JP2008154374A - Drive controller for ac motors - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change reference patterns of magnetic flux according to the operating state of an AC motor or requested torque so that the primary current of the motor exceeds the rated current value of an inverter for driving the motor by a certain level or more and enhance the accuracy of detection of the primary current during normal operation to enhance the accuracy of torque control. <P>SOLUTION: A drive controller for AC motors includes: an operating state determining means 19 for detecting the state of operation based on a speed command to an AC motor; and a magnetic flux reference pattern selection circuit 20 that has respective magnetic flux reference patterns for acceleration/deceleration and constant-speed operation, determines whether acceleration/deceleration or constant-speed operation is underway from a speed command to the motor, and changes magnetic flux reference patterns based on the result of determination. The controller carries out control so that the ratio of the primary current of the motor to the rating of an inverter controller for driving the AC motor is a certain value or higher regardless of whether acceleration/deceleration or constant-speed operation is underway. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive control device for an AC motor for driving a shaft used in a winding / rewinding device such as a paper roll.

In recent years, the rolls of paper rolls and other rewinding devices have larger diameters, and the torque required for roll acceleration / deceleration (especially during deceleration) and the torque required for emergency stops have increased. The torque required for operation only requires a torque to maintain a certain tension and a small amount of mechanical friction torque, and the torque required for constant speed operation is equivalent to the torque required for acceleration / deceleration and emergency stop. Tend to be significantly smaller.
In the center drive system for driving the take-up / rewinding shaft in such a paper roll take-up / rewinding device, a roll drive AC motor and a vector inverter control device for an AC motor for driving the AC motor The capacity is selected based on the torque required for acceleration / deceleration.
Therefore, the selected AC motor and the AC inverter vector inverter controller for driving the AC motor have an excessive capacity during constant speed operation, and the primary current of the AC motor during constant speed operation is large. It becomes a very small value with respect to the rated current value of the vector inverter control device for an AC motor.
As a result, the change in the current value due to the tension fluctuation is significantly smaller than the rating of the current detection device, the detection accuracy becomes worse, and the control accuracy of torque control and tension control during constant speed operation deteriorates. Yes.

FIG. 8 is a control block diagram of a control device for a vector inverter for driving an AC motor applied to a winding / rewinding device such as a paper roll. In FIG. 8, 1 is an AC induction motor, 2 is an inverter control device, 3 is A speed detector for detecting the speed of the AC motor 1, 4 is a current detector for measuring the primary current of the AC motor 1, 5 is a PWM control circuit, 6 is a first coordinate converter, and 7 is a second sensor. Coordinate converter, 8 current control circuit, 9 primary magnetic flux component current reference calculation circuit, 10 slip frequency calculation circuit, 11 integrator, 12 torque reference switching circuit, 13 tension control circuit, 14 speed control Circuit, 15 is a magnetic flux reference setting circuit, 16 is a tension reference setting circuit, 17 is a rotor position converter, 18 is a differentiator, 21 is a winding / rewinding roll, 22 is a winding diameter sensor, and 23 is a roll diameter detection circuit. , 24 is A deceleration compensation torque calculation circuit 25 is a line speed (MRH) setting circuit.
In the AC motor 1 applied to a winding / rewinding device such as a paper roll, it is required to wind the paper roll or the like with a constant tension. In the operation of such an apparatus, the target tension reference T_ref is given from the external tension reference setting device 16 and the AC motor 1 is controlled so as to maintain the target tension.
The tension control circuit 13 calculates a torque-converted tension reference TENS_R from the tension reference T_ref and roll diameter data, adds it to the torque reference TRQ_acc_comp necessary for acceleration / deceleration, and the torque reference switching circuit 12 controls the speed. The torque reference TRQ_REF is determined by comparison with the speed limit SPD_LMT that is the output result of the circuit 14.
In the roll having an increased diameter, the ratio between the tension reference TENS_R converted to torque and the torque compensation amount TRQ_acc_comp necessary for acceleration / deceleration is large.
In vector control, the primary current reference corresponding to the magnetic flux reference Φ2 * and the torque reference TRQ_REF is calculated as a vector quantity, the primary current amplitude I1, the primary torque component current reference I1q *, the primary flux component current reference I1d * And the phase θ1 are output.
The torque component current reference I1q * is calculated by the primary magnetic flux component current reference calculation circuit 9 from the torque reference T_R of the speed control output, and the magnetic flux component current reference I1d * is calculated from the magnetic flux reference Φ2 * and the excitation current.
Further, the slip frequency ωs * is calculated from the magnetic flux reference Φ2 *, the primary torque component current reference I1q * and the secondary time constant T of the AC induction motor 1, and the current phase angle θ is calculated from the torque component current I1q and the magnetic flux component current I1d. Calculated.
On the other hand, the current phase θ1 is calculated as the sum of the motor rotor position θr detected by the speed detector 3, the slip frequency θs, and the current phase angle θ. FIG. 9 shows these relationships.
The calculated torque component current reference I1q * and magnetic flux component current reference I1d * are converted into the voltage reference Vv *, Vu *, Vw * of each phase of the AC motor 1 in the current control circuit 8 and PWM controlled. In the circuit 5, the frequency is converted to a predetermined frequency, and the AC motor 1 is operated at a desired torque.
In the prior art, this magnetic flux reference Φ2 * is basically constant with respect to the speed regardless of whether the AC motor 1 is accelerating / decelerating or operating at a constant speed. It is set as shown.
Since the no-load exciting current of AC motor 1 is sufficiently small (about 20 to 30%) compared to the rated current, the vector diagram of torque component current, magnetic flux component current and primary current is as shown in FIG. It becomes.

JP 2001-112299 A

According to the conventional method, the magnetic flux reference is set as shown in FIG. 10 based on the rating of the AC motor, and the pattern is uniquely determined with respect to the speed of the AC motor. As described above, the AC motor and AC motor drive control device applied to the winding / rewinding device such as a paper roll are determined with a capacity that satisfies the torque required for emergency stop and acceleration / deceleration, and the set magnetic flux reference is also set. It is set based on the capacity of the AC motor that satisfies this required torque.
When outputting the torque required for constant speed operation in an AC motor, if the torque component current I1q is determined using the magnetic flux reference determined based on the acceleration / deceleration capacity described above, I1q is small as understood from the equation Value.
Φ = K · I1d (K: proportional constant)
T = Φ ・ I1q ＝ K ・ I1d ・ I1q
If the torque required for acceleration / deceleration and emergency stop requires n times the torque required for constant speed operation, the torque component current I1q_const at constant speed is the torque component required for acceleration / deceleration if the field reference is unchanged. It becomes 1 / n of the current I1q_dec.
Consider the value of the primary current at each. Since the primary current is the vector sum of the torque component current and the magnetic flux component current as described above,
I1_const = √ (I1q_const ^ 2 + I1d ^ 2)
I1_dec = √ (I1q_dec ^ 2 + I1d ^ 2)
The ratio is √ (I1q_const ^ 2 + I1d ^ 2) / I1_dec = √ (I1q_dec ^ 2 + I1d ^ 2)
It is represented by
As I1q becomes smaller, the vector sum I1_const of the torque component current I1q and the magnetic flux component current I1d shown in FIG. 3 naturally becomes smaller, and the larger the ratio between the capacity required for acceleration / deceleration and the torque required for constant speed operation is larger. The primary current I1 of the AC motor becomes smaller than the rated current of the AC motor and the rated current value of the vector inverter control device for driving the AC motor.
In the inverter control device for driving an AC drive motor, a current detector 4 for detecting a primary current is provided, but this current detector 4 is naturally selected based on the rated capacity of the inverter control device.
Therefore, if the primary current is significantly smaller than the rated current of the vector inverter control device for driving an AC motor during constant speed operation, the detection accuracy is deteriorated, and the detection accuracy for fluctuations in the primary current is also deteriorated. .
In a winding / rewinding device intended to wind or unwind a paper roll, etc., it is necessary to keep the tension of the paper roll constant in order to make the winding appearance beautiful. In order to suppress this, high-accuracy torque control is required in driving the AC motor.
If the detection accuracy of the primary current is deteriorated, the torque control system is deteriorated for the above-mentioned reason, resulting in a problem of inducing tension fluctuation and adversely affecting the winding shape of the product.

  The present invention has been made to solve the above-described problems, and the pattern of the magnetic flux reference is changed according to the operating state of the AC motor and the required torque, and the primary current of the AC motor is driven by the AC motor. It is intended to increase the accuracy of torque control by improving the primary current detection accuracy during steady operation so that the rated current value of the inverter is at a certain level or higher.

  In the AC motor drive control device according to the present invention, the primary current applied to the AC motor for driving the winding / rewinding shaft of the winding / rewinding device such as a paper roll is excited with the magnetic flux reference. Operation state determination for detecting the operation state based on the speed command for the AC motor in the case of controlling the torque of the AC motor by calculating the vector from the magnetic flux component current Iq calculated from the current and the torque component current Id corresponding to the torque reference. And a magnetic flux reference pattern during acceleration / deceleration and constant speed operation, and a magnetic flux that determines acceleration / deceleration or constant speed operation from the speed command for the AC motor and switches the magnetic flux reference pattern based on the determination result And a reference pattern selection circuit for supplying the primary current of the AC motor regardless of whether the motor is accelerating / decelerating or operating at a constant speed. And controls so as to be constant or rate with respect to Case.

  According to the present invention, by changing the magnetic flux reference according to the required torque, it becomes possible to set the primary current of the AC motor to a value greater than a certain value with respect to the rating of the AC motor driving vector inverter. The torque control accuracy can be improved by increasing the detection accuracy of the primary current during constant speed operation.

  Furthermore, by improving the torque control accuracy, it is possible to keep the appearance of the product (paper roll or the like) beautifully.

Embodiment 1 FIG.
Hereinafter, an AC motor drive control apparatus according to Embodiment 1 of the present invention will be described with reference to FIG.
In FIG. 1, 1 is an AC induction motor, 2 is an inverter control device, 3 is a speed detector for detecting the speed of the AC motor 1, 4 is a current detector for measuring the primary current of the AC motor 1, 5 is a PWM control circuit, 6 is a first coordinate converter, 7 is a second coordinate converter, 8 is a current control circuit, 9 is a primary magnetic flux component current reference arithmetic circuit, 10 is a slip frequency arithmetic circuit, and 11 is an integrator. , 12 is a torque reference switching circuit, 13 is a tension control circuit, 14 is a speed control circuit, 15 is a magnetic flux reference setting circuit, 16 is a tension reference setting circuit, 17 is a rotor position converter, 18 is a differentiator, and 19 is a speed. An operation state determination circuit for detecting an operation state based on the command, 20 stores a magnetic flux reference pattern during acceleration / deceleration and constant speed operation, and a magnetic flux reference pattern based on the determination result of the operation state determination circuit 19 Select Flux reference pattern selection circuit, 21 is winding and rewinding roll, the 22 winding diameter sensor, 23 a roll diameter detecting circuit, 24 acceleration and deceleration compensation torque calculation circuit, 25 is a line speed (MRH) setting circuit.
The drive control apparatus for an AC motor according to the present invention is obtained by adding an operation state determination circuit 19 and a magnetic flux reference pattern selection circuit 20 as compared with the prior art shown in FIG. The control blocks other than this additional circuit are the same as those in the prior art.

Next, the operation will be described. For an AC motor driving control device for driving a roll in a winding / rewinding device such as a paper roll, the speed reference of each roll is provided from an external MRH line speed setting circuit 25 having a function of instructing the winding speed. Is instructed. From this speed command and operation sequence, it can be determined whether the roll is currently accelerating or decelerating or winding at a constant speed.
Further, in the magnetic flux reference pattern selection circuit 20, as shown in FIG. 2, the acceleration / deceleration field reference pattern used during acceleration / deceleration and the constant speed operation used when the roll is operating at a constant speed are used. Two field reference patterns are set, and a field reference pattern to be used is selected based on the operating state determined above.
The acceleration / deceleration field reference pattern used during acceleration / deceleration operation is the field pattern Φ2_ that has been determined based on the rated capacity of the AC motor in the past, and the constant-speed operation field used during constant-speed operation. The magnetic reference pattern Φ2_cnst is set to 1 / n of the field reference Φ2_ determined based on the rated capacity of the AC motor.
Φ2_cnst = (1 / n) ・ Φ2_
Here, n is an appropriate constant so that neither the field current reference I1d * nor the torque component current reference I1q * during constant speed operation becomes too small, and the value of I1 is equal to the rated current of the inverter controller. It is a value determined so as to be a value that is not so small.

An example of the method for determining n described above will be shown.
The conventional field reference pattern is determined based on the rated capacity (rated torque) of the AC motor. This is assumed to be Φ2_. Assume that the field reference during constant speed operation is 1 / n of Φ2_ when the torque required during constant speed operation is 1 / k of the torque required during acceleration / deceleration.
At this time, the magnetic flux current reference I1q * _const and the torque current component standard calculated by the field reference (1 / n) and Φ2_ of the torque T_const required during constant speed operation of the winding / rewinding roll I1d * _const is an expression
I1d * _const = (1 / n) ・ Φ2_ / K = (1 / n) ・ I1d * _
I1q * _const = T_const / (K ・ I1d * _const) = 1 / k ・ T / (K ・ I1d * _const)
It becomes.
At this time, n may be determined so that the value of I1_const, which is a vector sum of I1d * _const and I1q * _const, becomes the target primary current value magnitude I1_target.
((1 / n) ・ Φ2_ / K) ^ 2 + (1 / k ・ T / (K ・ I1d * _const)) ^ 2 = I1_target ^ 2

Determine the field pattern to be used during constant speed operation so that both the field current reference I1d_const and torque component current reference I1q_const during constant speed operation do not become too small. It will be described with reference to the vector diagram of FIG. 3 that the primary current I1 during constant speed operation can be set to a larger value than in the prior art by switching.
The primary current I1 during acceleration / deceleration is naturally close to the rated current, so there is no problem.
On the other hand, when the torque required during constant speed operation is 1 / k during acceleration / deceleration, if the magnetic flux reference pattern is not changed, the torque component current reference I1q_dec is also 1 / of the torque component current I1q_dec during acceleration / deceleration. As described above, k.
The primary current I1_const at this time is expressed as a vector sum in FIG.
On the other hand, if the field reference during constant speed operation is set to 1 / n during acceleration / deceleration operation, it is necessary to flow n times the torque component current to satisfy the required torque. The current I1q_dec can be n / k. The primary current at this time is represented by I1′_const in FIG.
Even if the magnetic flux current component current I1d * is 1 / n, increasing the torque component current by n greatly contributes to increasing the primary current, as can be understood from FIG.

Embodiment 2. FIG.
Next, an AC motor drive control apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.
In FIG. 4, only the function of the operation state determination circuit 19 is different from the control block diagram of the first embodiment. The operation state determination circuit 19 according to the second embodiment determines the operation state of the roll based on the feedback signal from the speed detector 3 attached to the AC motor 1 instead of the speed command or the operation command for the roll. It has a function to do. Others are the same as those of the first embodiment shown in FIG.
If the feedback signal from the speed detector 3 does not change for a certain period of time, it is considered that the roll is operating at a constant speed, and if the speed is changing, it is determined that acceleration / deceleration is in progress.

Embodiment 3 FIG.
Next, an AC motor drive control apparatus according to Embodiment 3 of the present invention will be described with reference to FIG.
In FIG. 5, with respect to the control block diagram of the first embodiment, a two-winding roll / rewinding roll 21 serving as a load of the AC motor 1, a winding diameter sensor 22 for measuring the roll diameter, and the winding diameter A roll diameter detection circuit 23 for calculating the roll diameter based on a signal from the sensor 22 is additionally connected to the magnetic flux reference pattern selection circuit 20.

As described above, the torque required for an AC motor differs greatly during emergency stop, acceleration / deceleration, and constant speed operation. However, when the winding / rewinding roll shaft is driven by an AC motor, it is also necessary depending on the roll diameter. Torque changes greatly.
Therefore, a plurality of field reference patterns are prepared in accordance with the roll diameter even during acceleration / deceleration. During acceleration / deceleration, the field reference pattern is switched depending on the detected roll diameter, so that the primary current has a value larger than a certain value. Thus, the torque control accuracy can be improved.
The field reference setting method can be implemented in exactly the same manner as described in the first embodiment.

For the torque T_max required for acceleration / deceleration at the maximum rate at the maximum roll diameter Dmax, the acceleration / deceleration torque τ required for each roll diameter D is obtained, and this τ is the torque T_const required for constant speed operation in the first embodiment. The field reference pattern may be determined in the same manner as described above.
The roll diameter is divided into several ranges from the spool diameter D_core to the full diameter D_max, and a field reference pattern during acceleration / deceleration is provided for each of these roll diameter ranges to reduce the roll diameter. Even during acceleration / deceleration, more accurate torque control can be realized.

Embodiment 4 FIG.
Next, an AC motor drive control apparatus according to Embodiment 4 of the present invention will be described with reference to FIG.
In FIG. 6, a torque reference T_R signal is passed to the magnetic flux reference pattern selection circuit 20 with respect to the control block diagram of the third embodiment, and the magnetic flux reference pattern selection circuit 20 operates the roll (acceleration / deceleration / constant speed). In operation), in addition to the roll diameter, the winding / rewinding device such as a paper roll has a function of switching the field reference pattern in consideration of the torque reference required for winding / rewinding.
In a winding / rewinding device such as a paper roll, it is necessary to wind the roll while stretching the paper with a constant tension in order to align the winding form.
The torque T required to wind and unwind the roll with a tension TENS_R at a roll diameter D is
T = TENS_R · D / 2
In order to keep the tension constant, it is necessary to change the torque according to the roll diameter.
Therefore, not only the field reference during acceleration / deceleration is switched based on the roll diameter detection result, but also the field reference pattern is set according to the required torque regardless of whether it is constant speed operation, acceleration / deceleration operation, or emergency stop. The magnetic flux reference pattern selection circuit 20 is provided with a function of setting and switching according to the required torque.

A specific operation will be described.
Torque required for AC motors for driving the winding / rewinding shaft of paper rolls and other rewinding devices is divided into several required torque ranges including emergency stop, acceleration / deceleration and constant speed operation. Then, a plurality of field reference patterns are provided according to the required torque as shown in FIG. The field reference pattern setting method set for each required torque range can be calculated in the same manner as in the first embodiment.

Since the torque required for acceleration / deceleration can be calculated from GD2 based on the density of the paper to be wound, the required torque calculated from GD2 and acceleration / deceleration rate can also be calculated from the roll diameter and acceleration / deceleration rate. .
On the other hand, the torque required to keep the tension constant can also be calculated by the previous equation if the roll diameter is known.
That is, if the acceleration / deceleration rate and the roll diameter are known, the required torque required for the AC motor can be calculated.

Based on the detected roll diameter and the operation state of the roll, a preset field reference is switched, and control is performed so that the primary current of the AC motor becomes a certain level or more. As a result, the current value detected by the current detector 3 is not significantly reduced with respect to the rating of the current detector, and can always be detected as a current value of a certain level or more.
Further, when the primary current value falls within an appropriate range as the operation range of the current detector, the detection accuracy is improved, and as a result, the control accuracy of torque control for the AC motor is improved.
As described above, switching the field reference pattern according to the required torque makes it possible to increase the magnitude of the primary current of the AC motor to an appropriate value, improve the accuracy of torque control, Expected to improve the winding shape.

It is a control block diagram which shows the drive control apparatus of the alternating current motor in Embodiment 1 of this invention. It is a characteristic view which shows an example of the field reference pattern of the drive control apparatus of the alternating current motor in Embodiment 1 of this invention. It is a vector diagram which shows the change of a primary current when the field reference pattern of the drive control apparatus of the alternating current motor in Embodiment 1 of this invention is changed. It is a control block diagram which shows the drive control apparatus of the alternating current motor in Embodiment 2 of this invention. It is a control block diagram which shows the drive control apparatus of the alternating current motor in Embodiment 3 of this invention. It is a control block diagram which shows the drive control apparatus of the alternating current motor in Embodiment 4 of this invention. It is a characteristic view which shows an example of the field reference pattern of the drive control apparatus of the alternating current motor in Embodiment 4 of this invention. It is a control block diagram which shows the drive control apparatus of the conventional alternating current motor. It is a characteristic view which shows the relationship of the current phase of an alternating current induction motor. It is a characteristic view which shows an example of the field reference pattern of the conventional AC motor. It is a vector exploded view of the primary current of the conventional AC motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC induction motor 2 Inverter control apparatus 3 Speed detector 4 Current detector 5 PWM control circuit 6 1st coordinate conversion circuit 7 2nd coordinate conversion circuit 8 Current control circuit 9 Primary magnetic flux component current reference | standard calculation circuit 10 Slip frequency calculation circuit 11 integrator 12 torque reference switching circuit 13 tension control circuit 14 speed control circuit 15 magnetic flux reference setting circuit 16 tension reference setting device 17 rotor position converter 18 differentiator 19 operating state determination circuit 20 magnetic flux reference pattern selection circuit 21 Rewind roll 22 Reel diameter sensor 23 Roll diameter detection circuit 24 Acceleration / deceleration compensation torque calculation circuit 25 Line speed (MRH) setting circuit

Claims (4)

Applied to AC motors for driving the winding / rewinding shafts of winding / rewinding devices such as paper rolls, etc., using the primary current as the flux component current Iq calculated from the magnetic flux reference and excitation current, and the torque reference In a drive control device for an AC motor that calculates a vector from the corresponding torque component current Id and controls the torque of the AC motor,
Driving state determination means for detecting the driving state based on a speed command for the AC motor;
Magnetic flux reference pattern selection that has a magnetic flux reference pattern during acceleration / deceleration and constant speed operation, determines acceleration / deceleration or constant speed operation from the speed command for the AC motor, and switches the magnetic flux reference pattern based on the determination result With circuit,
AC motor drive control, wherein the primary current of the AC motor is controlled so as to be at a certain ratio or more with respect to the rating of the inverter control device for driving the AC motor regardless of whether during acceleration / deceleration or constant speed operation. apparatus.   2. The drive control apparatus for an AC motor according to claim 1, further comprising a speed change detection function for discriminating between acceleration / deceleration and constant speed operation from a feedback signal from a speed detector attached to the AC motor.   The primary reference current of the AC motor is always used to drive the AC motor by changing the magnetic flux reference pattern according to the winding diameter of the paper roll or the like and the torque required from the AC motor operation status (acceleration / deceleration operation or constant speed operation). 2. The drive control apparatus for an AC motor according to claim 1, wherein the control is performed so that the ratio is a certain ratio or more with respect to the rating of the inverter control apparatus.   The magnetic flux reference pattern is changed according to the torque required from the tension reference, the roll diameter of the paper roll, etc., and the AC motor operating status (acceleration / deceleration operation / during constant speed operation), and the AC motor primary current is always AC. 2. The drive control apparatus for an AC motor according to claim 1, wherein the control is performed so that the ratio is equal to or greater than a predetermined value relative to the rating of the inverter control apparatus for driving the motor.

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