Motor torque characteristic measurement method and device

Abstract

The present invention proposes a motor torque characteristic measurement method and device, which utilizes a servo motor with large overload capacity and high torque, and the hysteresis speed difference formed with a stepper motor during operation as a dynamic load, so as to quickly and continuously test the pull-out torque characteristic of the stepper motor. When the maximum speed is reached, the high torque of the servo motor when it stops is used as a fixed load to quickly and continuously measure the pull-in torque characteristic of the stepper motor. Not only can the pull-out torque and pull-in torque of the stepper motor be quickly tested, but also the torque of the motor at various speeds or the speed under various torque loads can be quickly detected.

Description

Technical Field

[0001] The present invention relates to the field of motor measurement, and in particular to a motor torque characteristic measurement method and a measuring device thereof, which are used for characteristic testing of pull-out torque and pull-in torque of a stepper motor and input and output power and efficiency testing of motors such as a DC brushless motor, a DC servo motor, and a DC brushed motor. Background Art

[0002] A stepper motor is an electric motor that converts an electrical pulse signal into a corresponding angular displacement or linear displacement. It is mainly used in situations that require speed control or position control. As the application of stepper motors becomes more and more widespread and the market demand increases, how to quickly and continuously measure the torque characteristics of stepper motors has become an important issue in the development of the industry.

[0003] At present, in the test of stepper motor torque characteristics, magnetic powder brakes or weights are generally used as fixed loads for detection. However, this detection method is time-consuming, slow, and inefficient. Frequent acceleration and deceleration are required during the detection process, and then the pull-out torque at a specific speed can be tested after the motor stops running.

[0004] In other DC micro motor torque characteristic tests, magnetic powder brakes or weights are also used as fixed loads for testing, which also have the problems of long time, slow speed and low efficiency. Frequent acceleration and deceleration are also required during the testing process, and the torque power curve at a specific speed can only be tested after the motor stops running. Summary of the invention

[0005] In view of the above situation, the present invention proposes a motor torque characteristic measurement method and device, which can not only quickly detect the torque of the motor at various speeds or the speed under various torque loads, but also quickly test the pull-out torque and pull-in torque of the stepper motor.

[0006] The motor torque characteristic measurement method according to the present invention comprises the following steps:

[0007] Step 1, connecting the output shaft of the motor under test and the servo motor through a coupling device;

[0008] Step 2, make the motor under test and the servo motor rotate in the same direction, and the running speed of the servo motor is less than the running speed of the motor under test, and adjust the speed of the motor under test to V1;

[0009] Step 3, measuring the torque between the motor under test and the output shaft of the servo motor, and when the motor under test loses step, collecting the maximum torque value Nmax1 at the speed of V1 to obtain the maximum pull-out torque of the motor under test at the speed of V1;

[0010] Step 4, adjusting the speed of the servo motor and the motor under test until the running speed of the motor under test is Vn;

[0011] Step 5, measuring the torque between the motor under test and the output shaft of the servo motor, and when the motor under test loses step, collecting the maximum torque value Nmaxn at the speed Vn, to obtain the maximum pull-out torque of the motor under test at the speed Vn;

[0012] Step 6, looping through steps 4 and 5 until the running speed of the motor under test reaches the preset maximum speed Vmax. When the motor under test loses step, the maximum torque value Nmax at the Vmax speed is collected to obtain the maximum pull-out torque of the motor under test at the Vmax speed.

[0013] Furthermore, after obtaining the maximum pull-out torque of the motor under test at the Vmax speed, the maximum pull-out torques of the motor under test at various set speeds in the stages from V1 to Vmax are summarized to form a pull-out torque characteristic curve of the motor under test.

[0014] Furthermore, before executing step 2, the motor under test and the servo motor are powered on and enabled respectively to obtain a locking force.

[0015] Furthermore, the difference between the rotation speeds V1, Vn, and Vmax of the measured motor is the interval rotation speed Vgap.

[0016] Furthermore, the rated torque of the servo motor is greater than the maximum torque of the motor being tested.

[0017] Furthermore, the operating speeds of the servo motor and the motor under test are set to:

[0018] Servo motor running speed Vs = measured motor running speed Vb - speed difference Vd

[0019] in,

[0020] The running speed Vb of the motor under test is the set value;

[0021] Speed ​​difference Vd = 60s ÷ number of pole pairs of the motor being tested ÷ T

[0022] in,

[0023] T is the time required to collect the maximum torque value when the motor under test loses step.

[0024] Preferably, after the motor under test loses step at a preset maximum speed Vmax, the servo motor stops and maintains the torque, the motor under test decelerates from Vmax to stop, and the maximum pull-in torque of the motor under test at each set speed is measured, thereby forming a maximum pull-in torque characteristic curve of the motor under test.

[0025] A motor torque characteristic measuring device comprises a servo motor, a torque sensor and an encoder. The torque sensor is connected to the encoder and the servo motor through a first coupling and a second coupling respectively, and the motor to be measured is connected to the encoder through a third coupling.

[0026] Furthermore, it also includes a bottom plate, the servo motor is mounted on the bottom plate through a servo motor mounting bracket, the torque sensor is mounted on the bottom plate through a carrier plate, the encoder is mounted on the bottom plate through an encoder mounting bracket, and the measured motor is mounted on the bottom plate through a measured motor bracket. The structural stability of the measuring device is improved, the reliable measurement work is ensured, and it is easy to assemble and install the measured motor.

[0027] Preferably, a connection gap is provided between two couplings of the first coupling, the second coupling or the third coupling.

[0028] Furthermore, the connection gap is arranged between the two couplings along the rotation direction of the coupling.

[0029] Preferably, the angle α of the coupling surfaces on both sides of the connection gap is equal to the step angle of the motor under test. By setting a connection gap equal to the step angle of the motor under test in one of the first coupling, the second coupling or the third coupling, when the motor under test loses step, the reverse impact force affecting the accuracy of the pull-out torque test is avoided.

[0030] After adopting the technology proposed in the present invention, according to the technical solution of the present invention, the following beneficial effects are achieved: it can quickly and continuously effectively detect the pull-out torque at the set speed and analyze the pull-out torque characteristics of the motor under test; at the same time, it can also use the deceleration time and the fixed servo torque to measure the pull-in torque at various speeds of the motor under test, which greatly improves the test efficiency. It can be used in laboratories to test multiple speed sections and accurately test the torque characteristics at more speeds, and it can also be used in production lines to test the torque characteristics at key speed sections. It has a wide range of applications, a small device size, a compact structure, and high flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural diagram of a motor torque characteristic measuring device according to an embodiment of the present application;

[0032] Figure 2 This is a schematic diagram of the connection gap structure of the third coupling of an embodiment of the present application.

[0033] Explanation of reference numerals: carrier plate 1; torque sensor 2; measured motor bracket 3; measured motor 4; servo motor 5; servo motor mounting bracket 6; base plate 7; encoder 8; encoder mounting bracket 9; first coupling 10; second coupling 11; third coupling 12; first coupling 121; second coupling 122. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the embodiments given in the accompanying drawings. The described embodiments include various specific details to help understanding, but they can only be regarded as exemplary and are part of the embodiments of the present invention, not all of the embodiments. At the same time, in order to make the description clearer and more concise, detailed descriptions of functions and structures well known in the art will be omitted.

[0035] Unless otherwise defined, technical or scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs.

[0036] The embodiment of the present application takes the detection of a stepper motor as an example. The test system sets the maximum speed Vmax to 1800 rpm and the interval speed Vgap to 50 rpm, that is, a pull-out torque is tested every 50 rpm until the maximum speed of 1800 rpm is tested and the motor decelerates and stops.

[0037] The motor torque characteristic measurement device used in the test system, such as Figure 1 As shown, it includes a servo motor 5, a torque sensor 2 and an encoder 8. The torque sensor 2 is connected to the encoder 8 and the servo motor 5 through a first coupling 10 and a second coupling 11 respectively, and the measured motor 4 is connected to the encoder 8 through a third coupling 12.

[0038] It also includes a bottom plate 7, the servo motor 5 is mounted on the bottom plate 7 through a servo motor mounting bracket 6, the torque sensor 2 is mounted on the bottom plate 7 through a carrier plate 1, the encoder 8 is mounted on the bottom plate 7 through an encoder mounting bracket 9, and the measured motor 4 is mounted on the bottom plate 7 through a measured motor bracket 3. The structural stability of the measuring device is improved, the reliable measurement work is ensured, and it is easy to assemble and install the measured motor.

[0039] A connection gap is provided between the two couplings of the first coupling 10, the second coupling 11 or the third coupling 12. By providing a connection gap equal to the step angle of the motor under test (e.g., 1.8°) in one of the first coupling 10, the second coupling 11 or the third coupling 12, when the motor under test loses step, the reverse impact force affecting the accuracy of the pull-out torque test is avoided. Figure 2 As shown, in the embodiment of the present application, the preferred arrangement on the third coupling 12 is used as an example for explanation, and the connection gap L is arranged between the first coupling 121 and the second coupling 122 along the rotation direction of the coupling, and the angle α of the coupling surfaces on both sides of the connection gap L is equal to the step angle of the motor 4 under test.

[0040] The specific method for measuring the torque characteristics of the motor under test is carried out according to the following steps.

[0041] The first step: putting the motor 4 under test into the fixture, that is, the motor bracket 3 under test, and connecting it with the third coupling 12 .

[0042] In the test system, the maximum speed Vmax and the interval speed Vgap can be set by the control program, and the speed of the motor under test can be collected in a closed loop through the encoder 8.

[0043] Step 2: Enable the motor 4 to be tested to obtain the locking force; enable the servo motor 5 to be powered to obtain the locking force. Set the torque value of the dynamic torque sensor 2 to zero.

[0044] Step 3: Make the motor 4 and the servo motor 5 rotate in the same direction (clockwise) at the same time. The servo motor runs at a speed of 48 rpm, which is less than the speed V1 of the motor 5, i.e., 50 rpm. During operation, due to the speed difference, the servo motor gradually lags behind, thus forming a dynamically increasing and continuous load.

[0045] A servo motor with strong overload capacity and large torque value is selected as the load. The speed difference of the servo motor lags behind that of the motor under test to form a dynamic continuous load. The rated torque of the servo motor is greater than the maximum torque of the motor under test to avoid loss of step or alarm due to insufficient torque of the servo motor during the test. When the motor under test loses step, it will be driven by the servo motor to quickly restore the speed, so as to achieve the effect of fast and continuous testing.

[0046] Step 4: The speed is collected in a closed loop through the encoder 8, and the torque is collected through the torque sensor 2. When the torque gradually increases to a certain extreme value (Nmax1), the motor 4 under test loses step. The test system collects the maximum torque value Nmax1 of the torque sensor 2, which is the maximum pull-out torque of the motor under test at the speed V1 (50rpm).

[0047] Step 5: Adjust the speed of the servo motor and the motor under test. The running speed of the motor under test is increased by an interval speed Vgap to V2, i.e. 100rpm, based on V1.

[0048] The rotation speeds of the servo motor and the motor to be measured may be adjusted individually each time.

[0049] However, in order to achieve the effect of fast and continuous testing, the servo motor and the motor under test can be accelerated continuously. When the speed of the motor under test is V1, V2, Vn...Vmax, the maximum torque values ​​Nmax1, Nmax2, Nmaxn...Nmax of the motor under test when it loses step at this speed are collected respectively. The motor under test does not need to stop frequently during the test. When the motor under test loses step, it will be driven by the servo motor to quickly restore the speed.

[0050] The adjustment of the servo motor speed and / or the measured motor speed described in the present application includes the above two methods.

[0051] Step 6: The speed is collected in a closed loop through the encoder 8, and the torque is collected through the torque sensor 2. When the torque gradually increases to a certain extreme value (Nmax2), the motor 4 under test loses step. The test system collects the maximum torque value Nmax2 of the torque sensor 2, which is the maximum pull-out torque of the motor under test at the speed V2 (100rpm).

[0052] Step 7: Execute the above two steps repeatedly until the running speed of the motor under test reaches the preset maximum speed Vmax, i.e., 1800rpm. When the motor under test loses step, the maximum torque value Nmax at the Vmax speed is collected to obtain the maximum pull-out torque of the motor under test at the Vmax speed.

[0053] Step 8: Summarize the maximum pull-out torque of the motor under test at each set speed from V1 to Vmax to form the pull-out torque characteristic curve of the motor under test.

[0054] Step 9: When the motor under test loses step at the preset maximum speed Vmax, after obtaining the maximum pull-out torque of the motor under test at the speed Vmax, the servo motor 5 stops running and only enables the holding torque to form a fixed load greater than the torque of the motor under test. The motor under test 4 decelerates from 1800rpm to 0rpm to stop, and the maximum pull-in torque of the motor under test 4 at each speed in the range of 0-1800rpm can be measured. The maximum pull-in torque characteristic curve of the motor under test 4 can be formed in this way.

[0055] After the pull-out torque characteristic test, the pull-in torque characteristic can be measured by decelerating and stopping the vehicle, effectively utilizing the test cycle and time to achieve the purpose of fast and continuous measurement.

[0056] To ensure fast measurement, the speed relationship between the servo motor and the motor being measured can be set according to the following formula.

[0057] Formula 1: Servo motor running speed Vs = measured motor running speed Vb - speed difference Vd

[0058] Among them, the running speed Vb of the motor under test is the set value, that is, the speed V1, Vn...Vmax when collecting data.

[0059] Formula 2: Speed ​​difference Vd = 60s ÷ number of pole pairs of the motor under test ÷ T

[0060] Wherein, T is the time required to collect the maximum torque value when the motor under test loses step.

[0061] According to the motor torque characteristic measurement method and motor torque characteristic measurement device of the embodiment of the present application, the servo motor with large overload capacity and high torque is used to form a hysteresis speed difference with the stepper motor during operation as a dynamic load, so as to quickly and continuously test the pull-out torque characteristic of the stepper motor. When the maximum speed is reached, the high torque of the servo motor when it stops is used as a fixed load to quickly and continuously measure the pull-in torque characteristic of the stepper motor.

[0062] When measuring other types of motors such as brushless DC motors, DC servo motors, and brushed DC motors, the speed and power of the motor under rated load can be quickly tested as a dynamic load. There are two measurement modes to choose from: speed and power under rated load, and load and power under rated speed.

[0063] According to the motor torque characteristic measurement method and motor torque characteristic measurement device of the embodiment of the present application, the beneficial effects are: compared with the prior art, it can quickly and continuously effectively detect the pull-out torque at the set speed, and analyze the pull-out torque characteristics of the motor under test; at the same time, it can use the deceleration time and the fixed servo torque to measure the pull-in torque at each speed of the motor under test, which greatly improves the test efficiency. It can be used in laboratory settings to test multiple speed sections and accurately test the torque characteristics at more speeds, and it can also be used in production lines to test the torque characteristics at key speed sections. It has a wide range of applications, a small device size, a compact structure, and high flexibility.

Claims

1. A method for measuring motor torque characteristics, It is characterized in that The steps include: Step 1: connecting the output shaft of the motor under test and the servo motor through a coupling device; the coupling device is provided with at least one coupling, a connection gap is provided between two couplings of the coupling, and the angle of the coupling surfaces on both sides of the connection gap is equal to the step angle of the motor under test; Step 2, make the motor under test and the servo motor rotate in the same direction, and the running speed of the servo motor is less than the running speed of the motor under test, and adjust the speed of the motor under test to V1; Step 3, measuring the torque between the motor under test and the output shaft of the servo motor, and when the motor under test loses step, collecting the maximum torque value Nmax1 at the speed of V1 to obtain the maximum pull-out torque of the motor under test at the speed of V1; Step 4, adjusting the speed of the servo motor and the motor under test until the running speed of the motor under test is Vn; Step 5, measuring the torque between the motor under test and the output shaft of the servo motor, and when the motor under test loses step, collecting the maximum torque value Nmaxn at the speed Vn, to obtain the maximum pull-out torque of the motor under test at the speed Vn; Step 6, looping through steps 4 and 5 until the running speed of the motor under test reaches the preset maximum speed Vmax. When the motor under test loses step, the maximum torque value Nmax at the Vmax speed is collected to obtain the maximum pull-out torque of the motor under test at the Vmax speed.

2. A motor torque characteristic measurement method according to claim 1, It is characterized in that After obtaining the maximum pull-out torque of the motor under test at the Vmax speed, the maximum pull-out torque of the motor under test at each set speed from V1 to Vmax is summarized to form a pull-out torque characteristic curve of the motor under test.

3. A motor torque characteristic measurement method according to claim 1, It is characterized in that Before executing step 2, the motor under test and the servo motor are powered on to obtain locking force.

4. A motor torque characteristic measurement method according to claim 1, It is characterized in that The rated torque of the servo motor is greater than the maximum torque of the motor being tested.

5. A motor torque characteristic measurement method according to claim 1, It is characterized in that The operating speeds of the servo motor and the motor under test are set to: Servo motor running speed Vs = measured motor running speed Vb - speed difference Vd in, The running speed Vb of the motor under test is the set value; Speed ​​difference Vd = 60s ÷ number of pole pairs of the motor being tested ÷ T in, T is the time required to collect the maximum torque value when the motor under test loses step.

6. A method for measuring motor torque characteristics according to any one of claims 1 to 5, It is characterized in that After the motor under test loses step at the preset maximum speed Vmax, the servo motor stops and maintains the torque. The motor under test decelerates from Vmax to stop, and the maximum pull-in torque of the motor under test at each set speed is measured, thereby forming the maximum pull-in torque characteristic curve of the motor under test.

7. A motor torque characteristic measuring device using the motor torque characteristic measuring method according to claim 1, It is characterized in that The invention comprises a servo motor (5), a torque sensor (2) and an encoder (8), wherein the torque sensor (2) is connected to the encoder (8) and the servo motor (5) via a first coupling (10) and a second coupling (11), respectively, and the motor (4) to be measured is connected to the encoder (8) via a third coupling (12).

8. A motor torque characteristic measuring device according to claim 7, It is characterized in that The device also comprises a base plate (7), the servo motor (5) being mounted on the base plate (7) via a servo motor mounting bracket (6), the torque sensor (2) being mounted on the base plate (7) via a carrier plate (1), the encoder (8) being mounted on the base plate (7) via an encoder mounting bracket (9), and the motor to be measured (4) being mounted on the base plate (7) via a motor to be measured bracket (3).

9. The motor torque characteristic measuring device according to claim 7, It is characterized in that A connection gap is provided between the two couplings of the first coupling (10), the second coupling (11) or the third coupling (12).

10. The motor torque characteristic measuring device according to claim 9, It is characterized in that The included angle of the coupling surfaces on both sides of the connection gap is equal to the step angle of the motor (4) being measured.

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