-off angle (VP) is reached after a zero crossing (vo) reference angle. Two ranges of operation called "chop" range and blocked voltage range must be differentiated. The switching-off angle (VP) for both ranges of operation of the reluctance engine is calculated according to the same algorithm and is set by a regulator. In the lower speed of rotation range, the "chop" range, a pulse width modulated voltage is applied to the conductive branch and in the upper range, the blocked voltage range, a constant voltage is applied. In both ranges, the switching-off angle is calculated from engine parameters and actual operation values to maximise torque yield and to trigger the switching-off process by converting said values into a switching-off pulse that switches off the conductive branch.
Abstract:
A current measuring apparatus measures current flowing through a phase winding (14a) of a switched reluctance motor while dissipating very little power. The apparatus includes a control (44a) for controlling the current flowing through the winding (14a). A gate (64) is operatively connected to the control (44a) for switching the current flowing through the winding (14a). The arrangement is such that in a first mode of the gate (64), the current flows through the phase winding (14a). In a second mode of the gate (64), flow of the current through the winding (14a) is inhibited. The gate (64) includes a sense means for sensing a fraction of the current when the gate (64) is in the first mode thereof. A resistor (52) of relatively high resistance is electrically connected in series with the sense means such that a voltage drop occurs across the resistor (52) when the gate (64) is in the first mode. The voltage drop signal is fed back to the control (44a) so that dependent on the signal, the current flowing through the phase winding (14a) of the motor is maintained in order to maximize motor efficiency.
Abstract:
A control circuit for a motor having at least two windings (28) is used to optimize noise reduction by controlling the deenergization of each winding (28) in a two-stage decay. The duration of the two-stage decay and particularly the first decaying current portion is controlled by a controller (30) operatively coupled to a switch device (32, 34). The duration of the first decaying current portion is varied between the various phases of the motor to provide optimum noise reduction.