Abstract: In an automatic transmission position control by a motor, it is determined whether the present instant belongs to a starting period, that is, the present instant is immediately after resetting of a control unit or application of power to it. If it is the starting period, an actual shift position that is detected from an output of an output shaft sensor for detecting a rotation position of a motor is set as an instructed shift position. With this measure, even if the control unit is reset for a certain reason while the vehicle is running, the instructed shift position is not changed in association with the resetting. This prevents trouble that the shift position is switched contrary to the intention of the driver, whereby the reliability of a position switching control can be increased.

Abstract: A method for determining a rotor position angle of a synchronous machine, the method comprising the steps of determining inductances (LA, LB, LC) of the synchronous machine in stator phase directions; generating an inductance vector (L) on the basis of the determined inductances (LA, LB, LC); and determining the rotor position angle (qr) on the basis of the determined inductance vector angle.

Abstract: An inverter that executes a d q-axis control of a three-phase synchronous motor needs a rotational position sensor that detects rotational positions of an electric motor for mutual conversion between two-phase and three-phase. An angle error of this rotational position sensor affects accuracy in the d q-axis control, so that it is necessary to make a compensation with accuracy. In the conventional method, however, there is a problem of occurrence of an ignorable error due to influence of noise. An origin offset calculation method according to the invention includes a first process of forcibly making d q-axis current command values zero; a second process of multiplying a magnetic flux component voltage command value at this time by a proportional integral gain; and a third process of storing a rotational position sensor phase error when a magnetic flux component voltage command value becomes zero being a result of the second process.

Abstract: A circuit configuration for operating an electric motor is described, the circuit configuration containing a timer. As a function of a first differential signal between a setpoint signal and an actual value signal, a regulator supplies a first switch signal for feeding current to the electric motor. Simultaneously, the timer is started which limits the current feed signal to a specified maximum time. A detection system detects a change in the setpoint signal and thereupon outputs a second switch signal that also starts the timer and is able to trigger the current feed to the electric motor. The circuit configuration both protects the electric motor from a thermal overload and also makes it possible to feed current to the electric motor if a setpoint changes. The circuit configuration is suitable to be used in a variable speed drive.

Abstract: In a conventional rotation state detecting apparatus of a synchronous machine, since short-circuiting must be carried out twice or more when a rotation speed is detected, there have been problems in that it takes a time to detect a rotation state, and it takes a time to start up. A rotation state detecting apparatus for a synchronous machine according to the present invention has been made to solve the above problem, and includes a calculation unit for outputting a voltage vector command and a trigger signal and for outputting a rotation state of a synchronous machine having at least three windings in an idle state, a circuit unit for applying voltages to the respective phases of the synchronous machine on the basis of the voltage vector command, and a detection unit for detecting a current of the synchronous machine on the basis of the trigger signal and outputting a value of the detected current to the calculation unit.

Abstract: In a synchronous motor control device that corrects a deviation in rotational position which is related to a rotational position detector for a synchronous motor on which vector-control is performed, the synchronous motor control device includes: a current instruction generator that disables a torque instruction to set d-axis and q-axis current instructions as zero when a phase correction instruction is inputted; a current controller that outputs d-axis and q-axis voltage instructions based on the d-axis and q-axis current instructions; a phase correction quantity detector for determining the amount of offset in which the d-axis voltage instruction becomes zero when the phase correction instruction is inputted and the d-axis voltage instruction is not zero; an adder for adding a rotor positional angle and the amount of offset; and a voltage converter for determining three-phase voltage instructions based on the additional value, the d-axis and q-axis voltage instructions.

Abstract: A brushless, synchronous direct current motor is operated by supplying a direct current voltage as an input voltage for commutating the motor phase windings. The speed of the synchronous motor is modified or varied in two speed ranges. In the first speed range, a linear change of the input voltage is carried out up to a speed threshold value. In the second speed range with higher speeds than in the first speed range, a vector modification of the input voltage is carried out, for example for controlling the speed of a fan motor.

Abstract: The invention has an object to provide a magnetic pole position estimating method and a control apparatus for a synchronous motor which reliably detect the position of a magnetic pole of the synchronous motor to carry out stable control also when a high load is applied or a load is suddenly changed. A coordinate transformer (8) transforms a detected current value is into an impedance observation axis positioned in a place shifted from an estimated magnetic pole position &thgr;{circumflex over ( )} by 45 degrees. A high-frequency impedance estimator (10) estimates high-frequency impedances Zdm and Zqm on two points which are advanced and delayed by an electrical angle of 45 degrees from a &ggr;-axis. A first magnetic pole position estimator (13) estimates a first magnetic pole position estimated value &thgr;{circumflex over ( )} to eliminate a deviation between the high-frequency impedances Zdm and Zqm.

Abstract: A control algorithm provides automatic control of the turn-on angle used to excite the switched-reluctance motor (SRM). The control algorithm determines the turn-on angle that supports the most efficient operation of the motor drive system, and consists of two pieces. The first piece of the control technique monitors the position of the first peak of the phase current (&thgr;p) and seeks to align this position with the angle where the inductance begins to increase (&thgr;m). The second piece of the controller monitors the peak phase current and advances the turn-on angle if the commanded reference current cannot be produced by the controller. The first piece of the controller tends to be active below base speed of the SRM, where phase currents can be built easily by the inverter and &thgr;p is relatively independent of &thgr;m. The second piece of the controller tends to be active above base speed, where the peak of the phase currents tends to naturally occur at &thgr;m, regardless of the current amplitude.

Abstract: Methods and apparatus permit: monitoring a level of a DC source that is used to provide an operating DC voltage to a control circuit and to provide DC bus voltage to a driver circuit for a polyphase motor, the control circuit being of a type that senses signals in windings of the polyphase motor to determine a rotor position thereof and to maintain synchronization therewith; converting kinetic energy of the polyphase motor into a secondary DC source when the level of the DC source has fallen and reached a threshold; and regulating a voltage level of the secondary DC source such that it is operable to provide the operating DC voltage to the control circuit, and such that the control circuit is capable of maintaining synchronization with the polyphase motor while the DC source remains substantially at or below the threshold.

Abstract: In an actuator having an integrated drive circuit, a switching current flowing in a coil within the actuator is included in a position sensor signal of the actuator. According to the present invention, by arranging a detection circuit which performs sampling in synchronization with noise, a rotational position which does not include higher harmonic waves can be detected even if the switching noise in a motor coil current in the actuator itself is generated. Consequently, elimination of the influence of the noise allows posture and position control with less vibration to be realized.

Abstract: The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.

Abstract: A method for controlling starting of a synchronous motor having an excellent starting ability and capable of coming into a commutation mode in a short time is provided. An AC current having a predetermined frequency is supplied to a field coil 81 of a synchronous motor 8 by an inverter 91, thereby starting the synchronous motor 8. By detecting a terminal voltage of the field coil 81 of the synchronous motor 8 at the starting time, and decreasing a voltage waveform component based on the AC current supplied by the inverter 91 from the detected voltage, the waveform is corrected so that the voltage waveform component based on the counter electromotive force can be confirmed (110). And after integrating the corrected waveform (111) and converting the same into a square wave (112), a phase difference between the same (104) and an output of a 120° energization waveform generating circuit 102 is detected to be fed back.

Abstract: A motor driver generates a signal synchronized with the rotation of a three-phase by comparing each of induction voltages generated in the motor's coils with a specified standard voltage. A triangular wave signal is generated such that its frequency increases with the speed of rotation of the motor increases. A standard value is set according to a change in the amplitude of the triangular wave signal and a noise mask signal is generated by comparing this standard value with the triangular wave signal. Noise is removed from the synchronized signals by using the noise mask signal, and currents are supplied to the coils of the motor by using the synchronized signals from which noise has been removed. With such a motor driver, noise can be effectively eliminated because both the noise mask time and the position detecting time can be varied gently.

Abstract: The present invention provides apparatus, systems and methods for fail passive servo controllers. In accordance with an exemplary embodiment of the present invention, servo controller is used with an ALS to control an aircraft during landing procedures. In accordance with one aspect of this exemplary embodiment, upon a failure (e.g., of one of the components of ALS) servo controller fails passively rather than actively. In an exemplary embodiment, the fail passive nature of the servo unit is accomplished by providing at least two independent signal and drive current paths for controlling the servo motor. As such, the servo motor will not generate torque unless the two independent signal lanes agree. For example, when a component such as processor, difference amplifier, or PWM fails or otherwise ceases to function properly, servo motor will not runaway, but rather will fail with only minor transient movement, or alternatively, servo unit will lock at its current position.

Abstract: The present invention relates to a control method and a control device for a position sensorless motor which has position sensorless operation and synchronized operation, wherein a rotation position of a rotor is detected on the basis of counter electromotive forces generated in stator coils in the position sensorless operation, the stator coils are excited in synchronization with the detected rotation position of the rotor to rotate the rotor and a deviation between a target position and the present position is determined from a target rotation position according to the position command signal and the detected rotation position, position sensorless close loop drive is made on the basis of the determined deviation, and when the synchronized operation is made, the stator coils of the motor are excited in synchronization with the position command signal to rotate the rotor.

Abstract: A motor driver generates a signal synchronized with the rotation of a three-phase by comparing each of induction voltages generated in the motor's coils with a specified standard voltage. A triangular wave signal is generated such that its frequency increases with the speed of rotation of the motor increases. A standard value is set according to a change in the amplitude of the triangular wave signal and a noise mask signal is generated by comparing this standard value with the triangular wave signal. Noise is removed from the synchronized signals by using the noise mask signal, and currents are supplied to the coils of the motor by using the synchronized signals from which noise has been removed. With such a motor driver, noise can be effectively eliminated because both the noise mask time and the position detecting time can be varied gently.

Abstract: The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.

Abstract: A circuit for the measurement of time intervals includes a generator providing primary periodic pulses, a frequency divider capable of transmitting secondary periodic pulses for scaling down the frequency of the primary periodic pulses, and a counter for counting the secondary periodic pulses transmitted during the measured time interval. The frequency divider is programmable by a digital factor which determines the frequency division. The circuit further includes a self-calibration circuit for modifying the digital factor as a function of the number of pulses counted by the counter during a previous time interval measurement.

Abstract: A pulse width modulation circuit (10) has a first set of windings with a first inverter circuit coupled thereto and a second set of windings having a second inverter circuit coupled thereto. A pulse width modulation controller pulse width modulates the first inverter circuit and the second inverter circuit so that the first inverter circuit has a predetermined phase shift therebetween to reduce input ripple.

Abstract: In a method of operating and controlling hysteresis motors energized by a three-phase power supply and individually monitored by an operating monitoring system, whereby the effective power output of the individual motors is determined and the three-phase voltage is changed if the effective power output deviates from a predetermined range, the hysteresis motors are first energized at an intermediate range voltage until they reach nominal speed and are then running at synchronous speed, the supply voltage is then increased to an upper range, where the remanent magnet pole strength is impressed on the armature and then reduced to a lower range for continuous operation of the motors, the power output of the individual motors is monitored and, if it drops below a threshold indicating a switch to asynchronous operation, the operating voltage is again increased to the intermediate range for renewed synchronization.

Abstract: A motor current detection amplifier detects a motor current's areas in two phase periods with reference to a motor voltage. A controlling microcomputer computed the ratio of the motor current areas of the two phase periods and provides the same as phase difference information which is in turn used to control a motor drive voltage to apply a sine wave of a predetermined period to the motor's coil to allow 180°-driving including a sine wave conduction resistant to noise and achieving a reduced cost hike.

Abstract: A system for starting synchronous motor from a pulse-width-modulated static inverter without using rotor position or speed measurements. The system monitors supply current to the stator and derives a relationship between that current and the magnetizing flux. The system utilizes a narrowband filter that is tuned to pass only the motor currents fundamental component and whose tuned frequency changes with variations in motor speed. Furthermore, the system reduces the excitation provided to the motor after a certain value of line voltage is sensed.

Abstract: A method and apparatus for transferring an AC machine between non volts per hertz drive and a power supply such as supply mains, or a generator. In a transfer procedure, the motor drive is placed in a quasi-voltage mode prior to transfer to permit the output of the motor drive to be synchronized to the output of the power supply. In capture procedure, the output of the drive is preconditioned based on detected states of the AC machine to synchronize the voltage at the terminals of the AC machine with the output of the drive. During the capture procedure, opening of a contactor is detected by comparing the frequency and/or voltage at the terminals of the AC machine with that of the power supply.

Abstract: A control system for an interior permanent magnet motor which includes five regulators to provide efficient control of the motor. Deviation from a desired maximum torque per amp trajectory is minimized by making two of the five regulators field-weakening regulators. First and second regulators provide current control of the quadrature-axis current and direct-axis current, respectively. A limiter limits the direct-axis current from exceeding the maximum allowed stator current and any excess current is added to the quadrature-axis current. Fourth and fifth regulators are field-weakening regulators. The fourth regulator generates a first field-weakening signal that increases the direct-axis signal when the quadrature-axis voltage approaches a desired maximum voltage. The fifth regulator generates a second field-weakening signal that decreases the quadrature-axis current signal when the direct-axis voltage approaches a desired maximum voltage.

Abstract: An image detecting apparatus comprises a rotating disk having pinholes that allow light to pass through, a photosensor for detecting the rotation of the disk, a CCD camera for capturing a confocal image of a specimen passed through the pinholes of the disk, a brushless DC motor for rotating the disk at a given speed, and an FPGA which produces a pulse-like brake signal having two levels for accelerating and decelerating the disk and its pulse width set variable and outputs it to the DC motor, thereby allowing the synchronization of the rotation of the disk with the image capture timing of the CCD camera.

Abstract: There is provided a synchronous control apparatus of high synchronous control accuracy, and the synchronous control accuracy is seldom deteriorated even if input of the position command and detection of the main shaft position are delayed. The synchronous control apparatus comprises a command generating device, a main shaft device, and a subsidiary shaft device.

Abstract: A device and method for driving a concentrated winding synchronous motor which, upon supply of a given electric current to a stator coil of the motor, generates an increased torque. Periodical corrections are executed to the waveform of the current to be supplied to the coils of each phase of the stator and corrections are executed to decrease the alternating current supplied to the coil of any tooth at which a portion of a magnetic field generated, with respect to the pole of the closest rotor, is in a direction reverse to a rotation of the rotor.

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: A position sensorless interior permanent magnet drive system and methods for use in electric and hybrid electric vehicles. The interior permanent magnet drive system and method use two rotor position estimation techniques for low and high speed operation and an initial rotor magnet polarity detection technique used at stand-still conditions. The use of the two different rotor position estimation techniques in combination enhances system efficiency and accuracy.

Abstract: A variable frequency motor starting system has a variable frequency AC power supply for generating an AC power output signal applied to an AC motor. A controller is coupled to the variable frequency AC power supply for producing a control signal for adjusting the frequency of the AC power output signal produced. Upon initially applying power to an AC motor or detection of a starting current for an AC motor, the controller adjusts the frequency of the power output signal applied to the AC motor. The frequency of the power output signal is adjusted to a value below the value of the typical operating frequency. The value of the frequency can be increased to the final operating value.

Abstract: A drive control apparatus for an electric synchronous machine is composed of armature current control means and transient operation detection means. When the synchronous machine is intended to increase power in a transient operation, the current control means supplies the armature winding with compensation current to cancel counter-electromotive force formed when field current is supplied to the field winding through a mutual inductance of the field winding and the armature winding.

Abstract: A generator set controller verifies the status of a synchroscope mode selector to determine whether the generator set controller is operating in a synchroscope mode. When operating in a synchroscope mode, the generator set controller uses an existing display panel to create an indication of the difference between the phase of the power on a power bus and the phase of the power output of the generator.

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: A synchronous motor control system which can freely regulate n-phase electric currents in a synchronous motor to control the characteristics of the synchronous motor. The synchronous motor control system can enhance the output torque per unit weight of a synchronous motor (40) simultaneously with reducing torque ripples. The waveform of three phase alternating currents is freely corrected over a range of +30 degrees from a specified electrical angle, at which a target phase current drawing a sine-wave curve reaches its peak value. It is assumed that this range of .+-.30 degrees corresponds to a range of 0 degree to 60 degrees. By way of example, the waveform is controlled to the peak value of the phase current in a range of 0 degree to 28 degrees. The correction of the phase current is carried out for the target phase which produces the primary magnetic flux of a revolving magnetic field.

Abstract: An AC machine comprises: a motor energized by an AC source subject to irregularities of frequency and voltage; a generator driven by the motor for supplying an AC output signal of substantially constant frequency and voltage, the generator having a rotor with a layer of a re-magnetizable, relatively high coercive magnetic material on the rotor and a stator of a soft magnetic material having a pole piece and an excitation coil on the pole piece, the stator and the rotor rotating relative to one another with a clearance enabling rotor poles to be formed on the re-magnetizable layer by current energizing the excitation coil; and, a control signal generator responsive to at least one of the AC output signal and a signal representative of the current energizing the excitation coil for generating pulses of programmed wave shapes which differ in at least one of width, phase and magnitude as necessary to modify the rotor poles during the irregularities of the AC source to maintain the substantially constant frequency

Abstract: The present invention provides a controller with a function of detecting status to be losing synchronism for a stepping motor driven by constant-current system. A current controller 404 applies the driving-current to a stepping motor 401 in accordance with the command derived from a control unit 407. The applied current is observed by a current measuring unit 403, and stored in a current observing unit 409 in response to the sampling signals generated from a sampling signal generating unit 408. After an excitation has completed, the observing waveform is compared with a predetermined reference waveform in the control unit, and it is determined that a loss of synchronism occurs in the stepping motor when these do not agree within a predetermined tolerance.

Abstract: Without consuming excessive energy, the invented control unit of refrigerating machine can pour out an accurate amount of refrigerant resting inside the lubricant in short time in order to prevent its foaming. A refrigerating machine provided with inverter-driven compressor comprises current detection circuit that detects current being supplied to drive the compressor and a control circuit that controls the compressor based on a detection result from the current detection circuit. The invented control unit for refrigerating machine is characterized in that the control circuit which applies fixed frequency and fixed voltage to the compressor on start-up. An operation of the compressor is valuated using detection result from the current detection circuit, and based on the result from the current detection circuit, operating frequency of the compressor is controlled.

Abstract: Electronic circuit having a digital controller operation of a synchronous motor.Precision motors for driving, for example, a video head drum in video recorders are normally designed as externally commutated synchronous motors. These motors are driven with square-wave voltages by a digital controller (CON), whose circuitry can easily be implemented.The object of the present invention is to specify an electronic circuit of the type mentioned initially for controlling a synchronous motor, which enables good synchronism and the motor to be operated with little electrical noise.This object is achieved in that the synchronous motor is driven by sinusoidal signals, a separate control signal from the controller (CON) influencing the amplitudes of the drive signals (U1, V1, W1). A regulating signal for regulating the synchronous motor is produced by a sensor (GE) which is arranged on the synchronous motor, which regulating signal produces a fixed phase relationship between rotor revolution and drive signals.

Abstract: A system for preventing objectionable large torque pulsations during the starting and synchronization of a line-start permanent magnet motor compares motor speed with motor synchronous speed and power source phase with the motor back-emf phasor. The motor starting armature is coupled to the power source and the PM armature is disconnected from the power source before motor speed has reached to within a predetermined margin of synchronous speed and before the back-emf phasor has dropped below a predetermined phase difference. After motor speed has approached synchronous speed to within the margin and the phase difference has dropped below the predetermined phase difference, connections are reversed so that the starting armature is disconnected from the power source and the PM armature is coupled to the power source.

Abstract: The sensing of BEMF signals in the motor's windings for synchronizing the phase switchings, in driving a brushless and sensorless motor with predefined constant voltage or current values or predefined voltage or current profiles stored permanently in a memory, is greatly simplified through a reconstruction technique that avails itself of the knowledge of the predefined drive values. The sensing does not require access to the center star point and is performed by sensing either the voltage difference between the terminals of two windings or of the current flowing in two windings, depending on whether a current or voltage mode is employed.

Abstract: In a state of synchronous operation in which a voltage and a frequency of an inverter output are increased in a stage of starting, when it is decided that a voltage difference signal is not at a specified level by a voltage difference signal level deciding section (41) or when a comparison result in a mode comparing section (42) signifies that a position signal and an inverter mode do not have a specified relation, a V/F pattern setting section (44) outputs a voltage command signal for lowering the inverter output voltage to a PWM section (54).

Abstract: A system for starting synchronous motor from a pulse-width-modulated static inverter without using rotor position or speed measurements. The system monitors supply current to the stator and derives a relationship between that current and the magnetizing flux. The system utilizes a narrowband filter that is tuned to pass only the motor currents fundamental component and whose tuned frequency changes with variations in motor speed. Furthermore, the system reduces the excitation provided to the motor after a certain value of line voltage is sensed.

Abstract: An angular position detector for generating trains of A- and B-phase pulses which are 90.degree. out of phase with each other and a C-phase pulse per rotation are mounted on a permanent-magnet synchronous motor such that a magnetic pole origin of permanent magnets and a position where the C-phase pulse is generated agree with each other. After a power supply voltage is applied and in an initial stage before the permanent-magnet synchronous motor is operated normally, a motor control apparatus operates a current control loop with an alternating current command having a constant amplitude and a low frequency to supply an alternating current having a low frequency to the permanent-magnet synchronous motor for thereby rotating the rotor of the permanent-magnet synchronous motor from a stop at a low speed.

Abstract: An induction synchronous motor comprises: a unitary rotor having a first and a second rotor core; a first and a second stator mounted surroundingly facing the first and the second rotor core; a voltage phase shifting means for producing a first and a second phase differences; a static magnetic field around each of the first and second rotor cores; and a rotor magnetizing means having diodes for rectifying alternating voltages and for having the resultant direct current produce magnetic poles in the first and second rotor cores. The motor is caused to initiate its operation as an induction motor based on the first phase difference produced by the voltage phase shifting means, to have the first phase difference shifted to the second phase difference produced by the phase shifting means operated, and to have the first and second rotor cores produce the magnetic poles attracted by the rotating magnetic field produced by the first and second stators, resulting in the synchronous operation of the motor.

Abstract: Synchronization of the phase switchings in driving a brushless motor with predefined excitation current profiles of substantially nonconstant value, is improved by continuously correcting the rotor position information detected by zero-cross detecting circuits with an updatable delay value. A switching delay counter is started by the raw zero-cross pulse to determine the generation of a corrected synchronization pulse. The delay counter is downloaded with a constantly updated value by monitoring the correction signal produced by a speed control loop and by incrementing or decrementing the downloaded value in the counter to minimize the correction signal.

Abstract: A control device for a switched reluctance motor which includes a target current determination device for determining a target value of a current which is supplied to each of a plurality of coil phases of a motor, a current supply timing determination device for determining timings at which the current begins to be supplied to each of the coil phases and at which the supply of the current is ended, a pulse width modulating device for generating a pulse width modulating signal so that the current which is supplied to each of the coil phases is modulated so as to correspond to the target value and a synchronization device for synchronizing a starting time of the pulse width modulating signal with the timing at which the current begins to be supplied to each of the coil phases.

Abstract: In a novel method and apparatus for controlling a synchronous motor, an angular position transducer, in whose output winding three-phase voltages with amplitude variations of N (N: an integer of 1 or more) cycles per revolution is induced, is directly coupled to a synchronous motor with 2N poles so that the demodulated a-phase voltage of the transducer has its positive peak value multiplied by the cosine of a selected angle as MMF phase angle when a direct axis of the motor is located in the position of its a-phase winding axis. The instructions to control three-phase currents of an inverter feeding the motor are produced by multiplying the current phase instructions by the amplitude instruction. The former is directly obtained using the three-phase voltages demodulated from the output of the transducer and the latter is derived from the detected speed deviation or torque instruction.

Abstract: An apparatus for restarting an inverter after momentary interruption by detecting a power restoration after a momentary outage of a power supply that supplies power to the inverter for driving a synchronous motor. The apparatus includes a frequency detecting portion that detects the frequency of a terminal voltage of the synchronous motor, a phase difference detector that detects the phase difference between the terminal voltage of the synchronous motor and the output voltage command value of the inverter, a phase controller that performs synchronous control so that the frequency and phase of the output voltage command value of the inverter and those of the terminal voltage of the synchronous motor agree with each other, and a restarting portion that restarts the inverter under the condition that the synchronization has been completed after the power restoration of the power supply.

Abstract: A converter for synchronous motor starting rectifies the input voltage from a polyphase input power source to develop a starting current having a substantial DC component. The starting current is then sequentially applied to each of the phase windings in the synchronous motor, with the sequential rate of application occurring at a continuously increasing frequency. The angular velocity of the motor synchronously increases with the increasing frequency of the sequential rate of application of the starting current to the phase windings. By application of the starting current at an increasing frequency, the synchronous motor operates in a forced commutation mode. The starting current is removed when the angular velocity of the motor is synchronous with the constant frequency of the polyphase input power source. When the starting current is removed, and the motor is synchronous with the input power, the input power may then be applied directly to the motor in a natural commutation mode.