Motor control device, motor control system, and motor control method

Abstract

A motor control device (100) has a speed detector (5) that detects a speed of a motor (2), a speed controller (4) that generates a torque command based on the speed of the motor and a speed command, a correction operator (6) that corrects the torque command to generate a corrected torque command, a current controller (3) that causes current to flow in the motor based on the torque command and the corrected torque command, a vibration detector (8) that detects a vibration amplitude and a vibration frequency that occur in the motor, and a parameter setting changer (9) that changes a parameter of the speed controller, the correction operator calculates the corrected torque command that stabilizes a transfer characteristic of the vibration frequency with respect to a feedback control system composed of the motor, the speed detector, the speed controller, the correction operator, and the current controller in a case where the vibration amplitude becomes larger than a threshold value, and the parameter setting changer changes the parameter of the speed controller in a case where the vibration amplitude decreases after the transfer characteristic is stabilized.

Description

Technical Field

[0001] This invention relates to a motor control device, a motor control system, and a motor control method for feedback control of an electric motor connected to a mechanical device. Background Technology

[0002] In mechanical devices requiring high-precision control of state variables such as position and velocity, electric motors are used as the drive source for feedback control. To achieve high-precision feedback control with a high response to commands, the parameters for the feedback control operation need to be appropriately designed. If the parameters deviate from the appropriate range, not only will high-precision feedback control with a high response be impossible, but the feedback control system may also become unstable, resulting in phenomena such as vibration.

[0003] The parameters of a feedback control system need to be set to match the characteristics of the load machinery connected to the motor. Examples of mechanical characteristics include the inertia and stiffness of the load machinery, and the parameters need to be set accordingly.

[0004] Furthermore, in load machinery driven by electric motors, mechanical characteristics sometimes change during operation. For example, in a roll-to-roll assembly where sheet material is wound or unwound from rollers while being processed, the moment of inertia of the motor that rotates the rollers varies depending on the amount of material wound on the rollers. This variation is particularly pronounced in roll-to-roll assemblies, sometimes changing by tens of times depending on the amount of material wound on the rollers. In the aforementioned assembly, if parameter settings are made to favor a state where the magnitude of the moment of inertia is biased in one direction, the control system may become unstable in the opposite direction. To prevent this, it is necessary to monitor the moment of inertia variation and set parameters in a way that stabilizes the entire range, or to have a mechanism to prepare for changes to parameter settings predetermined in response to the moment of inertia variation. This increases the workload of starting the assembly. Additionally, it is necessary to understand the overall characteristics of the variation range, making it difficult to utilize the automatic adjustment function during assembly startup.

[0005] Patent document 1 discloses an electric motor system that, in a mechanical device with changing inertia, has an inertia detection unit or a vibration detection unit to prevent the feedback control system from vibrating. Based on the detection results of each unit, the parameters of the feedback control system are changed to suppress the vibration of the electric motor.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-35676 Summary of the Invention

[0007] However, vibration can be caused by multiple factors, such as interference and instability in the control system, requiring different responses to each cause. Simply relying on the occurrence or increase in amplitude of vibration is insufficient to determine the primary cause. Therefore, it is sometimes impossible to appropriately modify the parameter settings in the motor system described in Patent Document 1. Furthermore, the inertia detection unit requires accompanying acceleration and deceleration, making inertia detection difficult depending on the operating mode.

[0008] The present invention was made in view of the above circumstances, and its object is to provide a motor control device that can stabilize the operation when the load connected to the motor of the controlled object changes.

[0009] To address the aforementioned issues and achieve the objective, the present invention provides an electric motor control device that controls an electric motor driving a load mechanism. This electric motor control device comprises: a speed detector that detects the speed of the electric motor; a speed controller that generates a torque command for the electric motor based on the motor speed and a speed command; a correction calculator that corrects the torque command to generate a correction torque command; a current controller that directs current into the electric motor based on the torque command and the correction torque command; a vibration detector that detects the amplitude (vibration amplitude) and frequency (vibration frequency) of vibrations generated by the electric motor; and a parameter setting changer that modifies the parameters of the speed controller. When the vibration amplitude increases compared to a threshold, the correction calculator calculates a correction torque command that stabilizes the transmission characteristics of the vibration frequency detected by the vibration detector, within the feedback control system comprised of the electric motor, speed detector, speed controller, correction calculator, and current controller. When the vibration amplitude detected by the vibration detector decreases after stabilizing the transmission characteristics, the parameter setting changer modifies the parameters of the speed controller.

[0010] The effects of the invention

[0011] The electric motor control device of the present invention has the following effect: it can stabilize the operation when the load connected to the electric motor of the controlled object changes. Attached Figure Description

[0012] Figure 1 This is a block diagram illustrating a structural example of a motor control system implemented using the motor control device described in Embodiment 1.

[0013] Figure 2 The Bode diagram is of the electric motor driven by the electric motor control device according to Embodiment 1.

[0014] Figure 3It is the Bode plot of the open-loop transfer function of the feedback control system of the motor control device involved in Implementation Method 1.

[0015] Figure 4 It is the Nyquist plot of the open-loop transfer function of the feedback control system of the motor control device according to Embodiment 1.

[0016] Figure 5 This is a diagram showing an example of the operating waveform of the motor control device according to Embodiment 1 when it becomes unstable.

[0017] Figure 6 It is the Bode plot of the transfer function of the correction arithmetic unit of the motor control device according to Embodiment 1.

[0018] Figure 7 It is the Bode plot of the open-loop transfer function of the feedback control system of the motor control device involved in Implementation Method 1.

[0019] Figure 8 It is the Nyquist plot of the open-loop transfer function of the feedback control system of the motor control device according to Embodiment 1.

[0020] Figure 9 This is a diagram showing the operating waveform of the feedback control system of the motor control device according to Embodiment 1 when it is stabilized.

[0021] Figure 10 It is the Bode plot of the open-loop transfer function of the feedback control system of the motor control device according to Embodiment 1 under the condition of stabilization.

[0022] Figure 11 It is the Nyquist plot of the open-loop transfer function of the motor control device according to Embodiment 1 under the condition of stabilization of the feedback control system.

[0023] Figure 12 It is a diagram showing the operating waveform when disturbance vibration enters the motor control device involved in Embodiment 1.

[0024] Figure 13 This is a flowchart illustrating an example of the operation of the motor control device according to Embodiment 1 to suppress the vibration of the motor.

[0025] Figure 14 This is a diagram illustrating an example of the hardware for implementing the motor control device according to Embodiment 1.

[0026] Figure 15 This is a block diagram illustrating a structural example of a motor control system implemented using the motor control device described in Embodiment 2.

[0027] Figure 16It is the Bode plot of the open-loop transfer function of the feedback control system of the motor control device involved in Implementation Method 2.

[0028] Figure 17 This is a diagram of an example of the waveform of the speed detection value of the electric motor, representing the process of the inertia of the load machinery decreasing.

[0029] Figure 18 It is the Bode plot of the open-loop transfer function of the feedback control system of the motor control device involved in Implementation Method 2.

[0030] Figure 19 This is a diagram showing the operating waveform of the feedback control system of the motor control device according to Embodiment 2 when it is stabilized.

[0031] Figure 20 It is the Bode plot of the open-loop transfer function of the motor control device according to Embodiment 2 under the condition of stabilization of the feedback control system.

[0032] Figure 21 It is a diagram showing the operating waveform when disturbance vibration enters the motor control device involved in Embodiment 2.

[0033] Figure 22 This is a block diagram illustrating a structural example of a motor control system implemented using the motor control device described in Embodiment 3.

[0034] Figure 23 This is a block diagram illustrating a structural example of a motor control system implemented using the motor control device described in Embodiment 4. Detailed Implementation

[0035] The electric motor control device, electric motor control system, and electric motor control method according to the embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0036] Implementation method 1.

[0037] Figure 1 This is a block diagram illustrating a structural example of a motor control system implemented using the motor control device described in Embodiment 1.

[0038] The electric motor control system 200 according to Embodiment 1 includes: an electric motor control device 100; an electric motor 2 controlled by the electric motor control device 100; and a load machine 1 connected to the electric motor 2.

[0039] The electric motor 2 receives current from the electric motor control device 100 to generate torque, which drives the load machinery 1.

[0040] The motor control device 100 includes a current controller 3, a speed controller 4, a speed detector 5, a calibration calculator 6, a position controller 7, a vibration detector 8, and a parameter setting and changing device 9. The speed detector 5 is composed of a position detector 51 and a differential calculator 52.

[0041] The current controller 3 controls the current supplied to the motor 2 based on the correction torque command input from the correction arithmetic unit 6.

[0042] The speed controller 4 generates a torque command based on the speed command input from the position controller 7 and the speed detection value input from the speed detector 5. Specifically, the speed controller 4 performs calculations including proportional and integral calculations to ensure that the speed detection value follows the speed command, thereby generating the torque command.

[0043] The position detector 51 of the speed detector 5 detects the position of the motor 2, specifically the position of the rotor (not shown in the diagram of the motor 2). The differential arithmetic unit 52 of the speed detector 5 differentiates the position detection value representing the position of the motor 2 obtained by the position detector 51 to calculate the speed of the motor 2. The speed of the motor 2 is the rotational speed of the rotor of the motor 2. The speed of the motor 2 calculated by the differential arithmetic unit 52 is output as the speed detection value to the speed controller 4 and the vibration detector 8.

[0044] If the vibration amplitude and frequency detected by the vibration detector 8 meet the specified conditions, the correction calculator 6 performs correction calculations on the torque command input from the speed controller 4 and generates a correction torque command. If the vibration amplitude and frequency do not meet the specified conditions, the correction calculator 6 outputs the input torque command as a correction torque command.

[0045] The position controller 7 performs a calculation including proportional calculation so that the position detection value of the motor 2 detected by the position detector 51 follows the position command input from the outside, thereby generating a speed command.

[0046] The vibration detector 8 detects the amplitude and frequency of the vibration contained in the waveform of the velocity detection value output by the velocity detector 5, and outputs the detected amplitude (vibration amplitude) and the detected frequency (vibration frequency) to the correction calculator 6 and the parameter setting changer 9.

[0047] The parameter setting changer 9 modifies the parameters of the speed controller 4 and the position controller 7 based on the vibration amplitude and frequency detected by the vibration detector 8.

[0048] Next, for Figure 1The operation of the electric motor control device 100 shown will be explained. This electric motor control device 100 is designed to enable the load machine 1 and the electric motor 2 to follow position commands.

[0049] In the motor control device 100, the position controller 7 performs a calculation including proportional calculation so that the position detection value representing the position of the motor 2 detected by the position detector 51 follows the position command, and calculates the speed command. The calculation of the position controller 7 is expressed in Equation (1) using the proportional calculation coefficient Kp.

[0050] Formula 1

[0051] Speed ​​command = Kp × (position command - position detection value) …(1)

[0052] The speed controller 4 performs calculations including proportional and integral calculations to calculate the torque command, so that the speed detection value of the motor 2 calculated by the differential arithmetic unit 52 of the speed detector 5 follows the speed command output by the position controller 7. The calculation of the torque command by the speed controller 4 is expressed in Equation (2) using the coefficients Kv for proportional calculation and Ki for integral calculation. In addition, s in Equation (2) is the Laplace operator, and 1 / s represents integral calculation.

[0053] Formula 2

[0054] Torque command = Kv × (1 + Ki × 1 / s) × (speed command - speed detection value) …(2)

[0055] The torque command output by the speed controller 4 is transformed into a corrected torque command in the correction arithmetic unit 6. The current controller 3 supplies current to the motor 2 with a value corresponding to the corrected torque command, thereby causing the motor 2 to generate torque and rotate. As described above, the motor control device 100 performs calculations in a feedback loop consisting of the position controller 7, speed controller 4, correction arithmetic unit 6, current controller 3, position detector 51, speed detector 5, motor 2, and load mechanism 1, i.e., feedback (hereinafter referred to as FB) control calculations, thereby enabling the load mechanism 1 and the motor 2 to follow the position command. Furthermore, in this case, the transfer function h(s) used in the calculation of correcting the torque command by the correction arithmetic unit 6 is set to h(s) = 1, and the torque command and the corrected torque command are the same. The details will be described later, but the correction arithmetic unit 6 corrects the torque command and generates a correction torque command when the amplitude of the vibration detected by the vibration detector 8 exceeds a predetermined threshold. When the amplitude is less than or equal to the threshold, the torque command is not corrected. That is, the transfer function h(s) is set to h(s) = 1 and the operation is performed. The correction torque command with the same value as the input torque command is output.

[0056] The aforementioned FB control system is widely used in applications where position and speed are controlled within the motor 2. To ensure high responsiveness and precision in guiding the load mechanism 1 and motor 2 to position commands, the FB control system needs to be configured with appropriate characteristics. These characteristics can be adjusted using the position controller 7 and speed controller 4, with the proportional and integral calculation coefficients performed by these controllers serving as parameters. Setting the parameters for the FB control system requires not only high responsiveness and precision but also stability. If the FB control system becomes unstable, large-amplitude oscillations may occur; therefore, parameter settings are necessary to ensure a stable, highly responsive, and highly precise control system.

[0057] Next, we will explain the case where the electric motor 2 drives the load mechanism 1, whose inertia changes. For example, when the load mechanism 1 is the roller part of a roller-to-roll assembly that processes sheet material while it is being unwound or wound from a roller, the inertia of the roller, i.e., the inertia of the load mechanism 1, changes depending on the amount of material wound on the roller. In roller-to-roll assemblies, the change in inertia is large; sometimes, depending on the amount of material wound on the roller, the inertia can even change by tens of times.

[0058] The impact on the FB control system when the inertia of the load machine 1 increases from the initial state will be explained. As an example, consider the case where the inertia of the load machine 1 increases from 5 times the motor inertia ratio (i.e., from the initial state) to 250 times the motor inertia ratio.

[0059] Figure 2 The Bode diagram is of the electric motor 2 driven by the electric motor control device 100 according to Embodiment 1. Figure 2 The Bode plot shows the transmission characteristics from the input current of the motor 2 to the speed detection value of the motor 2 when the inertia of the load machine 1 is 5 times, 31 times, and 250 times that of the motor.

[0060] Figure 3 It is the Bode plot of the open-loop transfer function of the FB control system of the motor control device 100 according to Embodiment 1. Figure 3 The Bode plot shows the open-loop transfer function of the FB control system when the inertia of the load machine 1 increases, with the parameters of the position controller 7 and speed controller 4 set for the load machine 1 in its initial state (5 times the inertia ratio of the motor), without changing these parameter settings. Furthermore, the resonance characteristics near 180Hz are suppressed by a notch filter, so the effect of changes in the inertia of the load machine 1 is almost negligible. Since this is not relevant to this embodiment, detailed explanation is omitted. Additionally, Figure 4 This is the Nyquist plot of the open-loop transfer function of the FB control system of the motor control device 100 according to Embodiment 1. Figure 3 and Figure 4 It can be seen that when the inertia of the load machine 1 increases to 31 times that of the motor inertia, the FB control system reaches its stability limit.

[0061] Figure 5 This is a diagram showing an example of the operating waveform of the motor control device 100 according to Embodiment 1 when it becomes unstable, and an example of the waveform of the speed detection value during the process of the inertia of the load machine 1 increasing. Figure 5 The speed detection value shown is at 3 seconds. The inertia of the load mechanism 1 is 31 times that of the motor, resulting in an oscillation of 7.5Hz due to instability. Furthermore, in... Figure 5 In order to observe the oscillation waveform, a high-pass filter is used to remove the component of the speed waveform that follows the speed command.

[0062] Vibration detector 8 calculates the amplitude and frequency of the vibration contained in the waveform of the velocity detection value output by velocity detector 5. In the event of an event such as... Figure 5 In the case of the vibration shown, the amplitude is calculated to be 0.5 r / min and the frequency is 7.5 Hz at 6.5 seconds. When vibration is determined to occur using an amplitude of 0.5 r / min as a threshold, the correction calculator 6 performs a correction operation to temporarily stabilize the characteristics of the FB control system near the vibration frequency, generating a corrected torque command, i.e., the corrected torque command. The correction calculator 6 uses the transfer function h(s) shown in equation (3) to perform the correction operation and calculate the corrected torque.

[0063]

Formula 3

[0064]

[0065] In equation (3), for the detected vibration frequency ω o = 7.5 × 2π [rad / s], ω h Set as ω h =ω o ×2.5 [rad / s]. The Bode plot of the transfer function h(s) at this point is as follows: Figure 6 As shown. Figure 6 This is the Bode plot of the transfer function of the correction arithmetic unit 6 of the motor control device 100 according to Embodiment 1. The Bode plot of the open-loop transfer function of the FB control system when the correction arithmetic unit 6 has performed the correction calculation is... Figure 7 Nyquist became Figure 8 The FB control system is stabilized by the correction operation of the correction arithmetic unit 6. Figure 7 It is the Bode plot of the open-loop transfer function of the FB control system of the motor control device 100 according to Embodiment 1. Figure 8 It is the Nyquist plot of the open-loop transfer function of the FB control system of the motor control device 100 according to Embodiment 1.

[0066] Under the condition that the FB control system is stabilized, such as Figure 9 As shown, oscillations are suppressed, and the vibration amplitude is reduced. The vibration amplitude is reduced through stabilization by the FB control system; therefore, for oscillations, the instability of the FB control system is determined to be the primary cause. Figure 9 This is a diagram showing the operating waveform of the FB control system of the motor control device 100 according to Embodiment 1 when it is stabilized. Based on this, the parameter setting changer 9 changes the coefficient Kp of the proportional calculation of the position controller 7 and the coefficient Ki of the integral calculation of the speed controller 4 when the vibration amplitude decreases after reaching the aforementioned threshold of 0.5 r / min, thereby stabilizing the FB control system. The parameter setting changer 9 changes each coefficient to a value of Kp = Ki = 7.5 × 2π / 4 based on the detected vibration frequency, thereby stabilizing the FB control system. The Bode plot of the open-loop transfer function of the FB control system representing this situation is shown in... Figure 10 As shown, the Nyquist plot is in Figure 11 As shown. Figure 10 This is the Bode plot of the open-loop transfer function of the FB control system of the motor control device 100 according to Embodiment 1 under the condition of stabilization. Figure 11 It is the Nyquist plot of the open-loop transfer function of the FB control system of the motor control device 100 according to Embodiment 1 under the condition of stabilization.

[0067] Furthermore, after the parameter setting changer 9 changes the parameters of the position controller 7 and the speed controller 4, the motor control device 100 restores the transfer function used by the correction arithmetic unit 6 during the correction calculation to h(s) = 1. Moreover, the stabilization obtained by using the correction calculation of the transfer function in equation (3) does not provide a large stability margin; therefore, it can be used for temporarily stabilizing the FB control system, but is not suitable for achieving steady-state stabilization. In a state where stabilization is achieved solely by changing the transfer function of the correction arithmetic unit 6, if the inertia of the load machine 1 further increases, the FB control system will become unstable again due to this slight increase.

[0068] Next, we will explain the situation where the main cause of vibration is interference. Figure 12 It is a diagram showing the operating waveform when interference vibration enters the motor control device 100 according to Embodiment 1. Figure 12 The waveform shows the operation when a 7.5Hz disturbance occurs. At 3 seconds, the disturbance is input, and the vibration detector 8 calculates the vibration amplitude (0.8 r / min) and frequency (7.5 Hz) based on the velocity detection value. Simultaneously, the calibration calculator 6 performs a calibration operation using the transfer function of equation (3) above, but there is no change in the vibration amplitude. Based on this result, the motor control device 100 determines that the vibration is not due to instability in the FB control system. Therefore, the parameter setting changer 9 does not change the parameter settings of the position controller 7 and the speed controller 4. Furthermore, after the calibration calculator 6 begins the calibration operation using the transfer function of equation (3) above, at a predetermined time elapsed, it restores the transfer function used in the calibration operation to h(s) = 1. The timing for the calibration calculator 6 to restore the transfer function to h(s) = 1 is set to the time required to determine whether the main cause of the vibration in the velocity detection value is disturbance or instability in the FB control system.

[0069] If the operation of the motor control device 100 to suppress the oscillation of the motor 2 is represented by a flowchart, it becomes... Figure 13 . Figure 13 This is a flowchart illustrating an example of the operation of the motor control device 100 according to Embodiment 1 to suppress the vibration of the motor 2.

[0070] When the motor control device 100 is controlling the motor 2, it follows... Figure 13 The flowchart determines whether the motor 2 is vibrating. If vibration is detected, the main cause of the vibration is determined. If the main cause is the instability of the FB control system, the parameter settings of the position controller 7 and the speed controller 4 are changed.

[0071] That is, the motor control device 100, which controls the motor 2, compares the vibration amplitude of the speed of the motor 2 with a threshold (step S1). If the vibration amplitude is less than or equal to the threshold (step S1: No), step S1 is repeated. If the vibration amplitude is greater than the threshold (step S1: Yes), the motor control device 100 changes the transfer function h(s) of the correction arithmetic unit 6 (step S2). Specifically, the transfer function h(s) used by the correction arithmetic unit 6 in the correction calculation of the torque command is changed to the transfer function shown in equation (3) above. The motor control device 100 then confirms whether the vibration amplitude of the speed of the motor 2 has decreased (step S3). For example, after the motor control device 100 changes the transfer function of the correction arithmetic unit 6 in step S2, it monitors the vibration amplitude until a predetermined time has elapsed and determines whether the vibration amplitude has decreased. If the vibration amplitude has decreased (step S3: Yes), the motor control device 100 adjusts the parameters of the position controller 7 and the speed controller 4 (step S4). After adjusting the parameters of the position controller 7 and the speed controller 4, the motor control device 100 changes the transfer function h(s) of the correction arithmetic unit 6 (step S5). In step S5, the transfer function h(s) is changed back to its state before step S2, i.e., the transfer function h(s) = 1. Furthermore, if the vibration amplitude does not decrease after changing the transfer function of the correction arithmetic unit 6 in step S2 (step S3: No), the motor control device 100 executes step S5, changing the transfer function h(s) to 1. After executing step S5, the motor control device 100 returns to step S1 and repeats the processing of steps S1 to S5.

[0072] As explained above, in the motor control device 100, when the amplitude of vibration detected by the vibration detector 8 exceeds a threshold, the transfer function used by the correction arithmetic unit 6 in the correction calculation is changed based on the frequency of the detected vibration, thereby changing the characteristics of the FB control system. Furthermore, based on the subsequent change in vibration amplitude, the primary cause of vibration occurring when the inertia of the load machine 1 increases from its initial state is determined. Additionally, if the primary cause of vibration is instability of the FB control system, the parameter setting changer 9 changes the parameters of the position controller 7 and the speed controller 4 to suppress large-amplitude oscillations. Conversely, if the primary cause is not instability of the FB control system, the parameter setting changer 9 does not change the parameters of the position controller 7 and the speed controller 4, i.e., does not change the characteristics of the FB control system. Therefore, the parameter settings of the position controller 7 and the speed controller 4 can be changed only when the inertia of the load machine 1 increases, causing instability in the FB control system and vibration of the motor 2. In other words, it can prevent the control from becoming unstable due to changes in the parameters of the position controller 7 and speed controller 4 when vibration occurs temporarily due to disturbance, and can stabilize the operation of the motor control system 200.

[0073] Furthermore, in the above description, the example of a load machine 1 whose inertia changes is a roller-to-roller device in which the inertia of the roller changes according to the amount of material wound on the roller. However, it is not limited to this. In the case of a device in which the inertia of the motor changes according to the presence or absence of a load object such as a conveying machine or an arm robot, or the change in posture of such an object, vibration can also be suppressed and the FB control system stabilized by the same method.

[0074] Furthermore, the electric motor control system 200 according to this embodiment includes: a load machine 1; an electric motor 2 that drives the load machine 1; a speed detector 5 that detects the speed of the electric motor 2; a speed controller 4 that generates a torque command for the electric motor 2 based on the speed of the electric motor 2 and the speed command; a correction arithmetic unit 6 that corrects the torque command to generate a correction torque command; a current controller 3 that flows current in the electric motor 2 based on the torque command and the correction torque command; a vibration detector 8 that detects the vibration amplitude and vibration frequency of the vibration generated by the electric motor 2; and a parameter setting changer 9 that changes the parameters of the speed controller 4.

[0075] Furthermore, the motor control method executed by the motor control device 100 according to this embodiment is as follows: detecting the position of the motor 2 that drives the load machinery 1; generating a speed command by performing calculations including proportional calculations based on the position of the motor 2 and the position command; detecting the speed of the motor 2; generating a torque command for the motor 2 by performing calculations including proportional calculations and integral calculations based on the speed of the motor 2 and the speed command; generating a correction torque command by correcting the torque command; flowing current in the motor 2 based on the torque command and the correction torque command; detecting the vibration amplitude and vibration frequency of the vibration occurring in the motor 2; repeating the detection of the position of the motor 2, the generation of the speed command, the detection of the speed of the motor 2, the generation of the torque command, the generation of the correction torque command, and the flow of current in the motor 2 when the vibration amplitude increases compared to a threshold; in the above-mentioned FB control system, stabilizing the transmission characteristics at the vibration frequency occurring in the motor 2; changing the parameters of the calculation for generating the speed command, i.e., the coefficients of the proportional calculation, and changing the parameters of the calculation for generating the torque command, i.e., the coefficients of the integral calculation, when the vibration amplitude decreases after the transmission characteristics are stabilized;

[0076] Furthermore, the vibration detector 8 of the motor control device 100 in this embodiment is configured to calculate the amplitude and frequency of vibration based on the waveform of the speed detection value, but it can also be configured to calculate the amplitude and frequency of vibration based on the waveform of the position detection value, speed command, torque command, correction torque command, and current.

[0077] Furthermore, in this embodiment, when the motor control device 100 determines that the main cause of vibration is the instability of the FB control system, it modifies the coefficient Kp calculated proportionally by the position controller 7 and the coefficient Ki calculated integrally by the speed controller 4 based on the detected vibration frequency. Kp is set to Kp = Ki = 7.5 × 2π / 4, which is 1 / 4 of the vibration frequency. However, it is not limited to 1 / 4; it is sufficient to change the coefficients Kp and Ki to values ​​smaller than the vibration frequency. Specifically, if the coefficients Kp and Ki are less than 1 / 2 of the vibration frequency × 2π, the instability of the FB control system can be suppressed. Furthermore, the coefficients Kp and Ki can be set to 1 / 4 or smaller than the original values. If they are less than 1 / 2 of the original values, the instability of the FB control system can be suppressed.

[0078] Furthermore, in the motor control device 100 according to this embodiment, the position controller 7 generates a speed command according to equation (1), and the speed controller 4 generates a torque command according to equation (2), but other structures are also possible. For example, it can be configured as a speed I-P control system structure, or a structure with an added differential arithmetic unit. In this case, based on the detected vibration frequency, it becomes Figure 10 , Figure 11 The parameters can be changed in the way the characteristics are shown.

[0079] Furthermore, in the motor control device 100 according to this embodiment, the correction arithmetic unit 6 is configured to use the transfer function h(s) of equation (3) to change the characteristics of the FB control system, but other transfer functions may also be used. For example, the following methods may also be applied: setting a low-pass filter to change the characteristics of the FB control system, using a phase advance compensator to change the characteristics of the FB control system, or adding the waveform after the speed detection value is shaped as shown in equation (4) to the torque command to change the characteristics of the FB control system. The same function can be achieved when these methods are applied.

[0080]

Formula 4

[0081]

[0082] Next, the hardware for implementing the electric motor control device 100 according to this embodiment will be described.

[0083] In the motor control device 100 according to this embodiment, the structure for changing the characteristics of the FB control system specifically includes a position controller 7, a speed controller 4, a correction arithmetic unit 6, a vibration detector 8, and a parameter setting changer 9. These components can be implemented using a dedicated processing circuit or a general-purpose processor that executes programs. Examples of dedicated processing circuits include ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), or circuits combining these. Alternatively, when the above structure is implemented using a processor, for example, a processor can be used... Figure 14 The control circuit consisting of processor 101 and memory 102 shown. Figure 14This diagram illustrates an example of the hardware implementing the motor control device 100 according to Embodiment 1. The processor 101 is a CPU (also known as a Central Processing Unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor)), system LSI (Large Scale Integration), etc. The memory 102 is RAM (Random Access Memory), ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), etc. The memory 102 stores programs describing the functions of the position controller 7, speed controller 4, calibration arithmetic unit 6, vibration detector 8, and parameter setting changer 9. The processor 101 executes the programs stored in the memory 102, thereby operating the position controller 7, speed controller 4, calibration arithmetic unit 6, vibration detector 8, and parameter setting changer 9. Furthermore, the position controller 7, speed controller 4, calibration calculator 6, vibration detector 8, and parameter setting changer 9 can be implemented through a dedicated processing circuit, and the remaining parts can be processed through... Figure 14 The control circuit shown is implemented.

[0084] The speed detector 5 of the motor control device 100 is implemented by an encoder. The current controller 3 is implemented by an electronic circuit that outputs a current value corresponding to the correction torque command input from the correction arithmetic unit 6.

[0085] Implementation method 2.

[0086] Figure 15 This is a block diagram illustrating a structural example of a motor control system 200a implemented using the motor control device 100a according to Embodiment 2. Figure 15 In the motor control device 100a shown, replacing Figure 1 The parameter setting changer 9 of the motor control device 100 shown in Embodiment 1 includes a parameter setting changer 9a that changes the parameters of the speed controller 4. Regarding other structural elements with the same reference numerals, since... Figure 1 Since they are the same, the explanation is omitted.

[0087] Next, for Figure 15The operation of the electric motor control device 100a shown will be explained. Similar to the electric motor control device 100 according to Embodiment 1, the electric motor control device 100a aims to make the load machine 1 and the electric motor 2 operate in accordance with position commands. Figure 1 The structural elements with the same designation perform the same actions as the motor control device 100. When the parameter setting changer 9a determines that the FB control system consisting of the position controller 7, speed controller 4, speed detector 5, correction calculator 6, current controller 3, motor 2, and load machinery 1 is unstable, it changes the parameters of the speed controller 4 based on the amplitude and frequency of the vibration calculated by the vibration detector 8.

[0088] Next, the effect on the FB control system and the operation of the motor control device 100a when the inertia of the load machine 1 decreases from its initial state in the motor control system 200a according to Embodiment 2 will be explained. Consider the case where the inertia of the load machine 1 decreases from an initial state of 250 times the motor inertia ratio to a final state of 5 times the motor inertia ratio. The Bode plot representing the transmission characteristics from the input current of the motor 2 to the speed detection value of the motor 2 is shown as... Figure 2 Same as shown.

[0089] Figure 16 It is the Bode plot of the open-loop transfer function of the FB control system of the motor control device 100a according to Embodiment 2. Figure 16 The Bode plot shows the open-loop transfer function of the FB control system when the inertia of the load machine 1 decreases, with the parameters of the position controller 7 and speed controller 4 set for the load machine 1 in the initial state and without changing these settings. The FB control system reaches its stability limit when the inertia of the load machine 1 decreases to approximately 5.5 times the motor inertia ratio. Furthermore, the resonance characteristics near 180Hz are suppressed by a notch filter, and the effect caused by the change in the inertia of the load machine 1 is almost negligible; since this is not relevant to this embodiment, detailed explanation is omitted. Figure 17 This is a diagram of an example of the waveform of the speed detection value of the motor 2, which represents the process of the inertia of the load machine 1 decreasing. Figure 17 The speed detection value shown indicates that at 7 seconds, the inertia of load machine 1 is 5.5 times that of the motor, resulting in an oscillation of 52Hz due to instability. Furthermore, in... Figure 17 In order to observe the oscillation waveform, a high-pass filter is used to remove the component of the velocity waveform that follows the velocity command.

[0090] Vibration detector 8, similar to embodiment 1, calculates the amplitude and frequency of vibrations occurring at velocity detection values. Figure 17In the case of vibration shown, vibration detector 8 calculates that at 8 seconds, the vibration amplitude is 0.5 r / min and the frequency is 52 Hz. With 0.5 r / min set as the threshold for detecting vibration, correction calculator 6 determines that vibration occurred at 8 seconds and performs a correction operation to temporarily stabilize the characteristics of the FB control system near the vibration frequency, generating a correction torque command for the torque command. Specifically, correction calculator 6 calculates the correction torque command using the transfer function h(s) of equation (3). In equation (3), the vibration frequency ω detected by vibration detector 8 is... o =52×2π[rad / s], ω h Set as ω h =ω o ×2.5 [rad / s]. The Bode plot of the open-loop transfer function of the FB control system when the correction arithmetic unit 6 performs the correction operation using the transfer function h(s) of equation (3) becomes... Figure 18 The FB control system is stabilized by the correction operation of the correction arithmetic unit 6. Figure 18 This is a Bode plot of the open-loop transfer function of the FB control system of the motor control device 100a according to Embodiment 2. Under the condition that the FB control system is stabilized, as... Figure 19 As shown, oscillations are suppressed, and the vibration amplitude is reduced. Figure 19 This is a diagram showing the operating waveform of the FB control system of the motor control device 100a according to Embodiment 2 when it is stabilized. The vibration amplitude decreases due to the stabilization of the FB control system; therefore, for oscillation, it can be determined that the instability of the FB control system is the main cause. Based on this determination, the parameter setting changer 9a changes the coefficient Kv calculated by the speed controller 4 to stabilize the FB control system. The changed coefficient Kv is, for example, a value that is half of the original value. The Bode plot of the open-loop transfer function of the FB control system in this case becomes... Figure 20 As shown. Figure 20 It is the Bode plot of the open-loop transfer function of the feedback control system of the motor control device 100a according to Embodiment 2 under the condition of stabilization.

[0091] Furthermore, after the parameter setting changer 9a modifies the parameters of the speed controller 4, the correction calculator 6, similar to Embodiment 1, restores the transfer function used for the correction calculation to h(s) = 1. The reason for restoring the transfer function of the correction calculator 6 to h(s) = 1 is the same as in Embodiment 1, where the inertia of the load machine 1 increases from its initial state.

[0092] Next, we will explain the situation where the main cause of vibration is interference. Figure 21This is a diagram showing the operating waveform when the disturbance vibration enters the motor control device 100a according to Embodiment 2. Figure 21 The waveform of the velocity detection value when a 52Hz disturbance occurs is shown. When the disturbance is input at 3 seconds, the vibration detector 8 calculates the vibration amplitude (0.5 r / min) and frequency (52Hz) based on the velocity detection value. Simultaneously, the correction calculator 6 begins the correction calculation using the transfer function of equation (3) above. However, there is no change in the vibration amplitude. Based on this result, it is determined that the vibration is not an instability of the FB control system. Therefore, the parameter setting changer 9a does not change the parameter settings of the position controller 7 and the speed controller 4. Furthermore, after starting the correction calculation using the transfer function of equation (3) above, the correction calculator 6 restores the transfer function used for the correction calculation to h(s) = 1 at the elapsed time.

[0093] The operation of the motor control device 100a to suppress the oscillation of the motor 2 is similar to the operation of the motor control device 100 to suppress the oscillation of the motor 2 according to Embodiment 1, and can be achieved by... Figure 13 The flowchart is shown. However, when the motor control device 100a is activated, in Figure 13 In step S4, the parameters of the speed controller 4 are adjusted.

[0094] As explained above, in the motor control device 100a, when the amplitude of the vibration detected by the vibration detector 8 exceeds a threshold, the transfer function used by the correction arithmetic unit 6 in the correction calculation is changed based on the frequency of the detected vibration, thereby changing the characteristics of the FB control system. Furthermore, based on the subsequent change in vibration amplitude, the primary cause of vibration occurring when the inertia of the load machine 1 decreases from its initial state is determined. Additionally, if the primary cause of vibration is instability of the FB control system, the parameter setting changer 9a changes the parameters of the speed controller 4 to suppress large-amplitude oscillations. Conversely, if the primary cause is not instability of the FB control system, the parameter setting changer 9a does not change the parameters of the speed controller 4, i.e., the characteristics of the FB control system are not changed. Thus, the parameter setting of the speed controller 4 can be changed only when vibration of the motor 2 occurs due to instability of the FB control system accompanying a decrease in the inertia of the load machine 1. In other words, it can prevent the control from becoming unstable by changing the parameters of the speed controller 4 in the event of temporary vibration due to disturbance, and can stabilize the operation of the motor control system 200a.

[0095] Furthermore, in the motor control device 100a according to this embodiment, instead of the parameter setting changer 9 of the motor control device 100 according to Embodiment 1, there is a parameter setting changer 9a for changing the parameters of the speed controller 4. Other structural elements are the same.

[0096] Furthermore, the motor control method executed by the motor control device 100a according to this embodiment is as follows: detecting the position of the motor 2 that drives the load machinery 1; generating a speed command by performing calculations including proportional calculations based on the position of the motor 2 and the position command; detecting the speed of the motor 2; generating a torque command for the motor 2 by performing calculations including proportional calculations and integral calculations based on the speed of the motor 2 and the speed command; generating a correction torque command by correcting the torque command; flowing current into the motor 2 based on the torque command and the correction torque command; detecting the vibration amplitude and vibration frequency of the vibration occurring in the motor 2; repeating the detection of the position of the motor 2, the generation of the speed command, the detection of the speed of the motor 2, the generation of the torque command, the generation of the correction torque command, and the flow of current into the motor 2 when the vibration amplitude increases compared to a threshold; in the above-described FB control system, stabilizing the transmission characteristics at the vibration frequency occurring in the motor 2; and changing the parameters of the calculations used to generate the torque command, i.e., the coefficients of the proportional calculations, when the vibration amplitude decreases after the transmission characteristics are stabilized.

[0097] Furthermore, the vibration detector 8 of the motor control device 100a according to this embodiment is configured to calculate the amplitude and frequency of vibration based on the waveform of the speed detection value, but it can also be configured to calculate the amplitude and frequency of vibration based on the waveform of the position detection value, speed command, torque command, correction torque command, and current.

[0098] Furthermore, in this embodiment, when the motor control device 100a determines that the main cause of vibration is the instability of the FB control system, it sets the proportional gain coefficient Kv of the speed controller 4 to half of the original coefficient Kv, but is not limited to half. The coefficient Kv can be changed to a value smaller than the original coefficient Kv. For example, if the coefficient Kv is made less than half of the original value, the instability of the FB control system can be suppressed.

[0099] Furthermore, in the electric motor control device 100a according to this embodiment, the position controller 7 generates a speed command according to equation (1), and the speed controller 4 generates a torque command according to equation (2), but other structures are also possible. For example, it can be configured as a speed I-P control system structure, or a structure with an added differential arithmetic unit. In this case, based on the detected vibration frequency, it becomes Figure 20The parameters can be changed in the way the characteristics are shown.

[0100] Furthermore, in the motor control device 100a according to this embodiment, the correction arithmetic unit 6 is configured to use the transfer function h(s) of equation (3) to change the characteristics of the FB control system, but other transfer functions may also be used. For example, the following methods may also be applied: setting a low-pass filter to change the characteristics of the FB control system, using a phase advance compensator to change the characteristics of the FB control system, or adding the waveform after the speed detection value is shaped as shown in equation (4) to the torque command to change the characteristics of the FB control system. The same function can be achieved when these methods are applied.

[0101] Implementation method 3.

[0102] Figure 22 This is a block diagram illustrating a structural example of a motor control system 200b implemented using the motor control device 100b according to Embodiment 3. Figure 22 The motor control device 100b shown is in Figure 1 In the motor control device 100 of Embodiment 1 shown, a characteristic change direction storage unit 10 is added, a vibration detector 8a is provided instead of a vibration detector 8, and a parameter setting changer 9b is provided instead of a parameter setting changer 9. Regarding other structural elements with the same reference numerals, since... Figure 1 Since they are the same, the explanation is omitted.

[0103] Next, for Figure 22 The operation of the motor control device 100b shown will be explained. Like the motor control device 100 of Embodiment 1 and the motor control device 100a of Embodiment 2, the motor control device 100b aims to make the load machine 1 and the motor 2 operate in accordance with position commands. Figure 1 The structural elements with the same reference numerals perform the same operations as the motor control device 100 described in Embodiment 1.

[0104] The characteristic change direction storage unit 10 stores information about the direction of increase or decrease of the inertia of the load machine 1 when it changes from the initial state, that is, whether the inertia increases or decreases.

[0105] The vibration detector 8a calculates the amplitude and frequency of vibration based on the filtered speed detection value input from the speed detector 5, corresponding to the increase or decrease direction of the inertia of the load machinery 1 stored in the characteristic change direction storage unit 10. For example, when the inertia of the load machinery 1 increases, the vibration that occurs when the FB control system becomes unstable occurs at a frequency close to the frequency calculated based on the coefficient Kp calculated proportionally from the position controller 7 and the coefficient Ki calculated integrally from the speed controller 4. Therefore, by using a bandpass filter, high-pass filter, or the like passing through this frequency band, the vibration components related to instability can be extracted and processed. Furthermore, when the inertia of the load machinery 1 decreases, the vibration that occurs when the FB control system becomes unstable occurs at a frequency close to the frequency calculated based on the coefficient Kv calculated proportionally from the speed controller 4 or close to the frequency of the limiting characteristic obtained when adjusting the FB control system in the initial state. Therefore, by using a bandpass filter, high-pass filter, or the like passing through this frequency band, the vibration components related to instability can be extracted and processed. That is, the vibration detector 8a performs filtering processing on the speed detection value input from the speed detector 5, which corresponds to the direction of increase or decrease of the inertia of the load machinery 1, and uses the speed detection value after the filtering processing to calculate the amplitude and frequency of the vibration.

[0106] When the parameter setting changer 9b determines that the FB control system, consisting of the position controller 7, speed controller 4, position detector 51, speed detector 5, correction calculator 6, current controller 3, motor 2, and load machine 1, is unstable, it changes the parameters of the position controller 7 or speed controller 4 in accordance with the direction of increase or decrease of the inertia of the load machine 1 stored in the characteristic change direction storage unit 10. When the inertia of the load machine 1 increases, the parameter setting changer 9b, similar to the parameter setting changer 9 of the motor control device 100 according to Embodiment 1, changes the proportional coefficient of the position controller 7 and the integral coefficient of the speed controller 4 based on the amplitude and frequency of the vibration calculated by the vibration detector 8a. Similarly, when the inertia of the load machine 1 decreases, the parameter setting changer 9b, similar to the parameter setting changer 9a of the motor control device 100a according to Embodiment 2, changes the proportional coefficient of the speed controller 4 based on the amplitude and frequency of the vibration calculated by the vibration detector 8a.

[0107] The operation of the motor control device 100b to suppress the oscillation of the motor 2 is similar to the operation of the motor control device 100 to suppress the oscillation of the motor 2 according to Embodiment 1, and can be achieved by... Figure 13 The flowchart is shown. However, in the case of the operation of the motor control device 100b, in Figure 13 In step S4, the parameters of both the position controller 7 and the speed controller 4, or the parameters of the speed controller 4, are adjusted in accordance with the direction of increase or decrease of the inertia of the load machine 1.

[0108] As explained above, in the motor control device 100b, when the amplitude of the vibration detected by the vibration detector 8a exceeds a threshold, the transfer function used by the correction arithmetic unit 6 in the correction calculation is changed based on the frequency of the detected vibration, thereby changing the characteristics of the FB control system. Furthermore, the primary cause of the vibration is determined based on the subsequent change in vibration amplitude. Additionally, if the primary cause of the vibration is instability of the FB control system due to a change in the characteristics of the load machine 1, the parameter setting changer 9b changes the proportional coefficient of the position controller 7 and the integral coefficient of the speed controller 4, or the proportional coefficient of the speed controller 4, in accordance with the direction of change in the characteristics of the load machine 1 stored in the characteristic change direction storage unit 10—that is, the direction of increase or decrease in the inertia of the load machine 1 from its initial state. Thus, by changing the parameter settings of the position controller 7 and the speed controller 4, and limiting the vibration of the motor 2 to instability of the FB control system, large-amplitude oscillations can be suppressed, as the inertia of the load machine 1 changes. Furthermore, if the primary cause of the vibration is not instability of the FB control system, the characteristics of the FB control system can be maintained without changing them. That is, it can prevent the control from becoming unstable by changing the parameters of the position controller 7 and speed controller 4 in the event of temporary vibration due to disturbance, and can stabilize the operation of the motor control system 200b.

[0109] Furthermore, the motor control device 100b according to this embodiment is the same as the motor control device 100 according to Embodiment 1, but with the addition of a characteristic change direction storage unit 10, a vibration detector 8a instead of a vibration detector 8, and a parameter setting changer 9b instead of a parameter setting changer 9. Other structural elements are the same as those of the motor control device 100.

[0110] Furthermore, the motor control method executed by the motor control device 100b according to this embodiment is as follows: detecting the position of the motor 2 that drives the load machinery 1; generating a speed command by performing calculations including proportional calculations based on the position of the motor 2 and the position command; detecting the speed of the motor 2; generating a torque command for the motor 2 by performing calculations including proportional and integral calculations based on the speed of the motor 2 and the speed command; correcting the torque command to generate a corrected torque command; flowing current in the motor 2 based on the torque command and the corrected torque command; storing the direction of increase or decrease of the inertia of the load machinery 1 driven by the motor 2; changing the filtering process of the drive waveform based on the position, speed, or torque of the motor 2 according to the stored direction of increase or decrease of the inertia of the load machinery 1; and modifying the filtering process according to the stored direction of increase or decrease of the inertia of the load machinery 1. The processed drive waveform detects the vibration amplitude and frequency of the vibration generated by motor 2. When the vibration amplitude of motor 2 increases compared to the threshold, the detection of motor 2's position, generation of speed command, detection of motor 2's speed, generation of torque command, generation of correction torque command, and current flow into motor 2 are repeated. In the above FB control system, the transmission characteristics at the vibration frequency generated by motor 2 are stabilized. When the vibration amplitude decreases after the transmission characteristics are stabilized, the coefficients of proportional calculation included in the calculation of generating speed command when the inertia of load machine 1 increases and the coefficients of integral calculation included in the calculation of generating torque command are changed. The coefficients of proportional calculation included in the calculation of generating torque command when the inertia of load machine 1 decreases are also changed.

[0111] Furthermore, the vibration detector 8a of the motor control device 100b involved in this embodiment is configured to calculate the amplitude and frequency of vibration based on the waveform of the speed detection value, but it can also calculate the amplitude and frequency of vibration based on the waveform of the position detection value, speed command, torque command, correction torque command, and current.

[0112] Furthermore, in the motor control device 100b according to this embodiment, the position controller 7 generates a speed command according to equation (1), and the speed controller 4 generates a torque command according to equation (2), but other structures are also possible. For example, it can be configured as a speed I-P control system structure, or a structure with an added differential arithmetic unit. In this case, based on the detected vibration frequency, it becomes Figure 10 , Figure 11 , Figure 20 The parameters can be changed in the way the characteristics are shown.

[0113] Furthermore, in the motor control device 100b according to this embodiment, the correction arithmetic unit 6 is configured to use the transfer function h(s) of equation (3) to change the characteristics of the FB control system, but other transfer functions may also be used. For example, the following methods may also be applied: setting a low-pass filter to change the characteristics of the FB control system, using a phase advance compensator to change the characteristics of the FB control system, or adding the waveform after the speed detection value is shaped as shown in equation (4) to the torque command to change the characteristics of the FB control system. The same function can be achieved when these methods are applied.

[0114] Implementation method 4.

[0115] Figure 23 This is a block diagram illustrating a structural example of a motor control system 200c implemented using the motor control device 100c according to Embodiment 4. Figure 23 The motor control device 100c shown is from Figure 22 The motor control device 100b according to Embodiment 3 shown omits the position controller 7 and replaces the parameter setting changer 9b with a structure having a parameter setting changer 9c. Regarding other structural elements with the same reference numerals, since... Figure 22 Since they are the same, the explanation is omitted.

[0116] Next, for Figure 23 The operation of the electric motor control device 100c shown will be explained. The electric motor control device 100c aims to make the load machine 1 and the electric motor 2 operate in accordance with speed commands input from an external source. Regarding... Figure 22 The structural elements with the same reference numerals perform the same operations as the motor control device 100b described in Embodiment 3.

[0117] The vibration detector 8a calculates the amplitude and frequency of vibration based on the filtered speed detection value input from the speed detector 5, corresponding to the increase or decrease direction of the inertia of the load machinery 1 stored in the characteristic change direction storage unit 10. For example, when the inertia of the load machinery 1 increases, the vibration that occurs when the FB control system becomes unstable occurs at a frequency close to the frequency calculated based on the coefficients of the speed controller 4. Therefore, by using a bandpass filter, high-pass filter, or the like passing through this frequency band, the vibration components related to instability can be extracted and processed. Furthermore, when the inertia of the load machinery 1 decreases, the vibration that occurs when the FB control system becomes unstable occurs at a frequency close to the frequency calculated based on the coefficients of the speed controller 4, or a frequency close to the limiting characteristic frequency obtained when adjusting the FB control system in the initial state. Therefore, by using a bandpass filter, high-pass filter, or the like passing through this frequency band, the vibration components related to instability can be extracted and processed.

[0118] When the parameter setting changer 9c determines that the FB control system, consisting of the speed controller 4, speed detector 5, correction calculator 6, current controller 3, motor 2, and load machine 1, is unstable, it changes the parameters of the speed controller 4 in accordance with the direction of increase or decrease of the inertia of the load machine 1 stored in the characteristic change direction storage unit 10. When the inertia of the load machine 1 increases, the parameter setting changer 9c changes the coefficients of the integral calculation of the speed controller 4 based on the amplitude and frequency of the vibration calculated by the vibration detector 8a. Furthermore, when the inertia of the load machine 1 decreases, the parameter setting changer 9c, similar to the parameter setting changer 9a of the motor control device 100a according to Embodiment 2, changes the coefficients of the proportional calculation of the speed controller 4 based on the amplitude and frequency of the vibration calculated by the vibration detector 8a.

[0119] The operation of the motor control device 100c to suppress the oscillation of the motor 2 is similar to the operation of the motor control device 100 to suppress the oscillation of the motor 2 according to Embodiment 1. It can be achieved by... Figure 13 The flowchart is shown. However, when the motor control device 100c is activated, in Figure 13 In step S4, the parameters of the speed controller 4 are adjusted.

[0120] As explained above, in the motor control device 100c, when the amplitude of vibration detected by the vibration detector 8a exceeds a threshold, the transfer function used by the correction arithmetic unit 6 in the correction calculation is changed based on the frequency of the detected vibration, thereby changing the characteristics of the FB control system. Furthermore, the primary cause of vibration is determined based on the subsequent change in vibration amplitude. Additionally, if the primary cause of vibration is instability of the FB control system due to a change in the characteristics of the load machine 1, the parameter setting changer 9c changes the coefficients of the integral or proportional calculation of the speed controller 4 in accordance with the direction of change of the characteristics of the load machine 1 stored in the characteristic change direction storage unit 10—that is, the direction of increase or decrease in the inertia of the load machine 1 from its initial state. Thus, in cases where vibration of the motor 2 occurs due to instability of the FB control system, the parameter setting of the speed controller 4 can be changed to suppress large-amplitude oscillations, coinciding with a change in the inertia of the load machine 1. Furthermore, if the primary cause of vibration is not instability of the FB control system, the characteristics of the FB control system can be maintained without alteration. That is, it can prevent the control from becoming unstable by changing the parameters of the speed controller 4 in the event of temporary vibration due to disturbance, and can stabilize the operation of the motor control system 200c.

[0121] Furthermore, the motor control device 100c according to this embodiment omits the position controller 7 from the motor control device 100b according to embodiment 3, and has a parameter setting changer 9c instead of the parameter setting changer 9b. Other structural elements are the same as those of the motor control device 100b.

[0122] Furthermore, the motor control method executed by the motor control device 100c according to this embodiment is as follows: The speed of the motor 2 driving the load machinery 1 is detected; based on the speed of the motor 2 and the speed command, a torque command for the motor 2 is generated through calculations including proportional and integral calculations; the torque command is corrected to generate a corrected torque command; based on the torque command and the corrected torque command, the direction of increase or decrease of the inertia of the load machinery 1 driven by the motor 2 is stored in the current flowing through the motor 2; corresponding to the stored direction of increase or decrease of the inertia of the load machinery 1, the filtering processing of the drive waveform based on the position, speed, or torque of the motor 2 is modified; and based on the filtered waveform... The drive waveform detects the vibration amplitude and frequency of the vibration generated by the motor 2. When the vibration amplitude of the motor 2 increases compared to the threshold, the detection of the speed of the motor 2, the generation of torque command, the generation of correction torque command, and the flow of current to the motor 2 are repeated. In the above FB control system, the transmission characteristics at the vibration frequency of the motor 2 are stabilized. When the vibration amplitude decreases after the transmission characteristics are stabilized, the coefficients of the integral calculation included in the calculation of generating torque command when the inertia of the load machine 1 increases are changed, and the coefficients of the proportional calculation included in the calculation of generating torque command when the inertia of the load machine 1 decreases are changed.

[0123] Furthermore, the vibration detector 8a of the motor control device 100c involved in this embodiment is configured to calculate the amplitude and frequency of vibration based on the waveform of the speed detection value, but it can also calculate the amplitude and frequency of vibration based on the waveform of torque command, correction torque command, and current.

[0124] Furthermore, in the electric motor control device 100c according to this embodiment, the speed controller 4 is configured to generate torque commands according to equation (2), but other structures are also possible. For example, it can be configured as a speed I-P control system, or a structure with an added differential arithmetic unit. In this case, based on the detected vibration frequency, it becomes... Figure 10 , Figure 11 , Figure 20 The parameters can be changed in the way the characteristics are shown.

[0125] Furthermore, in the motor control device 100c according to this embodiment, the correction arithmetic unit 6 is configured to use the transfer function h(s) of equation (3) to change the characteristics of the FB control system, but other transfer functions may also be used. For example, the following methods may also be applied: setting a low-pass filter to change the characteristics of the FB control system, using a phase advance compensator to change the characteristics of the FB control system, or adding the waveform after the speed detection value is shaped as shown in equation (4) to the torque command to change the characteristics of the FB control system. The same function can be achieved when these methods are applied.

[0126] The structure shown in the above embodiments is an example, and it can also be combined with other known technologies, and the embodiments can be combined with each other. Without departing from the spirit of the subject, some parts of the structure can be omitted or changed.

[0127] Explanation of the label

[0128] 1 Loading machinery, 2 Electric motor, 3 Current controller, 4 Speed ​​controller, 5 Speed ​​detector, 6 Correction arithmetic unit, 7 Position controller, 8, 8a Vibration detector, 9, 9a, 9b, 9c Parameter setting changer, 10 Characteristic change direction storage unit, 51 Position detector, 52 Differential arithmetic unit, 100, 100a, 100b, 100c Motor control device, 200, 200a, 200b, 200c Motor control system.

Claims

1. An electric motor control device for controlling an electric motor that drives a load mechanism. The electric motor control device is characterized by having: A speed detector that detects the speed of the electric motor; A speed controller that generates a torque command for the electric motor based on the speed of the electric motor and the speed command; A calibration arithmetic unit, which corrects the torque command to generate a calibration torque command; A current controller that controls the flow of current in the motor based on the torque command and the corrective torque command; A vibration detector that detects the amplitude of the vibration (vibration amplitude) and the frequency of the vibration (vibration frequency) generated by the motor; and A parameter setting changer, which modifies the parameters of the speed controller. When the vibration amplitude increases compared to a threshold, the correction arithmetic unit calculates a correction torque command to stabilize the transmission characteristics of the vibration frequency detected by the vibration detector, based on the feedback control system comprised of the motor, the speed detector, the speed controller, the correction arithmetic unit, and the current controller. The parameter setting changer modifies the parameters of the speed controller when the vibration amplitude detected by the vibration detector decreases after the transmission characteristics are stabilized.

2. The motor control device according to claim 1, characterized in that, It has a characteristic change direction storage unit, which stores the increase or decrease direction of the inertia of the load machinery. The speed controller generates the torque command through calculations including proportional and integral calculations. The parameter setting changer changes the coefficients of the integral calculation when the increase / decrease direction stored in the characteristic change direction storage unit is an increasing direction, and changes the coefficients of the ratio calculation when the increase / decrease direction is a decreasing direction.

3. The motor control device according to claim 2, characterized in that, When the direction of increase or decrease is increasing, the parameter setting changer changes the coefficient of the integral calculation of the speed controller to a value smaller than the original value or a value smaller than the vibration frequency.

4. The motor control device according to claim 2 or 3, characterized in that, When the direction of increase or decrease is the decreasing direction, the parameter setting changer changes the coefficient of the proportional calculation of the speed controller to a value smaller than the original value.

5. The motor control device according to claim 2 or 3, characterized in that, The vibration detector performs different filtering processes on the drive waveform based on the position, speed, or torque of the motor, when the increase / decrease direction stored in the characteristic change direction storage unit is an increasing direction and when it is a decreasing direction, and detects the vibration amplitude and vibration frequency based on the filtered drive waveform.

6. The motor control device according to claim 2 or 3, characterized in that, have: A position detector that detects the position of the motor; and A position controller that generates the speed command based on the position of the motor and the position command, through calculations including proportional calculations. When the direction of increase or decrease is increasing, the parameter setting changer changes the coefficient calculated by the position controller to a value smaller than the original value or a value smaller than the vibration frequency.

7. A motor control system, characterized in that, have: The electric motor control device as described in any one of claims 1 to 6; The electric motor is controlled by the electric motor control device; and The load mechanism is driven by the electric motor.

8. A method for controlling an electric motor, which is executed by an electric motor control device that controls an electric motor driving a load mechanism. The electric motor control method is characterized by including: Step 1: Detect the speed of the electric motor; Step 2: Based on the speed and speed command of the motor, output the torque command for the motor; Step 3: Correct the torque command to generate a corrected torque command; Step 4: Based on the torque command and the corrective torque command, the current flows in the motor; Step 5: Detect the amplitude of the vibration (i.e., vibration amplitude) and the frequency of the vibration (i.e., vibration frequency) generated by the motor. Step 6: When the vibration amplitude increases compared to the threshold, the transmission characteristics at the vibration frequency are stabilized by repeatedly detecting the speed of the motor, generating the torque command, generating the corrective torque command, and controlling the feedback of the motor's current flow. Step 7: After stabilizing the transmission characteristics and reducing the vibration amplitude, the parameters for generating the torque command are changed.

9. The electric motor control method according to claim 8, characterized in that, In the second step, the torque command is generated through calculations including proportional and integral calculations. In step 7, the coefficients for the integral calculation are changed when the inertia of the load machinery increases, and the coefficients for the proportional calculation are changed when the inertia of the load machinery decreases.

10. The motor control method according to claim 9, characterized in that, In the seventh step, if the inertia increases, the coefficients used for the integral calculation are changed to values ​​smaller than the original values ​​or values ​​smaller than the vibration frequency.

11. The motor control method according to claim 9 or 10, characterized in that, In the seventh step, when the inertia decreases, the coefficient used to calculate the ratio is changed to a value smaller than the original value.

12. The motor control method according to claim 9 or 10, characterized in that, In the fifth step, different filtering processes are performed on the drive waveform based on the position, speed or torque of the motor when the inertia increases and when the inertia decreases, and the vibration amplitude and vibration frequency are detected based on the filtered drive waveform.

13. The motor control method according to claim 9 or 10, characterized in that, Include: Step 8: Detect the position of the motor; Step 9: Based on the position of the motor and the position command, the speed command is generated through a calculation including proportional calculation; and In step 10, if the inertia increases, the coefficient calculated in step 9 is changed to a value smaller than the value before the change, or a value smaller than the vibration frequency.

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