JP5197896B1 - Cogging torque measuring device for rotating machine - Google Patents

Abstract

When the motor under test is directly connected to the drive motor without passing through the torque sensor and rotated, the cogging torque of the motor under test is measured from the q-axis current generated in the drive motor at that time. First of all, the q-axis current was measured by operating with no load under the cogging torque measurement condition as a single unit, and the q-axis current at the time of no load was rotated with the motor under test connected directly to the drive motor. The q-axis current component caused by the driving motor itself superimposed as a disturbance is subtracted from the loaded q-axis current obtained during load operation. Therefore, it is possible to ensure sufficient accuracy in the measured value of the cogging torque without selecting and using a motor having a structure in which the cogging torque component is ideally zero, such as a coreless or slotless drive motor.
[Selection] Figure 1

Description

  The present invention relates to a cogging torque measuring device for a rotating machine.

  Various proposals have been made for measuring the cogging torque of a rotating machine. For example, in Patent Documents 1 to 6, the cogging torque is measured by the following method.

  In Patent Document 1, a motor under test, a compensation joint, an encoder for measuring rotation speed, a torque sensor, and a driving motor are arranged in this order. A coreless motor is used as a driving motor. A technique is disclosed in which a coreless motor is driven by a belt driving device coupled to the shaft of the coreless motor, and the torque of the motor under test is measured from the q-axis current of the coreless motor.

  Patent Document 2 discloses a technique for measuring a cogging torque and a torque ripple component before actual operation as a micro-step driving device for a stepping motor, making a table, and subtracting a compensation component during operation.

  Patent Document 3 discloses a technique for suppressing a cogging component (6f) and a torque ripple component as a PM motor control device (inverter drive).

  In Patent Document 4, as an elevator control device, a technique for measuring a ripple component generated during low-speed operation and subtracting a ripple component generated during low-speed operation during normal operation in order to remove a torque ripple component generated from an electric control panel. Is disclosed.

In Patent Document 5, a motor having the same structure as the motor under test is considered in consideration of error factors of the apparatus including the drive motor by coupling the motor under test using a drive motor and measuring the cogging torque with a torque sensor. The cogging torque at low speed (30 [ r / min ] etc.) and high speed (600 [ r / min ]) is measured, and when the measured value is within a predetermined allowable range, the motor is A technique for determining a cogging torque reference value for a mass-produced product test as a master motor is disclosed.

  In Patent Document 6, there is a technique for measuring cogging torque by comparing a reference value when measuring a master work and a measured value of a mass-produced product with a configuration in which a drive motor and a rotor under test are connected via a torque sensor. It is disclosed.

JP 2005-37389 A Japanese Patent Laying-Open No. 2005-210786 JP 2007-267465 A JP 2005-247574 A JP 2009-42137 A JP 2010-14534 A

  However, in the technique disclosed in Patent Document 1, since the speed unevenness occurs in the belt driving device, disturbance is likely to occur in the q-axis current component, and the measurement accuracy is lowered. In such a case, it is necessary to provide a mechanism for correcting the disturbance on the driving side and a mechanism for stabilizing the speed. As a mechanism for stabilizing the speed in the low speed range, a method of using a reduction gear for the drive motor is conceivable. Even in that case, the drive motor itself rotates at a high speed, so the q-axis current component output from the control device is used. The cogging torque detection becomes difficult. In addition, since there are many components, it is necessary to consider the disturbances associated therewith.

  In general, it is desirable to measure the cogging torque at a lower speed than at a higher speed. This is because the q-axis current component increases during high-speed rotation, so that the cogging pulsation component becomes relatively small and the detection accuracy decreases. The number of data sampling is also affected. On the other hand, in order to measure at a low speed, it is necessary to reduce the speed unevenness of the driving motor.

  In the technique disclosed in Patent Document 2, the detent torque of the stepping motor itself needs to be measured in advance, but the detent torque cannot be measured by the micro drive device itself, so it must be measured by another device. .

  Further, in the technique disclosed in Patent Document 3, when the 6f component of the torque current value generated when the motor is operated compensates for the cogging torque, the 6f component when the motor is operated also has a ripple caused by the inverter itself. Since the components are superimposed, there is a problem that the correction accuracy is not improved.

  In the technique disclosed in Patent Document 4, the ripple component generated during motor low speed operation is subtracted from the torque current value during normal operation, but the ripple component generated by the electric control panel during actual operation is taken into consideration. Therefore, there is a problem that the accuracy is lowered.

  In the technique disclosed in Patent Document 5, the master motor is selected in a form including all of the drive motor and the torque sensor, and the reference value is set. In this case, a component in the apparatus fails and is replaced. If so, the master motor must be selected from scratch. As the number of types of master motors increases, this method cannot cope with failure. Moreover, since the torque sensor is used, there is a problem that the equipment cost cannot be reduced.

  Further, in the technique disclosed in Patent Document 6, as in Patent Document 5, in order to measure an apparatus error due to an apparatus failure, it is necessary to perform measurement of a master work from scratch, so that measurement accuracy is maintained. For this purpose, there is a problem that time and labor are required.

  The present invention has been made in view of the above, and an object of the present invention is to provide a cogging torque measuring device for a rotating machine that can ensure sufficient measurement accuracy and can reduce equipment costs and improve maintainability.

  In order to solve the above-mentioned problems and achieve the object, the present invention uses the q-axis current generated in the drive motor when the motor under test is directly connected to the drive motor and rotated. A cogging torque measuring device for a rotating machine that measures the cogging torque of a test motor, wherein the motor driving unit that operates the drive motor is configured to measure the drive motor before connecting the motor under test under a cogging torque measurement condition. No-load q-axis current generated in the drive motor when operated with the motor, and generated in the drive motor when the drive motor connected to the motor under test is operated under the cogging torque measurement conditions A q-axis current measuring means for measuring the q-axis current when there is a load, and outputting each to a calculation unit for calculating the cogging torque of the motor under test. First Fourier calculation means for performing a Fourier calculation on the no-load q-axis current and calculating each harmonic component of the no-load q-axis current, and performing a Fourier calculation on the loaded q-axis current. Second Fourier calculation means for calculating each harmonic component of the loaded q-axis current, and subtraction for subtracting each harmonic component of the unloaded q-axis current from each harmonic component of the loaded q-axis current Means for performing inverse Fourier computation on each harmonic component of the q-axis current caused only by the motor under test and generating q-axis current caused only by the motor under test, and the inverse Fourier computation And a cogging torque detecting means for detecting a cogging torque of the motor under test by performing a torque conversion process on the q-axis current caused only by the motor under test generated by the calculating means.

  According to the present invention, the motor under test is directly connected to the driving motor without using a torque sensor, and the cogging torque of the motor under test is measured from the q-axis current generated in the driving motor at that time. In this case, the drive motor is operated as a single unit with no load under the cogging torque measurement condition to measure the q-axis current, and the no-load q-axis current is used as the direct drive motor. The q-axis current component caused by the driving motor itself superimposed as a disturbance is subtracted from the loaded q-axis current obtained during the loaded operation that is connected and rotated. Therefore, it is possible to ensure sufficient accuracy in the measured value of the cogging torque without selecting and using a motor having a structure in which the cogging torque component is ideally zero, such as a coreless or slotless drive motor. There is an effect.

FIG. 1 is a block diagram showing a configuration of a cogging torque measuring device for a rotating machine according to Embodiment 1 of the present invention. FIG. 2 is a waveform diagram showing an example of the measured cogging torque. FIG. 3 is a block diagram showing a configuration of a cogging torque measuring device for a rotating machine according to Embodiment 2 of the present invention. FIG. 4 is a block diagram showing a configuration of a cogging torque measuring device for a rotating machine according to Embodiment 3 of the present invention.

  Embodiments of a cogging torque measuring device for a rotating machine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a cogging torque measuring device for a rotating machine according to Embodiment 1 of the present invention. In FIG. 1, a cogging torque measuring device 1a includes holding plates 6 and 7 for holding and fixing a motor under test 2 and a driving motor 3 with their output shafts 4 and 5 facing each other on the same straight line. , A coupling portion 8 that directly connects the tips of the output shafts 4 and 5 so as to be separable, a control device 9a that is a motor operating portion, and an arithmetic device 10a that is an arithmetic portion. The arithmetic device 10a is a computer device including a CPU, a ROM, and a RAM, and a so-called personal computer can be used. For example, data is exchanged with the control device 9a by an appropriate communication method such as serial communication.

  The cogging torque measuring device 1a sets the motor under test 2 to the holding plate 6 and sets the driving motor 3 to the holding plate 7 without connecting the coupling portion 8, that is, connecting the motor under test 2 Without driving, the drive motor 3 is operated alone under the same operating conditions (cogging torque measurement conditions) as when the motor under test 2 is rotated, and the motor under test with the coupling portion 8 mounted. 2 is connected, and the load motor is operated under a cogging torque measurement condition in which the drive motor 3 is rotated, and a test is performed using the q-axis current generated in the drive motor 3 during no-load operation and load operation. The cogging torque of the motor 2 is measured. This point is the same in each embodiment described below.

  Note that the measurement of the cogging torque of the motor under test 2 is performed by operating the driving motor 3 at a low speed, so that the driving motor 3 detects the rotational position in the first embodiment in order to reduce speed unevenness. A servo motor equipped with an encoder 11 is used.

  The control device 9a shows the q-axis current measuring unit 13 and the interface 14 extracted as a configuration related to the measurement of the cogging torque according to this embodiment. As a general position control operation, the control device 9a supplies drive power to the drive motor 3 based on the position signal detected and output by the encoder 11, and each of the dq axes generated by coordinate conversion from the three-phase drive current at that time. It is possible to cause the drive motor 3 to perform a predetermined operation by performing feedback control based on the current value. Here, the predetermined operation is a no-load operation and a load operation under the cogging torque measurement condition in this embodiment. Since the motor under test 2 is a mass-produced product, the control device 9a performs the no-load operation once, and then repeats the load operation for the number of times of the motor under test 2 to be measured.

  The q-axis current measurement unit 13 includes a q-axis current during no-load operation (referred to as “q-axis current q0”) and a q-axis current during load-operated operation (referred to as “q-axis current q1”). Are measured by converting the coordinates from the three-phase drive current at that time, and output to the interface 14. The interface 14 identifies the q-axis current q0 measured during the no-load operation and the q-axis current q1 measured during the loaded operation, which are input from the q-axis current measurement unit 13, as the format of the communication method to be employed. It inserts possible and outputs to the interface 16 in the arithmetic unit 10a via the communication line 15.

  The arithmetic device 10a includes an interface 16, a q0 data storage unit 17, a Fourier calculation unit 18, a no-load test ripple compensation table 19, a subtracter 20, a q1 data storage unit 21, a Fourier calculation unit 22, a filter A processing unit 23, an inverse Fourier calculation unit 24, a torque conversion processing unit 25, and a cogging torque storage unit 26 are provided.

Hereinafter, the operation of the arithmetic device 10a will be described.
In the computing device 10a, the interface 16 outputs the q-axis current q0 taken from the communication line 15 during no-load operation to the q0 data storage unit 17, and the q-axis current q1 taken from the communication line 15 during load-loaded operation is q1 data. The data is output to the storage unit 21 and stored in each.

  The Fourier calculator 18 performs a Fourier calculation on the q-axis current q0 stored in the q0 data storage 17 as a first Fourier calculator, and calculates each harmonic component q0f of the q-axis current q0. Each harmonic component q0f of the q-axis current q0 calculated by the Fourier calculation unit 18 is set in the no-load test ripple compensation table 19.

  The Fourier calculator 22 performs a Fourier calculation on the q-axis current q1 stored in the q1 data storage unit 21 as a second Fourier calculator, and calculates each harmonic component q1f of the q-axis current q1.

  The subtracter 20 subtracts each harmonic component q0f of the q-axis current q0 set in the no-load test ripple compensation table 19 from each harmonic component q1f of the q-axis current q1 calculated by the Fourier calculator 22. A disturbance component caused by the drive motor 3 is removed, and each harmonic component q2f of the q-axis current q2 caused only by the motor under test 2 is generated.

  The filter processing unit 23 removes noise components such as harmonic components included in the harmonic components q2f of the q-axis current q2 caused only by the motor under test 2 generated and output by the subtracter 20 from each q-axis current q2. The harmonic component q2f ′ is output.

  The inverse Fourier computation unit 24 performs an inverse Fourier computation on each harmonic component q2f ′ of the q-axis current q2 resulting from only the motor under test 2 output from the filter processing unit 23, and q resulting from only the motor under test 2 An axial current q2 is generated.

  The torque conversion processing unit 25 performs a torque conversion process on the q-axis current q2 generated by the inverse Fourier calculation unit 24 using a relational expression between the phase of the q-axis current and the torque, and performs cogging of the motor under test 2. Torque is detected and stored in the cogging torque storage unit 26.

  FIG. 2 is a waveform diagram showing an example of the measured cogging torque. Although the motor under test 2 has 6 poles and the drive motor 3 has 4 poles, FIG. 2 shows that only the pulsation of the 6 harmonic component that is the cogging torque component of the motor under test 2 appears. Yes.

  As described above, the motor under test 2 is directly connected to the drive motor 3 without a torque sensor and rotated, and the cogging torque of the motor under test is calculated from the q-axis current generated in the drive motor 3 at that time. In the measurement, the drive motor 3 is first operated as a single unit with no load under the cogging torque measurement conditions to measure the q-axis current q0, and the q-axis current q0 is directly used to drive the motor under test 2. By subtracting from the q-axis current q1 obtained during the load-loaded operation connected to the motor 3 and rotated, the q-axis current component caused by the driving motor itself superimposed as a disturbance is removed.

  Therefore, according to the first embodiment, sufficient accuracy for the measured value of the cogging torque can be obtained without selecting and using a motor having a structure in which the cogging torque component is ideally zero, such as a coreless or slotless drive motor. Can be secured.

  Further, since a generally used torque sensor is not required, the equipment cost can be reduced and the maintainability can be improved.

  Since the error factor only on the device side is measured, if any part of the device breaks down, it is only necessary to measure the q-axis current q0 during the drive motor no-load operation after repair. There is an effect that it is not influenced by the number of measurement types of the test motor.

  In addition, the measurement of the q-axis current q0 by no-load operation only needs to be performed once, and after the second time, the no-load operation is not performed and only the q-axis current q1 is measured by the load operation. Thus, the working time for measuring the cogging torque can be shortened for the motor under test which is a mass-produced product.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing a configuration of a cogging torque measuring device for a rotating machine according to Embodiment 2 of the present invention. In FIG. 3, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will be focused on the portion related to the second embodiment.

  In FIG. 3, the cogging torque measuring device 1b according to the second embodiment is the same as that shown in FIG. 1 (the first embodiment) except that the encoder 11 is deleted and a control device 9b is provided instead of the control device 9a. Yes. Other configurations are the same as those of the first embodiment.

  That is, in the second embodiment, the disturbance component by the encoder 11 is removed, and the control device 9b operates the drive motor 3 by sensorless control. In this case, since the drive system of the drive motor 3 is speed control based on each current value of the dq axis generated by coordinate conversion from the detected three-phase drive current, the speed stability is inferior to that of the first embodiment. The same operations and effects as those of Form 1 can be obtained.

  In the second embodiment, as disturbance components, (1) a component error component of the drive motor 3, (2) an assembly error component of the apparatus component, and (3) the drive motor 3 and the motor under test. 2 and (4) a current-carrying ripple component of the driving motor 3, (1), (2), and (4) can be removed by arithmetic processing.

Embodiment 3 FIG.
FIG. 4 is a block diagram showing a configuration of a cogging torque measuring device for a rotating machine according to Embodiment 3 of the present invention. In FIG. 4, the same reference numerals are given to components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1). Here, the description will be focused on the portion related to the third embodiment.

  In FIG. 4, the cogging torque measuring device 1c according to the third embodiment is provided with an arithmetic device 10b in place of the arithmetic device 10a in the configuration shown in FIG. 1 (Embodiment 1). In the arithmetic device 10b, the amplitude / phase compensation unit 28 is arranged at each output stage of the Fourier arithmetic units 18 and 22.

  The amplitude / phase compensator 28 includes the harmonic components q0f of the q-axis current q0 calculated by the Fourier calculator 18 and the harmonic components q1f of the q-axis current q1 calculated by the Fourier calculator 22. The respective amplitudes and phases are aligned and input to the subtracter 20.

  According to the third embodiment, in addition to obtaining the same operation and effect as in the first embodiment, the cogging torque measurement accuracy can be increased. In the third embodiment, the application example to the first embodiment has been described. Needless to say, the third embodiment can be similarly applied.

Embodiment 4 FIG.
In the fourth embodiment, several modifications are shown. Although described in the first embodiment, this is also applicable to the second and third embodiments.

(1) In Embodiment 1, in order to accurately measure the cogging torque of the motor under test 2 from the q-axis current value of the driving motor 3, the structure of the driving motor 3 is a coreless structure. In this case, since the cogging torque component by the drive motor 3 is ideally zero, it is possible to reduce the energization ripple component generated when the drive motor 3 is driven.

  As disturbance components, (1) a component error component of the drive motor 3, (2) an assembly error component of the apparatus component, (3) a disk component of the encoder 11, and (4) a drive motor 3 Although there are assembly error components with the motor under test 2, (1), (2), and (3) can be removed by arithmetic processing.

(2) In the first embodiment, the cogging torque component is mainly affected by the number of poles of the motor 2 under test. Therefore, in order to accurately measure the cogging torque of the motor under test 2 from the q-axis current value of the driving motor 3, the slot combinations of the motor under test 2 and the driving motor 3 are combined differently, The cogging torque component does not interfere with the pulsating component of the driving motor 3. By combining the motor under test 2 and the drive motor 3 with different combinations of slots, for example, the pulsation component of the drive motor 3 is added to the main component of cogging torque of the motor under test 2 (six harmonics in the case of a six-pole motor). It becomes difficult to superimpose.

  As disturbance components, (1) a component error component of the drive motor 3, (2) an assembly error component of the apparatus component, (3) a disk component of the encoder 11, and (4) a drive motor 3 There are assembly error components with the motor under test 2 and (5) energization ripple components of the driving motor 3, but (1), (2), (3), and (5) can be removed by arithmetic processing. .

(3) In the first embodiment, the measurement of the q-axis current q0 by no-load operation when the static friction torque and the dynamic friction torque by the motor under test 2 are large is for driving in a state where a load equivalent to that of the motor under test is applied. It is desirable to measure the q-axis current q0 ′ when the motor is operated alone. That is, in FIG. 1, q0 = q0 ′. This is because the no-load operation is performed under the cogging torque measurement conditions.

  As described above, the cogging torque measuring device for a rotating machine according to the present invention is useful as a cogging torque measuring device for a rotating machine that can secure sufficient measurement accuracy and can reduce equipment costs and improve maintainability. .

1a, 1b, 1c Cogging torque measuring device 2 Motor under test 3 Driving motor 4, 5 Output shaft 6, 7 Holding plate 8 Coupling portion 9a, 9b Control device (motor operating portion)
10a, 10b arithmetic device (arithmetic unit)
DESCRIPTION OF SYMBOLS 11 Encoder 13 q-axis current measurement part 14, 16 Interface 17 q0 data storage part 18, 22 Fourier calculation part 19 No load test ripple compensation table 21 q1 data storage part 20 Subtractor 23 Filter processing part 24 Reverse Fourier calculation part 25 Torque conversion Processing unit 26 Cogging torque storage unit 28 Amplitude / phase compensation unit

Claims (2)

A cogging torque measuring device for a rotating machine that measures the cogging torque of the motor under test using a q-axis current generated in the driving motor when the motor under test is directly connected to the driving motor and rotated. ,
Motor driving unit for driving the drive motor,
A no-load q-axis current generated in the driving motor when the driving motor before connecting the motor under test is operated under cogging torque measurement conditions, and the driving motor connected with the motor under test When the motor is operated under the cogging torque measurement conditions, the loaded q-axis current generated in the driving motor is measured, and each is output to the arithmetic unit that calculates the cogging torque of the motor under test. q-axis current measuring means,
The computing unit is
First Fourier calculation means for performing a Fourier calculation on the no-load q-axis current and calculating each harmonic component of the no-load q-axis current;
Second Fourier calculation means for performing a Fourier calculation on the loaded q-axis current to calculate each harmonic component of the loaded q-axis current;
Subtracting means for subtracting each harmonic component of the unloaded q-axis current from each harmonic component of the loaded q-axis current;
Reverse Fourier calculation means for performing a reverse Fourier calculation on each harmonic component of the q-axis current caused only by the motor under test and generating a q-axis current caused only by the motor under test;
Cogging torque detecting means for detecting a cogging torque of the motor under test by performing a torque conversion process on the q-axis current caused only by the motor under test generated by the inverse Fourier calculating means; and Cogging torque measurement device for rotating machines. The computing unit is
An amplitude / phase compensation means for making the subtraction means input the same amplitude and phase of each harmonic component calculated and output by each of the first and second Fourier arithmetic means. The cogging torque measuring device for a rotating machine according to claim 1.

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