Motor control method and motor control apparatus

Abstract

A motor control apparatus 1 that controls a rotation speed of a motor driven according to a speed command includes an abnormal-rotation detector 21 which determines that the motor is in an abnormal-rotation state, such as a runaway, when a speed deviation Ver obtained by subtracting a detection speed TSA of a motor rotation from a speed command VCMD is equal to or larger than a threshold value, when a sign of a product of acceleration TSA obtained by subtracting a last detection speed from a detection speed this time that is detected in a predetermined cycle and a torque command Tc obtained by proportionally integrating the speed deviation is negative, and when an integration value VerSUM of the speed deviation Ver exceeds a predetermined value ALMlevel. With this arrangement, an abnormal rotation of the motor can be instantly detected even during acceleration or deceleration of the motor, thereby increasing the performance of protecting the motor.

Description

technical field [0001] The present invention relates to a motor control method and a motor control device, and more particularly to a motor control method and a motor control device having a function of detecting an abnormal rotation state including runaway of a motor controlled by software servo. Background technique [0002] A conventional method for detecting abnormal rotation of a motor is to detect abnormal rotation of the motor as an excessive speed deviation if the speed deviation of the speed feedback from the command speed exceeds a predetermined threshold. [0003] For example, Patent Document 1 below proposes an overspeed protection method for a motor driven by an inverter device, and discloses a method for changing the overspeed protection range in response to a speed command signal. [0004] In addition, the following Patent Document 2 proposes a motor runaway detection method and a runaway detection device, and discloses a method and device for detecting the po...

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Problems solved by technology

[0007] However, with these prior art motor abnormal rotation detection methods, when the input speed command changes stepwise, the speed deviation becomes large during acceleration and deceleration of the motor, so the detection of excessive speed deviation during acceleration and deceleration is prohibited.

Therefore, there is a problem that it cannot be detected even if abnormal rotation of the motor occurs during acceleration and deceleration.

[0008] For example, in the method described in the above-mentioned Patent Document 1, there is a problem that when a motor is used for the main shaft, the input speed command often changes stepwise, so inputting a higher speed command stepwise to the motor has the opposite effect. When the direction is out of control, the specified value that determines the overspeed protection range is set higher, and the abnormal rotation of the motor cannot be detected during the period when the rotation speed of the motor does not exceed the specified value, and the overspeed of the motor is protected according to the overspeed The detector does not work, so the detection of abnormal motor rotation is slow

In this case, there is a problem that in the overspeed detector adopting the method described in Patent Document 1, since the rotation speed of the motor does not exceed the above-mentioned predetermined value, it is impossible to detect abnormal rotation of the motor.

[0010] On the other hand, the motor runaway detection method and its device described in the above-mentioned Patent Document 2 have the following problem: the position feedback is used for runaway detection using a servo motor, so it is not suitable for the speed command mode that uses a lot of position feedback. Servo motor for spindle

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