Motor control device

Abstract

A motor control device according to one embodiment of the present disclosure is provided with: a torque command creation unit to which a speed command for specifying the speed of a motor is input, and which creates a torque command for specifying the drive torque of the motor on the basis of the speed command; a filter unit that reduces the value of a set frequency range of the speed command or the torque command; an operation command creation unit that creates an operation command, which is the speed command for operating the motor; a measurement command creation unit that creates a plurality of measurement commands, which are the speed command or the torque command having a predetermined waveform, so as to adjust the setting value of the filter unit; a response characteristic calculation unit that calculates a frequency response characteristic of a signal on the downstream side of the torque command generation unit with respect to the measurement command; and a filter setting unit that determines the frequency width of the set frequency range of the filter unit using resonant frequencies corresponding to the frequency response characteristics for at least two of the measurement commands.

Description

Technical Field

[0001] The present invention relates to a motor control device. Background Art

[0002] A known technique for motor control devices is to provide a filter with a reduced gain near the resonant frequency of a control loop to suppress the peak of the resonance and smooth the frequency response. Another technique has been proposed for measuring the frequency response of the control loop and adjusting the filter width accordingly (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-306753 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In an ideal model, the frequency response characteristics of the control loop remain constant. However, in real motor drive systems, the frequency response characteristics of the control loop may vary depending on the operating conditions. Therefore, in motor drive systems, a technology that can more appropriately suppress the peak of resonance is desired.

[0008] Solutions for solving problems

[0009] A motor control device according to one embodiment of the present disclosure includes: a torque command generating unit, which receives a speed command for specifying the speed of a motor and generates a torque command for specifying the driving torque of the motor based on the speed command; a filter unit, which reduces the value of a set frequency range of the speed command or the torque command; an operation command generating unit, which generates an operation command, wherein the operation command is the speed command for operating the motor; a measurement command generating unit, which generates a plurality of measurement commands to adjust a setting value of the filter unit, wherein the plurality of measurement commands are the speed command or the torque command having a prescribed waveform; a response characteristic calculating unit, which calculates the frequency response characteristics of a signal on the downstream side of the torque command generating unit with respect to the measurement command; and a filter setting unit, which uses the corresponding resonant frequencies of the frequency response characteristics with respect to at least two of the measurement commands to determine the frequency width of the set frequency range of the filter unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a block diagram showing the configuration of a motor control device according to one embodiment of the present disclosure.

[0011] Figure 2 This is an example of Figure 1 A graph showing changes in the frequency response characteristics of a motor control device due to differences in command scanning directions.

[0012] Figure 3 It shows Figure 1 Flowchart of a process for determining a setting value of a filter unit in a motor control device. DETAILED DESCRIPTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Figure 1 This is a block diagram showing the configuration of a motor control device 1 according to one embodiment of the present disclosure.

[0014] Motor control device 1 controls motor 3 via amplifier 2. Specifically, motor control device 1 inputs a torque command, specifying the torque required to operate motor 3 at a target speed, into amplifier 2. Motor control device 1 is configured to perform feedback control by checking the detection value of speed detector 31, which detects the speed of motor 3, to optimize the torque command.

[0015] The motor control device 1 includes an operation command generator 11, a torque command generator 12, a filter unit 13, a measurement command generator 14, a response characteristic calculator 15, a measurement condition determination unit 16, and a filter setting unit 17. The motor control device 1 can be implemented by having one or more computer devices equipped with memory, a processor, and input / output interfaces execute an appropriate control program. The components of the motor control device 1 are categorized according to their functions and may not be clearly distinguishable in terms of physical or program structure.

[0016] The operation command generator 11 generates an operation command to operate the motor 3. This operation command is a speed command that specifies the speed of the motor 3. The operation command generator 11 reads data that specifies the required operation of the motor 3, that is, data describing the waveform of the change in the speed of the motor 3, such as an operation program described in a language such as G-code, and continuously outputs values ​​indicating the rotational speed of the motor 3 when the motor 3 is operated according to the operation program. For example, the operation command generator 11 may generate a position command that specifies the rotational position of the motor 3 and generate the operation command based on the position command.

[0017] The torque command generating unit 12 generates a torque command for designating the driving torque of the motor 3 based on the input speed command. That is, the torque command generating unit 12 calculates the magnitude of the driving torque required for the motor 3 to actually rotate at the speed designated by the speed command.

[0018] The filter unit 13 receives the torque command from the torque command generator 12 and reduces the value of the set frequency range of the input torque command. Specifically, the filter unit 13 can be configured to generate a speed command having a reduced set frequency value by performing a Fourier transform on the input torque command, multiplying the value of the set frequency range by a relatively small gain, and then performing an inverse Fourier transform.

[0019] The measurement command generator 14 generates multiple measurement commands having predetermined waveforms to adjust the set value of the filter unit 13. In this embodiment, the measurement commands generated by the measurement command generator 14 are speed commands input to the torque command generator 12, but they may also be torque commands input to the amplifier 2. To facilitate the calculation of the frequency response characteristics by the response characteristic calculator 15, the measurement commands generated by the measurement command generator 14 preferably have waveforms whose values ​​change periodically and are scanned in a frequency-varying manner. The measurement commands may be, for example, triangular, rectangular, or sawtooth waves, but are preferably sinusoidal waves to reduce the computational load on the response characteristic calculator 15. Furthermore, the measurement commands may also change in a ramp, pulse, or M-sequence signal pattern.

[0020] The measurement command generator 14 of this embodiment includes a scanning direction reversing unit 141 that reverses the scanning direction of the measurement command, and an amplitude changing unit 142 that changes the amplitude of the measurement command. This allows the measurement command generator 14 to generate three or more measurement commands. The measurement command generator 14 can be configured to sequentially generate different measurement commands in a predetermined order, or it can be configured to change the measurement command format in response to the determination result of the measurement condition determination unit 16. The measurement command generator 14 can also modify the measurement command format by combining the selection of the scanning direction by the scanning direction reversing unit 141 and the modification of the amplitude by the amplitude changing unit 142 in any order.

[0021] The scanning direction reversing unit 141 sets whether to scan in a decreasing direction where the frequency of the measurement instruction gradually decreases from a high frequency or in an increasing direction where the frequency gradually increases from a low frequency. Figure 2 As illustrated, the calculated resonant frequency may vary. Generally, the resonant frequency when sweeping in the frequency decreasing direction may be smaller than the resonant frequency when sweeping in the frequency increasing direction.

[0022] Amplitude changing unit 142 sets the amplitude of the measurement command. Changing the amplitude of the measurement command may change the frequency response curve, shifting the resonant frequency. For example, amplitude changing unit 142 may be configured to select an amplitude from a plurality of predetermined amplitudes, change the amplitude by multiplying the current amplitude by a predetermined ratio, or change the amplitude by adding a predetermined deviation to the current amplitude.

[0023] The response characteristic calculation unit 15 calculates the frequency response characteristics of the signal downstream of the torque command generation unit 12 with respect to the measurement command. Furthermore, the "signal downstream of the torque command generation unit 12" refers to the signal output from the torque command generation unit 12 and components downstream of the torque command generation unit 12, and is not determined based on the signal's input (feedback) location. Furthermore, if there are components (e.g., amplifiers, filters, etc.) that process the signal before feeding it back, the fed-back signal is also considered "the signal downstream of the torque command generation unit 12" based on the signal's flow to the output location. In the illustrated embodiment, the response characteristic calculation unit 15 calculates the frequency response characteristics of the motor 3 with respect to the measurement command based on the feedback value from the motor 3 with respect to the measurement command, that is, the detection value of the speed detector 31. The frequency response characteristic can be the gain of the target signal with respect to the measurement command, the phase difference between the speed of the motor 3 and the measurement command, or both. By using the frequency response characteristics of both the gain and the phase difference, it is possible to more appropriately set the frequency width (filter width) of the set frequency range for reducing the speed command of the filter unit 13 .

[0024] The measurement condition determination unit 16 determines whether calculation of a frequency response characteristic based on a different measurement command is necessary based on the frequency response characteristics already measured for multiple measurement commands. If the relationship between the newly measured frequency response characteristic and the previously measured frequency response characteristic does not satisfy a predetermined determination condition, the measurement condition determination unit 16 can be configured to instruct the measurement command creation unit 14 to create a measurement command with different conditions. For example, the measurement condition determination unit 16 can be configured to gradually increase or decrease the amplitude of the measurement command via the amplitude change unit 142 until the frequency response characteristic satisfies the predetermined determination condition. Alternatively, the measurement condition determination unit 16 can be configured to allow user-configurable determination conditions, such as thresholds.

[0025] Specifically, if the resonant frequency does not shift relative to the frequency response characteristics of the previous amplitude measurement command even when the amplitude of the measurement command is increased or decreased, that is, if the difference in resonant frequency is below a set threshold, measurement condition determination unit 16 may not perform a new frequency response characteristic measurement, but instead request filter setting unit 17 to determine the setting value for filter unit 13. Measurement condition determination unit 16 may also determine whether a new frequency response characteristic measurement is necessary based on, for example, the gain of the frequency response or the input-output ratio of the time response. Furthermore, if it becomes clear that the frequency response characteristics obtained before measurement command generation unit 14 completes the measurement command scan do not meet the determination conditions, measurement condition determination unit 16 may request measurement command generation unit 14 to interrupt the measurement command scan and begin outputting measurement commands with different conditions.

[0026] Filter setting unit 17 determines the frequency width of the set frequency range of filter unit 13 using the corresponding resonant frequencies of the frequency response characteristics for at least two measurement commands. When measurement condition determination unit 16 measures the frequency response characteristics for three or more measurement commands, the frequency width is preferably determined based on the maximum and minimum values ​​of the corresponding resonant frequencies for these measurement commands. In other words, filter setting unit 17 can be configured to calculate the filter width by taking into account the maximum and minimum frequencies of the same resonant point after shifting in response to changes in the measurement commands.

[0027] The filter setting unit 17 is configured to store information required when the response characteristic calculation unit 15 calculates the frequency response characteristic. When calculating frequency response characteristics for three or more measurement commands, the filter setting unit 17 may be configured to sequentially delete information not used in calculating the setting value for the filter unit 13, that is, to store the information by overwriting the old information with the new information. For example, a configuration may be configured to store only the minimum and maximum values ​​for the resonant frequency. If the resonant frequency of the newly acquired frequency response characteristic is smaller than the stored minimum value, the minimum value is overwritten. If the resonant frequency of the newly acquired frequency response characteristic is larger than the stored maximum value, the maximum value is overwritten.

[0028] As a specific example, if the minimum resonant frequency is f1, the filter width is x1, which is set using a known method based on a frequency response curve having this resonant frequency, the maximum resonant frequency is f2, and the filter width based on this frequency response curve is x2, the center frequency of the filter is set between f1 and f2, and the filter width is a frequency width that includes the range of f1 ± x1 and the range of f2 ± x2. Specifically, when f1 is the center frequency of the filter, the filter width W can be set to the larger of 2*(f2 - f1 + x2 / 2) and x1. Furthermore, when the average frequency of f1 + f2 [(f1 + f2) / 2] is set as the center frequency of the filter, if x2 > x1, the filter width W can be set to 2*((f2 - f1) / 2 + x2 / 2), and if x1 > x2, the filter width W can be set to 2*((f2 - f1) / 2 + x1 / 2).

[0029] Figure 2 This flowchart illustrates the process of determining the setting value of the filter unit 13 in the motor control device 1. Determining the setting value of the filter unit 13 includes: initializing the measurement command (step S1); measuring the frequency response characteristics (step S2); confirming whether the judgment condition is met (step S3); changing the setting of the measurement command (step S4); and calculating the setting value (step S5). In this process, the process of changing the amplitude of the measurement command in step S4 and measuring the frequency response characteristics for the measurement command in step S2 is repeated until the judgment condition is met in step S3. If the judgment condition is met in step S3, the filter width and other parameters are set based on the frequency response characteristics obtained so far in step S5.

[0030] As described above, the motor control device 1 includes a measurement command generator 14 that generates a plurality of measurement commands, and a filter setting unit 17 that determines the filter width of the filter unit 13 by taking into account the corresponding resonant frequencies in the plurality of measurement commands. This effectively reduces the peak value of the output caused by resonance, even if the resonant frequency shifts in response to the input. In other words, the motor control device 1 can make the output characteristic curve of the motor 3 relatively flat, thereby achieving more accurate control of the motor 3.

[0031] The following supplementary notes are further disclosed regarding the above-mentioned embodiment and modifications.

[0032] (Note 1)

[0033] The motor control device (1) comprises: a torque instruction generating unit (12) which receives a speed instruction for specifying the speed of a motor (3) and generates a torque instruction for specifying the driving torque of the motor (3) based on the speed instruction; a filter unit (13) which reduces the value of a set frequency range of the speed instruction or the torque instruction; an operation instruction generating unit (11) which generates an operation instruction, wherein the operation instruction is a speed instruction for operating the motor (3); a measurement instruction generating unit (14) which generates a plurality of measurement instructions to adjust a setting value of the filter unit (13), wherein the plurality of measurement instructions are speed instructions or torque instructions having a predetermined waveform; a response characteristic calculating unit (15) which calculates a frequency response characteristic of a signal on the downstream side of the torque instruction generating unit (12) with respect to the measurement instruction; and a filter setting unit (17) which determines a frequency width of a set frequency range of the filter unit (13) using corresponding resonant frequencies of the frequency response characteristics with respect to at least two measurement instructions.

[0034] (Note 2)

[0035] In the motor control device (1) of Appendix 1, the value of the measurement instruction may change periodically, and the measurement instruction may be scanned in a frequency-changing manner, and the measurement instruction generating unit (14) may include a scanning direction reversing unit (141) for reversing the scanning direction of the measurement instruction.

[0036] (Note 3)

[0037] In the motor control device (1) of Supplementary Notes 1 and 2, the measurement command generating unit (14) may include an amplitude changing unit (142) for changing the amplitude of the measurement command.

[0038] (Note 4)

[0039] In the motor control device (1) of Supplementary Notes 1 to 3, the filter setting unit (17) may determine the frequency width based on the maximum value and the minimum value among the corresponding resonant frequencies of the plurality of measurement instructions.

[0040] (Note 5)

[0041] The motor control device (1) of Appendix 1 to Appendix 4 may further include a measurement condition determination unit (16) that determines whether it is necessary to calculate the frequency response characteristics based on further different measurement instructions based on the frequency response characteristics for multiple measurement instructions.

[0042] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-mentioned embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. without departing from the scope of the present disclosure or the scope of the present disclosure derived from the contents recorded in the claims and their equivalents. In addition, these embodiments can also be implemented in combination. For example, in the above-mentioned embodiments, the order of each action and the order of each processing are shown as an example and are not limited to these. In addition, the same applies to the case where numerical values ​​or formulas are used in the description of the above-mentioned embodiments.

[0043] As an example, in the motor control device involved in the present disclosure, the measurement instruction production unit may be configured to output only two measurement instructions that differ only in the scanning direction. In this case, it can be configured so that: the measurement condition determination unit is not required, and the filter setting unit directly uses the resonant frequencies of the two measurement instructions to determine the filter width when calculating the frequency response characteristics of the two measurement instructions. In addition, in the motor control device involved in the present disclosure, the measurement instruction production unit may also have only an amplitude change unit. In addition, in the above-mentioned embodiment, the torque instruction is filtered, but the speed instruction may also be filtered. In addition, in the above-mentioned embodiment, the speed signal is fed back from the motor, but the position signal, torque signal, etc. may also be fed back. In addition, the position of the input feedback signal can be different depending on the feedback signal.

[0044] Description of Reference Numerals

[0045] 1: Motor control device; 11: Operation instruction generation unit; 12: Torque instruction generation unit; 13: Filter unit; 14: Measurement instruction generation unit; 141: Scan direction reversal unit; 142: Amplitude change unit; 15: Response characteristic calculation unit; 16: Measurement condition determination unit; 17: Filter setting unit; 2: Amplifier; 3: Motor; 31: Speed ​​detector.

Claims

1. A motor control device comprising: a torque command generating unit that receives a speed command for specifying a speed of the motor and generates a torque command for specifying a driving torque of the motor based on the speed command; a filter unit configured to reduce a value of the speed command or the torque command within a set frequency range; an operation instruction generating unit configured to generate an operation instruction, wherein the operation instruction is the speed instruction for operating the motor; a measurement command generating unit configured to generate a plurality of measurement commands for adjusting a setting value of the filter unit, wherein the plurality of measurement commands are the speed command or the torque command having a predetermined waveform; a response characteristic calculation unit that calculates a frequency response characteristic of a signal on a downstream side of the torque instruction generation unit with respect to the measurement instruction; and A filter setting unit determines a frequency width of the set frequency range of the filter unit using corresponding resonant frequencies of the frequency response characteristics for at least two of the measurement commands.

2. The motor control device according to claim 1, wherein: The value of the measurement instruction changes periodically, and the measurement instruction is scanned in a manner of changing frequency. The measurement command generating unit includes a scanning direction reversing unit that reverses a scanning direction of the measurement command.

3. The motor control device according to claim 1 or 2, wherein: The measurement command generating unit includes an amplitude changing unit that changes the amplitude of the measurement command.

4. The motor control device according to any one of claims 1 to 3, wherein: The filter setting unit determines a frequency width based on a maximum value and a minimum value among resonance frequencies corresponding to the plurality of measurement commands.

5. The motor control device according to claim 4, wherein: The device further includes a measurement condition determination unit configured to determine, based on the frequency response characteristics for a plurality of measurement commands, whether calculation of the frequency response characteristic based on a further different measurement command is necessary.

Images