Motor System

Patent metadata

Field	Value
Publication number	US-10666171-B2
Application number	US-201716089390-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Mar 30, 2016
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

A motor system includes a motor, and a multi-turn absolute encoder that detects a rotation number and an absolute angular position of a rotation shaft of the motor. The multi-turn absolute encoder includes: an absolute angular position detection device that detects the absolute angular position within one rotation period of the rotation shaft; and a storage element that stores the rotation number of the motor. Even if the driving of the multi-turn absolute encoder is stopped while the motor is stopped, the multi-turn absolute encoder detects the multi-turn position of the rotation shaft after startup. Further, the motor has a brake mechanism including: a gear-type brake wheel that rotates integrally with the rotation shaft; an engagement member capable of engaging with the teeth of the gear-type brake wheel; and an actuator which causes the teeth and the engagement member to engage with each other during braking.

First claim

The invention claimed is:

1. A motor system comprising:
a motor; and
a multi-turn absolute encoder which detects a rotation number and an absolute angular position of a rotation shaft of the motor,
wherein the multi-turn absolute encoder comprises an absolute angular position detection device which detects the absolute angular position within one rotation period of the rotation shaft, and a storage element which stores the rotation number of the motor, and
the motor comprises a brake mechanism including a gear-type brake wheel which rotates integrally with the rotation shaft, an engagement member which is engageable with teeth of the gear-type brake wheel, and an actuator which engages the teeth with the engagement member at the time of braking,
wherein the absolute angular position detection device comprises an incremental encoder, and an absolute position encoder having a resolution lower than that of the incremental encoder,
the absolute position encoder has a permanent magnet of which magnetic poles are disposed in a circumferential direction, and a magnetic sensor element which faces the permanent magnet,
the permanent magnet rotates integrally with the rotation shaft, and
the permanent magnet is provided on the gear-type brake wheel.

2. The motor system according to claim 1 , wherein
the storage element is a nonvolatile memory.

3. The motor system according to claim 1 , wherein
the magnetic sensor element is a Hall element.

4. The motor system according to claim 1 , wherein
the incremental encoder is an optical encoder, a magnetic encoder or a resolver.

5. The motor system according to claim 1 , wherein
when the motor starts up, the multi-turn absolute encoder compares an output value at stop output from the absolute position encoder when the rotation shaft was stopped last with an output value at startup output from the absolute position encoder when the motor was started up, sets the rotation number read out from the storage element as the rotation number of the rotation shaft at the time of starting the motor when the output value at stop is equal to the output value at start, and sets a rotation number corrected for the rotation number read out from the storage element as the rotation number of the rotation shaft at the time of starting the motor when the output value at stop is different from the output value at start.

6. The motor system according to claim 5 , wherein
the multi-turn absolute encoder compares three absolute angular positions obtained by interpolating the output value at startup in a relationship between the output value and the absolute angular position of the absolute position encoder in each of the rotation number read out from the storage element, a rotation number obtained by subtracting one turn from the rotation number, and a rotation number obtained by adding one turn to the rotation number with an absolute angular position at stop when the output value at stop is different from the output value at startup at the time of starting the motor, and sets the rotation number corresponding to the absolute angular position closest to the absolute angular position at stop among the three absolute angular positions as the rotation number of the rotation shaft at the time when the motor starts up.

7. The motor system according to claim 1 , wherein
the incremental encoder outputs an index signal at a period corresponding to the resolution of the absolute position encoder, and
the multi-turn absolute encoder corrects a detection result of the incremental encoder on the basis of the index signal.

8. The motor system according to claim 1 , wherein
in the gear-type brake wheel, the teeth coincide with a change point of an output from the absolute position encoder.

Assignees

• Nidec Corp

Inventors

• Odagiri Hideyuki
• Tsuneta Haruhiro
• Ayuzawa Yuu
• Yazawa Shunya

Classifications

• H02P6/16 Primary

  Circuit arrangements for detecting position · CPC title

• F16D63/006

  Positive locking brakes · CPC title

• H02K11/22

  Optical devices · CPC title

• H02P6/00

  Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor (vector control H02P21/00) · CPC title

• H02K7/1021

  Magnetically influenced friction brakes · CPC title