JP2018026921A - Servo system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology of estimating an abnormal shaft by detecting an abnormal magnetic pole position in a servo system for parallel-operating a servo motor with a plurality of shafts.SOLUTION: The servo motor is structured so that an output shaft of a first servo motor is mechanically coupled to an output shaft of a second servo motor, outputs of a first and a second position sensors mounted on each of the first and the second servo motors are connected with a first and a second servo amplifiers for driving the first and the second servo motors, the second servo amplifier is controlled based on a control command from the first servo amplifier and further so that the first servo amplifier compares DC voltages in each of the first and the second servo amplifiers to detect an abnormal magnetic pole position of the first and the second servo motors.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a servo system that operates a plurality of servomotors in parallel, and more particularly to detection of magnetic pole position abnormality of a plurality of servomotors.

  In an industrial servo system, a magnetic pole position of a permanent magnet built in a servo motor is detected, and a servo amplifier controls a motor current according to the position. The detection of the magnetic pole position of the permanent magnet has a low resolution (for example, an electrical angle of 60 degrees) by a method using a magnetic detector such as a Hall sensor. Therefore, a highly accurate position sensor such as an encoder can be used as a magnetic pole position detection means. High resolution is ensured (for example, electrical angle of 1 degree or less). When using a position sensor as a magnetic pole position detection means, adjust the positional relationship with the permanent magnet when assembling the position sensor, perform origin adjustment after assembly, and store the angle information in the electronic circuit of the position sensor. Realize high resolution. Here, when the origin of the position sensor is not properly adjusted, or when the position sensor is not fixed and mechanically displaced, the maximum speed at which the specified torque cannot be obtained and the motor operates in the reverse direction Unintended operation such as rotating at When the servo motor is operated alone, these unintended operations can be detected by overcurrent abnormality, overload abnormality, speed deviation abnormality, overspeed abnormality, etc., and the servo system can be safely stopped.

  As background art of this technical field, there is JP-A-2002-262591 (Patent Document 1). Patent Document 1 includes means for calculating instantaneous power by multiplying the current value and voltage value of each phase of the AC motor, and compares the instantaneous power with the power determined from the torque command and the rotational speed to estimate the magnetic pole. Inverting the estimated magnetic pole position by comparing the DC input power, the torque command, and the power determined by the rotation speed. The point to detect is described.

JP 2002-262591 A

  Patent Document 1 discloses a motor control device having a protection function such as detection of reversal of the magnetic pole position of a motor by a simple method, but does not consider the case of operating a multi-axis servo motor in parallel.

In servo systems that operate in parallel by mechanically connecting the output shafts of multiple axes of servo motors, even if magnetic pole position abnormalities such as poor magnetic pole position adjustment or position sensor deviation occur in some servo motors, other normal In some cases, the servo system can continue to operate with a simple servo motor. At this time, even if the servo system could be operated, there were the following problems.
(1) The magnetic pole position abnormality cannot be found while the servo system can be operated. During this period, the outputs of the normal axis and the abnormal axis interfere with each other, and wasteful power consumption that does not contribute to the output occurs. Moreover, it leads to secondary abnormalities such as motor overheating and equipment wear.
(2) Secondary abnormalities such as overload abnormalities and overvoltage abnormalities due to power regeneration occur in the parallel servo amplifiers in parallel, and the identification of the problem location is delayed, leading to an increase in downtime of the servo system. .

  Therefore, an object of the present invention is to provide a technique for detecting an abnormal magnetic pole position and estimating an abnormal axis in a servo system that operates a plurality of servo motors in parallel.

  In order to solve the above-described problems, the present invention is, as an example, an output shaft of the first servo motor and an output shaft of the second servo motor are mechanically coupled to each other. The outputs of the first and second position sensors respectively attached to the servo motors are connected to the first and second servo amplifiers that drive the first and second servo motors, and the second servo amplifier is the first servo. A servo system controlled based on a control command from an amplifier, wherein the first servo amplifier compares the DC voltages in the first and second servo amplifiers, and the first and second servo motors It is configured to detect magnetic pole position abnormality.

  According to the present invention, wasteful power consumption can be suppressed by promptly detecting the occurrence of a magnetic pole position abnormality. In addition, by estimating the servo motor in which the magnetic pole position abnormality has occurred, it is possible to suppress an increase in downtime.

1 is a schematic configuration diagram of a servo system that operates two servomotors in parallel in Embodiment 1. FIG. It is a figure explaining the behavior of the PN voltage in the power running state in Example 1, and a regeneration state. It is a schematic block diagram of the servo system which operates two servomotors in Example 2 in parallel.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a servo system that operates two servo motors in parallel in this embodiment.

  In FIG. 1, it is assumed that the first servo motor 3 and the second servo motor 13 are mechanically coupled at the load 5 by a gear, a timing belt, or the like. Further, the first AC power supply 4 and the second AC power supply 14 are converted into AC voltages having a desired frequency and supplied to the first servo motor 3 and the second servo motor 13 for driving, respectively. Servo amplifier 1 and second servo amplifier 11. The first position sensor 2 and the second position sensor 12 are connected to the first servo motor 3 and the second servo motor 13, and the outputs of the first position sensor 2 and the second position sensor 12 are output. The signals are input to the first servo amplifier 1 and the second servo amplifier 11, respectively.

  The first servo amplifier 1 includes a first rectification unit 102, a first power storage unit 103, a first power conversion unit 104, and a first calculation unit 101 connected to a first AC power supply 4. The Similarly, the second servo amplifier 11 includes a second rectification unit 202, a second power storage unit 203, a second power conversion unit 204, and a second calculation unit 201.

  The first rectifying unit 102 and the second rectifying unit 202 are configured by, for example, a DC conversion circuit configured by a diode or a DC conversion circuit using an IGBT and a flywheel diode, and the first AC power source 4 and the second rectification unit 202 are configured. The AC voltage input from the AC power supply 14 is converted into a DC voltage and output to the first power storage unit 103 and the second power storage unit 203.

  The first power storage unit 103 and the second power storage unit 203 smooth the DC voltage input from the first rectification unit 102 and the second rectification unit 202, and the first power conversion unit 104 and the second power A DC voltage is output to the conversion unit 204.

  The first power conversion unit 104 and the second power conversion unit 204 are configured by, for example, an AC conversion circuit using an IGBT and a flywheel diode, and the DC voltages of the first power storage unit 103 and the second power storage unit 203 are The output commands of the first control unit 101 and the second control unit 201 are input, the DC voltage is converted into an AC voltage, and the converted AC voltage having a desired frequency is converted into the first servo motor 3 and the second servo motor. 13 is supplied.

  The first control unit 101 and the second control unit 201 perform the first power conversion according to the output command calculated from the command given to drive the first servo motor 3 and the second servo motor 13. A PWM output command is given to the unit 104 and the second power conversion unit 204.

  Next, the magnetic pole position abnormality detection operation will be described.

  First, the first control unit 101 detects a PN voltage that is a voltage between terminals of the first power storage unit 103 in the first servo amplifier 1. Similarly, the second control unit 201 detects a PN voltage that is a voltage between terminals of the second power storage unit 203 in the second servo amplifier 11. Here, assuming that the second servo amplifier 11 is controlled based on a control command from the first servo amplifier 1, the PN voltage detected by the second control unit 201 is transmitted to the first control unit 101. Then, the first control unit 101 compares both PN voltage values. Then, when the inconsistent state continues for a certain time in the comparison result, the first control unit 101 determines that the first servo motor 3 or the second servo motor 13 is in the magnetic pole position abnormal state.

  Further, in the first servo amplifier 1, the first servomotor 3 is in a power running state (the direction of the torque output estimated value and the speed detected value coincide with each other from the torque output estimated value and the speed detected value of the first position sensor 2. The PN voltage decreases), or the regeneration state (the PN voltage increases when the direction of the torque output estimated value and the speed detection value is opposite) is determined, and the first If the determination of powering / regeneration estimated from the PN voltage of the power storage unit 103 and the determination of powering / regeneration estimated from the torque output estimated value and the speed detection value of the first position sensor 2 are inconsistent, It is estimated that the first servo motor 3 is an abnormal axis.

  Similarly, the second servo amplifier 11 determines whether the second servomotor 13 is in a power running state or a regenerative state from the estimated torque output value and the speed detection value of the second position sensor 12, and the second servo amplifier 11 If the determination of powering / regeneration estimated from the PN voltage of power storage unit 203 and the determination of powering / regeneration estimated from the torque output estimated value and the speed detection value of second position sensor 12 do not match, the second The servo motor 13 is estimated to be an abnormal axis.

  FIG. 2 illustrates the behavior of the PN voltage, taking as an example a case where a machine having a power running section (a) and a regeneration section (b) is operated at a constant speed.

  In FIG. 2, the behavior at normal time is indicated by a solid line. As shown in FIG. 2, in normal times, the machine output and the regenerative energy are shared by two motors, so that the PN voltage 1 of the first livestock power unit 103 and the P of the second livestock power unit 203 are normal. -N voltage 2 is balanced.

  In FIG. 2, as a behavior at the time of abnormality, a case where a magnetic pole position abnormality occurs in the first servomotor 3 is taken as an example and indicated by a dotted line. As shown in FIG. 2, due to the magnetic pole position abnormality, the first servomotor 3 cannot obtain a predetermined torque, and the machine output and the regenerative energy cannot be equally shared. The voltage 1 and the PN voltage 2 of the second livestock power storage unit 203 behave differently. That is, the tendency of increase and decrease of the PN voltage is inconsistent. By continuing this inconsistency state for a fixed time, it can be detected that at least one of the servomotors is in a magnetic pole position abnormal state.

  At this time, the output torque of each servo motor interferes and the output torque increases, which may cause overload abnormality, abnormal overheating, and the like. Further, the change in the PN voltage of the normal axis becomes large, which may cause an undervoltage abnormality and an overvoltage abnormality.

  As described above, the PN voltages of the plurality of servo amplifiers are monitored and compared to detect the magnetic pole position abnormality.

If the servo amplifier is connected by a DC bus, it is difficult to measure the PN voltage separately for each servo motor. Therefore, by monitoring and comparing the current value of the P line or N line, the magnetic pole Detect position error.
Also, it is determined from the polarity of the output current value (torque output estimated value) from the servo amplifier and the speed detection value whether the servo motor is in the power running state or the regenerative state, and is estimated from the change in the PN voltage. By comparing with the judgment of power running / regeneration to be performed, an abnormal axis whose deviation exceeds an electrical angle of 90 ° is estimated. In a system in which three or more servo motors are arranged in parallel, the abnormal axis whose deviation is less than 90 ° is estimated by using the minority group as the abnormal axis in the comparison result with the PN voltage.

  Note that the estimated torque value 1 and the estimated torque value 2 are balanced even in the normal state / abnormal state, so that even if they are compared, the magnetic pole position abnormality cannot be detected.

  When an abnormality in the magnetic pole position is detected, it cannot be determined which axis is abnormal. However, since the servo system can be continuously operated by a normal servo motor, production can be continued without stopping for this reason. However, since there is a possibility that wasteful electric power is consumed, an early countermeasure can be promoted by issuing a warning without stopping the operation.

  In addition, the servo amplifier has a display unit and a storage unit, and the history of warnings is held in the storage unit.If there is a history of warnings at the start of the next operation, a request for magnetic pole alignment is displayed on the display unit. You may make it display. Alternatively, if there is a history of issuing warnings, the operation may not be performed unless the operation is once canceled and the magnetic pole alignment is performed.

  Thus, the magnetic pole position abnormality is detected by comparing the PN voltages of a plurality of servo amplifiers. Further, based on the output torque and speed detection value from each servo amplifier, the magnetic pole position abnormality is detected and the abnormal axis is estimated. Thereby, wasteful power consumption can be suppressed by quickly detecting the occurrence of the magnetic pole position abnormality. In addition, by estimating the servo motor in which the magnetic pole position abnormality has occurred, it is possible to suppress an increase in downtime.

  In the first embodiment, the case where the magnetic pole position abnormality detection is applied to the control unit of the servo amplifier has been described. However, in this embodiment, a case where the magnetic pole position abnormality detection is performed by the host apparatus will be described.

  FIG. 3 is a schematic configuration diagram of a servo system that operates two servo motors in parallel in this embodiment. 3, components having the same functions as those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

3 is different from FIG. 1 in that the magnetic pole position abnormality detection device 6 is performed by a host device of the servo amplifier.
That is, the PN voltages that are the voltages between the terminals of the first power storage unit 103 and the second power storage unit 203 are detected by the first control unit 101 and the second control unit 201, and each PN voltage is detected. The values are transmitted from the first control unit 101 and the second control unit 201 to the magnetic pole position abnormality detection device 6 and compared in the magnetic pole position abnormality detection device 6. Then, the magnetic pole position abnormality detection device 6 determines that the first servo motor 3 or the second servo motor 13 is in the magnetic pole position abnormal state when the mismatched state of both continues for a predetermined time.

  Further, the magnetic pole position abnormality detection device 6 is based on the torque output estimated value and the speed detection value of the first position sensor 2 or the second position sensor 12 in the first servo amplifier 1 and the second servo amplifier 11. The determination result of whether the first servo motor 3 or the second servo motor 13 is in the power running state or the regenerative state is received, the determination of the power running / regeneration estimated from the PN voltage, the torque output estimated value, and the position sensor If the power running / regeneration judgment estimated from the speed detection value is inconsistent, it is estimated that the first servo motor 3 or the second servo motor 13 is an abnormal axis. The magnetic pole position abnormality detection device 6 receives the torque output estimated value and the speed detection value of the first position sensor 2 or the second position sensor 12, and estimates from the torque output estimated value and the position sensor speed detection value. The determination of power running / regeneration to be performed may be performed in the magnetic pole position abnormality detection device 6.

  Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, in the above-described embodiment, the servo system that operates two servo motors in parallel has been described. However, the present invention can be applied to a case where three or a plurality of servo motors are operated in parallel. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1: first servo amplifier, 2: first position sensor, 3: first servo motor, 4: first AC power supply, 5: load, 6: magnetic pole position abnormality detection device, 11: second Servo amplifier, 12: second position sensor, 13: second servo motor, 14: second AC power supply, 101: first control unit, 102: first rectification unit, 103: first power storage unit , 104: first power conversion unit, 201: second control unit, 202: second rectification unit, 203: second power storage unit, 204: second power conversion unit

Claims (6)

An output shaft of the first servo motor and an output shaft of the second servo motor are mechanically coupled, and outputs of the first and second position sensors respectively attached to the first and second servo motors are The servo system is connected to first and second servo amplifiers for driving first and second servo motors, and the second servo amplifier is controlled based on a control command from the first servo amplifier. ,
The first servo amplifier compares a DC voltage in each of the first and second servo amplifiers to detect a magnetic pole position abnormality of the first and second servomotors. . The servo system according to claim 1,
The comparison is made by comparing whether or not the DC voltage increase and decrease tendencies in the first and second servo amplifiers are inconsistent for a certain period of time. And detecting that the first servo motor or the second servo motor is in a magnetic pole position abnormal state. The servo system according to claim 1,
Furthermore, the magnetic pole position abnormality of the first and second servo motors is detected based on the output torque and speed detection value from the first and second servo amplifiers, and the abnormal axis is estimated. Servo system. The servo system according to claim 1,
Based on the output torque and speed detection value from each of the first and second servo amplifiers, the first and second servo amplifiers regenerate whether the first and second servomotors are in a power running state. Determine whether
The determination result and the first and second servo motors estimated from the DC voltage in the first and second servo amplifiers are compared with the determination result of the power running state or the regenerative state. A servo system characterized by estimating that the servo motor is abnormal magnetic pole position. The servo system according to any one of claims 1 to 4,
A servo system that issues a warning without stopping operation when the magnetic pole position abnormality is detected. The servo system according to claim 5,
A servo system that retains a history of issuing the warning and issues a magnetic pole alignment request at the next start of operation.

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