Abstract: A three region control strategy for a permanent magnet motor is presented. In a first control region, the permanent magnet motor is operated at, a 120° conduction square wave mode at reduced phase current, and below a no-load speed. The motor phase current commutation causes eddy current losses in the rotor magnets and core which are insignificant due to the low phase currents and relatively low rotor speed. Meanwhile, the inverter switching losses are kept low as two switches are in use (on/off) for each current commutation during the 120° conduction mode. In a second control region, the permanent magnet motor is operated at a 180° conduction sinusoidal wave mode with high phase currents. The 180° conduction sinusoidal wave mode minimizes the commutation loss. In a third control region, the permanent magnet motor is operated above its no-load speed or in a field weakening mode.

Abstract: An inverter for use in a switched reluctance (SR) motor drive is provided. The inverter comprises a first and second transistor for selectively providing current to an SR motor winding. A resonant-type snubber circuit is connected to the transistors to reduce turn-off loss. The snubber circuit includes a pair of diodes, a capacitor, and an inductor. The snubber circuit is reset during switch-on time of the transistors. At transistor turn-off time, the snubber circuit uses the capacitor to effectively limit the rate of change of voltage across the transistors. This allows the transistors to turn off with lower losses, and can also reduce the acoustical noise generated by the motor drive.

Abstract: A method for monitoring the speed of a synchronous motor, the synchronous motor having a permanent magnet rotor (3) and coils (1, 2), sinusoidal currents being applied to the coils (1, 2). Also a device for monitoring the speed of such a motor, wherein in at least one of the coils (1, 2) the power supply is disconnected and one or more voltage characteristics (U1, U2) are evaluated which are induced by the permanent magnet rotor (3) in one or more of the coils (1, 2) disconnected from the power supply, the minimum duration of the interruption of the power supply of the coils (1, 2) and the evaluation of the voltage characteristic (U1, U2) being equal to the temporal spacing between two consecutive zero crossings of the respectively induced voltage characteristics (U1, U2).

Abstract: Several embodiments of improved 2-phase DC brushless motors. In each embodiment, there are pluralities of windings and the current flow through the windings is controlled by a reduced number of main switches from the prior art type of devices. In accordance with a feature of certain embodiments, pair of windings are provided with a common CT that detects the current flowing through the connected pair of windings and which functions to control the main switching device in a pulse width modulated manner. As a result, the control circuit can be simplified and reduced in cost without sacrificing performance.

Abstract: The teachings herein comprise a method and apparatus for determining the position of a rotor by applying a voltage across a pair of phases of a motor and using a voltage measurement responsive to the applied voltage and indicative of the distribution of the phase inductances within the phase pair to which a test voltage is applied to determine the rotor position.

Abstract: Hall ICs 23u, 23v and 23w are provided to detect the magnetic fields of magnetic regions 8 of a rotor 9 and are offset in position by an electrical angle of 30° from central positions of a U-phase stator pole 1, V-phase stator pole 6 and W-phase stator pole 2. A driving circuit 21 controls the timing of rotor driving signals that are supplied to respective stator coils for respective phases based upon rotor position signals outputted from the Hall ICs 23u through 23w. For example, in order to rotate the rotor in a forward direction, the driving circuit 21 controls the timing of the rotor driving signals according to a first logic. Similarly, in order to rotate the rotor in a reverse direction, the driving circuit 21 controls the timing of the rotor driving signals according to a second logic.

Abstract: The present invention concerns a device (20) for controlling an electric motor (1) including a rotor (6) and at least three stator coils (2, 3, 4) connected between three connection terminals, means (5) for providing three control signals (Ua, Ub, Uc) to said connection terminals, and means (22) for dectecting said rotor angular postion. Said dectecting means include measuring means (24) designed to be connected to the motor, such that the means form with said coils at least two oscillating circuits supplying two respective signals (U1, U2) at two measurement frequencies respectively which are themselves periodic functions of said rotor angular position, and means (26) for calculating a single value corresponding to the two measurement frequencies, this value being the desired angular position.

Abstract: A method and device for controlling a synchronous permanent magnet motor with at least one phase, a coil and a rotor, wherein the method and device controls the powering of each motor phase, simultaneously measures the voltage of each motor phase, determines the rotor speed and the motor load from the measured voltage; determines a variable frequency from the speed and the load, samples at the variable frequency output signals from the voltage measurement of each phase; determines the rotor position from the sampled signals; and controls the powering of each motor phase as a function of the rotor position. The device is powered from an electric power source and comprises a power bridge powering the motor coil, a unit for controlling the powering of the coil, a circuit for measuring the voltage of each motor phase and means for sampling, at a variable frequency, signals from the measuring circuit.

Abstract: A brushless repulsion motor which includes a stator and rotor rotatably mounted on the stator is provided. The stator and rotor are contained within a first housing, the stator having at least one pair of poles, a field winding on the stator for producing a field on the stator, and a plurality of coils on the rotor adapted to electromagnetically interact with the field of the stator winding. Switches are located on the rotor shaft outside the first housing to selectively short successive ones of the coils when the coils are in a preferred angular position relative to the stator poles. Thus, the stator field is effective to induce a current in the rotor and produce a resultant relative rotation between the rotor and the stator which can be controlled by non-contact signaling means which activate the switches.

Abstract: A modulation control type of AC motor includes a modulator and a modulation motor. The modulation motor has the structure in which a DC field power source of a two-phase synchronous motor is replaced by a load and a DC main magnetic flux is replaced by an alternate main magnetic flux. There is no interference between the frequency of an AC power source and the frequency of a modulation signal. Therefore, the synchronous torque and the rotation speed can be controlled separately and independently. The controllable range is wide.

Abstract: A more compact and light-weight drive unit is required for an electric vehicle in order to improve its mileage per charge, acceleration performance and overall efficiency. A control apparatus which generates drive signals to drive power devices in the power converter includes: a current reference generator calculates from a torque reference value a d-axis exciting current reference value on the basis of which the ac motor generates a magnetic flux, and a q-axis torque current reference value, the d-axis and the q-axis being orthogonal to each other; a current control circuit generates ac voltage reference values Vu*, Vv* and Vw* from the d-axis exciting current reference value and the q-axis torque current reference value; and a drive signal generator generates drive signals to drive power devices from the ac voltage reference values. Both the current reference generator and the current control circuit are processed digitally by the same arithmetic unit.

Abstract: The driver circuit (10) comprises a first triac or the like (11) for connection in series with the stator winding (5, 6) of the motor between the terminals (12, 13) of an alternating-current voltage supply, the gate of the first triac (11) being arranged for connection to an intermediate point (C) of the stator winding (5, 6) of the motor (M). A second triac or the like (15) is connected between the intermediate point (C) of the winding (5, 6) and the terminal (13) of the voltage supply to which the first triac (11) is connected. A control circuit (15-27) is connected to the gate of the second triac (15) such that, each time the motor (M) is connected to the voltage supply, it initially makes the second triac (15) conductive and consequently cuts off the first triac (11) for a predetermined initial period of time. and cuts off the second triac (15) and allows the first triac (11) to become conductive after this period of time.

Abstract: In an a.c. motor control method and apparatus, operations are carried out at a current controller and a voltage setting using interrupt signals generated in synchronism with maximum and minimum values of a carrier wave at a control device for controlling an inverter for driving an alternating current motor. In operations at the voltage setting part carried out using one of the interrupt signals, a carrier wave is corrected in such a manner that phases of voltage command values gradually come into synchronism with a carrier wave. An integral multiple of the period of the carrier wave becomes the period of the a.c. voltage and current control operation timing is carried out in synchronism with the carrier wave.

Abstract: A dynamo-electric machine which can function as a motor or a generator. The machine comprising a stator and an armature, and switching of the armature coils is accomplished by means of a switching control assembly which is mounted to, and rotates with, the armature. In operation as a motor, direct current is supplied through brushes to slip rings that rotate with the armature, and the DC current supplied is first passed through switch means in the control assembly to deliver the current in properly timed relationship with respect to the rotation of the rotor. This provides greater versatility in the operation of the motor/generator and eliminates many of the problems related to the use of conventional brush commutation commonly used in present day DC motors and generators.

Abstract: A method for restarting a three-phase synchronous permanent magnet motor in which the rotor is still rotating and in which the motor is connected to a drive unit having a DC-stage with voltage measuring means, a variable voltage and frequency output stage including power switching devices, and a means for determining the current in two of the output phases from the drive unit, wherein the motor with the output stage is momentarily short-circuited, the current magnitudes generated by the motor in the two output phases are measured during the short-circuiting moment, the phase angle generated by the motor during the short-circuiting moment is calculated, the rotor speed is determined, and the drive unit is synchronized with the rotor to enable restarting of the motor.

Abstract: In order to estimate a magnetic pole position of a permanent magnet type brushless motor, the following steps are conducted. A given &ggr; axis and a given &dgr; axis in an advanced from the &ggr; axis by an electrical angle of 90° are set. A closed-loop electric current control system in the &ggr; axis direction is formed while forming an open-loop electric current control system in the &dgr; axis direction. It is calculated an interference current generating in the &dgr; axis direction when a current command in the &ggr; axis direction is given as a stepwise alternating current command. The &ggr; axis is finely advanced by an angle of &Dgr;&thgr; when a sign of a product of an integral value of the interference current and a value of the current command in the &ggr; axis direction is positive. Alternatively, the &ggr; axis is finely delayed by an angle of &Dgr;&thgr; when the sign is negative.

Abstract: A control apparatus of an electric motor vehicle includes a device for operating an initial magnetic pole location based on three phase magnetic pole location signal pulses of a permanent magnet electric motor upon starting the electric motor vehicle, a device for operating a magnetic pole phase of the permanent magnet electric motor on the basis of the initial magnetic pole location, a rotation pulse of the permanent magnet electric motor, and a correction value which are operated with the rise and fall of the three phase magnetic pole location signal pulse after the starting, a device for determining a current to be supplied into the permanent magnet electric motor based on the magnetic pole phase and a torque reference value, and a device for correcting the magnetic pole phase when a predetermined one of the three phase magnetic pole location signal pulses rises or falls.

Abstract: A motor drive apparatus for driving a motor with power derived from a main power source, including a signal input device configured to input a start signal and a stop signal to initiate starting and stopping of the motor; a voltage regulator configured to output regulated electric power to the motor; and a semiconductor switching device disposed between the main power source and the voltage regulator, coupled to the signal input device, and configured to switch electric power from the main power source to the voltage regulator in accordance with the start signal input from the signal input device, and to shut off the electric power to the voltage regulator in accordance with the stop signal input from the signal input device.

Abstract: A system for detecting the position of a rotor for a switched reluctance (SR) machine having an irregular pole configuration. The system does not require the use of a conventional sensing device, and provides accurate position information, without disrupting operation of the machine. A voltage ratio is used to infer the position of the rotor relative to the stator.

Abstract: A speed control system for a brushless repulsion motor of the type including a series of armature mounted switches for shorting circumferentially spaced armature coils, said system comprising: a digital counter on the armature for creating a repetitive succession of switch activating signals in a selected sequence at a given rate determined by the counting rate of the counter; means for activating the switches with the signals in the sequence and at the rate to control the speed of the armature; and, means for directing a reference pulse signal at a reference frequency to the counter to set the counting rate of the counter.

Abstract: The driver circuit (10) comprises a first triac or the like (11) for connection in series with the stator winding (5, 6) of the motor between the terminals (12, 13) of an alternating-current voltage supply, the gate of the first triac (11) being arranged for connection to an intermediate point (C) of the stator winding (5, 6) of the motor (M). A second triac or the like (15) is connected between the intermediate point (C) of the winding (5, 6) and the terminal (13) of the voltage supply to which the first triac (11) is connected. A control circuit (15-27) is connected to the gate of the second triac (15) such that, each time the motor (M) is connected to the voltage supply, it initially makes the second triac (15) conductive and consequently cuts off the first triac (11) for a predetermined initial period of time, and cuts off the second triac (15) and allows the first triac (11) to become conductive after this period of time.

Abstract: There is disclosed a synchronous motor drive in which in a record disc drive of an information recording device a quantity of generated excitation noise is reduced to a small level to which a reading/writing signal is not influenced and a substantial motor generation torque is prevented from lowering. An absolute value of a maximum voltage gradient of a coil excitation voltage waveform is set to a certain value or less. The waveform alternates at a synchronous frequency which is determined by the number of poles of a rotating magnetic field produced in an air gap by a stator winding and the number of revolutions.

Abstract: A digital motor drive control system comprises drive means for performing phase switching by use of the phase timing signal from phase switching timing generating means and driving of the motor in response to a PWM clock signal generated by PWM signal generating means where means is provided for synchronizing the PWM clock signal of the PWM signal generating means with a phase switching timing. The number of PWM clock pulses of each phase of the motor is made equal to each other, so that rotational irregularities of the motor are decreased.

Abstract: In an a.c. motor control method and apparatus, operations are carried out at a current controller and a voltage setting using interrupt signals generated in synchronism with maximum and minimum values of a carrier wave at a control device for controlling an inverter for driving an alternating current motor. In operations at the voltage setting part carried out using one of the interrupt signals, a carrier wave is corrected in such a manner that phases of voltage command values gradually come into synchronism with a carrier wave. An integral multiple of the period of the carrier wave becomes the period of the a.c. voltage and current control operation timing is carried out in synchronism with the carrier wave.

Abstract: At the time of starting a synchronous motor (40), one method of the present invention assumes that the synchronous motor (40) rotates at a revolving speed of not less than a predetermined level, and detects an electrical angle of a rotor (50) according to a first detection process, which has a practical accuracy when the revolving speed of the rotor (50) is not less than the predetermined level (step S120). In case that the electrical angle has not been detected successfully, the method detects the electrical angle of the rotor (50) according to a second detection process, which has a practical accuracy when the revolving speed of the rotor (50) is less than the predetermined level (step S160). Another method first detects the revolving speed of the rotor (50).

Abstract: In a brushless motor having a field permanent-magnet part, an altering signal producing circuit produces altering signals which vary analogously with output signals of a position detector. Then, at least one distributing circuit distributes current to first and/or second three-phase distributed current signals which vary analogously with the output signals of the altering signals. The first and/or second distributed current signals may be composed by a distributing composer to produce three-phase distributed signals. A driving block uses the three-phase distributed signals to produce driving signals for the three-phase coils.

Abstract: The prior art technique should return the voltage applied to a synchronous motor to zero in the process of measurement of an electrical angle. This causes foreign noises. The structure of the present invention utilizes the fact that the electrical angle of a three-phase synchronous motor 40 depends upon the inter-coil inductances. The procedure of the present invention applies a predetermined voltage for measurement to each combination of coils, and measures variations in electric currents flowing through the respective coils. The electric current flowing through each coil is attenuated in the presence of a driving current in the three-phase synchronous motor 40, compared with the case in the absence of a driving current. The procedure of the present invention accordingly refers to a table 122A to correct the observed values of electric currents based on the variations in electric currents, and refers to another table 122B to read the electrical angle .pi.

Abstract: A brushless repulsion motor in which the rotor carries electronic switch circuits for selectively shorting the rotor windings at appropriate times in its rotational cycle. A non-contact reference signal source on the stator enables the electronic circuitry to operate as desired. The disclosed motor arrangements are useful as substitutes for conventional brush-type repulsion motors, universal series motors, synchronous motors, servomotors and stepping motors.

Abstract: A permanent magnet synchronous motor controller includes an inverter for supplying an alternating current power converted from a direct current power to a three-phase permanent magnet synchronous motor, having a pair of switching elements for each of said three phases of the motor; a smoothing capacitor for smoothing the direct current power connected to the inverter in parallel; and a control unit for controlling the motor by ON-OFF controlling each of the switching elements of the inverter, which further including a short circuit transition processing portion for changing control to 3-phase short circuit after performing precursory ON-OFF control of each of the switching elements so as to avoid occurrence of over current at an initial period of performing the 3-phase short circuit while the motor is being rotated.

Abstract: A permanent magnet synchronous motor having multiple-phase armature windings and a rotor is subjected to sensor-less control. Phase voltages are generated in response to voltage command values. The generated phase voltages are applied to the armature windings. Phase currents through the armature windings are detected. The detected phase currents depend on the voltage command values. An angular position and an angular velocity of the rotor are calculated from the detected phase currents. The voltage command values are adjusted in response to the calculated angular position and the calculated angular velocity of the rotor to implement feedback control of the motor. An angular velocity of the rotor is estimated from a time-domain variation in the calculated angular position of the rotor. A determination is made as to whether or not the calculated angular velocity of the rotor and the estimated angular velocity of the rotor are substantially equal to each other.

Abstract: The torque characteristic of an electrically driven brushless motor may be optimized by driving the phase windings of the motor with predefined, digitized and stored current or voltage profiles. Appropriate sequences of digital samples of the predefined driving profile are sequentially read from a nonvolatile memory where they are permanently stored to drive, through a DAC, the relative winding of the motor in synchronism with a signal representative of the rotor position.

Abstract: In a brushless motor having a field permanent-magnet part (10), an altering signal producing circuit (22) produces altering signals which vary analogously with output signals of a position detector (21). Then, a first distributing circuit (31) and a second distributing circuit (32) distributes first and second output current signals of a command block 15 to first and second three-phase distributed current signals which vary analogously with the altering signals. The first and second distributed current signals are composed by a distributing composer (33) to produce three-phase distributed signals. A driving block (14) uses the three-phase distributed signals to produce driving signals for the three-phase coils.

Abstract: A sensor-less control apparatus is designed for a permanent magnet synchronous motor having multiple-phase armature windings and a rotor. The sensor-less control apparatus includes a first device for calculating a rotational angle and an angular velocity of the rotor from phase currents and phase voltages of the armature windings. A second device is operative for controlling energizations of the armature windings in response to the rotational angle and the angular velocity calculated by the first device. A third device is operative for correcting the rotational angle calculated by the first device into a correction-resultant rotational angle and informing the second device of the correction-resultant rotational angle, and for feeding back information of the correction-resultant rotational angle to the first device.

Abstract: A current regulation process and device for a three-phase, static-converter-fed, permanently excited synchronous machine with a trapezoidal magnet wheel voltage. A phase angle sensor is mounted on the motor shaft of the machine and is coupled to an evaluating device providing an actual speed of rotation value. Current measurement devices measure the currents to the machine. A current actual value spatial vector is generated from two phase current actual values, which spatial vector is estimated as a function of a calculated normalized magnet wheel voltage, whose rotor flux-oriented current components are supplied to current regulators, which generate a voltage spatial vector. A simple field-oriented current regulation is achieved for a three-phase, static-converter-fed, permanently excited synchronous machine with a smooth torque at low rotation speeds and low intermediary circuit or battery current ripple at high rotation speeds.

Abstract: The present invention relates to a control circuit for a motor, the motor including a rotor having a non-magnetic body portion and a peripheral portion, the peripheral portion being formed on permanently magnetized material, one arcuate portion thereof having north magnetic pole and another arcuate portion having south magnetic pole, a pair of motor coils, a diode bridge circuit having opposed input connections and opposed output connections, a circuit for connecting the respective opposed input connections of the bridge circuit in series with the pair of coils across an alternating current source, a first circuit portion connected across the opposed output connections of the diode bridge circuit including a controllable switch device having a control gate, circuitry to control the voltage applied to the control gate to control the conducting condition thereof and hence current flow through the pair of coils, circuit means including first and second parallel circuits each having a resistor in series with a di

Abstract: A brushless repulsion motor in which the rotor carries electronic switch circuits for selectively shorting the rotor windings at appropriate times in its rotational cycle. A non-contact reference signal source on the stator enables the electronic circuitry to operate as desired. The disclosed motor arrangements are useful as substitutes for conventional brush-type repulsion motors, universal series motors, synchronous motors, servomotors and stepping motors.

Abstract: A circuit arrangement for driving an inductive load (M) having a first (1) and a second sub-winding (2), which sub-windings can be connected to an energy source (5) via switch devices (9, 10) periodically driven by a controller (16). The source produces a DC voltage (U5) to supply energy to the load (M). Alternatively, the sub-windings are coupled electrically (3) and magnetically (6) like an autotransformer, while voltages (for example U8) for feeding the controller (16) can be tapped from the transformer end terminals (7,8) which are formed by non-interconnected terminals of the sub-windings (1,2). In this circuit arrangement start and operation is ensured with the least possible additional circuitry even if the DC voltage taken from the energy source is less than the supply voltage necessary for the controller.

Abstract: A brushless repulsion motor in which the rotor carries electronic switch circuits for selectively shorting the rotor windings at appropriate times in its rotational cycle. A non-contact reference signal source on the stator enables the electronic circuitry to operate as desired. The disclosed motor arrangements are useful as substitutes for conventional brush-type repulsion motors, universal series motors, synchronous motors, servomotors and stepping motors.

Abstract: An electric motor having optimum torque, comprising a motor having a shaft, a rotor and stator, permanent magnets generating flux and current in windings generating additional flux. A control circuit generates a velocity signal proportional to shaft velocity and a current signal proportional to the current in the windings. The current signal is multiplied by the velocity signal to produce an input signal. The input signal is fed to the motor to thereby adjust the phase angle of the current so that the angle between the flux from the current and the flux from the permanent magnet are 90.degree. apart.

Abstract: A brushless repulsion motor in which the rotor carries electronic switch circuits for selectively shorting the rotor windings at appropriate times in its rotational cycle. A non-contact reference signal source on the stator enables the electronic circuitry to operate as desired. The disclosed motor arrangements are useful as substitutes for conventional brush-type repulsion motors, universal series motors, synchronous motors, servomotors and stepping motors.

Abstract: A circuit arrangement for operating a multi-phase synchronous motor includes a switching device (13) composed of semiconductor switches (14-16) for the successive connection of the winding phases (u, v, w) of the armature winding (10) to a direct mains voltage and a commutation device (21) for the actuation of the semiconductor switches (14-16) in the correct sequence by means of switching signals (S1-S3) in conformance with the rotary position of the rotor. In order to reduce commutation noise and radio interference with low circuit engineering expenditures, each control input (G) of the semiconductor switches (14-16) is preceded by an analog difference former ( 18-20 ) which receives, on the one hand, the switching signal (S1-S3) associated with the semiconductor switch (14-16) and, on the other hand, a reference signal derived from the phase sum current of the armature winding (10).

Abstract: A hard disk drive having a plurality of disks mounted on the rotor of a current limited, electronically commutated dc motor. Windings on the stator of the motor are divided into serially connected run and start sections and first and seconds drive circuits are provided to operate the motor by alternatively enabling the first drive circuit to pass currents serially through the two sections of the winding and enabling the second drive circuit to pass currents through only the run sections of the windings. During spin up of the disk drive to operating speed, the first drive circuit is enabled and the second drive circuit is disabled to drive the disks to the speed at which the back emf limits on the acceleration of the motor using both sections of the windings reduces the acceleration to the maximum acceleration achievable at the current limit using the run sections alone. Spin up is then completed by enabling the second drive circuit and disabling the first drive circuit.

Abstract: A drive system has a drive motor with an associated current regulator. The current regulator controls the semiconductor contact elements of an electronic power stage, which is arranged downstream from the drive motor. This control is a function of a rotor-position sensor, whose rotor part is coupled to the rotor of this motor and has a number of magnetic poles corresponding to the number of poles of the drive motor. Furthermore, the current setpoint that is supplied to the current regulator is increased by overlapping an auxiliary voltage during the respective instant of commutation. Torque fluctuations which are caused by manufacturing tolerances can be then be eliminated. On the circumference of the rotor part, a number of magnetic field sensors corresponding to the number of phases m of the drive motor are mounted at a spatial distance of 360.degree. /(p.m) to each other where p is the number of pole pairs of the drive motor.

Abstract: The disclosure is related to a driving arrangement for a drive motor which is provided with an electronic power stage (9) which is controlled by a current controller (13). During the commutation phase, a breakdown of the torque occurs in such drive motors due to the shape of the B-field current, so that the torque has a wavy shape. The torque breakdown can be counteracted by raising the load current in the commutation region. This raising of the load current during the commutation phase is achieved by the provision that the current reference value of the current controller (13) is increased correspondingly by means of an auxiliary voltage at the respective commutation instant.

Abstract: When a single-phase electric rotating machine has a stator provided with a main armature winding which is composed of, at least, four winding circuits in such a bridge circuit way as can be formed by connecting one set of series-connected two winding circuits in parallel with the other set of series-connected two winding circuits, in the circuit between two outside electric terminals of the main armature winding, and with an exciting winding of which electric terminals are connected electrically with two intermediate electric terminals for the main armature winding, so that the main armature winding may not only supply or be supplied with a load current through the outside electric terminals but also may be supplied with an exciting current from the exciting winding through the intermediate terminals of the main armature winding, two kinds of currents can flow simultaneously in the armature winding, therefore, two different numbers of poles can be produced simultaneously in the stator, the machine can operate

Abstract: To provide for fast response of a servo drive with a synchronous machine in which the same torque is available over the entire rotational range of the machine regardless of angular position of the rotor, phase currents to phase windings, preferably three-phase, are controlled in dependence on required torque, and steered to the respective phase windings by a rotor position transducer in such a manner that the sum of all the phase currents remains constant, and is connected to the respective phase windings, in pulses, during an electrical angular range when induced armature counter electromotive force voltages in the respective phase windings, which have an essentially trapezoidal shape, are in their flat or unvarying range within the voltage distribution during revolution of the rotor. Thus, currents are supplied to the phase windings only when the counter EMF voltages are essentially constant.

Abstract: A stepping motor with toothed stator poles and two sets of oppositely magnetized rotor teeth has its stator poles energized by a driver which responds to input pulses to successively deenergize alternate poles and keep them deenergized and then successively reenergize the alternate poles in the opposite direction. Thereafter the driver successively deenergizes the poles intermediate the alternate poles and keeps them deenergized until all intermediate poles are deenergized and then successively reenergizes the intermediate poles in the other direction until all the intermediate poles are reenergized. This drives the rotor in fractional steps. For larger fractional steps, larger numbers of poles are deenergized in response to each pulse. For even larger fractions the deenergization process is eliminated.

Abstract: A slip-recovery AC motor drive includes two inverters connected in series between the DC link terminals derived from the rectifier coupled with the rotor, and the thyristors are controlled asymmetrically between pairs of half-bridges pertaining to different inverters, thereby to by-pass the output of one inverter alternately during successive equal time intervals of conduction. The recovery transformer has two secondaries each connected to a corresponding inverter output.

Abstract: A phase lock loop commutation position control and method for a drive system for a DC field motor having a rotor and a plurality of stator windings is disclosed. Electric power is supplied to the stator windings in accordance with gating signals. The gating signals are generated in accordance with timing signals, which are provided in response to a clocking signal. A position signal is furnished as a function of the position of the rotor with respect to a preselected stator position. An error signal is generated proportionally to the phase difference between a preselected timing signal and the position signal. The clocking signal is produced as a function of the error signal. The invention also can include a shift signal produced as a function of the rotation of the rotor. The shift signal is added to the error signal effectively to cause the preselected timing signal to be advanced with respect to the position signal.

Abstract: A back EMF controlled, synchronous, permanent magnet motor capable of extremely high rotation speeds at high efficiency. The motor includes a permanent magnet flux source and excitation coils for producing a rotating magnetic field mounted on an iron free form to substantially eliminate core loss and resulting rotor drag. Back EMF is determined directly from the excitation and controls the excitation to produce a torque angle of substantially 90.degree. between the magnet and coil fluxes. Coil excitation is used at maximum efficiency and hunting is avoided. The permanent magnet provides a high flux density that also allows a low current in the motor coils and thus reduces coil copper losses to further improve efficiency.