Instantaneous rotating speed real-time compensation method of motor test bench

Abstract

The invention discloses an instantaneous rotating speed real-time compensation method for a motor test board, which comprises the following steps of: firstly, carrying out self-inspection on equipment, then testing by using a qualified motor, judging the reasonability of an error, then carrying out measured value compensation on a component, continuously carrying out rotating speed test on the compensated test board, and carrying out real-time compensation on the instantaneous rotating speed on the basis of a secondary test result. The angle error represented by the number of teeth of the fluted disc is reasonably compensated, real equipment to be tested is tested, and whether the equipment to be tested is qualified or not is judged. According to the invention, through the core idea of variable control, a qualified motor is taken as a test object, numerical compensation is carried out on components of a test bench, the main compensation is the influence brought by the instrument reaction time difference, and then the compensation amount of the fluted disc angle is derived according to the compensated numerical value. The influence on errors caused by oscillation and distortion generated in the processes of a fluted disc structure on a motor shaft, installation conditions and rotation is eliminated, the finally measured instantaneous rotating speed of the motor is compared with a product standard requirement to judge whether the instantaneous rotating speed is qualified or not, and the result is more scientific and accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of motor test benches, and more particularly to a real-time compensation method for instantaneous rotation speed of a motor test bench. Background Art

[0002] For induction motors, determining their starting characteristics requires measuring the instantaneous speed, from which acceleration and torque can be calculated. For induction motors equipped with a centrifugal switch, the instantaneous speed, once the motor is spinning and the switch is open, must be measured to determine the motor's compliance. Measuring the motor's instantaneous speed is crucial, but because the speed changes rapidly during startup and other transient processes, conventional test benches are unable to measure this. Advances in computer technology have overcome this challenge by adding microcontrollers, DSPs, and optical sensors to test benches.

[0003] Instantaneous speed measurement is primarily achieved using photoelectric or magnetoelectric sensors. Specifically, a uniformly distributed toothed disc is coaxially connected to the motor, or the motor itself is used to drive the toothed disc, ensuring synchronous rotation. The photoelectric or magnetoelectric sensor generates a signal that, after passing through a photoresistor, generates an electrical pulse. This pulse is fed into a counter, which records the pulse intervals. The instantaneous speed of the motor can be calculated using pulse counting. The main methods for measuring speed based on pulse counting include the M method (frequency measurement), the T method (period measurement), and the M / T method.

[0004] The basic principle of the M method is that within a certain measurement time Tg, the number of pulses generated by the speed pulser is m1, then the motor speed should be

[0005]

[0006] Where n is the motor speed (r / min), and M is the number of pulses generated by the pulse generator when the motor rotates one circle, that is, the number of gears on the gear disk.

[0007] The basic principle of the T method is to use a pulse width TP generated by a pulse generator to determine the motor speed, which can be expressed by the number of clock pulses m2. The motor speed should be

[0008]

[0009] Where fc represents the reference clock pulse frequency generated by the hardware device.

[0010] M / T method combines the above two methods. The motor speed can be determined by measuring the number of pulses m1 and clock pulses m2 in the same time T. T is equal to Tg plus ΔT, so the motor speed should be

[0011]

[0012] Among the three speed measurement methods mentioned above, in terms of measurement accuracy, the T method has higher accuracy at low speeds, but the accuracy deteriorates as the speed increases; the M method is the opposite, with higher accuracy at high speeds; the M / T method combines the advantages of both methods, with higher resolution in the entire speed range and accuracy between the two.

[0013] However, due to the actual error in the detection time and the error in the installation angle caused by the gear structure and installation condition of the motor shaft during the test installation process, both of these directly lead to inaccurate detection of the instantaneous speed, that is, the measurement of the instantaneous speed has errors, which ultimately leads to misjudgment of whether the motor is qualified. Summary of the Invention

[0014] In view of the deficiencies in the prior art, the present invention aims to provide a real-time compensation method for instantaneous speed of a motor test bench to solve one or more of the above problems.

[0015] To achieve the above object, the present invention provides the following technical solutions:

[0016] The instantaneous speed real-time compensation method of the motor test bench is as follows:

[0017] S1. After the test bench passes the self-test, it is started and the test motor is installed to perform component compensation test;

[0018] S2. Start the test motor and measure the frequency according to the M method in the set low-speed range to determine whether the error is reasonable;

[0019] S3. According to the error rationality judgment in step S2, if the error is unreasonable, the component measurement value compensation is performed;

[0020] If the error is within a reasonable range, skip the current step;

[0021] S4. After the component measurement and compensation in step S3 or by directly skipping step S3, quantify the test time and re-measure the frequency in the low-speed range according to the M method to obtain different values ​​of the same variable parameter at the output end and the test end. The difference between the two values ​​is the relative error;

[0022] S5. Calculate and obtain a final angle compensation coefficient based on the relative error obtained in step S4;

[0023] S6. Replace the test motor with the motor to be tested, retain the component measurement compensation in step S3 or do not need to compensate the component measurement values, calculate the speed calculation formula according to the M method, M / T method, and T method frequency measurement in the low-speed range, medium-speed range, and high-speed range of the motor to be tested, and calculate the instantaneous speed of the motor to be tested in combination with the angle compensation coefficient, and determine whether the motor to be tested is qualified according to the product standard.

[0024] Furthermore, in step S1, self-test is mainly performed on two components of the test bench, namely the pulse generator and the high-precision timer, to ensure that the test bench is level and has reasonable jitter.

[0025] Furthermore, in step S2, data is collected and tested randomly according to different values ​​in the low-speed range, a single variable is controlled, the values ​​of other variables corresponding to the output end and the test end are obtained and the difference is calculated, and whether the error is reasonable is determined according to the corresponding error standard q.

[0026] Furthermore, in step 2, the frequency is measured in the low-speed range according to the M method, based on the formula

[0027]

[0028] Among them, n1 is the speed of the test motor in the low speed range, T1 is the test time, m1 is the number of pulses generated by the pulse generator during this time period, and M is the number of pulses generated by the pulse generator when the motor rotates one circle.

[0029] During the test of step S2, the test time T1 is an abnormal variable that cannot be directly analyzed, and the controllable analysis variables are the motor speed n1 and the number of pulses m1 generated by the pulse generator;

[0030] For the two controllable analysis variables mentioned above, P1 experiments are performed in each of step S2.1 and step S2.2.

[0031] Furthermore, in step S2.1, the test time T1 and the motor speed n1 are controlled to remain unchanged, and the pulse generator corresponding to the output end generates the pulse number m1.1 according to the formula. The pulse generator of the test bench itself feeds back the pulse number m1.2 generated by the pulse generator corresponding to the test end, and the difference between m1.1 and m1.2 is calculated. At this time, the error standard q1 is ±1. If more than half of the cases exceed the error standard q1, the error is judged to be unreasonable. If half or less of the cases exceed the error standard q1, the error is judged to be reasonable.

[0032] Furthermore, in step S2.2, the test time T1 is controlled to remain unchanged, the value m1 of the fixed pulse generator is set within a reasonable speed range, the motor speed n1.1 corresponding to the test end is calculated, the actual speed of the motor is read, that is, the speed n1.2 corresponding to the output end, and the difference between n1.1 and n1.2 is calculated. At this time, the error mark q2 is 14. If more than half of the cases exceed the error standard q1, the error is judged to be unreasonable. If half or less of the cases exceed the error standard q1, the error is judged to be reasonable.

[0033] Furthermore, in step S3, if the error is judged to be reasonable, no intervention is performed;

[0034] To determine if the error is unreasonable, the compensation coefficient μ1 of the pulse generator m1 is calculated based on the speed of the test motor, that is, the speed of the output end. The derivation formula is as follows:

[0035]

[0036] Among them, the ratio of n1.1 to n1.2 and the ratio of m1.1 to m1.2 are the average values ​​of P1 trials;

[0037] The formula for calculating the motor speed after component measurement compensation is as follows:

[0038]

[0039] Among them, n2 is the speed of the motor in the low speed range, T2 is the test time, m2 is the reading of the pulse generator during this time period, and M is the number of pulses generated by the pulse generator when the motor rotates one circle.

[0040] Furthermore, in step S4, p2 acquisition experiments are performed, each quantitative test time T2 and the reading m2 of the test bench pulse generator is read, according to the formula

[0041]

[0042] Calculate the motor speed n2 corresponding to the test end and the motor speed reading n3 corresponding to the actual output end, and the difference between the two is the relative error.

[0043] Furthermore, in step S5, the formula for deriving the angle compensation coefficient μ2 according to the value obtained in step S4 is as follows:

[0044]

[0045] μ2 needs to be averaged based on the calculated values ​​of p2 experiments.

[0046] Furthermore, the calculations of the three test methods in step S6 are all compensated according to the following rules:

[0047] The angle compensation coefficient μ2 is added to the value of the number of pulses M generated by the pulse generator when the motor rotates one circle, and the value is taken as a multiple of 1+μ2; the value of the pulse generator reading m1 in the same time period is taken as a multiple of μ1.

[0048] In summary, the present invention has the following beneficial effects: through the core idea of ​​controlling variables, a qualified motor is used as the test object, and numerical compensation is performed on the components of the test bench. The main compensation here is for the influence of the instrument response time difference, and then the compensation amount of the gear disc angle is derived based on the compensated numerical value, and the error caused by the gear disc structure, installation conditions and vibration and distortion generated during the rotation process on the motor shaft is eliminated. Finally, the measured instantaneous speed of the motor is compared with the product standard requirements to determine whether it is qualified, and the result is more scientific and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0050] Example:

[0051] The following is combined with Figure 1 The present invention is described in further detail.

[0052] The entire algorithm for real-time instantaneous speed compensation in a motor test bench is designed based on the premise of frequency measurement using the M method in the low-speed range. Because the clock pulse m2, reference clock pulse frequency fc, and the number of pulses M generated by the pulse generator per motor revolution in the three formulas corresponding to the M method (frequency measurement), the T method (period measurement), and the M / T method are stable for the same motor without component replacement, the only factor that can be interfered with in actual testing is the number of pulses m1 generated by the pulse generator within the corresponding time period, corresponding to the M frequency measurement method in the motor's low-speed range. The motor is tested as the output terminal, and the test bench and its components as the test terminal. The output terminal serves as the primary reference, representing the actual variable value, while the test terminal serves as the secondary reference, representing the reference variable value.

[0053] like Figure 1 The specific steps are as follows:

[0054] S1. After the test bench passes the self-test, it is started and the test motor is installed to perform component compensation test;

[0055] In step S1, the pulse generator and high-precision timer of the test bench are mainly self-checked to ensure that the test bench is level and has reasonable jitter;

[0056] S2. Start the test motor, activate the algorithm, measure the frequency according to the M method in the set low-speed range, and determine whether the error is reasonable;

[0057] In step S2, in the low-speed range, random sampling and testing are performed according to different values, a single variable is controlled, and the values ​​of other variables corresponding to the output end and the test end are obtained and the difference is calculated. Based on the corresponding error standard q, whether the error is reasonable is determined;

[0058] In step 2, the frequency is measured in the low-speed range according to the M method, based on the formula

[0059]

[0060] Among them, n1 is the speed of the test motor in the low speed range, T1 is the test time, m1 is the number of pulses generated by the pulse generator during this time period, and M is the number of pulses generated by the pulse generator when the motor rotates one circle.

[0061] During the test of step S2, test time T1 is a non-normal variable that cannot be directly analyzed. That is, as a variable, changes in test time T1 will also change the pulse generator count m1. Since motor speed n1 remains unchanged, changing test time T1 has no practical significance. Therefore, the controllable analysis variables throughout the process are motor speed n1 and pulse count m1 generated by the pulse generator. For these two controllable analysis variables, P1 experiments are conducted in each of steps S2.1 and S2.2. These two conditions are parallel, not selective.

[0062] Step S2.1: Keep the test time T1 and motor speed n1 constant. Calculate the number of pulses m1.1 generated by the pulse generator corresponding to the output terminal according to the formula. The pulse generator on the test bench itself feeds back the number of pulses m1.2 generated by the pulse generator corresponding to the test terminal. Calculate the difference between m1.1 and m1.2. The error standard q1 is ±1.

[0063] If more than half of the cases in the p experiments exceed the error standard q1, the error is judged to be unreasonable;

[0064] If half or less of the cases exceed the error standard q1, the error is judged to be reasonable;

[0065] Step S2.2: Control the test time T1 unchanged, set the pulse generator value m1 within a reasonable speed range, calculate the motor speed n1.1 corresponding to the test end, read the actual motor speed, that is, the speed n1.2 corresponding to the output end, and calculate the difference between n1.1 and n1.2. At this time, the error mark q2 is 14;

[0066] If more than half of the cases in the p experiments exceed the error standard q2, the error is judged to be unreasonable;

[0067] If half or less of the cases exceed the error standard q2, the error is judged to be reasonable;

[0068] S3. Based on the error rationality judgment in step S2, if one or all of the errors are unreasonable, then perform component measurement compensation;

[0069] Based on the speed of the test motor, that is, the speed of the output end, calculate the compensation coefficient μ1 of the pulse generator m1. Theoretically,

[0070]

[0071] Based on the reliability analysis of the data set, the error factors of the two ratios are different, and it is difficult to achieve complete equivalence. Therefore, the average of the pan-dataset is the best, and the derivation formula is as follows:

[0072]

[0073] Among them, the ratio of n1.1 to n1.2 and the ratio of m1.1 to m1.2 are the average values ​​of P1 trials;

[0074] The formula for calculating the motor speed after component measurement compensation is as follows:

[0075]

[0076] Where n2 is the speed of the motor in the low speed range, T2 is the test time, m2 is the reading of the pulse generator during this time period, and M is the number of pulses generated by the pulse generator when the motor rotates one circle;

[0077] If the error is within a reasonable range, skip the current step without any intervention;

[0078] S4. After the component measurement and compensation in step S3 or by directly skipping step S3, quantify the test time and re-measure the frequency in the low-speed range according to the M method to obtain different values ​​of the same variable parameter at the output end and the test end. The difference between the two values ​​is the relative error;

[0079] In step S4, p2 acquisition experiments are performed, each quantitative test time is T2 and the reading m2 of the test bench pulse generator is read. According to the formula

[0080]

[0081] Calculate the motor speed n2 corresponding to the test end and the motor speed reading n3 corresponding to the actual output end. The difference between the two is the relative error.

[0082] S5. Calculate and obtain a final angle compensation coefficient based on the relative error obtained in step S4;

[0083] n2 represents the theoretical value, n3 represents the actual value. The angle error should be calculated based on the incremental algorithm rather than the multiplication algorithm. Therefore, n3 should be the value of the additional compensation coefficient based on 1, that is, the angle compensation coefficient should be (1+μ2)×n2=n3.

[0084] In step S5, the formula for deriving the angle compensation coefficient μ2 based on the value obtained in step S4 is as follows:

[0085]

[0086] μ2 needs to be averaged based on the calculated values ​​of p2 experiments;

[0087] S6. Replace the test motor with the motor to be tested, retain the component measurement compensation in step S3 or do not need to compensate the component measurement value, and calculate the speed calculation formula of the frequency measurement according to the M method, M / T method, and T method in the low-speed interval, medium-speed interval, and high-speed interval of the motor to be tested, and calculate the instantaneous speed of the motor to be tested in combination with the angle compensation coefficient, and judge whether the motor to be tested is qualified according to the product standard;

[0088] The calculations of the three test methods in step S6 are all compensated according to the following rules:

[0089] The angle compensation coefficient μ2 is added to the value of the number of pulses M generated by the pulse generator when the motor rotates one circle, and the value is taken as a multiple of 1+μ2; the value of the pulse generator reading m1 in the same time period is taken as a multiple of μ1.

[0090] In summary, the frequency is measured in the low-speed range according to the M method, and the motor speed calculation formula is:

[0091]

[0092] Where n is the motor speed (r / min), M is the number of pulses generated by the pulse generator per motor revolution, that is, the number of gears on the geared disc, Tg is the measurement time, and m1 is the number of pulses generated by the speed pulse generator during this time period.

[0093] The medium speed range is tested according to the M / T method, and the motor speed calculation formula is:

[0094]

[0095] Where n is the motor speed (r / min), M is the number of pulses generated by the pulse generator per motor revolution, that is, the number of gears on the geared disc, m1 is the number of pulses generated by the speed pulser per unit time period, fc represents the reference clock pulse frequency generated by the hardware device, and m2 is actually the pulse width Tp, which can be expressed in terms of the number of clock pulses.

[0096] The high-speed range is tested according to the M method, and the motor speed calculation formula is:

[0097]

[0098] Where n is the motor speed (r / min), M is the number of pulses generated by the pulse generator when the motor rotates one circle, that is, the number of gears on the gear wheel, fc represents the reference clock pulse frequency generated by the hardware device, and m2 is actually the pulse width Tp, which can be expressed in the number of clock pulses.

[0099] According to the time relative error calculation formula,

[0100]

[0101] Among them, dK is the calculation error, which is generally set to ±1, τ is the time scale signal period corresponding to the pulse transmitter, and K is the pulse count. The error can be reduced by increasing the number of gears on the gear wheel.

[0102] The test formula for the motor speed can be deduced by hypothetically reversing the number of pulses generated by the pulse generator within the measurement time to the motor rotation angle α within the time period. The formula is as follows:

[0103]

[0104] It can be seen that when the motor rotation angle is sufficiently small within the specified time, the calculated speed can be considered the motor's instantaneous speed. Furthermore, due to inconsistent gear spacing caused by process precision during the sprocket manufacturing process, errors in the rotation angle occur. Too dense a gear count and machining difficulties will amplify this error. In specific applications, the optimal number of gears should be selected based on a comprehensive analysis of the speed. As the motor's rotation speed and oscillation amplitude increase, this error also increases. Under strong distortion, measurement accuracy is difficult to guarantee. Therefore, the number of gears on the sprocket cannot be too large. Therefore, interference cannot be determined solely based on the number of gears on the sprocket. Secondary compensation is required to compensate for the time error caused by equipment response time and the angular error caused by sprocket installation. The instantaneous speed calculated based on the pulse generator reading, the number of sprocket teeth, and the relevant compensation coefficients is more closely aligned with the actual motor output and can more accurately determine whether the motor is qualified.

[0105] It should be noted that this specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A real-time compensation method for instantaneous speed of a motor test bench, characterized by: The steps are as follows, S1. After the test bench passes the self-test, it is started and the test motor is installed to perform component compensation test; S2. Start the test motor and measure the frequency according to the M method in the set low-speed range to determine whether the error is reasonable; S3. According to the error rationality judgment in step S2, if the error is unreasonable, the component measurement value compensation is performed; If the error is within a reasonable range, skip the current step; S4. After the component measurement and compensation in step S3 or by directly skipping step S3, quantify the test time and re-measure the frequency in the low-speed range according to the M method to obtain different values ​​of the same variable parameter at the output end and the test end. The difference between the two values ​​is the relative error; S5. Calculate and obtain a final angle compensation coefficient based on the relative error obtained in step S4; S6. Replace the test motor with the motor to be tested, retain the component measurement compensation in step S3 or do not need to compensate the component measurement values, calculate the speed calculation formula according to the M method, M / T method, and T method frequency measurement in the low-speed range, medium-speed range, and high-speed range of the motor to be tested, and calculate the instantaneous speed of the motor to be tested in combination with the angle compensation coefficient, and determine whether the motor to be tested is qualified according to the product standard.

2. The instantaneous speed real-time compensation method of the motor test bench according to claim 1 is characterized in that: In step S1, self-test is mainly performed on the pulse generator and high-precision timer of the test bench to ensure that the test bench is level and has reasonable jitter.

3. The instantaneous speed real-time compensation method of the motor test bench according to claim 1 is characterized in that: In step S2, data is collected and tested randomly according to different values ​​in the low-speed range, a single variable is controlled, the values ​​of other variables corresponding to the output end and the test end are obtained and the difference is calculated, and whether the error is reasonable is determined according to the corresponding error standard q.

4. The instantaneous speed real-time compensation method of the motor test bench according to claim 3 is characterized in that: In step 2, the frequency is measured in the low-speed range according to the M method, based on the formula Among them, n1 is the speed of the test motor in the low speed range, T1 is the test time, m1 is the number of pulses generated by the pulse generator during this time period, and M is the number of pulses generated by the pulse generator when the motor rotates one circle. During the test of step S2, the test time T1 is an abnormal variable that cannot be directly analyzed, and the controllable analysis variables are the motor speed n1 and the number of pulses m1 generated by the pulse generator; For the two controllable analysis variables mentioned above, P1 experiments are performed in each of step S2.1 and step S2.

2.

5. The instantaneous speed real-time compensation method of the motor test bench according to claim 4 is characterized in that: Step S2.1, control the test time T1 and the motor speed n1 to remain unchanged, calculate the pulse number m1.1 generated by the pulse generator corresponding to the output end according to the formula, and use the pulse generator of the test bench itself to feedback the pulse number m1.2 generated by the pulse generator corresponding to the test end, and calculate the difference between m1.1 and m1.

2. At this time, the error standard q1 is ±1. If more than half of the cases exceed the error standard q1, the error is judged to be unreasonable. If half or less of the cases exceed the error standard q1, the error is judged to be reasonable.

6. The instantaneous speed real-time compensation method of the motor test bench according to claim 5 is characterized in that: Step S2.2, control the test time T1 unchanged, set the value m1 of the pulse generator within a reasonable speed range, calculate the motor speed n1.1 corresponding to the test end, read the actual speed of the motor, that is, the speed n1.2 corresponding to the output end, calculate the difference between n1.1 and n1.2, at this time the error mark q2 is 14, more than half of the cases exceed the error standard q2, then the error is judged to be unreasonable, half or less of the cases exceed the error standard q2, then the error is judged to be reasonable.

7. The instantaneous speed real-time compensation method for a motor test bench according to claim 6, characterized in that: In step S3, if the error is judged to be reasonable, no intervention is performed; To determine if the error is unreasonable, the compensation coefficient μ1 of the pulse generator m1 is calculated based on the speed of the test motor, that is, the speed of the output end. The derivation formula is as follows: Among them, the ratio of n1.1 to n1.2 and the ratio of m1.1 to m1.2 are the average values ​​of P1 trials; The formula for calculating the motor speed after component measurement compensation is as follows: Among them, n2 is the speed of the motor in the low speed range, T2 is the test time, m2 is the reading of the pulse generator during this time period, and M is the number of pulses generated by the pulse generator when the motor rotates one circle.

8. The instantaneous speed real-time compensation method of a motor test bench according to claim 7, characterized in that: In step S4, p2 acquisition experiments are performed, each quantitative test time is T2 and the reading m2 of the test bench pulse generator is read. According to the formula Calculate the motor speed n2 corresponding to the test end and the motor speed reading n3 corresponding to the actual output end, and the difference between the two is the relative error.

9. The instantaneous speed real-time compensation method of a motor test bench according to claim 8, characterized in that: In step S5, the formula for deriving the angle compensation coefficient μ2 based on the value obtained in step S4 is as follows: μ2 needs to be averaged based on the calculated values ​​of p2 experiments.

10. The instantaneous speed real-time compensation method of a motor test bench according to claim 9, characterized in that: The calculations of the three test methods in step S6 are all compensated according to the following rules: The angle compensation coefficient μ2 is added to the value of the number of pulses M generated by the pulse generator when the motor rotates one circle, and the value is taken as a multiple of 1+μ2; the value of the pulse generator reading m1 in the same time period is taken as a multiple of μ1.

Images