JPH0462420A - Abnormality detector for encoder signal line - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a device for detecting an abnormality in a signal line of an encoder used in a feedback control system for the rotational position of a motor.

<Conventional technology> In a feedback control system for the rotational position of a motor,
The wiring from the encoder to the servo driver is usually left up to the user, and the number of wires is often 10 or more.

<Problems to be Solved by the Invention> For this reason, incorrect wiring or wire breakage easily occur while the motor is being driven. When incorrect wiring or disconnection occurs, the following phenomena occur.

■The motor does not move.

■The encoder outputs an incorrect position detection signal.

■The motor runs out of control.

In particular, the phenomenon (■) has a high probability of causing a serious disaster. Furthermore, even if it does not lead to a disaster, users have difficulty finding the cause of the abnormality.

In the invention described in Japanese Patent Application No. 1-286983 filed by the present applicant, since the encoder section is constructed by combining an nX resolver and a 1X resolver, the number of encoder signal lines increases, which poses a particular problem.

The present invention has been made to solve these problems, and provides a device that can detect an abnormality in the encoder signal line by simply adding a simple means by utilizing the characteristics of the detection signals of the nX resolver and the 1X resolver. The purpose is to realize the following.

Means for Solving the Problems> The present invention provides a device for detecting an abnormality in a signal line of an encoder used in a feedback control system for the rotational position of a motor, in which the phase of the detection signal is modulated by 360 degrees when the motor rotates once. A 1X encoder, an nX encoder whose detection signal phase is modulated by 3610" when the motor rotates 1/n (n is an integer), and a motor with a resolution of 1/n rotation based on the detection signal of the 1X encoder. a 1X signal processing unit that detects the rotational position φ, χ of the motor; an nX signal processing unit that detects the rotational position φηχ of the motor within 1/n rotation based on the detection signal of the nX encoder; Absolute position that detects the absolute rotational position of the motor by first detecting the rotational position with a resolution of 1/n rotation, and then detecting the rotational position within the detected 1/n rotation based on the detected value φηχ. a detection unit, and an abnormality detection unit that generates an alarm signal when the following formula is not satisfied based on the detected values of the 1X signal processing unit and the nX signal processing unit, Δ1χ/Δ1χ:n Δ1χ:φηχ per unit time. This is an abnormality detection device for an encoder signal line, characterized in that the amount of change in phase per unit time is Δ1χ:φ,χ.

<Operation> In the present invention, the ratio of the amount of variation per unit time of the detection signal of the nX resolver to the amount of variation per unit time of the detection signal of the 1X resolver is such that when the encoder signal line is normal, Using the characteristic that the ratio becomes n, the value of the ratio becomes n
Notifies you of an abnormality when the error occurs.

<Example> The present invention will be explained below using the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.

In the figure, 1 is a motor section, 2 is an encoder section that detects the rotation of motor section 1, and when the motor rotates 1/n (n is an integer), the phase of the detection signal is modulated by 360 degrees.
It consists of a resolver 21 and a 1X resolver 22 that modulates the phase of the detection signal by 360 degrees when the motor rotates once.

3 is an encoder for processing the detection signal of the encoder section 2;
Interface section (hereinafter referred to as encoder 1/F section)
, which excites the nX resolver 21 and processes the detection signal.
It consists of an X signal processing section 31 and an nX signal processing section 32 that excites the 1X resolver 22 and processes detection signals. The 1X signal processing unit 32 performs processing to detect the rotational position of the motor with 1/n rotation as the resolution, and the nX signal processing unit 31
/ Performs processing to detect the rotational position of the motor within n rotations.

4 is an absolute position detection means, which detects the rotational position of the motor with a resolution of 1/n rotation based on the detection values φ and χ of the 1X signal processing unit 32, and detects the rotational position within the detected 1/n rotation. The absolute rotational position of the motor is detected by detecting nXfg based on the detection values φ and χ of the processing unit 31. That is, the value of φ1χ is detected as the main scale reading, and φηχ is detected as the vernier scale reading. The detected absolute position is sent to the upper controller C.

A main control section 5 outputs a current command value for the excitation coil of the motor based on the rotation command from the host controller C and the signal from the nX signal processing section 31.

Reference numeral 6 denotes a current control section that controls the current flowing to the motor section 1 based on the current command value output from the main control section 5.

Reference numeral 7 denotes an abnormality detection section, which monitors the presence or absence of an abnormality in the signal line of the encoder based on the detected values φ1χ and φ and χ, and sends an alarm signal to the host controller C and the main control section 5 when an abnormality occurs.

In such a device, abnormality detection is performed as follows.

If there is no abnormality in the signal line of the encoder, the detection value φ1χ of the nX signal processing section 31 and the detection value φ1 of the 1X signal processing section 32
The following equation holds true for the phase change amount ΔπX of χ per unit time and the difference of Δ1χ.

Δηχ/Δ1χ−n ■The abnormality detection unit 7 detects φ1X and φ given from the encoder I/F unit 3.
Based on the value of 1χ, it is monitored whether or not Equation 0 holds true, and if it does not hold, an alarm signal is sent to the main controller 5 and the host controller C to notify that an abnormality has occurred. Main control unit 5
When the alarm signal is received, the current command value is set to 0. The host controller C thereby detects the occurrence of an abnormality.

Note that the determination of the presence or absence of an abnormality is not limited to equation 0, and may be performed based on the following conditions.

In Δ1x/nl>Sz or 1Δ+xl>Sz, n・Δ1χ−ΔπχI〉ε However, Sz〉0. ε〉0 If so, output an alarm signal.

<Effects> According to the present invention, in the feedback control system for the rotational position of the motor using an encoder that combines an nX resolver and a 1X resolver, the phase of the detection signal of the nX resolver changes 360 degrees when the motor rotates 1/n. , the detection signal of the 1X resolver has a phase of 360 degrees when the motor rotates once.
Using the changing characteristics, abnormalities in the encoder signal line are monitored based on the ratio of the amount of change in phase of these detection signals per unit time. Because of this, an abnormality in the encoder signal line can be effectively detected with a simple configuration that only requires adding a means for comparing the amount of change in the two detection signals.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an example of a cotton sewage according to the present invention. 1...Motor section, 2...Encoder section, 21...
nX resolver, 22...1X resolver, 3...encoder I/F section, 31...nX signal processing section, 32...
・1X signal processing section, 4... Absolute position detection section, 5...
Main control section, Figure 1

Claims (1)

[Claims] A device for detecting an abnormality in a signal line of an encoder used in a feedback control system for the rotational position of a motor, comprising: a 1X encoder whose detection signal phase is modulated by 360° when the motor rotates once; Based on the nX encoder whose detection signal phase is modulated by 360 degrees when the motor rotates /n (n is an integer) and the detection signal of the 1X encoder, the rotational position φ_1χ of the motor is detected with a resolution of 1/n rotations. 1X signal processing unit; An nX signal processing unit that detects the rotational position φηχ of the motor within 1/n rotation based on the detection signal of the nX encoder; an absolute position detection unit that detects the absolute rotational position of the motor by detecting the rotational position within the detected 1/n rotation based on the detected value φηχ; and the 1X signal processing unit. An abnormality detection unit generates an alarm signal when the following formula is not satisfied based on the detected value of An abnormality detection device for an encoder signal line, characterized in that it has a phase change amount per unit time.