JP2015008579A - Motor control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an anomaly even if a current flowing through a motor does not exceed a maximum allowable value.SOLUTION: A motor 11 is driven by supplied power. A mechanical section 12 moves a mobile body 124 by rotation of the motor 11. A motor drive device 13 drives the motor 11 on the basis of a moving stroke and a moving speed of the mobile body 124. A host control device 14 controls the motor drive device 13 on the basis of operational information about the motor 11. A storage section stores a desired normal relationship between time in a series of operation periods comprising an accelerating operation period, a constant speed operation period and a decelerating operation period, and a value of current flowing through the motor 11. A determination section determines that there is an anomaly if a difference between a value of current flowing through the motor 11 and the value of current stored in the storage section is greater than a predetermined threshold.

Description

  The present invention relates to a motor control system for controlling a motor.

  Conventionally, in a motor control system including a motor, a motor drive device that drives the motor, and a host control device that communicates with the motor drive device, the motor is driven by an operation command from the motor drive device and is connected to the motor. The moving body is moved by the mechanism unit, and the driving of the motor is stopped based on the moving amount (movement distance) of the moving body. For example, Patent Document 1 describes a system that drives a motor by determining a current that flows through the motor based on the position of a moving body that is moved by the motor. Patent Document 2 describes a system for determining a current to be supplied to a motor based on a torque to be exhibited by the motor and driving the motor. In such a system, when the current flowing through the motor exceeds a predetermined allowable maximum value, the operation is determined to be abnormal and stopped.

JP 2011-36061 A JP 2011-155801 A

However, for example, in a configuration in which the mechanism portion includes a guide rail and a ball screw, and the motor rotates the ball screw and moves the moving body along the guide rail, if the guide rail deteriorates or the oil runs out, it slides. Although the load sometimes increases, even if the torque that the motor should exert becomes larger than usual, if the current flowing through the motor does not exceed the allowable maximum value, it is not judged as abnormal.
Further, in a configuration in which the mechanism portion includes a rotating shaft, a pulley, and a belt, and the motor rotates the rotating shaft by rotating the belt, when the belt deteriorates and breaks, the rotation of the motor is not transmitted to the rotating shaft, and the motor Is in a no-load state, the current flowing through the motor is reduced. Also in this case, since the current flowing through the motor does not exceed the allowable maximum value, it is not determined to be abnormal.

Thus, even if some problem occurs in the mechanism unit, it cannot be determined as abnormal if the current flowing through the motor does not exceed the allowable maximum value.
The present invention has been considered in view of such problems, and an object thereof is to determine whether the current flowing through the motor is normal or abnormal even when the current does not exceed the allowable maximum value.

  The present invention relates to a motor driven by supplied electric power, a mechanism unit that moves the moving body by rotation of the motor, a motor driving device that drives the motor based on the moving amount and moving speed of the moving body, and the motor In a motor control system comprising a host controller that controls a motor drive device based on the operation information of the above, an acceleration operation period for accelerating the moving body, a constant speed operation period for moving the moving body at a constant speed, and movement A storage unit for storing a desired relationship between a series of operation periods including a deceleration operation period for decelerating the body and a value of a current flowing through the motor in the series of operation periods at a normal time; a value of the current flowing through the motor; A determination unit that determines that the difference is larger than a predetermined threshold value when the difference between the current value stored in the unit is larger than a predetermined threshold value.

  The determination unit may be provided in the motor drive device, or may be provided only in the host control device.

  According to the motor control system of the present invention, the storage unit stores a normal relationship between a series of operation periods and the current flowing through the motor in the operation period, and the storage unit stores the value of the current flowing through the motor. Since the determination unit detects an abnormality when the difference from the current value is larger than the threshold value, it can be determined whether the current flowing through the motor does not exceed the allowable maximum value.

The block diagram which shows a motor control system. The block diagram which shows an abnormality determination part. The graph which shows the relationship between time and an electric current. The flowchart which shows a motor control process. The graph which shows the relationship between time and an electric current.

  A motor control system 10 shown in FIG. 1 is based on a motor 11 driven by supplied power, a mechanism unit 12 that moves a moving body 124 by rotation of the motor 11, and a moving amount and moving speed of the moving body 124. A motor drive device 13 that drives the motor 11, a host control device 14 that controls the motor drive device 13, and a communication unit 15 that mediates communication between the motor drive device 13 and the host control device 14 are provided.

  The mechanism unit 12 is, for example, a ball screw mechanism, and includes a screw shaft 121 coupled to the motor 11, bearings 122 a and 122 b that rotatably support the screw shaft 121, and a guide rail 123 a that is disposed in parallel with the screw shaft 121. , 123b. The moving body 124 includes an engaging portion that engages with the screw shaft 121. When the motor 11 rotates the screw shaft 121, the moving body 124 moves in a direction parallel to the screw shaft 121 and the guide rails 123a and 123b. .

  The motor driving device 13 includes a position control unit 131 that controls the position of the moving body 124, a speed control unit 132 that controls the speed of the moving body 124, and a torque control unit 133 that controls the torque of the motor 11.

  The position control unit 131 compares the position of the moving body 124 with a target position where the moving body 124 should be moved, and calculates a target speed at which the moving body 124 should be moved. The position of the moving body 124 is detected by, for example, a position detection unit including a sensor or an encoder that detects how many times the motor 11 has rotated. For example, when the position of the moving body 124 is more than a predetermined distance away from the target position, the position control unit 131 sets the predetermined maximum speed as the target speed, and the distance between the position of the moving body 124 and the target position is predetermined. If the distance is less than the distance, the speed proportional to the distance between the moving body 124 and the target position is set as the target speed.

  The speed control unit 132 compares the speed of the moving body 124 with the target speed calculated by the position control unit 131 and calculates a target torque that the motor 11 should exhibit. For example, the speed of the moving body 124 may be configured to calculate a change per unit time of the position detected by the position detecting unit, or may be detected by a speed detecting unit that detects the speed of the moving body 124. Also good.

  The torque control unit 133 calculates a target current value of the current that should flow through the motor 11 based on the target torque calculated by the speed control unit 132 and supplies the target current value to the motor 11 so that the current flowing through the motor 11 becomes the target current value. Adjust the power. In addition, the motor drive device 13 transmits operation information of the motor 11 to the host control device 14. The operation information of the motor 11 includes, for example, the number of rotations of the motor 11, the value of the current supplied to the motor 11, the value of the torque of the motor 11, and the like.

  The host controller 14 receives the operation information of the motor 11 from the motor drive device 13, determines whether there is an abnormality based on the received operation information of the motor 11, and if there is an abnormality, the motor drive device 13. In response, a stop command for stopping the operation of the motor 11 is transmitted.

  When the motor drive device 13 receives a stop command from the host control device 14, the motor drive device 13 stops the operation of the motor 11 by stopping the power supply to the motor 11.

  The abnormality determination unit 20 shown in FIG. 2 is disposed in the motor drive device 13 or the host control device 14 or both. The abnormality determination unit 20 includes a storage unit 21 that stores the relationship between the operation period of the motor 11 and the value of the current flowing through the motor 11 during the operation period, and a determination unit 22 that determines whether or not an abnormality has occurred.

  During the operation period of the motor 11, an acceleration operation period in which the moving body 124 is accelerated from a state where the moving body 124 is stopped until the moving body 124 reaches a predetermined moving speed, and the moving body 124 moves at a constant moving speed. There is a constant speed operation period during which the moving body 124 is decelerated and stopped. The time in the operation period of the motor 11 is based on a predetermined reference time in a series of operation periods including an acceleration operation period, a constant speed operation period, and a deceleration operation period. For example, the time when the moving body 124 starts to move is set as the reference time. Alternatively, the time when the processing means fixed to the moving body 124 comes into contact with the processing target and the processing is started is set as the reference time. The detection that processing has been started may be performed by, for example, detecting that the moving body 124 has reached a predetermined position, or by detecting that the load of the motor 11 has fluctuated. It may be.

  As shown in FIG. 3, the current value 311 of the current flowing through the motor 11 at normal time increases in proportion to the speed of the moving body 124 in the acceleration operation period 321, and is substantially constant in the constant speed operation period 322, In the deceleration operation period 323, the speed decreases in proportion to the speed of the moving body 124. The storage unit 21 stores in advance a desired relationship between the time at the normal time and the current at the time.

  The determination unit 22 calculates the difference between the current value actually flowing through the motor 11 and the current value stored in the storage unit 21, and compares the calculated difference with a predetermined determination threshold value. When the difference between the current values is larger than the determination threshold, the determination unit 22 determines that it is abnormal. That is, the determination unit 22 determines that the current value 311 of the current flowing through the motor 11 is abnormal when the current value 311 is greater than the upper threshold 33 or smaller than the lower threshold 34. If the current flowing through the motor 11 is within the allowable range 35 indicated by hatching, the determination unit 22 determines that there is no abnormality. In practice, the value of the current flowing through the motor 11 may be once stored in the storage unit, and then the difference from the value of the current stored in the storage unit 21 may be calculated.

  For example, when the guide rails 123a and 123b shown in FIG. 1 are deteriorated or the frictional resistance when sliding with the moving body 124 is increased due to running out of oil or the like, the load on the motor 11 is increased. The current value 312 of the current flowing through becomes larger than in the normal state. Since the current value 312 exceeds the upper threshold 33, the determination unit 22 determines that there is an abnormality. Alternatively, the mechanism unit 12 is configured to transmit the torque of the motor 11 to the screw shaft 121 via a power transmission unit such as a pulley or a belt. When the motor 11 is not transmitted to the shaft 121, the motor 11 is in a no-load state, and the current value 313 of the current flowing through the motor 11 is smaller than that in the normal state. Since the current value 313 is smaller than the lower limit threshold 34, the determination unit 22 determines that there is an abnormality.

  As described above, when the normal current value is used as a reference, the allowable range 35 is provided above and below, and when the value of the current flowing through the motor 11 deviates from the allowable range 35, the determination unit 22 determines that it is abnormal. Since the value of the current at normal time changes with time, the allowable range also changes with time. Thereby, even if the current flowing through the motor 11 does not exceed the allowable maximum value, it can be determined whether the current is normal or abnormal.

The determination unit 22 may be configured to always monitor the current flowing through the motor 11 to determine abnormality, or sample the current flowing through the motor 11 at spaced sampling times 361, 362, 363,. The configuration may be such that abnormality is determined based on the sampled current. As shown in FIG. 3, when an abnormality has occurred, the current flowing through the motor 11 remains within the allowable range 35 in the initial stage of the acceleration operation period 321. Therefore, an abnormality cannot be detected in the early stage of the acceleration operation period 321. Thereafter, when the current flowing through the motor 11 deviates from the allowable range 35, the state continues. Therefore, it is not always necessary to monitor the current flowing through the motor 11.
The determination unit 22 may be configured to determine the abnormality by monitoring the current flowing through the motor 11 in real time, or may store the current flowing through the motor 11 and determine the abnormality later. May be.

  When the motor drive device 13 does not include the abnormality determination unit 20 and only the host control device 14 includes the abnormality determination unit 20, the abnormality determination unit 20 included in the host control device 14 receives the operation information received from the motor drive device 13. An abnormality is determined based on the above. When the abnormality determination unit 20 detects an abnormality, the host control device 14 transmits a stop command to the motor drive device 13, and the motor drive device 13 receives the stop command from the host control device 14 to change the motor 11. Stop.

  When only the motor drive device 13 includes the abnormality determination unit 20 and the host control device 14 does not include the abnormality determination unit 20, when the abnormality determination unit 20 detects an abnormality, the motor drive device 13 stops the motor 11. Let

  In a configuration in which both the motor drive device 13 and the host control device 14 include the abnormality determination unit 20, for example, the determination threshold value in the abnormality determination unit 20 of the motor drive device 13 is greater than the determination threshold value in the abnormality determination unit 20 of the host control device 14. Set smaller. In the motor drive device 13, when the abnormality determination unit 20 detects an abnormality, it is next determined whether or not the abnormality is acceptable in the host control device 14. If it is determined that there is an abnormality, it is possible to stop the motor 11 by outputting a command to the motor drive device 13 according to the determination of the host control device 14, and to display an alarm without stopping the motor 11. You can also just give a warning.

A motor control process 40 shown in FIG. 4 is a process example in a configuration in which both the motor drive device 13 and the host control device 14 include the abnormality determination unit 20.
First, in the current value acquisition step 41, the abnormality determination unit 20 of the motor drive device 13 acquires the value of the current flowing through the motor 11 every time a predetermined time elapses. Next, in the lower abnormality determination step 42, the abnormality determination unit 20 of the motor drive device 13 determines whether or not the current value acquired in the current value acquisition step 41 is within an allowable range. If it is determined that it is within the allowable range, the process proceeds to the arrival determination step 45. If it is determined that the value is outside the allowable range, the motor drive device 13 transmits information indicating that an abnormality has been detected to the host controller 14, and the process proceeds to a host abnormality determination step 43.

  In the higher order abnormality determination step 43, the higher order control device 14 receives that the motor drive device 13 has detected an abnormality, and the abnormality determination unit 20 of the higher order control device 14 determines whether or not to continue the operation of the motor 11. To do.

  In the upper abnormality determination step 43, the abnormality determination unit 20 of the upper controller 14 determines whether or not the value of the current flowing through the motor 11 is within an allowable range. If it is determined that the value is within the allowable range, the process proceeds to a warning process 44 to warn of an abnormality by displaying an alarm. Then, after the warning process 44, the process proceeds to an arrival determination process 45. On the other hand, if it is determined that the value of the current flowing through the motor 11 is outside the allowable range, the host control device 14 transmits a stop command to the motor drive device 13 and ends the motor control process 40. In the arrival determination step 45, the motor drive device 13 determines whether or not the moving body 124 has reached the target position. If the moving body 124 has not reached the target position, the process returns to the current value acquisition step 41. If the moving body 124 has reached the target position, the motor control process 40 ends.

  In this way, by making an abnormality determination in duplicate between the motor drive device 13 and the host control device 14, appropriate measures can be taken according to the degree of abnormality.

When the screw shaft 121 shown in FIG. 1 is not horizontal and the moving body 124 moves up and down, the storage unit 21 stores the relationship between two types of time and current as shown in FIG. .
When moving the moving body 124 upward or diagonally upward, it is necessary to resist gravity, whereas when moving the mobile body 124 downward or diagonally downward, gravity is assisted. For this reason, the current value 314 flowing through the motor 11 when the moving body 124 is moved upward is generally larger than the current value 315 flowing through the motor 11 when the moving body 124 is moved downward. The determination unit 22 determines which of the current values 314 and 315 is read from the storage unit 21 based on the moving direction of the moving body 124, and compares the read current value with the value of the current flowing through the motor 11. To determine whether an abnormality has occurred.

  As described above, when the value of the current flowing through the motor 11 that moves the moving body 124 in the normal state varies depending on the rotation direction of the motor, the relationship between the time and the current in the rotation direction of the motor is stored in the storage unit 21. The determination unit 22 determines which is the rotation direction of the motor, and performs abnormality determination based on the current value corresponding to the rotation direction of the motor. Thereby, it is possible to determine whether the value of the current flowing through the motor 11 that moves the moving body 124 is normal or abnormal according to the motor rotation direction.

  The embodiment described above is an example, and the present invention is not limited to this. For example, the configuration of the non-essential part may be replaced with another configuration. For example, the mechanism unit is not limited to the ball screw mechanism, but may be any mechanism that moves the moving body. The moving body is not limited to a configuration that moves linearly, but may have a configuration that rotates like a turntable or an arm, for example. The structure which rotates like this may be sufficient.

10 motor control system, 11 motor,
12 Mechanism part,
121 screw shaft, 122 bearing, 123 guide rail, 124 moving body,
13 motor drive device,
131 position control unit, 132 speed control unit, 133 torque control unit,
14 host control device, 15 communication means,
20 abnormality determination unit, 21 storage unit, 22 determination unit,
311 to 315 current value, 321 acceleration operation period, 322 constant speed operation period,
323 Deceleration period, 33 Upper threshold, 34 Lower threshold, 35 Permissible range,
361-363 sampling time,
40 motor control processing, 41 current value acquisition process, 42 subordinate abnormality determination process,
43 upper abnormality determination process, 44 warning process, 45 arrival determination process

Claims (3)

A motor driven by the supplied power;
A mechanism for moving the moving body by rotation of the motor;
A motor driving device for driving the motor based on the moving amount and moving speed of the moving body;
A host controller that controls the motor driving device based on the operation information of the motor;
In a motor control system with
Time in a series of operation periods consisting of an acceleration operation period for accelerating the moving body, a constant speed operation period for moving the moving body at a constant speed, and a deceleration operation period for decelerating the moving body, and a current flowing through the motor A storage unit for storing a desired relationship between the normal value and the normal value;
A determination unit that determines that the difference between the value of the current flowing through the motor and the value of the current stored in the storage unit is greater than a predetermined threshold;
With a motor control system.   The motor control system according to claim 1, wherein the determination unit is disposed in the motor driving device.   The motor control system according to claim 1, wherein the determination unit is disposed only in the host controller.

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