Abstract: In a method of controlling a servomotor, a high output can be fetched from the servomotor by a motor-current control unit of a simple construction, while protecting switching elements of the control unit against excess current. The deviation between a command current (Ir) for of a plurality of winding portions constituting an armature winding of each phase and a current (Ia, Ib) flowing through each winding portion is integrated by an integrating element (9, 9'). The current (Ia, Ib) is amplified by means of a proportional element (10, 10'), and the individual currents (Ia, Ib) are controlled for substantially independent and equal values by means of one PWM control section (3) operating in response to a control signal which is obtained by adding outputs from both the elements (9.about.10').

Abstract: A servo control system has a first integrator to which the speed of a servomotor is fed back and a second integrator to which the speed of a mechanical load of low rigidity is fed back. The speed of the servomotor and the speed of the mechanical load driven by the servomotor are simultaneously reflected at a prescribed ratio on a transfer function of the servo control system, whereby appropriate servo control is made possible for the mechanical load to achieve speed control having a quick response and stability.

Abstract: A counter circuit for counting pulses inputted thereto asynchronously during a fixed period includes a counter 12' for counting the input pulses, a register 13 for storing pulses outputted by the counter 12' at fixed periods, and a control circuit 11' for generating a signal that controls the operating state of the counter 12' and register 13. When a signal that decides the operating period of the counter 12' is not being generated, namely between pulses indicative of the operating period, the counter 12' performs an ordinary counting operation. If an input pulse for counting is applied to the counter 12' during a period of time in which the abovementioned pulse is being generated, the control circuit 11' causes the counting operation to continue without clearing the counted value in the counter 12', after which the counted value in counter 12' is outputted to the register 13 to be latched therein, thereby preventing miscounting in the register 13.

Abstract: In reference point return control, a grid point position at which a one-revolution signal (RTS) is first generated by a rotary encoder (24) following restoration of a deceleration limit switch (29) is adopted as a reference point. When a zero point return mode (ZRN="1") for returning a movable element to the reference point is in effect, a numerical controller (21) regards the position at which the one-revolution signal (RTS) is generated by the rotary encoder (24) as being zero. A commanded position REF.sub.n, until the next one-revolution signal is generated, is monitored at every predetermined time, such monitoring of the commanded position being repeated until the movable element arrives in the vicinity of the reference point. When the movable element approaches the reference point and the deceleration limit switch (29) is restored, the commanded position REF.sub.n at an initial time every .sub..DELTA. T is obtained, a distance (N-REF.sub.

Abstract: In order to obtain an injection drive apparatus which is low-priced, can produce a great output torque, and has a satisfactory acceleration/deceleration characteristic, in an injection-molding machine which performs injection by driving a screw by means of servomotors, one or more ball screws (7), used to drive a screw (2) in the axial direction, are driven by means of a plurality of servomotors (M1, M2), a position detector (P1) for detecting the screw position is provided only for one servomotor (M1), and the servomotors (M1, M2) are provided individually with power amplifiers, which are controlled by means of one control circuit so that the individual servomotors (M1, M2) are controlled in synchronism with one another.

Abstract: A dwell control system of an injection molding machine is adapted to drive an injection shaft by an electric motor (20) and to control the electric motor (20) by a numerical control unit (30). At the time of a dwell operation, the numerical control unit (30) operates the electric motor (20) under the application of a torque limit to apply a predetermined pressure to a molten material in a mold (4).

Abstract: A motor control apparatus including an arithmetic circuit (113) for calculating a current command, a holding circuit (118) for holding the current command, a pulse-width modulating circuit (114) for pulse-width modulating an output signal from the holding circuit (118) and provided with a dead zone with respect to the output signal, and a transistorized amplifier/converter circuit (117) for controlling a motor by the pulse-width modulated signal. The arithmetic circuit (113) adds a compensating signal, to the current command to compensate for motor control losses due to the dead zone, and delivers the result to the holding circuit (118).

Abstract: A method and apparatus for controlling a permanent magnet synchronous motor (M), wherein an inverter (4) is controlled in response to PWM signals (PA-PF) obtained by comparing a reference carrier wave (VA) with signals representing differences between armature winding current command signals (RTC, STC, TTC) of the respective phases and detected armature currents (IR, IS, IT).The degree of saturation of the difference signals defined in association with a peak value of the reference carrier wave (VA) is detected. The phases of the current command signals (RTC, STC, TTC) are changed from those which provide an orthogonal relation between a resultant armature current and a main flux of a magnetic field.

Abstract: When a synchronous motor (6) using a permanent magnetic field is controlled by the control of an inverter (4) receiving a pulse width modulation signal, wherein the reactive component of an armature winding current is defined as I.sub.b, the inductance of the armature winding as L, the counter electromotive force constant of the synchronous motor as K.sub.1, and the constant introduced from the pole number of the synchronous motor as K.sub.2, the value of the reactive component I.sub.b of the armature winding current is limited so that the multiplied product of K.sub.2, L, and I.sub.b does not exceed the value of K.sub.1.

Abstract: A servomotor velocity control system has an estimating unit (4) for obtaining an estimated value (V) of velocity based on rotary encoder position information (.theta.), which includes a current (I.sub.L) indicative of load torque, and motor current (I) of a servomotor (5). The system is adapted to obtain a torque command signal (U) based on the estimated value (V) of velocity and a velocity comman signal (V.sub.c).

Abstract: A servomotor velocity control system according to the present invention control velocity by using an observer for obtaining a sensed value of velocity while estimating motor load torque. When resolution of a rotary encoder is a problem in a region of low motor velocities, this is compensated for to improve the velocity sensing precision in the low-velocity region. In a region of high motor velocities, velocity processing is executed based on the output of the rotary encoder considering the processing time of a CPU. Use or non-use of the observer for obtaining the estimated value of velocity is selected in dependence upon the velocity of the motor.

Abstract: A synchronous motor control system includes a sensor (112) for sensing the rotational angle of a synchronous motor (101), and a control circuit (108) for generating a sinusoidal value corresponding to the rotational angle sensed by the sensor (112) and for multiplying the sinusoidal value by an effective value current command. The multiplied output of the control circuit (108) is applied as a current command value to the armature winding of the synchronous motor (101). In this case, the arrangement is such that the control circuit (108) compensates the sensed rotational angle by the actual velocity of the synchronous motor (101) or by a rotational command velocity for the synchronous motor.

Abstract: A synchronous motor control system for preventing a torque efficiency reduction on high-speed rotation and acceleration to produce a torque efficiently at all times. The synchronous motor control system detects when inverter drive signals for controlling currents supplied to the synchronous motor exceed a physical saturable quantity of an inverter, and corrects current waveforms applied to the synchronous motor to make sure that they are sine waves at all times.

Abstract: A pulse encoder (2) is provided for generating a position code IP corresponding to the rotational position of a rotor of a motor (1), as well as rotation pulses AP, BP each of which is produced whenever the rotor rotates by a predetermined amount. The rotation pulses AP, BP are applied to a counter (32) via quadrupling pulse generating circuit (30). A leading edge/trailing edge sensing circuit (31) is provided for sensing a transition point of the position code, with the counter (32) being preset by an output from the circuit (32). Thus, the position of the rotor is capable of being indicated precisely based on the position code and the value counted by the counter.

Abstract: There are provided a sensor (113) for sensing the velocity of an AC motor (101), a sensor (112) for sensing an actual current flowing into the AC motor (101), a power drive circuit for driving the AC motor (101), and a control unit (108) for performing a velocity loop computation to obtain a current command from an offset velocity between a velocity command for the AC motor (101) and the sensed actual velocity, and for performing a current loop computation to obtain an offset current between the current command and the sensed actual current.

Abstract: A servomotor control system includes a sensor for sensing the velocity of a servomotor (101), a sensor for sensing an actual current flowing into the servomotor (101), a power drive circuit for driving the servomotor (101), and control units (MP1, MP2). The control unit MP1 performs a velocity loop computation to derive a current command for the servomotor based on an offset velocity between a velocity command for the servomotor and the sensed actual velocity. The control unit MP2 performs a current loop computation to obtain a command for the power drive circuit. In the current loop computation of the control unit MP2 a velocity compensation signal is obtained by amplifying the sensed actual velocity by a predetermined magnification, so that the command for the power drive circuit is compensated by the velocity compensation signal. The velocity loop computation is executed at a period longer than that at which the current loop computation is executed.

Abstract: To reduce adverse effects due to a dead zone in a pulse-width modulation circuit provided for avoiding short-circuiting in an inverter circuit, distortions of sine wave currents generated when low-frequency current commands are given, sound produced due to the excitation, and torque variations, a synchronous motor drive apparatus has been provided.

Abstract: An apparatus for processing the energy regenerated by an AC motor, which comprises a regeneration detection logic circuit (7) that produces a regeneration detection signal when the AC motor driving semiconductor switches are nonconductive and when the direction of the current flowing through the AC motor is opposite to that of the current when the AC motor is driven and a regeneration drive circuit 8 which drives the regenerated energy processing semiconductor switches responsive to the regeneration detection signal. The apparatus renders the regenerated energy processing semiconductor switches conductive so that the regenerated energy is returned to the AC power source only when the AC motor is in a regenerative condition. Therefore, electric power need be consumed in only small amounts by the resistors that protect the semiconductor switches for processing the regenerated energy, and the apparatus can be constructed so that it is small in size.

Abstract: In servo-controlling a servomotor by a rotational velocity feedback loop and current feedback loop, a compensatory rotational velocity signal is produced to render the current feedback loop independent of the actual rotational velocity of the servomotor. To this end, the actual rotational velocity of the servomotor is amplified by a predetermined multiplication factor, and the resulting amplified signal is applied to a pulse width modulation signal obtained on the basis of a current difference between the actual current of the servomotor and a commanded current, which is based on a commanded velocity. The modulation signal resulting from the application of the amplified signal is applied to a current drive circuit of the servomotor.

Abstract: An apparatus for driving an A.C. motor includes a circuit for computing the sum of polyphase A.C. signals used to drive a pulse-width modulation circuit for controlling an inverter, and for limiting the amplitude of a current command when said sum is other than zero. When an imbalance occurs in the polyphase A.C. signals, the current command amplitude is immediately limited in accordance with the state of the imbalance to prevent saturation of a current amplifier that is operable to produce the polyphase A.C. signals by amplifying the outputs of an arithmetic circuit. These outputs are difference currents obtained by computing the difference between polyphase command currents and corresponding ones of detected polyphase currents actually applied to the A.C. motor. Preventing saturation of the current amplifier assures that the polyphase currents actually applied to the A.C. motor will be held in a balanced state at all times.