Fanuc Corporation

Fujitsu Fanuc Limited

Mitsuhiko Hirota

Yoshiki Fujioka

Shigeki Kawada

Naoto Ota

Shigeaki Oyama

Yutaka Koiwai

Naoto Ohta

Tadashi Inoue

Toyohiko Nishimori

Driving system for an induction motor having a circuit for generating a

Power supply regenerating circuit

Motor velocity control apparatus

Plural motor changeover control system

A method of controlling an AC motor which exhibits a constant torque characteristic at a rotational speed N below a base speed Nb and a constant output characteristic at a rotational speed N above the base speed Nb, comprising the steps of finding a base speed N.sub.L after limiting the output power of the AC motor, N.sub.L being derived from the base speed Nb and the ratio .eta. between maximum output power Pmax.sub.1 and maximum output power Pmax.sub.2 before and after the output power of the AC is limited, respectively, rendering the slip frequency of the AC motor constant until the rotational speed N of the AC motor reaches the base speed N.sub.L, varying the slip frequency in inverse proportion to the rotational speed N for N between N.sub.L and Nb (N.sub.L &lt;N.ltoreq.Nb), and varying the slip frequency in proportion to the rotational speed N for N above Nb (Nb&lt;N), whereby the output power of the AC motor is rendered constant at a rotational speed N above N.sub.L.

AC motor control system

Position control apparatus

AC motor control apparatus

AC Motor control method

Disclosed is a DC motor drive circuit adapted to prevent thyristor commutation failure when a thyristor-controlled three-phase full-wave reversible bridge undergoes a transition in operating mode from a power inversion mode to a power rectification mode. The drive circuit includes a thyristor-controlled three-phase full-wave reversible bridge whose firing phase is controlled in accordance with a speed deviation between the actual speed of a DC motor and a command speed, polarity discrimination means for discriminating the polarity of the speed deviation, firing phase narrowing means operable in the power inversion mode to narrow the thyristor firing phase down to a minimum firing phase due to a reversal in the polarity of the speed deviation, detection means for detecting an intermittence in armature current, and blocking means for blocking firing of the three-phase thyristor-controlled inverter for a prescribed period of time when the intermittence of the armature current has been detected, the operation mode of the inverter being changed over from the power inversion mode to the power rectification mode after the lapse of said prescribed time period.

Driving circuit for DC motor

A system for controlling DC motors of the type employing permanent magnets as field poles. The firing phase angle of a thyristor is controlled in response to an error signal representative of an error between a commanded motor speed and an actual motor speed. For preventing demagnetization of the permanent magnets due to the armature reaction, the clamp level of the error signal is changed in accordance with the actual motor speed.

Control system for a DC motor

An actual speed N of a DC motor and an armature current Ia are detected to detect the motor output N.times.Ia. The motor speed is changed so that the detected motor output may not exceed a predetermined value. The spark generation of the motor brush is prevented when an over load is applied to the motor.

DC Motor drive system

A speed detector produces a spindle speed signal proportional to the revolving speed of a spindle. A specified position detector provides a specified position signal when the spindle assumes a specified rotational position. A spindle motor speed control unit controls the spindle motor so that the motor speed agrees with a speed command. When spindle orientation is requested, one integrator circuit responds to the specified position signal to integrate the spindle speed signal. The output from the integrator circuit is applied to the speed control unit in place of the speed command.

Spindle control system

Growing community of inventors

Tokyo, Japan

Mitsuhiko Hirota