Abstract: A system for speed-sensorless control of an induction machine includes a flux regulator & torque current calculator for operating the machine in a heavily saturated state to produce a saturation induced saliency; a saliency tracker for tracking an angle of the saturation-induced saliency; a signal injector for injecting an AC signal aligned with a saliency axis; voltage and current determiners for determining stator voltages and currents; and a rotor flux calculator for using the saturation-induced saliency angle, the determined stator voltages, and the determined stator currents to determine a magnitude and a location of a rotor flux vector. The flux regulator & torque current calculator is adapted to use the rotor flux vector to control the induction machine.

Abstract: A controller for an electric motor, includes a reference circuit and control circuitry. The reference circuit generates a reference signal having a phase and frequency determined in accordance with a set of motion parameters input to the circuit. The control circuitry receives the reference signal and receives a feedback signal from a rotation detector coupled to the motor, the detector having a predetermined rotational resolution, and compares the reference signal and the feedback signal to generate a drive signal used to drive the motor at a speed and phase of rotation determined by the frequency and phase of the reference signal. The phase of rotation of the motor is locked to the phase of the reference signal such that deviation of the phase of rotation relative to the phase of the reference signal at steady state is substantially smaller than the rotational resolution of the rotation detector.

Abstract: A method for controlling an asynchronous machine which is operated below a cutoff frequency in the base speed region with variable magnetization current and above a cutoff frequency in a field control speed region is provided. The maximum possible fundamental oscillation of a stator voltage is determined from a existing intermediate circuit voltage or battery voltage and a stator current is defined as a setpoint and impressed onto the asynchronous machine. A calculation is made of a rotor frequency needed, with that definition of the stator voltage to impress the current setpoint. A rotor frequency which corresponds to the current setpoint is compared via a control characteristic curve to the calculated rotor frequency and that rotor frequency value which is the greater of the two is used to determine the current setpoint. The method is advantageously performed with a microprocessor, with which the calculation algorithm may be executed rapidly, effectively, and contemporaneously.

Abstract: A field weakening control method in an induction motor, wherein a voltage limit is set up in an oval while a current limit is established in a circle on a current plane, where x-coordinate represents a current value for flux portion and y-coordinate defines a current value for torque portion when the motor is in a normal state of constant speed and no load applied, to thereby form a current command according to a juncture thereof for generation of a torque, such that the oval voltage limit moves to a predetermined -(minus) quadrant against a coordinate representing the current value for torque portion in an excessive state where accelerated speed is formed or load is applied, to thereby cause torque of excessive state to increase in comparison with the normal state, such that there is an advantage in that torque is increased to improve an accelerated speed efficiency when the induction motor is under excessive state, and field weakening is conventionally controlled when the induction motor is under a normal s

Abstract: The invention provides a sensorless control method and apparatus of a permanent magnet synchronous motor where magnetic axis can be assigned in all speed regions and speed can be controlled continuously irrespective of the speed command. In the control method, the d-q axis being the magnetic axis rotating in the real rotation speed .omega..sub.R of the motor is set and also the .gamma.-.delta. axis being the assigned magnetic axis of the motor is set, and when the rotation speed .omega..sub.R.sbsb..gamma. of the .gamma.-.delta. axis is determined, a distribution gain K1 is set so as to be decreased as the absolute value of the rotation speed command .omega..sub.RREF becomes large and a distribution gain K2 is set so as to be increased as the absolute value of the rotation speed command .omega..sub.RREF becomes large, and the rotation speed command .omega..sub.RREF is multiplied by K1 and the speed estimated value .omega..sub.

Abstract: A motor control processor controls motor spin-up in a disk drive by detecting environmental temperature at the spindle motor of the disk drive, controlling commutation phase advance to generate substantially maximum torque if the detected environmental temperature indicates that maximum torque is needed, and adjusts the commutation phase advance for optimal efficiency after the maximum torque is no longer needed. Following motor start and reaching operational speed, the motor is operated in a steady-state maximum operating efficiency mode unless sensed environmental temperature indicates that maximum torque, rather than maximum efficiency, is needed. The system determines that the need for maximum torque has passed either when a predetermined time interval after motor start expires or by repeatedly polling motor temperature information.

Abstract: A drive circuit for a sensorless three-phase brushless DC motor provides improved drive characteristics by generating a pseudo back-electromotive signal in response to the voltages of the stator coils, and then using the pseudo back-electromotive signal to commutate the current through the stator coils before maximums in the back electromotive force, thereby providing smoother motor rotation. The drive circuit includes comparators for generating rectangular difference signals by comparing the voltages of the stator coils, an edge detector and control circuit for generating a pulse signal that is delayed from the difference signals, signal generators for generating a trapezoidal signal and three step signals responsive to the pulse signal, and an output control circuit for generating drive signals for a commutator drive circuit responsive to the trapezoidal step signals.

Abstract: A control apparatus for variably controlling a speed of an induction motor includes a voltage generator, adders, a rotating speed calculating device, a rotating direction detecting device, and a multiplier. The voltage generator is operated for a predetermined period of time at the start or restart of the induction motor to cause self-excited oscillation in a control system including the voltage generator, the induction motor and the PWM inverter. The rotating speed calculating device obtains the rotating speed data, and the rotating direction detecting device detects the rotating direction of the induction motor based on the .alpha.- and .beta.-axis components, on the stationary coordinate, of the primary current of the induction motor. And, the PWM inverter is started based on the obtained rotating speed data and rotating direction.

Abstract: A method for the field-oriented control of an induction motor (2) by means of a frequency converter (1) is disclosed, in which method a transformation angle (.delta.) is determined by estimation and is corrected in dependence on a rotational speed (.omega..sub.mR) of a rotor flux vector (i.sub.mR) or of the induction motor (2) and/or in dependence on a delay time (T.sub.del). In this connection it is desirable to improve the control behavior. To that end, the transformation angle (.delta.) is corrected a second time to compensate for a phase shift in the frequency converter (1).

Abstract: A method and apparatus for starting a motor drive into a rotating motor, the method including determining an initial search frequency and search current wherein the current is less than a rated drive current, providing a d-axis flux generating current to the motor at the search frequency and at a magnitude equal to the search current, monitoring a q-axis flux error, decreasing the search frequency until the d-axis flux error is less than a threshold value, thereafter increasing the search current to the rated drive current and, after a flux-up period, providing both q-axis torque producing current and d-axis flux producing current to the motor.

Abstract: The present invention addresses a problem as to how to provide a motor control apparatus which has a magnetic pole position inferring means capable of inferring the position of a magnetic pole of a synchronous motor by adopting a simple method in a short period of time with a high degree of accuracy. In order to solve this problem, a signal id1* for inference use is applied and a peak value iqh of a response current iq' is detected by an iq' peak detecting unit. The peak value iqh is then supplied to a magnetic pole position inferring unit for inferring the position of the magnetic pole of the synchronous motor by carrying out multiplication processing.

Abstract: A system and method of calculating optimum angle advance for brushless permanent magnet motors. The calculations are based on the motor and drive parameters, and on operational variables including the motor speed and the motor load. The angle advance is calculated dynamically as a function of motor speed and where reluctance torque is involved, as a function of load current as well. For a given motor, the advance is calculated according to the speed and load together with the motor and drive parameters according to one or more angle advance equations.

Abstract: A power corresponding to an A/C voltage command id1* is applied in the d-axis direction of rotational coordinates of a stopped synchronous motor via a current control unit, a three-phase converting unit, and a power converter. Further, by using "an amplitude value of a current iq' in the q-axis direction of the rotational coordinates generated in response to the A/C voltage command id1*" which is fed back and detected via a current detector and a dq converting unit, a field pole position estimation value .theta. is converged. The field pole position is estimated by using the converged field pole position estimation value .theta. as a true value of the field pole position .theta. of the synchronous motor.

Abstract: A capacitively powered motor having a power switching circuit adapted to be connected between a power source and its winding for selectively energizing the winding to generate a magnetic field which causes a rotating assembly to rotate. A position sensing circuit provides a position signal representative of the position of the rotating assembly and a commutating circuit controls the power switching circuit to commutate the power switching circuit at a commutating angle and at a substantially constant duty cycle to achieve a desired rotating speed of the rotating assembly. The commutating circuit varies the commutating angle in response to the position signal to maintain the substantially constant rotating speed of the rotating assembly. As result, the efficiency of the motor is varied to maintain the substantially constant rotating speed.

Abstract: A method and apparatus for minimizing motor instability under no load conditions, the method including identifying instability by comparing consecutive current half cycle periods and, where the difference between half cycle periods is sufficiently large, determining that instability exists and modifying controller modulating waveforms by reducing waveform magnitude until stability is achieved. Preferably the apparatus for achieving stability includes only a single current zero crossing sensor to minimize hardware costs.

Abstract: When an induction motor is variable-speed-controlled via an electric power converting circuit, the magnetic flux of the induction motor is modulated by adding an alternating current signal to, for example, a magnetizing current command. For example, the component depending on the slip frequency of the induction motor is extracted by an extracting means from at least one of the amounts of changes of the voltage, the electric current, and the magnetic flux, which are caused by the modulation of the magnetic flux. The amount of the voltage or the electric current supplied to the motor, etc. is controlled based on the extracted component via an adjusting unit and a control means, thereby implementing superior control of the induction motor.

Abstract: A controller (400) for a variable-speed induction motor (498) includes field-oriented control (410, 476), which in a feedback (402) arrangement senses motor parameters to form field and torque error signals. The field error signals are processed by a first limited-state PI processor (490a), which individually limits the magnitude of the proportional component of the field voltage to no greater than the bus voltage. The field error signals are also processed by a state-limited integrator (426a) which limits the integral component of the field voltage to the difference between the proportional component and the bus voltage. A first summer (432a) sums the proportional and integral components to make the field voltage command. The torque error signals are processed by a further limited-state PI processor (490b) which individually limits the proportional component of the torque voltage to a value not greater than the available bus voltage, after the first PI processor has been given preference.

Abstract: The inverter controller includes a deviation arithmetic circuit which calculates the deviation between the current command (reference) and the output current, a vector angle arithmetic circuit which calculates the deviation current vector angle on the basis of the deviation calculated by this deviation arithmetic circuit, and a switching sequence logic circuit which selects the switching signal on the basis of the deviation current vector angle calculated by the vector angle arithmetic circuit and its own switching signal being output or on the basis of the deviation current vector angle and its own switching signal and the switching signal output previously, and obtains an output current by controlling self-turn-off switching devices on the basis of the switching signal output by the switching sequence logic circuit.

Abstract: An excitation circuit is disclosed for balancing the phase voltages in a two phase motor. The excitation circuit includes a first and second switch and a port for receiving a signal to drive the switches. The excitation circuit also includes additional electrical circuitry which can be designed to adjust the speed and timing of the first and second switches and balance the phase voltages in the two phase motor.

Abstract: A motor controller comprising drive unit for supplying power to the stator windings of a motor based on a current command, a stator current detection unit for detecting the stator current flowing in the stator windings, a saturation degree production unit for producing the saturation degree data indicating the extent to which the stator current deviates from the current command based on the current command and the stator current, a reference value production unit for producing a reference value of the saturation degree, a gain production unit for producing a gain indicating the rate at which the current command is changed, and a current command production unit for producing the current command data based on the saturation degree, the reference value and the gain, wherein the gain production unit produces the gain data based on at least one of the rotational speed of the motor and the current command.

Abstract: A device for driving a DC brushless motor by outputting commutation control signals based on voltages induced in the drive windings includes a position detection circuit having low-pass filter circuits that remove a chopping frequency component and have a phase lag of 60-90.degree. at maximum motor rotational speed, a rotational frequency computing section, and a phase correction amount computing section that effects a computation based on the rotational frequency computed by the rotational frequency computing section to set the commutation time point to produce a 30.degree. phase lag in a rotational speed range in which the phase lag falls in the range of 0.degree. to less than 30.degree. and to produce a 90.degree. phase lag in a rotational speed range in which the value of the phase lag falls in the range of 30-90.degree.. The device achieves high efficiency at optimum commutation timing in the high rotational speed region and suppresses vibration and noise in the low rotational speed region.

Abstract: A motor starter circuit providing recovery of the energy trapped in the motor windings when the supply voltage and current have opposite polarities by selectively controlling actuation of a plurality of high speed switches. The circuit, for use with a multiphase motor and power source that provides positive and negative voltage alternations which result in the generation of a load current in the motor having positive and negative alternations, includes a plurality of switch-diode combinations electrically configured such that for a given pair of supply voltage/load current polarities, only one diode of each combination may be forward biased.

Abstract: A motor control system for controlling the operating speed and direction of a three-phase induction motor. The invention particularly finds use for bringing a rotary printing cylinder precisely into register for processing products in sheet form, such as for printing sheets of corrugated cardboard in a machine for printing corrugated boxes. A three phase induction motor is single phase powered by an AC drive through a first and a second electrical conductor. Direction switching signals and time delay speed switching signals are applied to the appropriate terminals of the AC drive by the second and a third electrical conductor. This allows motor powering and control using only three conductors, such from as the slip rings on industry standard corrugated box printing equipment.

Abstract: A motor drive control apparatus has a number of revolution setting circuit, a driving circuit for driving a motor to rotate at a predetermined number of revolution based on a number of revolution command signal output from the number of revolution setting circuit, a number of revolution detecting circuit for detecting the number of revolution of the motor, a driving voltage adjusting circuit for adjusting a level of the driving voltage of the motor to be supplied to the driving circuit, a motor control circuit including a PLL control circuit for controlling the number of revolution of the motor so that the phase difference between the phase of the number of revolution command signal and the phase of the number of revolution detection signal becomes within a predetermined range of value, and a voltage control circuit for instructing the driving voltage adjusting circuit to adjust the driving voltage of the motor to be at a level in the vicinity of the PLL controllable minimum level.

Abstract: A slip controlled induction motor using a variable frequency feedback transducer comprises a motor stator, a motor rotor and a variable frequency feedback transducer (VFFT). The VFFT includes an input winding transformer coupled to an output winding by a VFFT rotor. The VFFT rotor is operably connected to the motor rotor so as to rotate with the motor rotor at the same angular velocity. The input winding is excited with an input AC voltage of predetermine frequency. The transformer coupling combines the predetermined frequency AC input with the signal produced by the VFFT rotor to produce a variable frequency signal in the output winding which is fed as an input to the motor stator. Since the stator input is tied to the motor rotor angular velocity, the stator input will always have a constant absolute frequency difference with the motor rotor.

Abstract: To provide a trans-vector controller for an alternating current ("AC") motor that facilitates operating the secondary resistance of the AC motor without experimentally rotating the AC motor.In a preferred embodiment, the variable speed control circuit, including a secondary resistance value generating device, changes the direct current ("DC") exciting current and operates the secondary resistance of an induction motor by superimposing an AC signal with small amplitude outputted from a AC signal generator onto a reference current value immediately before the start of the induction motor in the state of DC excitation.

Abstract: An electric current compensation circuit for use with a multiple-phase burshless motor to reduce ripples in the output torque is disclosed. It contains a plurality of electric current compensation loops each for a respective phase winding and each of the electric compensation loops contains: (a) a first input for receiving a line current from the driver; (b) a second input for receiving the compensation current from the motor sensor; (c) a forward rectifying circuit for forwardly rectifying the line current and the compensation current; (d) a reverse rectifying circuit for reversely rectifying the line current and the compensation current; and (e) a summation circuit for summing the forwardly rectified compensation current and the reversely rectified compensation current and outputting a synthetic current to a phase winding of the motor.

Abstract: An induction motor controlling device realizes precise and discretional revolutional speed vector control without requiring a speed detector using an algorithm which is suitable for a system including a microcomputer.A three-phase-to-two-phase converter detects a torque current inside a motor as a DC quantity based on instantaneous values of motor currents. A slip frequency is estimated using the torque current, and the slip estimation is used to obtain a motor's revolutional speed. An error in revolutional speed estimation is compensated by a compensation value which is obtained by amplifying an excitation current common phase voltage command.

Abstract: A method for controlling the power supplied by a sinusoidal source (1) wherein the power supplied is determined, on the one hand, by the integer number of the pulses comprised in a burst which is fully switched through to the load (17) at the output of the circuit and, on the other hand, by the length of the last phase angle-controlled pulse within each burst. To provide the actuation signal for a switch which connects the sinusoidal pulses to the load, the zero passages of the sinusoidal pulses (A) of the sinusoidal source (1) are determined in a zero passage detector (5). A division circuit (7) generates trigger pulses (C) of a lower frequency from the zero passage pulses (B), which trigger pulses reset the ramp voltage (D) of a sawtooth generator (9). The ramp voltage (D) is compared in a comparator (15) to a regulated quantity (E) of a desired value device (11).

Abstract: A balanced and synchronized phased detector circuit is provided for a three phase power controller for AC induction motors. The power controller includes a thyristor or switching element for each motor phase winding between a line phase terminal of a three power line and the motor's input terminals, and decides the sequence for firing the thyristors. The phase detector includes a dividing resistor network between each phase's line terminal and the front-end operational amplifiers used in the phase detector, and an adjustable dividing resistor network between each motor terminal and the front-end operational amplifiers. The resistor networks allow a differential voltage to be set between the phase line terminal and the motor terminal for each phase, to a voltage appropriate for firing the respective thyristor. By allowing control over the front-end differential voltage, the phase detector virtually elements vibrations encountered during operation of the motor.

Abstract: A commutation control strategy for eliminating torque ripple and noise from a brushless motor which has a plurality of motor phases connected in a bridge, each phase having a top switching device provided between a phase winding and a positive voltage supply and a bottom switching device provided between the phase winding and a less positive voltage supply in which following commutations of the motor, when the current flowing in a first phase is decaying towards zero and the current in a second phase is rising from zero, the switching devices are operative between a state in which the current flowing in the first phase is caused to decay at a first rate, and another state in which the current flowing in the first phase is caused to decay at a second rate which is lower than the first rate so that the rate of decay of the current in the first phase substantially matches the rate of rise of the current in the second phase.

Abstract: The invention concerns an improved system for windshield wipers in vehicles. An induction motor is used, in which speed is accurately controlled by controlling frequency of power supplied to the motor. The induction motor may be of the consequent-pole type, which ordinarily does not produce sufficient torque. Addition of (a) auxiliary tooth slotting and (b) skew has raised the torque produced to acceptable levels.The invention includes a control system, which senses excess load on the motor, which occurs as the windshield dries, and reduces motor speed, subject to a minimum, in response.

Abstract: A system for accurately determining a torque current i.sub.qe for use in field oriented control of an induction motor at low rotor frequencies (e.g., about half of the motor rated frequency) which provides an ideal no load current and still enables high torque at low speed. The system includes a frequency/correction angle identifier which, based on an applied stator voltage frequency, provides a correction angle which is added to a perceived phase angle to generate a corrected phase angle which is used to calculate the torque current component i.sub.qe. The torque current component is then used by a slip calculator and an IR compensator to adjust motor operation.

Abstract: A disk drive including firmware for overcoming stiction and breaking free the heads of a disk drive which may adhere to the disk surface when the disk is at rest. Upon start-up of the disk drive, if stiction at the head/disk interface occurs, the voltage to the spindle motor and/or actuator motor may be rapidly fluctuated so as to cause a pulsing of the spindle motor and/or actuator motor. Pulsing both the spindle motor and actuator motor creates forces in a plurality of radial directions to allow the head(s) to break free from the disk(s) in the direction of least resistance. Moreover, as the resonant frequency of the spindle motor varies depending on the number of heads that are stuck, the firmware pulses over a range of frequencies including the various resonant frequencies of the spindle motor corresponding to various numbers of heads stuck.

Abstract: An inverter control system for operating an induction motor calculates the primary magnetic flux vector and instantaneous torque value from the primary terminal voltage and primary current of the motor and produces a voltage vector to be delivered to the PWM inverter depending on the deviations of primary flux vector and instantaneous torque value from their command values and the phase angle of primary flux vector, with the switching of voltage vector being controlled so that the PWM inverter operates in a prescribed range of switching frequency irrespective of the period of calculation of the primary flux vector and instantaneous torque value. Setting the upper limit of switching frequency reduces the heat generation of the PWM inverter, allowing it to suffice with a smaller cooling device, and setting the lower limit of switching frequency reduces the magnetic noise and torque fluctuation of the motor.

Abstract: A rotation position detecting circuit for a sensor-less motor and a motor device include a motor (1) which is rotated and driven by adding a sensor signal having a high frequency to a sine wave drive signal and cosine wave drive signal through adders (5S) and (5C), respectively. Further, a sensor signal is extracted and demodulated from a signal flowing in the motor (1) by a band pass filer (9), and this is defined as a rotation position detection signal. In the sensor signal from the band pass filter (9), its current value is changed corresponding to a change of an impedance resulting from a rotation of a magnet of the motor. As a result, it is possible to detect the rotation position of a rotor magnet by detecting the change of the current value.

Abstract: In a motor drive circuit, the collector-emitter paths of two npn-type transistors are connected in series between a power line and ground, and the junction between the two transistors is connected to a motor coil. A control circuit feeds a control current to the base of the transistor connected to the power line so that this transistor supplies a drive current to the motor coil. A current mirror circuit is provided which is constituted of two pnp-type transistors whose emitters are connected to the power line, and the base and collector of the input-side transistor is connected to the control circuit through a diode. The base of another pnp-type transistor is connected to the cathode of the diode, and the emitter of this transistor is connected to the collector of the output-side transistor of the current mirror circuit and to the base of the transistor connected to the power line.

Abstract: Apparatus and method for controlling the electromagnetic torque of an asynchronous machine. The apparatus includes a corrector which controls the electromagnetic torque of an asynchronous machine by regulating the magnetic flux and by controlling the electromagnetic torque C.sub.m, the corrector including a regulator circuit (3) for regulating the rotor magnetic flux .phi..sub.r , having non-linear control using input/output linearization by static looping and whose output controls the d-component of the stator current i.sub.s, a first linear corrector (1) of the proportional, integral type whose output v is the input to the regulator circuit, and a second linear corrector (2) of the proportional, integral type whose output controls the angular frequency of the rotor currents .omega..sub.s1.

Abstract: The invention relates to an X-ray apparatus, comprising a rotary-anode X-ray tube, a device for monitoring the rotational speed of a rotary-anode drive motor of the X-ray tube, a sensor circuit for determining an angle signal which is dependent on the phase angle between a reference voltage and a current associated with the motor, a comparator circuit for detecting the angle signal variation which serves as a criterion for the rotational speed of the motor, and also comprising a frequency changer. Thanks to the fact that there is provided a device for forming a brief keying signal so as to trigger a reduction of the frequency of the rotary-anode drive motor, the device is also suitable for induction motors in which only a small phase angle variation is measured between standstill and the operating rotational speed.

Abstract: Methods and apparatus for switching a load between first and second sources is shown to include first and second solid state switches connected to the load. First and second mechanical breakers are connected between the switches and the sources so that each source is connected to the load through a circuit breaker and solid state switch. A controller is connected to sense the voltage from the first and second sources. The controller is connected to the first and second switches and the first and second mechanical breakers. The controller senses the phase difference between the voltages from the first and second sources. The controller causes the first and second mechanical breakers to open and close in response to sensing the phase difference between the sources. The first and second mechanical breakers can include medium voltage vacuum breakers.

Abstract: In a vector control method for controlling a motor by detecting a primary current in a motor driven by an inverter circuit with an electric current detector, dividing the primary current detection value detected by the electric current detector to a current-for-torque detection value and a detected current-for-excitation detection value, and thus dividing a primary current instruction value to a current-for-torque instruction value and a current-for-excitation value, a portion between the current-for-torque detection value and current-for-excitation detection value each obtained from the primary current detection value is changed by an Iq gain circuit (gain Kqc) and an Id gain circuit (gain Kd), which are discrete circuits, and the rated torque characteristics of the motor is changed according to change of the apportion.

Abstract: A control system (100) for a five-phase brushless DC motor (102) including a stator having five windings and a rotor (116) mounted for rotation relative to the windings (114). The windings (114) are adapted to be electronically commutated in response to the rotary position of the rotor (116). The control system (100) includes a sensing circuit (106) to sense the rotary position of the rotor (116) using an optical or magnetic sensor or the back electromotive force voltages in the windings (114). Electronic switches (112) control the flow of current through the windings (114) in response to control signals generated by a control circuit (110) in response to the rotary position of the rotor (116). The control circuit (110) includes start-up logic to start the motor (102).

Abstract: A control apparatus for conducting a variable speed control of an AC motor by controlling an M-axis component and a T-axis component of a current flowing through the AC motor.

Abstract: An apparatus for controlling the speed of an induction motor includes a first winding and a second winding. The first winding and second winding are adapted to be coupled to an AC source for supplying an AC input signal. A first switching device is coupled to the first winding and a second switching device is coupled to the second winding. Each of the switching devices is operative in a low impedance state enabling current to flow through the associated winding of each switching device and a high impedance state preventing significant current flow through the associated winding of each switching device. A controller switches each of the switching devices from the high impedance state to the low impedance state in a sequence for controlling the current in the windings, which induces a phase shift between the AC voltages across the windings.

Abstract: A current control method for a servo motor capable of compensating a delay in a current loop. A corrective electrical angle corresponding to the delay in the current loop is obtained and a phase angle is corrected using the corrective electrical angle. Then the delay of the current loop is compensated by a DQ coordinate conversion for converting a three-phase AC current into a two-phase DC current, or a two-phase DC voltage into a three-phase AC voltage, using the corrected phase angle. The phase angle is corrected by subtracting the corrective electrical angle from the phase angle and the DQ conversion is performed for obtaining a two-phase DC current from a three-phase AC current using the corrected phase angle. Alternatively, the phase angle is corrected by adding the corrective electrical angle to the phase angle and the DQ conversion is performed for obtaining a three-phase AC voltage from a two-phase AC voltage using the corrected phase angle, to compensate the delay of the current loop.

Abstract: A brushless resolver having a stator and a rotor, and a resolver part axially displaced to one another and a transformer part and having associated windings is provided. An additional short-circuited winding arranged parallel with the transformer rotor winding with few turns on the iron core thereof is also provided. A lowpass filter is thereby formed, which compensates the unwanted frequency-dependent phase displacement between the input voltage and the output voltages for the respective frequency.

Abstract: A time delay compensated synchronous reference frame controller for a drive motor having a rotor and using an alternating current having a phase angle includes a low pass filter electrically connected to the drive motor for eliminating high frequency components of the alternating current, a coordinate transformer electrically connected to the low pass filter for receiving the alternating current and for defining a moving reference frame based on the phase of the alternating current, a controller electrically connected to the coordinate transformer for driving the alternating current to a proper phase relative to a flux of the rotor of the motor, an inverse coordinate transformer electrically connected to the compensator for receiving the alternating current and for transforming the moving reference frame to a stationary reference frame, and a reference frame shifter operatively connected to this coordinate transformer and the inverse coordinate transformer wherein the reference frame shifter defines a shift i

Abstract: An input power control apparatus for use with an AC induction motor adjusts a firing angle to allow the motor to run at near a rated speed of the motor and then to find a minimum power point at some voltage level in a variation of the applied voltage.

Abstract: A control system for an induction motor of the present invention independently commands the torque current component and the exciting current component of a stator current group supplied to the stator of an induction motor so as to feed-back control the amplitude and phase of the stator current group. The torque current component is commanded to control the output torque of the induction motor in correspondence with the output of a steering force sensor for detecting the steering force. According to an electric power steering apparatus using an induction motor controlled by the control system, a permanent magnet is not used for the motor so additional equipment such as a clutch is not required. Consequently, the structure can be simplified and the size of the unit can be reduced. Further, manual steering operation can be performed in the case of failure.

Abstract: A driving device controls a permanent-magnet synchronous motor having a permanent magnet in its rotor using a voltage-type inverter supplying drive power for the synchronous motor, makes the torque of the synchronous motor and the d-axis current flowing in the synchronous motor in the direction of the magnetic flux generated by the permanent magnet approach their own command values, and performs weakening field control by decreasing the d-axis current. To perform the above described control without complicated d-axis current command value operations or temperature amendments to motor constants, the driving device includes a proportional controller for outputting a d-axis signal proportional to the deviation between a d-axis current detection value and a d-axis current command value for the motor.