Servo control apparatus having function of sensorless controlled stop

Patent metadata

Field	Value
Publication number	US-9823647-B2
Application number	US-201715483134-A
Country	US
Kind code	B2
Filing date	Apr 10, 2017
Priority date	May 11, 2015
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

A servo control apparatus includes a sensor unit for detecting a motor speed; an amplifier for driving a motor and feeding back a current; a magnetic pole position detector; a position controller for outputting a speed command; a speed controller for outputting a current command; a current controller for outputting a voltage command; a speed estimator for calculating an estimated speed from the voltage command; a magnetic pole position estimator for calculating an estimated magnetic pole position from the estimated speed; a sensor malfunction detector; a stop position command generator; and a first switch for switching from the position command to the stop position command, a second switch for switching from the magnetic pole position to the estimated magnetic pole position, and a third switch for switching from the detected speed to the estimated speed, when the sensor malfunction detector has detected a malfunction.

First claim

What is claimed is:

1. A servo control apparatus for controlling a servomotor installed in a machine tool or an industrial machine, comprising:
a sensor unit for detecting a speed of the servomotor and outputting the speed as speed feedback;
an amplifier for driving the servomotor, and feeding back a current flowing through the servomotor;
a magnetic pole position detector for detecting a magnetic pole position of the servomotor;
a position controller for outputting a speed command based on a position command for the servomotor and a position of the servomotor calculated from the detected speed;
a speed controller for outputting a current command based on the speed command and the detected speed;
a current controller for outputting a voltage command based on the current command and the detected current;
a speed estimator for calculating an estimated speed based on the voltage command;
a magnetic pole position estimator for calculating an estimated magnetic pole position from the estimated speed;
a sensor malfunction detector for detecting a malfunction in the sensor unit;
a deceleration command generator for generating a deceleration command to decelerate the servomotor;
a fourth switch for switching from the speed command to the deceleration command, when the sensor malfunction detector has detected the malfunction in the sensor unit;
a second switch for switching from the magnetic pole position to the estimated magnetic pole position, when the sensor malfunction detector has detected the malfunction in the sensor unit; and
a third switch for switching from the speed feedback to the estimated speed, when the sensor malfunction detector has detected the malfunction in the sensor unit.

Assignees

• Fanuc Corp

Inventors

• Kameta Kouki
• Sonoda Naoto

Classifications

• B23Q5/58

  Safety devices {(protecting the operator B23Q11/0089)} · CPC title

• B23Q5/10

  driven essentially by electrical means · CPC title

• G05B19/4062 Primary

  Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference · CPC title

• B23Q15/08

  Control or regulation of cutting velocity (B23Q15/12 takes precedence) · CPC title

• G05B2219/42329

  Defective measurement, sensor failure · CPC title