JP6708517B2 - Servo system - Google Patents

Description

The present invention relates to a servo system in which servomotors having a plurality of axes are operated in parallel, and more particularly to detection of magnetic pole position abnormalities 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. Since the magnetic pole position of the permanent magnet is detected with a magnetic detector such as a Hall sensor having a low resolution (for example, an electrical angle of 60 degrees), a highly accurate position sensor such as an encoder can be used as the magnetic pole position detecting means. , High resolution is secured (for example, electrical angle of 1 degree or less). When using the position sensor as the magnetic pole position detection means, adjust the positional relationship with the permanent magnet when assembling the position sensor, perform the origin alignment operation after assembly, and save the angle information in the electronic circuit of the position sensor. Achieve high resolution. Here, if the origin of the position sensor is not properly adjusted, or if the position sensor is loosely fixed and mechanically misaligned, the specified torque cannot be obtained, the motor operates in the reverse direction, and the maximum speed It will be an unintended operation such as rotating with. When the servo motor is operated alone, these unintended operations can be detected by an overcurrent abnormality, an overload abnormality, a speed deviation abnormality, an overspeed abnormality, etc., and the servo system can be stopped safely.

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

JP, 2002-262591, A

Patent Document 1 discloses a motor control device having a protective function such as detection of magnetic pole position reversal of a motor by a simple method, but no consideration is given to the case of parallel operation of servo motors having a plurality of axes.

In a servo system in which the output shafts of multiple servo motors are mechanically linked and run in parallel, even if some magnetic pole position adjustments such as magnetic pole position misalignment or position sensor displacement occur in some servo motors, other normal There are cases where the servo system can continue operating with a different servo motor. At this time, even if the servo system could be operated, there were the following problems.
(1) Abnormal magnetic pole position cannot be detected while the servo system can be operated. During this period, the outputs of the normal axis and the abnormal axis interfere with each other, resulting in unnecessary power consumption that does not contribute to the output. In addition, it leads to secondary abnormalities such as motor overheating and wear of the device.
(2) Secondary abnormalities such as overload abnormalities and overvoltage abnormalities due to power regeneration occur in the parallel-axis servo amplifiers for normal axes, which delays the identification of problem areas and leads to an increase in the downtime of the servo system. ..

Therefore, it is an object of the present invention to provide a technique of detecting a magnetic pole position abnormality and estimating an abnormal axis in a servo system in which servo motors having a plurality of axes are operated in parallel.

In order to solve the above-mentioned problems, the present invention, to give an example thereof, mechanically couples an output shaft of a first servo motor and an output shaft of a second servo motor, and The outputs of the first and second position sensors attached to the servo motors are respectively 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 amplifier. A servo system controlled based on a control command from an amplifier, wherein a first servo amplifier compares direct-current voltages in the first and second servo amplifiers, It is configured to detect a magnetic pole position abnormality.

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

FIG. 3 is a schematic configuration diagram of a servo system that operates two servo motors in parallel in the first embodiment. FIG. 5 is a diagram illustrating the behavior of the P-N voltage in a power running state and a regenerative state in Example 1. 6 is a schematic configuration diagram of a servo system that operates two servo motors in parallel in Example 2. FIG.

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 in which two servo motors are operated in parallel in this embodiment.

In FIG. 1, it is assumed that the first servomotor 3 and the second servomotor 13 are mechanically coupled to each other in the load 5 by a gear, a timing belt, or the like. In addition, the voltage from the first AC power supply 4 and the second AC power supply 14 is converted into an AC voltage having a desired frequency and is supplied to and driven by the first servomotor 3 and the second servomotor 13, respectively. It has a servo amplifier 1 and a 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. They are input to the first servo amplifier 1 and the second servo amplifier 11, respectively.

The first servo amplifier 1 is composed of a first rectification unit 102, a first power storage unit 103, a first power conversion unit 104, and a first calculation unit 101, which are connected to the first AC power supply 4. It Similarly, the second servo amplifier 11 also includes a second rectifying unit 202, a second power storage unit 203, a second power converting unit 204, and a second computing unit 201.

The first rectification unit 102 and the second rectification 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 supply 4 and the second rectification unit 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 to generate the first power conversion unit 104 and the second power. The 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 have a DC voltage of the first power storage unit 103 and the second power storage unit 203. , 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 of a desired frequency is converted into the first servo motor 3 and the second servo motor. Supply to 13.

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 operation of detecting the magnetic pole position abnormality will be described.

First, the first control unit 101 detects the PN voltage, which is the voltage between terminals of the first power storage unit 103 in the first servo amplifier 1. Similarly, the second control unit 201 detects the P-N voltage, which is the voltage between the 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 the 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 the P-N voltage values of the two. Then, when the result of the comparison indicates that the disagreement state continues for a certain period of time, the first control unit 101 determines that the first servomotor 3 or the second servomotor 13 is in the magnetic pole position abnormal state.

In the first servo amplifier 1, the first servo motor 3 is in the power running state (the estimated torque output value and the detected speed value are in the same direction) based on the estimated torque output value and the detected speed value of the first position sensor 2. The PN voltage decreases when the torque output estimated value is decreasing) or the regenerative state (the P-N voltage increases when the directions of the estimated torque output value and the speed detection value are opposite). If the determination of power running/regeneration estimated from the P-N voltage of the power storage unit 103 and the determination of power running/regeneration estimated from the torque output estimated value and the speed detection value of the first position sensor 2 do not match, It is estimated that the first servomotor 3 is an abnormal axis.

Similarly, the second servo amplifier 11 determines whether the second servo motor 13 is in the power running state or the regenerative state from the torque output estimated value and the speed detection value of the second position sensor 12, and the second servo amplifier 13 If the determination of power running/regeneration estimated from the P-N voltage of power storage unit 203 and the determination of power running/regeneration estimated from the torque output estimated value and the speed detection value of second position sensor 12 do not match, the second It is presumed that the servo motor 13 of is an abnormal axis.

The behavior of the PN voltage will be described by taking as an example a case where a machine having a power running section (a) and a regenerative section (b) is operated at a constant speed in FIG.

In FIG. 2, the behavior at the normal time is shown by a solid line. As shown in FIG. 2, during normal operation, since the mechanical output and the regenerative energy are shared by the two motors, the P-N voltage 1 of the first electricity storage unit 103 and the P-N voltage of the second electricity storage unit 203 are shared. -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 servo motor 3 is shown as an example 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 mechanical output and the regenerative energy cannot be evenly shared. The voltage 1 and the P-N voltage 2 of the second power storage unit 203 behave differently. That is, the increasing and decreasing tendencies of the P-N voltage do not match. By continuing this non-coincidence state for a certain period of time, it can be detected that at least one of the servo motors is in the magnetic pole position abnormal state.

At this time, the output torque increases due to the interference of the outputs of the servo motors, which may cause overload abnormality, abnormal overheating, or the like. Further, the change in the P-N voltage of the normal axis becomes large, which may cause an undervoltage abnormality or an overvoltage abnormality.

In this way, the magnetic pole position abnormality is detected by monitoring and comparing the PN voltages of the plurality of servo amplifiers.

If the servo amplifier is connected via a DC bus, it is difficult to separately measure the PN voltage for each servo motor. Therefore, the current value of the P line or N line is monitored and compared to determine the magnetic pole. Detects position error.
Also, it is estimated from the change in PN voltage whether the servomotor is in the power running state or the regenerative state, based on the polarity of the output current value (torque output estimated value) from the servo amplifier and the speed detection value. By comparing with the judgment of the power running/regeneration, the abnormal axis whose deviation exceeds the electrical angle of 90° is estimated. In a system in which three or more servo motors are arranged in parallel, the minor axis is used as the abnormal axis in the result of comparison with the P-N voltage, and thus the abnormal axis whose deviation is less than 90° is estimated.

Since the estimated torque value 1 and the estimated torque value 2 are balanced even in the normal state/abnormal state, the magnetic pole position abnormality cannot be detected even by comparison.

When an abnormality in the magnetic pole position is detected, it cannot be determined which axis is abnormal, but since the servo system can continue to operate with a normal servo motor, production can be continued without stopping for this reason. However, since there is a possibility that wasteful power is consumed, it is possible to prompt prompt measures by issuing a warning without stopping the operation.

In addition, the servo amplifier has a display section and a storage section, and the history of warnings is stored in the storage section. If there is a history of warnings issued at the start of the next operation, a request for magnetic pole alignment is displayed on the display section. It may be displayed. Alternatively, if there is a history of issuing a warning, the operation may be disabled once the operation is canceled and the magnetic pole alignment is not performed.

Thus, the magnetic pole position abnormality is detected by comparing the P-N voltages of the 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. As a result, wasteful power consumption can be suppressed by promptly detecting the occurrence of the magnetic pole position abnormality. Further, by estimating the servo motor in which the magnetic pole position abnormality has occurred, it is possible to suppress the expansion of the 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, but in the present embodiment, a case where the magnetic pole position abnormality detection is performed by the host device will be described.

FIG. 3 is a schematic configuration diagram of a servo system in which two servo motors are operated in parallel in this embodiment. In FIG. 3, components having the same functions as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be 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 respective P-N voltages, which are the inter-terminal voltages 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 the respective P-N voltages are detected. The value is transmitted from the first control unit 101 and the second control unit 201 to the magnetic pole position abnormality detection device 6, and is compared in the magnetic pole position abnormality detection device 6. Then, the magnetic pole position abnormality detection device 6 determines that the first servomotor 3 or the second servomotor 13 is in the magnetic pole position abnormality state when the mismatched state continues for a certain period of time.

Further, the magnetic pole position abnormality detection device 6 uses 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, respectively. , The first servo motor 3 or the second servo motor 13 receives the determination result of the power running state or the regenerative state, the power running/regenerative determination estimated from the P-N voltage, the estimated torque output value and the position sensor If the power running/regenerative judgment estimated from the speed detection value does not match, 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 speed detection value of the position sensor. The determination of power running/regeneration 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, although the above-described embodiment has been described with respect to the servo system in which two servo motors are operated in parallel, the present invention can be applied to the case where three or more servo motors are operated in parallel. Further, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

1: 1st servo amplifier, 2: 1st position sensor, 3: 1st servomotor, 4: 1st 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 rectifying unit, 103: first power storage unit , 104: first power converter, 201: second controller, 202: second rectifier, 203: second power storage unit, 204: second power converter

Claims (6)

The output shafts of the first servo motor and the output shaft of the second servo motor are mechanically coupled to each other, and the outputs of the first and second position sensors attached to the first and second servo motors are output from the first and second position sensors, respectively. A servo system connected to first and second servo amplifiers for driving first and second servo motors, wherein the second servo amplifier is controlled based on a control command from the first servo amplifier. ,
The first servo amplifier detects a magnetic pole position abnormality of the first and second servo motors by comparing voltages between terminals of power storage units in the first and second servo amplifiers. Servo system. The servo system according to claim 1, wherein
The comparison is performed by comparing whether or not the tendency of increase and decrease of the voltage between terminals of the power storage unit in each of the first and second servo amplifiers does not match for a certain period of time, and the state of mismatch does not change. A servo system, which detects that the first servomotor or the second servomotor is in a magnetic pole position abnormal state when it continues for a time. The servo system according to claim 1, wherein
Further, the magnetic pole position abnormality of the first and second servo motors is detected based on the output torque and the speed detection value from the first and second servo amplifiers, and the abnormal axis is estimated. Servo system to do. The servo system according to claim 1, wherein
Based on the output torque and the speed detection value from the first and second servo amplifiers, the first and second servo amplifiers are in the power running state or the regenerative state of the first and second servo motors. Determine whether the state,
The results of another said-size, the first, the first estimated from the terminal voltage of the power storage unit in the second respective servo amplifiers, the determination result of the second respective servo motors powering state or a regenerative state The servo system is characterized by estimating that the servo motors that do not match have an abnormal magnetic pole position in comparison with. The servo system according to any one of claims 1 to 4,
A servo system which issues a warning without stopping the operation when the magnetic pole position abnormality is detected. The servo system according to claim 5, wherein
A servo system, wherein the history of issuing the warning is retained and a magnetic pole alignment request is issued at the start of the next operation.

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