TWI751514B - A yarn delivery device and a method for delivering yarn to a textile machine - Google Patents

Abstract

A yarn delivery device comprises at least two positive feeders and a common control unit, wherein each positive feeder comprises a yarn delivery wheel, a brushless d. c. motor and an individual control unit.

The motor comprises a sensor device with Hall sensors. The individual control unit compares the monitored position of the motor with a given position of the motor corresponding to a movement of the textile machine adjusts the currents for the coils of the motor.

For each feeder, the sensor device comprises three analog Hall sensors which are arranged with a displacement of 120° to each other and generate signals as sinusoidal waves. The individual electronic control unit determines the monitored position of the motor by analyzing the three signals of sinusoidal waves with the help of their inverse trigonometric functions and, if so, by selecting the two of three signals without discontinuity for this determination.

Description

Yarn delivery device and method for delivering yarn to a textile machine

The present invention relates to a yarn delivery device and a method for delivering yarn to a textile machine, having at least two forward yarn feeders and a common control unit according to the preamble of the independent item. The subject of the present invention is the use of a forward yarn feeder with an electric motor to synchronize the yarn delivery of the forward yarn feeder with the speed of the textile machine.

US 2005/0146294 A1 describes an electronic device for delivering yarn to a textile machine, which is capable of regulating the delivery of the yarn by varying the rotational speed of at least one motor so as to be completely relative to the rotational speed of the textile machine according to an adjustable scaling factor Possibly synchronously maintaining the rate.

A device is associated with each yarn winding wheel for delivering each single thread to the textile machine. It includes a motor and an electronic control board for the motor equipped with at least one microcontroller, capable of controlling the rotational speed of the motor and the current in each phase of the motor, and capable of maintaining a rotational speed synchronized with the rotational speed of the cylinder of the textile machine. The motor is a DC brushless motor that includes sensor means for detecting the position of the rotor outside the motor. The motor's electronic control board controls a driver that switches the phases of the motor and the current to be delivered to the phases.

The electronic board is able to detect the input frequency from a first encoder device engaged with the cylinder of the textile machine in order to compare the input frequency with the output frequency from a second encoder device mounted on the shaft of the motor.

The second encoding device fitted to the shaft of the motor does not allow to determine that one of the motors is abnormal precise location.

Known from US 2007/0272784 A1 is a yarn transfer device for a knitting machine, which has a yarn transfer wheel, an electric motor for the yarn transfer wheel, and means for detecting the rotational position of the yarn transfer wheel. An angle encoder.

Especially in one embodiment, the angle encoder includes a rotatable permanent magnet M and four Hall sensors arranged in the magnetic field of the permanent magnet M. It should be noted that angle encoders of this type are installed in some brushless electric motors in order to control the electronic switches used to trigger the motor coils. It is stated that this angle encoder can be used as a position sensor for the connected control loop, but this is not specific.

The control loop includes a regulating circuit, an actual value input connected to the angle encoder, and a desired value input connected to a preselection unit.

In operation, several yarn conveying devices are controlled by a central control device. The central control unit sends control pulses to the preselected units of each unit, e.g. the central control unit sends individual pulses, wherein each individual pulse of rotation of the electric motor corresponds step by step to the annular resolution of the angle encoder. resolution).

The angular encoder has an angular resolution at least so great that the ratio s/d between the angular resolution s of the yarn transfer wheel and the diameter d is greater than 3 mm ⁻¹ .

In the case of a knitting machine with several forward feeders, many winding wheels, ie many motors, must be synchronized. The position of the motor must be determined more precisely.

The subject of the present invention is to improve the synchronization of the yarn delivery with the speed of the weaving machine, in particular to improve the resolution of the position determination of the motor position of the forward yarn delivery feeder for synchronization.

The yarn transfer device for transferring yarn to a textile machine according to the present invention comprises at least two forward yarn feeders and a common control unit. Each feeder includes a yarn transfer wheel, a brushless DC motor for driving the yarn transfer wheel, and an individual control unit with at least one microcontroller. horse The DA includes a sensor device with Hall sensors to monitor the position of the motor in order to control the motor's coils. The common control unit is designed to provide information about the movement of the textile machine to the individual control units.

Each individual control unit is designed to control the position of its motor corresponding to the movement of the textile machine. It is designed to compare the monitored position of the motor with a given position of the motor corresponding to the movement of the textile machine and adjust the current of the motor coils according to the difference between the two. The given position of the motor is determined with respect to the motion of the textile machine, such as the rotational speed of the needle cylinder, and an adjustable scale factor or ratio factor.

The sensor device of each feeder is provided with three analog Hall sensors for monitoring the position of the motor used. Considering a motor shaft, the sensors are configured with a displacement of 120° relative to each other. The three analog Hall sensors are designed to generate a signal like a sine wave.

The individual control unit is designed to determine the monitored position of the motor by analyzing the three signals of the sine wave by means of its inverse trigonometric function. When a discontinuity in the inverse trigonometric function of one of the sine waves occurs, it is designed to do so continuously by selecting two of the three signals to determine the monitored position of the motor.

Since the three analog Hall sensors are configured with a 120° displacement relative to each other, the discontinuities of the inverse trigonometric function of the sine wave are also displaced. Thus, at each rotation angle, if so, at most one of the three inverse trigonometric functions exhibits a discontinuity.

As a result, it is possible to determine the value of the motor position for each angle, ie each point of the sine wave. The resolution of the determination is limited only by the number of bits that provide the value for the motor position.

This very precise determination of the motor position of each feeder enables the use of forward feeders with electric motors to achieve a uniform knitted fabric.

In one embodiment, the individual control units are designed to determine the position of the textile machine from the motion information and to determine a given position of the motor associated with the determined position of the textile machine.

The motion information of a textile machine, ie a circular knitting machine, is for example a rate signal with a pulse train from an encoder arranged at the motor of the knitting cylinder or at the knitting cylinder itself. In one embodiment, the individual control units are designed to analyze the rate signal, ie the pulse sequence, in order to determine the rate or frequency of the knitting cylinder and to determine the position of the knitting cylinder. The individual control units are designed to assign a given position of the motor to the position of the knitting cylinder, eg depending on the desired knitting pattern.

In one embodiment, the individual control units are designed to control the motors using a field-oriented control (FOC) method. Field Oriented Control (FOC) for motor rotation requires precise indication of motor position. As mentioned above, this precise indication of motor position is provided by a sensor arrangement with three analog Hall sensors.

In one embodiment, individual controllers are designed to adjust the position of the motor by adjusting the current to the coils of the motor using a pulse width modulation (PWM).

Therefore, individual units are designed to determine the monitored position by analyzing the sine wave, and use a Field Oriented Control (FOC) method for controlling the motor rotation by adjusting the current of the motor's coils.

The method for transferring yarn to a textile machine according to the invention is suitable for using a yarn transfer device having the above-mentioned features and advantages.

A method for delivering yarn to a textile machine by means of a yarn delivery device comprising at least two forward yarn feeders and a common control unit, wherein each forward yarn feeder has a yarn delivery wheel , a brushless DC motor for driving the yarn transfer wheel, and an individual control unit having at least one microcontroller; the foregoing method comprising monitoring the position of the motor for control by means of a sensor device having a Hall sensor The coils of the motors provide information about the movement of the textile machine to the individual control units through the common control unit, and control the position of the motors by the individual control units corresponding to the movement of the textile machine.

The monitored position of the motor is linked by the individual control unit to the operation of the textile machine. The given position of the moving motor is compared, and according to the difference between the two, the current of the coil of the motor is adjusted by the individual control unit.

For each forward feeder, the above method further comprises providing the signals of three analog Hall sensors provided with sensor devices displaced by 120° relative to each other as a sine wave taking into account the motor axis, and by The individual control unit determines the monitored position of the motor by analysing the three signals of the sine wave by means of its inverse trigonometric function, and if so, does so without interruption by selecting two of the three signals.

In one embodiment, the above-described method comprises determining the position of the textile machine and the given position of the motor relative to the determined position of the textile machine from the motion information by the individual control units.

In one embodiment, the above-described method includes controlling the coils of the motor using a Field Oriented Control (FOC) method by an individual electronic control unit.

In one embodiment, the above-described method includes adjusting the position of the motor by using a pulse width modulation (PWM) to adjust the current of the coils of the motor by the individual electronic control unit.

In one embodiment, the above method comprises: for calibration, recording the shapes of three sine waves by individual control units at a given rotational speed, and for synchronization, determining the position of the motor during partial rotation of the motor. The magnitude of the partial rotation depends on the number of magnetic pole pairs of the motor, where the aforementioned magnitude is one rotation divided by the number of magnetic pole pairs.

In one embodiment, the above method comprises providing, by the individual control unit, a stop signal for the textile machine when the difference between the monitored position of the motor and the given position is greater than 1 mm.

In one embodiment, the above method comprises automatically reducing, by its individual control unit, the rotation of the motor of the yarn feeder by a given degree when a drop in yarn tension is recognized. Therefore, the yarn tension is increased as fast as possible. In one example, the rotational speed of the motor is reduced by a given modification of an adjustable scale or ratio factor relative to the speed of the syringe. The yarn tension drop is detected, for example, by an output sensor of the yarn feeder. Identifying the yarn tension eg when the speed of the loom is reduced or when the loom is about to stop decline.

1: Forward yarn feeder

2: Shared control unit

3: Knitting tube

4: Shell

5: Electric motor

6: Knitted fabric

7: Rack

8: Electric motor

9: Roller

10: Roller

11: Electric Motor

12: Electric Motor

13: Mechanical Control Unit

14: Second shell

15: Display

16: Mechanical ring

17: Suspension device

20: Yarn feeder housing

21: Yarn transfer wheel

22: Motor

23: Individual Electronic Control Units

24: Fastening device

25: Shuttle Eye

26: Brake device

27: Input sensor

28: Output sensor

L1: Communication Line

L2: Communication Line

L3: Communication Line

L4/5: Communication Line

L6/7: Communication line

Y: Yarn

A: Motor shaft

S: sensor device

p: period

W1, W2, W3: Sine wave

Θ: (rotation) angle

The invention is further explained using an embodiment of a yarn transfer device arranged on a circular knitting machine, which is shown schematically in the drawings. It shows: Fig. 1 is a schematic diagram of a yarn transfer device arranged on a circular knitting machine; Fig. 2 is a schematic diagram of a forward yarn feeder of the yarn transfer device; Fig. 3 is a sine wave W1 as a function of the rotation angle Θ , W2 and W3; Figure 4 is a flow chart of the calibration procedure; Figure 5 is a flow chart of the synchronization procedure; and Figure 6 is a detailed flow chart of the third step of Figure 5.

FIG. 1 schematically shows a yarn transfer device for transferring a yarn Y to a textile machine with several forward yarn feeders 1 and a common control unit 2 . Only in FIG. 2 the yarn Y conveyed by a forward yarn feeder 1 is shown.

In this embodiment, the yarn transfer device is arranged at the weaving machine, ie at the circular knitting machine. The circular knitting machine comprises: a knitting cylinder 3 ; a casing 4 ; and an electric motor 5 of the knitting cylinder 3 inside the casing 4 and a take-off device for taking out the knitted fabric 6 . The extraction device has a frame 7 with an electric motor 8, and two sets of rollers 9, 10 with their electric motors 11, 12. The circular knitting machine includes a mechanical control unit 13 disposed in a second housing 14 . The housing is provided with a display 15 .

The forward yarn feeder 1 of the yarn transfer device is fixed to a mechanical ring 16 supported by a suspension device 17 . Only two forward feeders 1 are shown schematically, the other forward feeders are indicated by short lines in FIG. 1 .

The common control unit 2 of the yarn conveying device is built into the second housing 14 . The common control unit 2 is connected to each forward yarn feeder 1 through a communication line L1. The mechanical control unit 13 is controlled by a second The communication line L2 is connected to the motor 5, to the common control unit 2 via a third communication line L3, to the two motors 11 of the drum 9 via communication lines L4, L5, and to the drum via communication lines L6, L7 10 bis Motor 12.

A forward yarn feeder 1 is shown schematically in FIG. 2 . Each forward yarn feeder 1 includes a yarn feeder housing 20 , a yarn transfer wheel 21 , a brushless DC motor 22 for driving the yarn transfer wheel 21 , and an individual control unit 23 . The motor 22 and the individual control unit 23 are arranged inside the feeder housing 20 shown by dashed lines. The shaft A of the motor 22 on which the drive wheel 21 is fixed is also shown by dashed lines.

The forward feeder 1 is provided with a fastening device 24 for fastening the feeder 1 to the mechanical ring 16 . It is also provided with a bobbin 25 for the yarn Y, a braking device 26, an input sensor 27, and an output sensor 28.

The motor 22 has a sensor device S with three analog Hall sensors to monitor the position of the motor 22 in order to control the coils of the motor. Considering the axis of the motor shaft A, ie the motor axis, the sensors are arranged with a displacement of 120° relative to each other.

The three analog Hall sensors of the sensor arrangement S are designed to generate signals as sinusoidal waves W1, W2, and W3. Figure 3 shows the sine waves W1, W2, and W3 as a function of the angle of rotation Θ. For example, a sinusoidal curve of the sinusoidal wave W1 corresponds to the period p of one of the pole pairs of the motor 22 .

The motor 22 has at least five pole pairs. In this embodiment, the motor 22 has seven pole pairs of rotor permanent magnets and stator coils.

The individual control unit 23 is designed as an electronic control unit with at least one microcontroller. The individual control unit 23 is designed to precisely determine the monitored position of the motor 22 by analyzing the three signals of the sine waves W1, W2, W3 by means of its inverse trigonometric function. It is designed to select two of the three signals to make this determination without interruption.

The individual control units 23 are designed to determine the value of the motor position at each angle Θ, ie at each point of the sine waves W1, W2, and W3.

The resolution of the monitored motor position is limited only by the bits provided for the value of the motor position. In this embodiment, the value of the motor position for each pole pair is monitored by a 16-bit variable. The resolution of the motor position for each pole pair p is 5,5° 10 ^-3 . In this case of seven pole pairs, the resolution is 7,85°10 ^-4 .

The individual control units 23 are designed to control the motor 22 using a Field Oriented Control (FOC) method and adjust the position of the motor by adjusting the currents for the three coils of the motor 22 using a pulse width modulation (PWM).

The individual control units 23 are designed to determine the position of the textile machine from the motion information and to determine a given position of the motor 22 in relation to the determined position of the textile machine. The motion information of a textile machine, ie a circular knitting machine, is for example a rate signal with a pulse sequence from an encoder (not shown in FIG. 1 ), which is arranged in the motor 5 of the knitting cylinder 3 .

In an alternative, the encoders are connected to the individual control units via the communication line L2, the mechanical control unit 13 and the communication line L3. In another alternative, the encoders are connected to individual control units 23 via separate communication lines (not shown in Figure 1).

The individual control units 23 are designed to analyze the rate signal, ie the pulse sequence, in order to determine the rate or frequency of the knitting cylinder and the position of the knitting cylinder. The individual control units 23 are designed to assign a given position of the motor to the position of the knitting cylinder depending on the desired knitting pattern.

The individual control units 23 are designed to compare the monitored position of the motor with a given position of the motor 22 corresponding to the movement of the textile machine, and to adjust the current to the coils of the motor according to the difference between the two.

Therefore, the individual unit 23 is designed to accurately determine the monitored position by analyzing the sine waves W1, W2, W3, and by using the Field Oriented Control (FOC) method and by using the Pulse Width Method (PWM) adjustment The rotation of the motor is controlled by the current in the coil of the motor 22 .

In operation, the yarn is fed by at least two forward feeders 1 and A common control unit 2 is transmitted to the textile machine, wherein each forward yarn feeder 1 comprises a yarn transfer wheel 21, a brushless DC motor 22 for driving the yarn transfer wheel 21, and has at least one microcontroller An individual control unit 23, and by: ˙ For each feeder 1, monitoring the position of the motor 22 by means of a sensor device S with three Hall sensors of the motor 22 in order to control the motor 22 coils in which the signals of the three analog Hall sensors arranged at a displacement of 120° relative to each other are provided as sine waves W1, W2, W3; ˙ by the individual control unit 23, by means of its inverse trigonometric function to analyze the three signals of the sine waves W1, W2, W3 to determine the monitored position of the motor 22 and, if so, to do so continuously by selecting two of the three signals; ˙ by common control unit 2 to provide the individual control units 23 with information on the movement of the textile machine; by comparing the monitored position of the motor 22 with the given position of the motor 22 corresponding to the movement of the textile machine by means of a sensor device S, and according to both The difference between them is that the position of the motor 22 is controlled by the individual control unit 23 by adjusting the current of the coil of the motor 22 by the individual control unit 23 .

In order to determine the monitored position of the motor 22, analysis of each of the three signals of the sine waves W1, W2, W3 results in three monitored rotation angles Θi shifted in phase by 120°. Therefore, the inverse trigonometric functions of the monitored sine waves W1, W2, and W3 are calculated and stored in a data reducing form, and the rotation angle Θi is reconstructed therefrom. Discontinuities can occur using reduced data. If a discontinuity occurs, the data for two of the three signals are continuously selected for this decision.

The position of the textile machine is determined by the individual control unit 23 from the motion information and the given position of the motor 22 in relation to the determined position of the textile machine.

The coils of the motor 22 are controlled by the individual electronic control unit 23 using a Field Oriented Control (FOC) method.

The position of the motor 22 is adjusted by the individual electronic control unit 23 by using pulse width modulation (PWM) to adjust the current of the coils of the motor 22 .

FIG. 4 shows a block diagram of the calibration procedure performed by each individual control unit 23 for its motor 22 .

After the first start initialized to the Start1 command, a calibration procedure is performed.

In the first step, it is checked whether the calibration data CD of the motor 22 is recorded. If so, the synchronization procedure is initialized by the Start2 command.

If not, in a second step, the rotation of the motor 22 is controlled so as to rotate at, for example, 200 revolutions per minute, ie 200 rpm.

In the third step, the sine waves W1, W2, W3 are analyzed. It is checked whether a certain starting value of the sine wave W2 is reached, eg a minimum value W2 _min . If not, do the analysis.

If so, in the fourth step, the calibration data CD for one full revolution of the motor 22, ie the values of the sine waves W1, W2, and W3 for all periods p of the pole pair, are recorded once.

In the sixth step, the calibration data CD is stored in the non-volatile memory of the individual control unit 23 .

After the calibration data CD is stored, the calibration procedure is terminated by the End command.

Therefore, for calibration, the shape of the three sine waves W1, W2, W3 of one full revolution of the motor 22 is recorded at a given rotational speed by means of the individual control unit 23, depending on the angle of rotation θ named as calibration data CD are the values of the sine waves W1, W2, and W3.

The calibration data CD is used to overcome deviations of the sine waves W1, W2, W3 measured from normal conditions, such as due to mechanical tolerances during the motor assembly process, the imbalance of the rotor magnets, and the configuration of the three Hall sensors from which Deviation of 120° displacement.

FIG. 5 shows a block diagram of the synchronization procedure performed by each individual control unit 23 for its motor 22 .

If the calibration data CD of the motor 22 is recorded, at each start of the yarn transfer by the Start1 command, the synchronization procedure is initialized to the Start2 command.

In the first step, the values of the sine waves W1, W2, and W3 are reset.

In the second step, the values Wi(p) of the sine waves W1, W2, and W3 are recorded and checked if a complete period p corresponding to a magnetic pole pair is recorded. If not, continue recording.

If so, in a third step, the recorded values Wi(p) are analyzed and compared with the calibration data CD in order to determine the period P of the calibration data CD(P) to which the recorded values Wi(p) best match.

In the fourth step, the position of the motor 22 is determined by means of the calibration data CD(P). The recorded value Wi(P) is assigned to the position of the motor 22, ie its angle Θ for subsequent operation.

After determining the position of the motor 22, the synchronization procedure is ended by the End command.

Therefore, for synchronization, the position of the motor 22 is determined by means of the calibration data CD during a partial rotation of the motor 22, ie corresponding to a complete period p of a pole pair.

The third step of FIG. 5 is further described in FIG. 6 .

The recorded value Wi(p) is analyzed, for example, by determining characteristic terms such as peak-to-peak items ΔAp. The characteristic terms are compared with the corresponding terms of the calibration data CD of the period P0, P1, ... of the pole pair, eg the peak-to-peak terms ΔA0, ΔA1, ..., in order to use the recorded values Wi(p), especially The period P is determined by the calibration data CD(P) best matched by its peak-to-peak term ΔAp. In this case, the period P with the calibration data CD(P) is determined by the smallest difference between the recorded value Wi(p) and the peak-to-peak term ΔA _{min of the calibration data CD.}

When the difference between the monitored position of the motor 22 and the given position at any position is greater than a threshold of the difference, eg greater than 1 mm, a stop signal for the textile machine is provided by the individual control unit 23 .

When a drop in yarn tension is recognized by the output sensor 28, the rotation of the motor 22 is automatically reduced by a given degree by its individual control unit 23.

p: period

W1, W2, W3: Sine wave

Θ: (rotation) angle

Claims (10)

A yarn transfer device for transferring yarn to a textile machine, which has at least two forward yarn feeders (1) and a common control unit (2), wherein each forward yarn feeder (1) contains a yarn wire transfer wheel (21), a brushless direct current motor (22) for driving the yarn transfer wheel (21), and an individual control unit (23) with at least one microcontroller, wherein the motor (22) ) comprising a sensor device (S) with a Hall sensor for monitoring the position of the motor (22) in order to control the coils of the motor (22), wherein the common control unit (2) is designed to report to the motor (22) An individual control unit (23) provides information about the movement of the textile machine, wherein the individual control unit (23) is designed to control the position of its motor (22) in correspondence with the movement of the textile machine, and wherein the individual control unit (23) (23) Designed to compare the monitored position of the motor (22) with a given position of the motor (22) corresponding to the movement of the textile machine, and to adjust for the motor (22) according to the difference between the two ), characterized in that, for each feeder, the sensor device (S) comprises three analog Hall sensors, considering an axis of a motor shaft (A), the Hall sensors are configured with a displacement of 120° relative to each other, wherein the analog sensors are designed to generate signals like sine waves (W1, W2, W3), and wherein the individual electronic control units (23) are designed to be Determine the monitored position of the motor (22) by analyzing the three signals of the sine waves (W1, W2, W3) by means of their inverse trigonometric functions, and if so, by selecting two of the three signals. This determination is made continuously. The yarn conveying device of claim 1, wherein the individual control unit (23) is designed to determine the position of the textile machine from the motion information, and to determine the motor (22) associated with the determined position of the textile machine the given location. Yarn conveying device as claimed in claim 1 or 2, wherein the individual electronic control unit (23) is designed to control the coils of the motor (22) using a Field Oriented Control (FOC) method. Yarn conveying device as claimed in claim 1 or 2, wherein the individual electronic control unit (23) is designed to regulate the motor by adjusting the current of the coils of the motor (22) using a pulse width modulation (PWM) (22) location. A method for delivering yarn to a textile machine by means of a yarn delivery device comprising at least two forward yarn feeders (1) and a common control unit (2), wherein each forward yarn feeder The device (1) comprises a yarn transfer wheel (21), a brushless DC motor (22) for driving the yarn transfer wheel (21), and an individual control unit (23) with at least one microcontroller ), wherein the position of the motor (22) is monitored by a sensor device (S) with a Hall sensor in order to control the coils of the motor (22), wherein the individual control unit (23) Information about the movement of the textile machine is provided by the common control unit (2), wherein, corresponding to the movement of the textile machine, the position of the motor (22) is determined by the individual control unit (23). Control wherein, by the individual control unit (23), the position of the motor (22) monitored by the sensor device (S) is associated with the feeding of the motor (22) corresponding to the movement of the textile machine The fixed position is compared, and according to the difference between the two, the current of the coil of the motor (22) is adjusted by the individual control unit (23), characterized in that, For each forward feeder (1), the sensor device (S) comprises three analog Hall sensors which, considering an axis of a motor shaft (A), are are arranged with a displacement of 120° relative to each other, wherein the signals of the three analog Hall sensors are provided as sine waves (W1, W2, W3), and wherein the sine waves (W1) are analyzed by means of their inverse trigonometric functions , W2, W3) to determine the monitored position of the motor (22) by the individual control unit (23) and, if so, to do so without interruption by selecting two of the three signals determination. A method for conveying yarn as claimed in claim 5, wherein the position of the textile machine from the motion information and the motor (22) related to the determined position of the textile machine are determined by the individual control unit (23). ) at the given position. A method for conveying yarn as claimed in claim 5 or 6, wherein the coils of the motor (22) are controlled by the individual electronic control unit (23) using a Field Oriented Control (FOC) method. A method for conveying yarn as claimed in claim 5 or 6, wherein the current of the coils of the motor (22) is adjusted by the individual electronic control unit (23) by using a pulse width modulation (PWM) Adjust the position of the motor (22). A method for conveying yarn as claimed in claim 5 or 6, wherein for calibration, the shape of the three sine waves during one full revolution of the motor (22) at a given rotational speed is determined by the The individual control units ( 23 ) are recorded as calibration data (CD) and, for synchronization, the position of the motor ( 22 ) is determined during a partial rotation of the motor ( 22 ) by means of the calibration data (CD). A method for conveying a yarn as claimed in claim 5 or 6, wherein the rotation of the motor (22) of the yarn feeder (1) is performed by its individual control unit ( 23) Automatically reduce to a given degree.

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