High-precision servo motor torque ripple test system and method

Abstract

The invention discloses a high-precision servo motor torque pulsation test system and method, and relates to the field of motor testing, the system comprises a loading test module, the loading test module comprises a dynamometer, a torque rotating speed sensor, a coupler, an adapter shaft and an index plate; a rotor of a to-be-tested motor is connected with one end of the index plate, the other end of the index plate is sequentially connected with the adapter shaft, the coupler and the torque and rotating speed sensor, and the other end of the torque and rotating speed sensor is connected to the output end of the dynamometer. The dynamometer is used for applying a reverse torque to the rotor of the motor to be tested. The defects of a dynamic torque pulsation measurement method are overcome, high-precision measurement of the torque pulsation of the servo motor is achieved, and the high-precision requirements of the high-precision servo motor for the positioning precision and the output torque are met.

Description

Technical Field

[0001] The invention relates to a motor testing system, and in particular to a motor torque pulsation testing system and method. Background Art

[0002] High-precision servo motors have high requirements for positioning accuracy and torque accuracy. Conventional torque pulsation test methods cannot meet the requirements. The present invention proposes a new type of high-precision static torque pulsation test system. The test system adopts a static test method and can test the precise torque pulsation of the motor.

[0003] Conventional torque pulsation testing uses a PWM wave servo drive to run the motor at the lowest speed, and uses a dynamometer to measure and record the output torque of the motor for one rotation. The maximum and minimum torques are found to obtain the torque pulsation value of the motor. The traditional dynamic torque measurement method uses a control driver that outputs PWM waves. The output PWM wave has a large harmonic content, which will cause load changes and cause harmonic pulsation in the motor.

[0004] During the conventional torque pulsation dynamic measurement process, the motor speed is not completely controlled at a fixed value, and there are slight speed fluctuations. That is, during the measurement process, the motor rotor has slight acceleration and deceleration, and the torque causing acceleration and deceleration also affects the accuracy of torque measurement.

[0005] Conventional torque pulsation measurement methods rely on the output accuracy of a dynamometer or other loading equipment, resulting in the inability to eliminate torque pulsation caused by dynamometer accuracy errors in the measurement data.

[0006] The measuring device introduced in the article "A device for measuring motor torque pulsation" (CN206671497U) can realize the torque pulsation measurement during the operation of the motor. It is a dynamic torque pulsation measurement method. It cannot overcome the accuracy error caused by the large harmonic content of the control drive output PWM wave and the torque fluctuation of the dynamometer, and cannot meet the high-precision servo motor torque pulsation test requirements.

[0007] The patent "A novel method for detecting torque pulsation of switched reluctance motor" (CN110864831A) introduces the relationship between the torque and speed change rate of the switched reluctance motor, and uses frequency-voltage conversion technology to convert the pulse signal reflecting the instantaneous speed of the motor into a frequency-voltage conversion. After conversion to the host computer, the collected data is programmed to display the torque pulsation. This invention uses a PMW control driver, and the output PWM wave contains a large number of harmonics in addition to the fundamental wave, which can cause torque fluctuations. At the same time, this invention cannot overcome the accuracy error caused by the dynamometer accuracy, and cannot meet the needs of high-precision servo motor torque pulsation testing.

[0008] The torque pulsation value measured by the traditional torque pulsation measurement method has a large error and cannot meet the test requirements of the torque pulsation of high-precision servo motors. Summary of the invention

[0009] The technical problem solved by the present application is: to overcome the deficiencies of the prior art, to provide a high-precision servo motor torque pulsation test system, to overcome the deficiencies of the dynamic torque pulsation measurement method, to achieve high-precision measurement of the torque pulsation of the servo motor, and to meet the high-precision requirements of the servo motor for positioning accuracy and output torque.

[0010] The technical solutions provided by this application are as follows:

[0011] A high-precision servo motor torque pulsation test system includes a loading test module, the loading test module includes a dynamometer, a torque and speed sensor, a coupling, a transfer shaft and a dividing plate;

[0012] The rotor of the motor to be tested is connected to one end of the indexing plate, the other end of the indexing plate is connected to the adapter shaft, the coupling and the torque and speed sensor in sequence, and the other end of the torque and speed sensor is connected to the output end of the dynamometer;

[0013] The dynamometer is used to apply a reverse torque to the rotor of the motor to be tested.

[0014] It also includes a control drive module, which includes a host computer and a sine wave driver; the host computer collects data of the motor to be tested for calculation, and outputs a current signal to the motor to be tested through a high-precision sine wave driver.

[0015] The sine wave driver envelope controller and three power amplifier circuits are respectively Uu, Uv and Uw, the power amplifier circuits are respectively connected to the positive power supply and the negative power supply, the signal input end of the power amplifier circuit is connected to the controller, the output end of the power amplifier circuit is connected to the input end of the motor to be tested, and outputs Iu, Iv and Iw current signals to the motor to be tested.

[0016] It also includes a measurement and control module, which includes data acquisition, an industrial control computer and a dynamometer loading controller. The data acquisition collects the output signal of the torque and speed sensor and transmits it to the industrial control computer for calculation and outputs the signal to the dynamometer loader. The dynamometer loader loads the dynamometer according to the signal output by the industrial control computer.

[0017] A dividing plate stand is arranged outside the dividing plate, the dividing plate stand is fixedly connected to the installation table, a scale line is arranged at one end of the dividing plate stand, and the dividing plate is rotatably connected to the dividing plate stand.

[0018] A high-precision servo motor torque pulsation test method, using any of the above-mentioned high-precision servo motor torque pulsation test systems for measurement, comprising:

[0019] S1: Use a sine wave driver to input three-phase current to the motor to be tested, so that the motor to be tested runs at a low speed not exceeding 100r / min;

[0020] S2: The dynamometer starts to output torque from no-load, and the dynamometer loading controller controls the dynamometer to gradually increase the output torque until the speed of the motor to be tested drops to 0; the output torque of the dynamometer is further increased to be greater than the output torque of the motor to be tested. When the rotor of the motor to be tested is stationary, that is, when the speed displayed by the dynamometer loading controller is 0, the real-time position signal transmitted by the rotor position sensor of the motor to be tested received by the host computer and the torque output value displayed on the dynamometer loading controller fed back by the torque speed sensor are recorded;

[0021] S3: Turn the dividing plate to change the rotor position of the motor to be tested, so that the rotor of the motor to be tested rotates one scale, while the rotor of the motor to be tested remains stationary; the sine wave driver adjusts the three-phase current values ​​of the input motor according to the rotor position through the current closed loop, and the loading controller 3-3 controls the loading torque of the dynamometer to be consistent with S2, and records the torque output value of the rotor of the motor to be tested at this scale;

[0022] S4: Repeat S3, taking one rotation of the motor to be tested as one torque pulsation cycle, and obtaining multiple torque output values ​​within one torque pulsation cycle; the torque output values ​​of multiple torque pulsation cycles can be obtained repeatedly; according to the torque output values, the output torque values ​​corresponding to the absolute positions of the motor to be tested rotor at different positions are obtained, so as to draw a torque curve and obtain the maximum value T of the output torque of the motor to be tested when it rotates one circle max and the minimum value T min , according to the maximum value T of the output torque of the motor to be tested when it rotates one circle max and the minimum value T min , calculate the torque pulsation coefficient K Tb .

[0023] The torque ripple coefficient K Tb =K Tb =(T max -T min ) / (T max +T min ).

[0024] The number of poles of the motor to be tested is 2p, the number of slots is Z, the least common multiple of the number of poles and the number of slots is N=[2p,Z], the number of torque fluctuations when the rotor of the motor to be tested rotates one circle is N, and the number of sampling points in each torque fluctuation cycle is not less than 5.

[0025] The main innovative features of the present invention are as follows:

[0026] (1) The present invention is based on a sine wave control driver to drive a motor test. The sine wave control driver control module generates a sine wave current of a specific frequency and then passes it into a drive module. The drive module amplifies the current through a linear amplifier circuit, outputs a sine wave current, and passes it into the motor, thereby outputting a corresponding torque.

[0027] (2) The sine wave control driver used in the present invention is different from the PWM wave control driver. The driving module used by the conventional PWM wave control driver is an IGBT, MOS tube or SiC device, all of which realize PWM output through high switching frequency. The driving module of the sine wave control driver adopts a linear amplifier circuit, and the output current is an ideal sine wave.

[0028] (3) The driving module of the sine wave control driver in the present invention adopts a linear amplifier circuit to achieve high current output through multi-channel parallel connection.

[0029] (4) In the present invention, the dynamometer loading torque is set to 1.5 times the output torque of the motor to achieve motor stalling, and the torque sensor records the output torque of the motor in the stalled state. The motor rotor position is adjusted by manually rotating the indexing plate, and the output torque at different positions is recorded. The torque error of the dynamometer does not affect the value recorded by the torque sensor.

[0030] (5) In the present invention, when testing torque pulsation, the motor speed is 0, there is no acceleration and deceleration torque caused by speed fluctuation, and the measurement accuracy is more accurate.

[0031] (6) The dividing plate in the present invention is used to accurately locate the rotation position during the measurement process. Different scales are engraved on the dividing plate, and the highest scale accuracy can be set to 0.2°.

[0032] (7) The torque measurement accuracy of the present invention avoids the influence of the dynamometer and the control driver. When the output torque of the motor is in the range of 0-20Nm, the test accuracy is less than 0.005Nm; when it is 20-100Nm, the test error is less than 0.01Nm.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] (1) The present invention adopts a sine wave driver to drive the servo motor to operate, and an ideal sinusoidal three-phase current is passed into the motor. The torque output by the motor is the output torque corresponding to the sine wave.

[0035] (2) The mechanism of the present invention adopts a static measurement method to avoid torque changes caused by speed fluctuations, and the measurement accuracy is more precise.

[0036] (3) In the present invention, the loading torque of the dynamometer is greater than the motor output torque, and the motor output torque value avoids the error range of the dynamometer, thereby avoiding the motor rotation pulsation caused by the dynamometer's own error.

[0037] (4) The indexing plate of the present invention can accurately control the rotation position and realize accurate positioning of the rotor position, with the highest positioning accuracy reaching 0.2°. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a mechanism structure diagram in an embodiment of the present invention;

[0039] Figure 2 It is a principle diagram in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of a sine wave driver according to an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of a dividing plate according to an embodiment of the present invention;

[0042] Figure 5 Flow chart for implementing the present invention. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0044] The present application embodiment discloses a high-precision servo motor torque pulsation test system. Figure 1 As shown, Figure 1 It is a structural composition diagram of an embodiment of the present invention, including a control drive module 2, a loading test module 1 and a measurement and control module 3.

[0045] Figure 2 The schematic diagram of the embodiment of the present invention shows that the loading test module 1 includes a dynamometer 1-1, a torque and speed sensor 1-2, a coupling 1-3, an adapter shaft 1-4, a dividing plate 1-5 and a motor to be tested 1-6. The dynamometer 1-1 is connected to the torque and speed sensor 1-2, the coupling 1-3 is connected to the torque and speed sensor 1-2 and the adapter shaft 1-4, and the adapter shaft 1-4 is connected to the dividing plate 1-5 and the rotor of the motor to be tested 1-6. The control drive module 2 includes a host computer 2-1 and a high-precision sine wave driver 2-2; the host computer 2-1 collects data from the motor to be tested 1-6 for calculation, and outputs a current signal through the high-precision sine wave driver 2-2. The measurement and control module 3 includes a data acquisition 3-1, an industrial control computer 3-2 and a dynamometer loading controller 3-3. The data acquisition 3-1 collects electrical signals such as current and voltage and mechanical models such as speed and torque from the torque and speed sensor 1-2, and transmits them to the industrial control computer 3-2 for calculation and outputs signals to the dynamometer loader 3-3. The dynamometer loader 3-3 loads torque on the dynamometer 1-1 according to the signals output by the industrial control computer 3-2.

[0046] Figure 3Schematic diagram of a sine wave control driver in an embodiment of the present invention. The sine wave control driver 2-2 includes an envelope controller and three power amplifier circuits, namely Uu, Uv, and Uw. The power amplifier circuits are connected to the positive power supply and the negative power supply, respectively. The signal input end of the power amplifier circuit is connected to the controller, and the output end of the power amplifier circuit is connected to the input end of the motor to be tested 1-6, and outputs Iu, Iv, and Iw current signals to the motor to be tested 1-6 respectively.

[0047] Figure 4 The schematic diagram of the dividing plate and the dividing plate stand in the present invention. The dividing plate in the present invention has an outer diameter of Φ40mm and an axial length of 60mm. It is a solid cylindrical structure with a scale on the end face. The dividing plates 1-5 are coaxially connected to the connecting shaft 1-4 and the motor to be tested 1-6 respectively. The dividing plate stand has a thickness of 10mm and an inner diameter of Φ45mm. There are 720 points engraved on the circumference near the inner diameter of the dividing plate. Each 0.5 degree is set as a scale, and a numerical point is set every 60 points. The first numerical point is marked as 60, the second numerical point is marked as 120, and so on.

[0048] During measurement, the hysteresis dynamometer 1-1 provides the stall torque of the motor. When the torque value set by the hysteresis dynamometer 1-1 is greater than the motor output torque, the motor is in a stalled state. When the motor rotor is stationary, the position sensor signal value of the real-time position of the test motor 1-6 rotor and the detection value of the torque sensor 1-2 are recorded, which is the torque value of the test motor 1-6 at this time. There are 720 values ​​on the corresponding scale of the dividing disk 1-5. By rotating the torque disk 1-5 by one value, the torque value measurement under the scale can be completed. Similarly, after completing 720 measurements in one circle, the maximum value of the output torque of the motor after one rotation is T max The minimum output torque per rotation is T min , the absolute value of the torque ripple is T b =T max -T min , the torque ripple coefficient formula is

[0049] K Tb =(T max -T min ) / (T max +T min ) (1)

[0050] The torque ripple test is now completed.

[0051] Figure 5 The following is a diagram of the implementation process of the present invention, and the specific implementation method is as follows:

[0052] (1) After the components of the device are connected, a high-precision sinusoidal wave driver 2-2 is used to input three-phase current to the motor 1-6 to be tested, and the motor runs at a low speed.

[0053] (2) The output torque of the hysteresis dynamometer 1-1 starts from no-load, and the dynamometer loading controller 3-3 controls the dynamometer 1-1 to increase the output torque until the speed of the test motor 1-6 drops to 0, and this value can be observed by the loading controller 3-3. The output torque of the hysteresis dynamometer 1-1 is further increased to be greater than the output torque of the test motor 1-6. Preferably, the output torque can be set to 1.5 times the output torque of the test motor 1-6 in the loading controller 3-3 of the hysteresis dynamometer 1-1. When the rotor of the test motor 1-6 is stationary, that is, when the speed displayed by the loading controller 3-3 is 0, the real-time position signal transmitted by the rotor position sensor received by the host computer 2-1 and the detection value displayed on the dynamometer loading controller 3-3 fed back by the torque and speed sensor 1-2 are recorded.

[0054] (3) By turning the indexing plate 1-5, the rotor position of the motor to be tested 1-6 is changed, so that the rotor of the motor to be tested 1-6 rotates one scale, while the rotor of the motor to be tested 1-6 remains stationary. The sine wave control driver 2-2 adjusts the three-phase current values ​​of the input motor according to the rotor position through a current closed loop, and the loading controller 3-3 controls the loading torque of the hysteresis dynamometer 1-1 to be consistent with (2), and records the torque output value of the rotor at this scale, that is, the value displayed by the torque speed sensor 1-2.

[0055] Repeat step (3) to collect 720 data for each mechanical cycle. Generally, 20 to 30 measurements can be made to complete the test of two torque pulsation cycles. The number of tests can be appropriately increased according to demand to test more torque fluctuation cycle values.

[0056] The output torque values ​​corresponding to the absolute positions of the rotors at different positions are obtained through the data points recorded by the host computer, so as to draw the torque curve, obtain the average value, maximum value and minimum value of the torque, and calculate according to formula (1) to obtain the precise torque fluctuation value of the motors 1-6 to be tested. The torque pulsation curve of the test motors 1-6 under the torque can also be obtained.

[0057] The number of repeated measurements in the present invention can preferably be performed according to the following formula: the number of motor poles is 2p, the number of slots is Z, the least common multiple of the number of poles and the number of slots is N=[2p, Z], the number of torque fluctuations when the rotor rotates one circle is [2p, Z], the number of sampling points for each torque fluctuation cycle should not be less than 5, the more sampling points, the more cycles can be collected, and it also brings inconvenience to the motor test. It is preferred to set the number of sampling points for each torque fluctuation cycle to 10, so the number of tests for one rotation of the motor is 10*N, that is, the total number of scales of the dividing plate is 10*N. Taking an 8-pole 9-slot motor as an example, the least common multiple of the number of poles and the number of slots is 72, the number of torque fluctuation cycles is 72, and the number of points for each torque fluctuation cycle is set to 10, so the number of scales of the dividing plate is 720, and the minimum scale accuracy is 0.2°.

[0058] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0059] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A high-precision servo motor torque ripple test system, characterized by: The invention comprises a loading test module (1), wherein the loading test module (1) comprises a dynamometer (1-1), a torque and speed sensor (1-2), a coupling (1-3), a transfer shaft (1-4) and a dividing plate (1-5); The rotor of the motor to be tested (1-6) is connected to one end of the indexing plate (1-5), the other end of the indexing plate (1-5) is sequentially connected to the adapter shaft (1-4), the coupling (1-3) and the torque and speed sensor (1-2), and the other end of the torque and speed sensor (1-2) is connected to the output end of the dynamometer; The dynamometer (1-1) is used to apply a reverse torque to the rotor of the motor (1-6) to be tested.

2. A high-precision servo motor torque ripple test system according to claim 1, characterized in that: The invention also comprises a control drive module (2), wherein the control drive module (2) comprises a host computer (2-1) and a sine wave driver (2-2); the host computer (2-1) collects data of the motor to be tested (1-6) for calculation, and outputs a current signal to the motor to be tested (1-6) through the sine wave driver (2-2).

3. A high-precision servo motor torque ripple test system according to claim 2, characterized in that: The sine wave driver (2-2) comprises an envelope controller and three power amplifier circuits, namely Uu, Uv and Uw, the power amplifier circuits being connected to a positive power source and a negative power source respectively, the signal input end of the power amplifier circuit being connected to the controller, the output end of the power amplifier circuit being connected to the input end of the motor to be tested (1-6), and outputting Iu, Iv and Iw current signals to the motor to be tested (1-6).

4. A high-precision servo motor torque ripple test system according to claim 1, characterized in that: The invention also comprises a measurement and control module (3), wherein the measurement and control module (3) comprises a data acquisition module (3-1), an industrial control computer (3-2) and a dynamometer loading controller (3-3). The data acquisition module (3-1) acquires an output signal of a torque and speed sensor (1-2), transmits the signal to the industrial control computer (3-2), performs calculations and outputs a signal to the dynamometer loading controller (3-3). The dynamometer loading controller (3-3) loads the dynamometer (1-1) according to the signal output by the industrial control computer (3-2).

5. The high-precision servo motor torque ripple test system according to claim 1, characterized in that: A dividing plate stand is arranged outside the dividing plate (1-5), the dividing plate stand is fixedly connected to the installation table, a scale line is arranged at one end of the dividing plate stand, and the dividing plate (1-5) is rotatably connected to the dividing plate stand.

6. A high-precision servo motor torque pulsation test method, characterized in that: The high-precision servo motor torque ripple test system according to any one of claims 1 to 5 is used for measurement, comprising: S1: using a sine wave driver (2-2) to input a three-phase current to the motor to be tested (1-6), so that the motor to be tested (1-6) runs at a low speed not exceeding 100r / min; S2: the dynamometer (1-1) starts to output torque from no-load, and the dynamometer loading controller (3-3) controls the dynamometer (1-1) to gradually increase the output torque until the rotation speed of the motor to be tested (1-6) drops to 0; the output torque of the dynamometer (1-1) is further increased to be greater than the output torque of the motor to be tested (1-6), and when the rotor of the motor to be tested (1-6) is stationary, that is, when the rotation speed displayed by the dynamometer loading controller (3-3) is 0, the real-time position signal transmitted by the rotor position sensor included in the motor to be tested (1-6) received by the upper computer (2-1) and the torque output value displayed on the dynamometer loading controller (3-3) fed back by the torque speed sensor (1-2); S3: the indexing plate (1-5) is turned to change the rotor position of the motor to be tested (1-6), so that the rotor of the motor to be tested (1-6) rotates one scale, while the rotor of the motor to be tested (1-6) remains stationary; the sine wave driver (2-2) adjusts the three-phase current values ​​of the input motor according to the rotor position through a current closed loop, and the loading controller 3-3 controls the loading torque of the dynamometer (1-1) to be consistent with that in S2, and records the torque output value of the rotor of the motor to be tested (1-6) at this scale; S4: Repeat S3, taking one rotation of the rotor of the motor to be tested (1-6) as one torque pulsation cycle, and obtaining multiple torque output values ​​within one torque pulsation cycle; the torque output values ​​of multiple torque pulsation cycles can be obtained repeatedly; according to the torque output values, the output torque values ​​corresponding to the absolute positions of the rotors of the motors to be tested (1-6) at different positions are obtained, thereby drawing a torque curve, and obtaining the maximum value T of the output torque of the motor to be tested (1-6) when it rotates one circle max and minimum value T min , according to the maximum value T of the output torque of the motor (1-6) to be tested after one rotation max and minimum value T min , calculate the torque pulsation coefficient K Tb .

7. The testing method according to claim 6, characterized in that: The torque ripple coefficient K Tb =K Tb =(T max -T min ) / (T max +T min ).

8. The testing method according to claim 6, characterized in that: The number of poles of the motor to be tested (1-6) is 2p, the number of slots is Z, the lowest common multiple of the number of poles and the number of slots is N=[2p, Z], the number of torque fluctuations when the rotor of the motor to be tested (1-6) rotates one circle is N, and the number of sampling points in each torque fluctuation cycle is not less than 5.

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