JPH05344775A - Controller for ac servo motor - Google Patents

Abstract

PURPOSE:To provide a controller for AC servo motor comprising a detector for detecting the pole position of a permanent magnet rotor and controlling the speed based on a signal from an encoder carried on the rotor shaft of a conduction controller, in which the AC servo motor can be stopped by detecting a state where the signal from the encoder is not inputted correctly. CONSTITUTION:The controller for AC servo motor comprises a detector 4 for detecting the edge of a signal fed from a detector 2 for detecting the position of permanent magnet in a rotor, a comparing circuit 9 for comparing a rotational direction detection signal obtained from an edge detection signal with a rotational direction detection signal obtained from an edge detection signal 3 fed from an encoder 1, and a control unit 10 for making a decision that the encoder signal is abnormal if more than one pulse signal is not obtained from the encoder signal between two pulse signals of rotational direction detection signal obtained from pole position detection signal and receiving a signal for stopping a servo motor 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC servo motor control device, and more particularly to a safety device for an AC servo motor control device used in a machine tool or a robot device when an error occurs in an encoder signal. Regarding those with.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing the concept of a conventional AC servo motor control device, in which 20 is an AC servo motor having three-phase windings, and 22 is the AC.
A permanent magnet magnetic pole position detection device provided on the rotor shaft of the servo motor, 21 is an encoder also provided on the rotor shaft of the AC servo motor, 23 is an energization control circuit for the AC servo motor, 25 is a speed setting device, 24 Is a deviation detecting device that compares the output of the speed setting device with the speed signal obtained from the output of the encoder to detect a deviation signal and sends a drive signal to the energization control device 23.

The control device for the AC servo motor shown in FIG. 4 compares the speed signal set by the speed setting device 25 with the speed signal of the servo motor 20 obtained from the encoder 21 by the deviation detecting device 24, and agrees with the set speed. The energization control device 23 is controlled so that the servomotor 20 is rotated at the set speed.

[0004]

In order for the control device for the AC servomotor shown in FIG. 4 to operate normally, the position detection device 22 and the encoder 21 operate normally, and the signals thereof are input to the control device. Need to be. Therefore, when the signal from the position detection device 22 is not correctly transmitted to the energization control device 23, the energization control device 23 does not operate normally, so that the current for continuously rotating the motor does not flow to the servo motor 20 and the servo motor does not rotate. Disappear. Next encoder 2
If the signal 1 is not correctly transmitted to the deviation detecting device 24, there is no speed feedback signal, so the output of the deviation detecting device 24 is only the signal of the speed setting device 25, and there is a danger of becoming an extremely high speed operation state. SUMMARY OF THE INVENTION An object of the present invention is to obtain an AC servo motor control device capable of detecting a state where an encoder signal is not correctly transmitted and stopping the operation of the servo motor.

[0005]

A control device for an AC servomotor according to the present invention compares an encoder signal, its rotation direction signal, a signal of a position detection device and its rotation direction signal, and outputs both signals. The object is achieved by a configuration for detecting a case in which a predetermined criterion is not satisfied between the two and generating a signal for stopping the energization of the energization control device.

[0006]

[Operation] When comparing the signal of the magnetic pole position detector and the signal of the encoder, the signal interval of the magnetic pole position detector is generally much longer than the signal interval of the encoder signal, so if the encoder signal is input correctly, , Two or more encoder signals are continuously input during the signal interval of the magnetic pole position detection device in the same rotation direction, but if one encoder signal fails, the encoder signal will be forward and reverse rotation. Pulse signal is generated and two or more pulse signals in the same rotation direction are continuously input and input is stopped, it is determined that the encoder signal is faulty, and a signal for stopping the servo motor is sent to the control device. The same applies when not all encoder signals are input.

[0007]

1 is a circuit diagram of an embodiment of the present invention, in which 1 is an encoder, 2 is a permanent magnet position detecting device, 3 is an edge detector of the encoder 1 and 4 is an edge detector of the magnetic pole position detecting device 2. , 5 and 6 are phase delay circuits, 7 and 8 are rotation direction detection circuits, 9 is a rotation direction detection circuit signal comparison circuit, and 10 is AC.
A servomotor control circuit, and 11 is an AC servomotor.

Output signals of the encoder 1 and the magnetic pole position detection device 2 are directly input to the control device 10 to drive the servo motor, the edge detectors 3 and 4, and the phase delay circuits 5 and 6.
To the rotation direction detection circuits 7 and 8, and the outputs of the rotation direction detection circuits 7 and 8 are input to the comparison circuit 9.
Compare the pulse signal of the encoder signal and the pulse signal of the position detection device with the rotation direction of each signal, and two or more encoder signals are consecutive during the signal interval of the position detection device with the signals in the same rotation direction. Is judged to be normal, a signal to continue operation is sent to the control device 10, and if this condition is not satisfied, it is judged that the encoder signal has failed,
It operates to send a stop signal to controller 10.

FIG. 2 is a time chart showing the states of signals at various parts of the control device for the AC servomotor shown in FIG. 1, showing a state in which it is operating normally. a is a signal of the magnetic pole position detecting device, b is an A phase signal of the encoder 1, and c is an encoder 1.
B phase signal, d is the CW direction output of the edge detection circuit 4 of the position detection device 2, and e is the edge detection circuit 4 of the position detection device 2.
In the CCW direction, f is the CW direction output of the edge detection circuit 3 of the encoder 1, g is the CCW direction output of the edge detection circuit 3 of the encoder 1, h is the output of the rotation direction detection circuit 8,
i is the output of the rotation direction detection circuit 7, and j is the output of the comparison circuit 9.

In FIG. 2, since this is a normal operation, the output of the position detector 2 and the output of the encoder 1 correspond to the respective rotation directions of the edge detector and the output of the rotation direction detection circuit. Since two or more output pulses of the encoder 1 are continuously input during the pulse interval of the rotation direction detector 8 obtained from the output of the position detection device 2, the output of the comparison circuit 9 is L level. And the control device 10
A signal to continue driving is sent to. Rotation direction is CW or C
The same applies to any of the CWs.

FIG. 3 is a time chart when an abnormality occurs in the encoder signal, and the names of the signals of the respective parts are the same as those in FIG. When the servo motor is rotating in the CW direction, T
The case where the A-phase signal of the encoder 1 is not input at the point will be described. The CW direction output of the edge detection signal of the encoder 1 of f is normally input up to the position of T, but On the further right, only the edge detection signal of the B-phase signal of the C encoder is output, and the outputs of the CW direction of f and the CCW direction of g are alternately output. Therefore, the output of the direction detection circuit 7 of i is at the time of T. No output on the right side. Therefore, the output of the detection circuit 9 becomes H level because the encoder pulse is not detected during the interval of the output pulse of the direction detection circuit 8, and it is determined that the encoder signal is abnormal, and the control circuit 10 is instructed to stop the servomotor. ..

If the signal from the encoder 1 is not input to both the A phase and the B phase, there is no output from the edge detection circuit 4 for d and e, so that the output from the comparison circuit 9 becomes H level as well.
Judge that the encoder signal is abnormal and issue a command to stop the servo motor.

If the output of the position detecting device 2 is not normally input, for example, if the output of one phase among the three phases is not input, the energization signal of the energization control device is not completed and the servo motor rotates normally. Stop without doing.

[0014]

Since the control device for the AC servomotor according to the present invention has the above-described structure, when the encoder signal becomes abnormal, the comparison circuit 9 sends a stop signal to the servomotor control circuit to cause the servomotor to stop. It operates so as to stop the motor, and has the effect of preventing abnormal rotation of the servo motor.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a control device for an AC servomotor according to the present invention.

FIG. 2 is a time chart showing signals of respective parts of the control device for the AC servo motor according to the present invention shown in FIG. 1, which is for a normal rotation.

FIG. 3 is a time chart showing signals of respective parts of the control device for an AC servomotor according to the present invention shown in FIG. 1, and shows a case where an encoder signal is abnormal.

FIG. 4 is a block diagram showing the concept of a conventional AC servomotor control device.

[Explanation of symbols]

 1, 2: Encoder 2, 22: Permanent magnet position detection device 3: Encoder signal edge detector 4: Position detection device signal edge detector 5, 6: Phase delay circuit 7: Encoder signal rotation direction detection circuit 8: Rotation direction detection circuit of signal of position detection device 9: Comparison circuit 10: Servo motor control circuit 11, 20: AC servo motor 23: Energization control circuit 24: Deviation signal detection circuit 25: Speed command circuit

Claims (1)

[Claims] 1. A stator having a plurality of windings, a rotor provided with a permanent magnet having a plurality of magnetic poles facing the stator with an air gap, and a rotor shaft supporting the rotor. An encoder provided on the rotor shaft, which is a controller for an AC servo motor that rotates the rotor by sequentially energizing the plurality of windings through an energization controller by the output of the magnetic pole position detector of the permanent magnet. In a configuration in which the speed is controlled by the signal of, the detector that detects the edge of the signal of the magnetic pole position detector of the permanent magnet, the detector that detects the rotation direction from the edge detection signal, and the edge of the encoder signal A detector for detecting the rotation direction and a detector for detecting the rotation direction from the edge detection signal are provided, and the rotation direction detection signal and the encoder signal obtained from the edge detection signal of the signal of the magnetic pole position detector are detected. The rotation direction detection signal obtained from the edge detection signal is compared, and two pulse signals obtained from the encoder signal are continuously obtained between two pulses of the rotation direction detection signal obtained from the magnetic pole position detection signal. An AC servo motor control device having a configuration for generating a signal for stopping a servo motor when the above occurrence does not occur.