JP6783498B2 - Shaft torsion vibration suppression control device - Google Patents

Description

An embodiment of the present invention relates to a shaft torsional vibration suppression control device used for a motor speed control device for driving a motor to which a mechanical load having a shaft torsional vibration characteristic is connected.

Conventionally, when driving a motor to which a mechanical load having shaft torsional vibration characteristics is connected, the gain of the speed response is adjusted in advance so that the speed response is sufficiently far from the natural frequency of the mechanical system including the connecting shaft. The resonance of the torsional vibration of the connecting shaft is suppressed. In addition, torque ripple occurs when power pulsates due to switching of a variable speed control device, for example. By setting the carrier frequency of switching so that this torque ripple and the mechanical system do not resonate, the resonance of the torsional vibration of the connecting shaft Is suppressed.

As a prior example of a motor control device to which a mechanical load having a shaft torsional vibration characteristic is connected, in Patent Document 1, the shaft torsional vibration compensation value is corrected according to the speed difference between the motor speed and the machine load speed. A motor control device has been proposed that can suppress overshoot of the speed response and make the speed of the mechanical load respond to the speed command value with a short rise time.

Japanese Unexamined Patent Publication No. 7-15591

However, since the carrier frequency and speed response gain are fixed values set in advance, there are cases where there are resonance points that cannot be grasped in advance, changes in the shaft spring constant due to aging, and changes in the moment of inertia due to replacement of the mechanical load itself. When the natural frequency of the shaft changes, it may be difficult to prevent the torsional vibration that resonates and becomes excessive.

Further, Patent Document 1 describes that the motor control device has a control characteristic of suppressing torsional vibration of the shaft, but prevents a resonance phenomenon between the speed response, torque ripple, etc. and the natural frequency of the mechanical system. There is no mention of that.

The embodiment is made to solve the above-mentioned problems, and the resonance of the shaft torsional vibration is determined by determining the presence / absence and the cause of the resonance of the shaft torsional vibration and correcting the operation parameter of the motor speed control device. It is an object of the present invention to provide a shaft torsional vibration suppression control device that suppresses the vibration.

The shaft torsional vibration suppression control device according to the embodiment mechanically combines a motor driven by a motor speed control device based on PWM control, a mechanical load driven by the motor, and the motor and the mechanical load. Suppresses vibration due to resonance of the shaft torsional vibration system including the connecting shaft. This shaft torsional vibration suppression control device determines the presence or absence of resonance of the shaft torsional vibration system based on the frequency calculator that calculates the data in the frequency domain related to the shaft torque of the connecting shaft and the data in the frequency domain. The shaft torsional vibration resonance determination unit that determines the cause when it is determined that there is resonance, and the velocity response gain when it is determined that the cause of the resonance is the velocity response gain that sets the velocity response of the motor. A speed response gain correction value generation unit that corrects the carrier frequency, and a carrier frequency correction value generation unit that corrects the carrier frequency when it is determined that the cause of the resonance is torque ripple generated by the carrier frequency of the PWM control. , Equipped with.

In the present embodiment, since the shaft torsional vibration resonance determination unit is provided, the presence or absence of resonance of the shaft torsional vibration system can be determined, and if it is determined that there is resonance, the cause can be determined. Further, since the embodiment includes a speed response gain correction value generation unit and a carrier frequency correction value generation unit, it is possible to correct the operating parameters of the motor speed control device according to the cause of resonance.

It is a block diagram which illustrates the shaft torsional vibration suppression control device which concerns on Embodiment 1. FIG. It is a block diagram which illustrates the shaft torsional vibration suppression control device which concerns on Embodiment 2. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between the parts, and the like are not necessarily the same as the actual ones. Further, even when the same parts are represented, the dimensions and ratios may be different from each other depending on the drawings.
In addition, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

(Embodiment 1)
FIG. 1 is a block diagram illustrating an axial torsional vibration suppression control device according to the first embodiment.
FIG. 1 shows the configuration of the motor speed control device 20 in addition to the configuration of the shaft torsional vibration suppression control device 30. The shaft torsional vibration suppression control device may be housed in the same housing or panel as the motor speed control device, or may be housed in another physically separated housing or the like.

As shown in FIG. 1, the motor speed control device 20 is connected to the motor 1, the speed detector 4, and the shaft torsional vibration suppression control device 30. The motor speed control device 20 controls the motor 1 so that the actual speed of the motor 1 detected by the speed detector 4 matches the separately supplied speed command value. The motor speed control device 20 resonates with the shaft torsional vibration system including the motor 1, the mechanical load 2, and the connecting shaft 3 by setting the operation parameters according to the correction value supplied from the shaft torsional vibration suppression control device 30. It can operate by suppressing vibration.

In the motor 1, the rotating shaft and the mechanical load 2 having a torsional vibration characteristic are connected by a connecting shaft 3. The drive torque of the motor 1 is transmitted to the mechanical load 2 via the connecting shaft 3. The motor speed control device 20 drives the motor 1 by controlling the variable speed. For example, the motor 1 is a motor driven by AC power, and is an induction motor, a synchronous motor, or the like. For example, the motor speed control device 20 is an inverter device that drives an induction motor, a synchronous motor, or the like.

The motor speed control device 20 includes a speed response gain multiplication unit 5, a current controller 6, and a power converter 7. The speed response gain multiplication unit 5 generates a command value for the drive torque by multiplying the speed deviation between the speed command value and the speed detected by the speed detector 4 of the motor 1 by the speed response gain. The speed command value is supplied from, for example, a programmable controller (PLC) or the like. In the speed response gain multiplication unit 5, increasing the speed response gain improves the speed response (frequency), and decreasing the speed response gain decreases the speed response (frequency).

The current controller 6 is connected to the output of the speed response gain multiplication unit 5. The current controller 6 outputs a control amount generated according to the difference between the command value of the drive torque supplied from the speed response gain multiplication unit 5 and the torque current component supplied to the motor 1.

The power converter 7 is connected to the output of the current controller 6. The power converter 7 is a PWM-controlled converter. The power converter 7 outputs a voltage and a current for driving the motor 1 according to a controlled amount generated by the current controller 6.

A shaft torque detector 8 is provided on the connecting shaft 3. The shaft torque detector 8 supplies the detected shaft torque data to the shaft torsional vibration suppression control device. The shaft torsional vibration suppression control device 30 determines whether or not resonance has occurred in the shaft torsional vibration system based on the supplied shaft torque data. The shaft torsional vibration suppression control device 30 corrects the gain value of the speed response gain multiplication unit 5 or the carrier frequency of the PWM control of the power converter 7 when resonance occurs in the shaft torsional vibration system. To correct.

The configuration of the shaft torsional vibration suppression control device 30 will be described in detail.
The shaft torsional vibration suppression control device 30 includes a frequency calculator 9, a torsional vibration resonance determination unit 10, a speed response gain correction value generation unit 11, and a carrier frequency correction value generation unit 12.

The frequency calculator 9 is connected to the output of the shaft torque detector 8. The frequency calculator 9 converts the shaft torque data in the time domain detected by the shaft torque detector 8 into the data in the frequency domain. The frequency calculator 9 is, for example, an FFT (Fast Fourier Transform) analyzer.

The torsional vibration resonance determination unit 10 is connected to the output of the frequency calculator 9. In the torsional vibration resonance determination unit 10, the axial torsional vibration system including the motor 1, the mechanical load 2, and the connecting shaft 3 generates vibration due to resonance based on the data of the axial torque in the frequency domain (hereinafter, simply causes resonance). , Also called). When the torsional vibration resonance determination unit 10 determines that the shaft torsional vibration system is causing resonance, it determines whether it is resonance due to speed response gain or torque ripple based on the carrier frequency of PWM control. ..

For example, the torsional vibration resonance determination unit 10 has a threshold value T0 regarding a shaft torque regardless of frequency. The torsional vibration resonance determination unit 10 determines that resonance has occurred when the axial torque data in the frequency domain is equal to or greater than this threshold value T0. The torsional vibration resonance determination unit 10 determines that resonance has not occurred when the axial torque data in the frequency domain is smaller than this threshold value T0.

When the shaft torque data in the frequency domain is equal to or higher than the threshold value T0, the shaft torque data is considered to have a peak value centered on any frequency. The torsional vibration resonance determination unit 10 determines which component of the motor speed control device 20 causes the vibration of the axial torsional vibration system based on the frequency at which the axial torque data reaches the peak value.

Specifically, the torsional vibration resonance determination unit 10 determines whether the resonance is due to the speed response gain of the speed response gain multiplication unit 5 or the resonance due to torque ripple based on the carrier frequency of the PWM (Pulse Width Modulation) of the power converter 7. judge.

For example, the torsional vibration resonance determination unit 10 uses the carrier frequency of the power converter 7 and its harmonic components as frequencies for determination. Specifically, when the carrier frequency fc of the power converter 7 and the operating frequency f0 of the motor 1 are set, the frequencies fn for determination are n × (fc ± f0), n = 1, 2, 3, ... Set to (natural number). In the torsional vibration resonance determination unit 10, a threshold value Tn is preset for each frequency fn for determination.

The setting of the frequency fn for the determination is not limited to the above, and can be appropriately set. The frequency fn may be set in a wider range with respect to n × (fc ± f0), for example, n × (fc ± k × f0) (k> 1). Further, in the case of fc >> f0 or the like, the frequency may be set as fn = n × fc.

When the torsional vibration resonance determination unit 10 detects shaft torque data of the set threshold value Tn or more at any of the frequencies of fn, it is said that resonance due to torque ripple based on the carrier frequency is generated. judge.

When the torsional vibration resonance determination unit 10 does not detect the data of the shaft torque equal to or higher than the set threshold value Tn at any of the frequencies fn, it determines that the resonance is caused by the speed response gain.

A speed response gain correction value generation unit 11 and a carrier frequency correction value generation unit 12 are connected to the output of the torsional vibration resonance determination unit 10, respectively. When the torsional vibration resonance determination unit 10 determines that the resonance is due to the speed response gain, the torsional vibration resonance determination unit 10 supplies an enable signal to the speed response gain correction value generation unit 11. The enable signal puts the speed response gain correction value generation unit 11 into an operating state. The speed response gain correction value generation unit 11 that has received the enable signal generates a speed response gain correction value and supplies the correction value to the speed response gain multiplication unit 5.

When the torsional vibration resonance determination unit 10 determines that the resonance is due to torque ripple based on the carrier frequency, the torsional vibration resonance determination unit 10 supplies an enable signal to the carrier frequency correction value generation unit 12. The enable signal puts the carrier frequency correction value generation unit 12 into an operating state. The carrier frequency correction value generation unit 12 that has received the enable signal generates the correction value of the carrier frequency and supplies it to the power converter 7.

The operation of the shaft torsional vibration suppression control device 30 of the present embodiment will be described.
The shaft torque data in the time domain is detected by the shaft torque detector 8 and supplied to the frequency calculator 9.

The frequency calculator 9 converts the axial torque data in the time domain into the data in the frequency domain. The converted shaft torque data is supplied to the torsional vibration resonance determination unit 10.

The torsional vibration resonance determination unit 10 compares the shaft torque data at all the supplied frequencies with a constant threshold value T0 with respect to the frequency. If the axial torque data is smaller than the threshold value T0 at the frequency fn, the torsional vibration resonance determination unit 10 determines that the torsional vibration resonance has not occurred. The motor speed control device 20 maintains the current operation.

When the torsional vibration resonance determination unit 10 has the shaft torque data equal to or higher than the threshold value T0, the torsional vibration resonance determination unit 10 compares the shaft torque data for each frequency fn with the threshold value Tn set for each frequency fn. The frequency fn for which the threshold value is set is set based on the carrier frequency of the power converter 7. This frequency fn is n × (fc ± f0). Here, n is a natural number, fc is a carrier frequency, and f0 is an operating frequency of the motor 1.

The threshold values T1, T2, ... Are set for f1, f2, ..., Respectively. The threshold values T1, T2, ... May be different values, or some or all of them may be the same value. For example, the threshold value Tn is set based on a value measured by an experiment or the like or a value obtained by a simulation or the like.

When the shaft torque data is at any frequency fn and is equal to or greater than the threshold value Tn, the torsional vibration resonance determination unit 10 supplies an enable signal to the carrier frequency correction value generation unit 12.

The carrier frequency correction value generation unit 12 generates a correction value of the carrier frequency fc. The correction value of the carrier frequency fc is generated by acquiring the value of the carrier frequency fc from, for example, the power converter 7 and multiplying it by a preset coefficient α (0 <α <1). α is set, for example, 1% (0.01). For example, the carrier frequency correction value generation unit 12 calculates a new carrier frequency (1 + α) × fc using the coefficient α. The calculated new carrier frequency is supplied to the power converter 7. The carrier frequency correction value generation unit 12 also supplies a new carrier frequency to the frequency calculator 9, and the frequency calculator 9 updates the frequency fn for determination to the new carrier frequency.

The power converter 7 updates the value of the carrier frequency to (1 + α) × fc, and resumes or continues the operation.

The above operation is repeated at all frequencies n × (fc ± f0) until the shaft torque data falls below the threshold value.

An upper limit of the carrier frequency that can be updated is set, and if the shaft torque data does not fall below the threshold value Tn even if the upper limit is reached, a new carrier frequency is set to (1-α) × fc. The carrier frequency may be corrected so as to decrease with respect to the initial value. Further, a lower limit of the correction value may be provided, and if the shaft torque data does not fall below the threshold value even if the lower limit value is reached, the carrier frequency correction value generation unit 12 may generate an alarm.

The upper and lower limits of the carrier frequency correction range are set, for example, ± 5% (± 0.05). By providing the upper and lower limits in the correction range of the carrier frequency, it is possible to avoid a decrease in efficiency of the power converter 7 and an increase in noise generation.

The torsional vibration resonance determination unit 10 sends an enable signal to the speed response gain correction value generation unit 11 when the shaft torque data is equal to or higher than the threshold value T0 and smaller than the threshold value Tn corresponding to each frequency fn. Supply.

The speed response gain correction value generation unit 11 to which the enable signal is supplied generates a correction value of the speed response gain G. The speed response gain correction value generation unit 11 is generated by, for example, acquiring the value of the current speed response gain G from the speed response gain multiplication unit 5 and multiplying it by a preset coefficient β (0 <β <1). .. The coefficient β is set to, for example, 5% (0.05). The velocity response gain multiplication unit 5 calculates a new velocity response gain (1 + β) × G using the coefficient β. The calculated new velocity response gain is supplied to the velocity response gain multiplication unit 5.

The speed response gain multiplication unit 5 updates the speed response gain to (1 + β) × G and restarts the operation.

The above operation is repeated until the shaft torque data falls below the threshold value T0.

As in the case of the carrier frequency correction value generation unit 12, upper and lower limits may be set for the correction value of the speed response gain, and the shaft torque data and the threshold value T0 may be compared within the upper and lower limits of the correction value. By setting in this way, it is possible to prevent the response speed to the load fluctuation from being lowered to an allowable level or less, or the speed response to be too fast to cause an overshoot or the like.

When the shaft torque data becomes smaller than the threshold value T0 due to the above correction, the motor speed control device 20 restarts the operation with the updated speed response gain.

The calculation of the respective correction values of the carrier frequency fc and the speed response gain G is not limited to the above, and can be appropriately set. For example, each correction value may be set in advance by an experiment or the like, stored in a table as values α1, α2, ... According to the number of corrections, read out for each number of corrections, and applied. Alternatively, 1 <α <2 may be set, and the new carrier frequency may be calculated as a power of the number of corrections i, such as α ^ i × fc.

The shaft torsional vibration suppression control device 30 may be realized by, for example, a CPU (Central Processing Unit) that expands a program stored in a storage device (not shown) or sequentially reads and executes each step of the program. .. Some or all of the components described above are part of a program executed by the CPU. When the operation of the motor speed control device 20 is executed and realized by the CPU, the program of the shaft torsional vibration suppression control device 30 may be executed by the CPU of the motor speed control device 20.

The shaft torsional vibration suppression control device 30 may be realized by a PLC. The shaft torsional vibration suppression control device 30 may be realized as a part of a PLC program that supplies a speed command value to the motor speed control device 20, or may be realized by another PLC.

The effect of the shaft torsional vibration suppression control device 30 of the present embodiment will be described.
Since the shaft torsional vibration suppression control device 30 of the present embodiment includes the frequency calculator 9 and the torsional vibration resonance determination unit 10, it is possible to determine the presence or absence of torsional vibration resonance by frequency analysis of the measured value of the shaft torque. .. When the frequency component of the shaft torque includes the torsional vibration resonance, the torsional vibration resonance determination unit 10 generates a harmonic due to torque ripple based on the carrier frequency of PWM from the resonance frequency, or is based on the speed response gain. It can be determined whether or not there is. Therefore, the resonance state can be eliminated by correcting the operating parameters of the motor speed control device 20 according to each cause. Therefore, the shaft torsional vibration suppression control device 30 can suppress the resonance of the shaft torsional vibration.

In the above description, an example has been described in which the carrier frequency and the speed response gain are corrected in the direction of increasing from the initial value of the operating parameter, and in the direction of decreasing from the initial value when the resonance state is not resolved. It is not limited to. After correcting in the direction of decreasing from the initial value of the operation parameter, an appropriate correction value may be searched for in the direction of increasing from the initial value. Further, when searching for an appropriate correction value, the correction value may be switched by a learning function that stores the search history and provides the shortest search time.

The shaft torsional vibration suppression control device 30 may be realized by a CPU (Central Processing Unit) or the like that develops a program stored in a storage device (not shown) and sequentially executes each step of the program. A part or all of each component of the shaft torsional vibration suppression control device 30 described above is executed as a part of the program. The motor speed control device 20 may be executed by a CPU or the like, and in that case, the program for realizing the shaft torsional vibration suppression control device 30 may be executed by the CPU of the motor speed control device 20 or separately. It may be executed by the CPU of.

The shaft torsional vibration suppression control device 30 may be realized by a PLC. A part or all of each component of the shaft torsional vibration suppression control device 30 is realized by a PLC program. The PLC that realizes the shaft torsional vibration suppression control device 30 may be the same as the PLC that supplies the speed command value to the motor speed control device 20, or may be another PLC.

(Embodiment 2)
For the data on the shaft torque for determining the presence or absence of the torsional vibration resonance of the shaft torsional vibration system, parameters other than the shaft torque data detected by the torque detector can be used.
FIG. 2 is a block diagram illustrating the shaft torsional vibration suppression control device according to the second embodiment.
As shown in FIG. 2, the shaft torsional vibration suppression control device 130 of the second embodiment calculates based on the voltage and current data output by the power converter 7 instead of the actual shaft torque data by the torque detector. The calculated value of the shaft torque to be calculated is used.

The shaft torsional vibration suppression control device 130 includes a magnetic flux calculation unit 13 and a torque calculation unit 14. The shaft torsional vibration suppression control device 130 of the second embodiment is different from the case of the first embodiment described above in that it includes the magnetic flux calculation unit 13 and the torque calculation unit 14, and in other respects, the first embodiment 1 It is the same as the case of. The same components as in the case of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

The magnetic flux calculation unit 13 is connected to the power converter 7. The magnetic flux calculation unit 13 acquires voltage and current data output by the power converter 7 from the power converter 7. The magnetic flux calculation unit 13 calculates the magnetic flux based on the voltage and current data output by the power converter 7 and the winding resistance value of the motor 1. The winding resistance value of the motor 1 is preset by actual measurement or the like.

The torque calculation unit 14 is connected to the output of the magnetic flux calculation unit 13. The torque calculation unit 14 calculates the value of the shaft torque based on the value of the magnetic flux calculated by the magnetic flux calculation unit 13. The calculated shaft torque value is supplied to the frequency calculator 9, and the torsional vibration resonance is determined and corrected as in the case of the first embodiment described above.

The shaft torsional vibration suppression control device 130 of the first embodiment can use the value of the shaft torque obtained by calculation. Therefore, even when it is difficult to attach the shaft torque detector, it is possible to determine the presence / absence and the cause of the torsional vibration resonance and suppress the shaft torsional vibration resonance.

According to the embodiment described above, the shaft torsional vibration suppression control device that suppresses the resonance of the shaft torsional vibration is realized by determining the presence / absence and the cause of the resonance of the shaft torsional vibration and correcting the operating parameters of the motor speed control device. can do.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention and its equivalents described in the claims. In addition, the above-described embodiments can be implemented in combination with each other.

1 motor, 2 mechanical load, 3 connecting shaft, 4 speed detector, 5 speed response gain multiplier, 6 current controller, 7 power converter, 8-axis torque detector, 9 frequency calculator, 10 torsional vibration resonance judgment unit , 11 Speed response gain correction value generator, 12 Carrier frequency correction value generator, 13 Magnetic current calculation unit, 14 Torque calculation unit, 20 Motor speed control device, 30, 130 Shaft torsional vibration suppression control device

Claims (7)

A shaft torsional vibration system including a motor driven by a motor speed control device based on PWM control, a mechanical load driven by the motor, and a connecting shaft that mechanically connects the motor and the mechanical load. A shaft torsional vibration suppression control device that suppresses vibration due to resonance.
A frequency calculator that calculates data in the frequency domain related to the shaft torque of the connecting shaft, and
Based on the data in the frequency domain, the axial torsional vibration resonance determination unit determines the presence or absence of resonance of the axial torsional vibration system, and if it is determined that there is resonance, the cause is determined.
When it is determined that the cause of the resonance is the speed response gain that sets the speed response of the motor, the speed response gain correction value generating unit that corrects the speed response gain,
When it is determined that the cause of the resonance is the torque ripple generated by the carrier frequency of the PWM control, the carrier frequency correction value generating unit that corrects the carrier frequency and the carrier frequency correction value generating unit.
Shaft torsional vibration suppression control device equipped with. The shaft torsional vibration suppression control device according to claim 1, wherein the frequency calculator inputs data of the shaft torque detected by a shaft torque detector provided on the connecting shaft. The shaft torsional vibration suppression control device according to claim 1, wherein the frequency calculator inputs data of the shaft torque calculated based on the values of the voltage and the current output by the motor speed control device. The shaft torsional vibration suppression control device according to claim 1, further comprising a torque calculation unit that calculates the shaft torque data based on the voltage and current values output by the motor speed control device and supplies the data to the frequency calculator. .. The speed response gain correction value generation unit calculates a new speed response gain set based on the initial value of the speed response gain as a speed response gain correction value, and uses the speed response gain correction value as the motor speed control device. Send to
The shaft torsional vibration resonance determination unit is any one of claims 1 to 4 that determines the presence or absence of the resonance based on new data of the shaft torque acquired by the restarted operation of the motor speed control device. Shaft torsional vibration suppression control device according to. The carrier frequency correction value generator calculates a new carrier frequency set based on the initial value of the carrier frequency as a carrier frequency correction value, and transmits the carrier frequency correction value to the motor speed control device.
The shaft torsional vibration resonance determination unit is any one of claims 1 to 5 that determines the presence or absence of the resonance based on new data of the shaft torque acquired by the restarted operation of the motor speed control device. Shaft torsional vibration suppression control device according to. The axis according to claim 6, wherein the speed response gain correction value generation unit and the carrier frequency correction value generation unit include a learning function for setting the optimum speed response gain correction value and the carrier frequency correction value in the shortest search time. Torsional vibration suppression control device.

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