A method for calibrating the linearity of a rotary transformer

Abstract

A method for calibrating the linearity of a rotary transformer belongs to the technical field of motor control. The method is used in a motor testing system composed of a driver, a motor, a rotary transformer, and a photoelectric encoder. The method includes data acquisition, deviation calculation, and compensation correction. Data acquisition involves the driver acquiring position data of the rotary transformer and the photoelectric encoder in real time. Deviation calculation involves the driver controlling the motor shaft to rotate slowly and calculating the deviation between the position data of the photoelectric encoder at each position and the position data of the corresponding position of the rotary transformer. The linear deviation data is integrated and processed to generate a deviation array. Compensation correction involves constructing a compensation difference table based on the deviation array. The driver reads the real-time position of the rotary transformer, searches for a corresponding compensation value based on the compensation difference table, applies the compensation value to the output signal of the rotary transformer, and corrects the real-time position of the rotary transformer, thereby improving the accuracy and linearity of the rotary transformer.

Description

Technical Field

[0001] The invention discloses a method for calibrating the linearity of a rotary transformer, and belongs to the technical field of motor control. Background Art

[0002] With the rapid development of industrial automation, robotics, electric vehicles, and precision machinery, the requirements for motor control precision are becoming increasingly higher. In motor control systems, the accuracy of the position feedback device is directly related to the motor control effect and the overall performance of the system. As a commonly used motor position feedback sensor, the resolver is widely used in various motor drive systems due to its high reliability, strong anti-interference ability, and adaptability to harsh environments. However, in actual applications, the resolver has a linearity deviation problem due to its poor installation coaxiality, which leads to position inaccuracy or speed fluctuation when detecting the motor rotation position and speed.

[0003] Traditional resolver calibration methods rely primarily on hardware adjustments, such as precise installation and calibration of the resolver, or the use of high-precision manufacturing processes to improve its linearity. While these methods can improve resolver performance to a certain extent, they extend installation time and difficulty, increase labor costs, and are one-time calibration methods that are unable to recalibrate the dynamic deviations of the resolver under different operating conditions. Consequently, the resolver's linearity deviation may not be effectively controlled during actual operation. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for calibrating the linearity of a rotary transformer to solve the technical problems that the existing calibration method takes a long time, is difficult to calibrate and cannot achieve multiple calibrations.

[0005] To achieve the above object, the present invention is implemented through the following technical solution: a method for calibrating the linearity of a rotary transformer, which is used in a motor testing system composed of a driver, a motor, a rotary transformer and a photoelectric encoder, characterized in that:

[0006] S1, data acquisition step: the driver collects position data of each position of the rotary transformer and the photoelectric encoder in a rotation cycle in real time;

[0007] S2, deviation calculation step: the driver controls the motor shaft to rotate slowly and calculates the deviation between the position data of the photoelectric encoder at each position and the position data of the corresponding position of the resolver; and integrates the calculated linear deviation data of each position to generate a deviation array;

[0008] S3. Compensation correction step: construct a compensation difference table based on the generated deviation array, the driver reads the real-time position of the resolver, and searches for the corresponding compensation value according to the compensation difference table, applies the compensation value to the output signal of the resolver, and corrects the real-time position of the resolver, thereby improving the accuracy and linearity of the resolver.

[0009] Furthermore, the rotary transformer is arranged on the motor, the motor is connected to the photoelectric encoder through a coupling, and the driver is connected to the motor and the photoelectric encoder respectively.

[0010] Furthermore, in S1 , the driver simultaneously collects data of the resolver and the photoelectric encoder at each position in a single turn at a sampling interval of 62.5 μs.

[0011] Furthermore, the resolution of the rotary transformer is 4096, and the resolution of the photoelectric encoder is 131072, and the resolutions of the two are kept consistent through conversion.

[0012] Furthermore, in S2, the motor rotates at a speed of 8-12 rpm.

[0013] Furthermore, in S2, the deviation array contains 4096 data, and the data corresponding to its index is the position data of the resolver, and the data corresponding to each position is the position data of the photoelectric encoder.

[0014] Furthermore, the position data of each rotary transformer corresponds to the position data of the photoelectric encoder after multiple sampling and averaging.

[0015] The beneficial effects of the present invention are:

[0016] This application effectively improves the linearity and position feedback accuracy of the resolver by compensating for the linear deviation of the photoelectric encoder and resolver at each position, ensuring the high precision and stability of the motor control system.

[0017] This application realizes real-time compensation of the position feedback of the rotary transformer through software adjustment, and the adjustment can be achieved by integrating the corresponding control software into the existing motor control system. Moreover, since it is a low-speed calibration, the installation accuracy requirements for the coupling and optical encoder are also very low. It only needs to ensure that there is no slipping during rotation, which reduces the difficulty and cost of adjusting the linearity of the rotary transformer, and has wide applicability and compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0019] Figure 1 Schematic diagram of a process for calibrating the linearity of a rotary transformer according to the present invention;

[0020] Figure 2 A schematic diagram of the system structure of a rotary transformer linearity calibration according to the present invention;

[0021] Figure 3 This is a rotation speed fluctuation diagram before linear compensation of the present invention;

[0022] Figure 4 This is a rotation speed fluctuation diagram after linear compensation of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0024] like Figure 1 、 Figure 2 As shown, the present invention provides a method for calibrating the linearity of a rotary transformer, which is used in a motor testing system composed of a driver, a motor, a rotary transformer and a photoelectric encoder, and is characterized in that the method includes:

[0025] S1, data acquisition step: the driver collects position data of each position of the rotary transformer and the photoelectric encoder in a rotation cycle in real time;

[0026] S2, deviation calculation step: the driver controls the motor shaft to rotate slowly and calculates the deviation between the position data of the photoelectric encoder at each position and the position data of the corresponding position of the resolver; and integrates the calculated linear deviation data of each position to generate a deviation array;

[0027] S3. Compensation correction step: construct a compensation difference table based on the generated deviation array, the driver reads the real-time position of the resolver, and searches for the corresponding compensation value according to the compensation difference table, applies the compensation value to the output signal of the resolver, and corrects the real-time position of the resolver, thereby improving the accuracy and linearity of the resolver.

[0028] In order to maintain data flow between devices, the rotary transformer is arranged on the motor, the motor is connected to the photoelectric encoder through a coupling, and the driver is connected to the motor and the photoelectric encoder respectively.

[0029] In order to accurately calculate the position data, in S1, the driver simultaneously collects the data of the rotary transformer and the photoelectric encoder at each position in a single turn at a sampling interval of 62.5 μs.

[0030] In order to ensure the consistency of the position data of the two in the initial state, the resolution of the single-turn position of the resolver is 4096, and the resolution of the single-turn position of the photoelectric encoder is 131072. The resolutions of the two are kept consistent through conversion.

[0031] In order to reduce vibration and interference, in S2 , the motor rotates at a speed of 8-12 rpm.

[0032] In order to fully cover the position range of the resolver, in S2, the deviation array contains 4096 data, and the data corresponding to its index is the position data of the resolver, and the data corresponding to each position is the position data of the photoelectric encoder.

[0033] In order to reduce the influence of data fluctuation, the position data of each rotary transformer corresponds to the position data of the photoelectric encoder after multiple sampling and averaging.

[0034] Example 1:

[0035] The specific workflow of this application method is as follows:

[0036] (1) Equipment preparation:

[0037] Prepare to install the motor with the resolver, the calibrated photoelectric encoder, the driver and the dragging platform. The driver is used to collect and analyze feedback position data and control the operation of the motor; the dragging platform is used to connect the motor and the photoelectric encoder to ensure that the two rotate synchronously.

[0038] (2) Device connection:

[0039] Install the motor with a rotary transformer on the towing platform, and connect the motor and the photoelectric encoder through a coupling to ensure that the two rotate synchronously; connect the rotary transformer and the photoelectric encoder to the driver to ensure that the driver can normally control the motor and receive feedback data.

[0040] (3) Parameter configuration:

[0041] Set the driver-related parameters through the driver panel, set the basic parameters of the motor (including motor type, speed, rated current, etc.) and control mode (position control or speed control), and set the driver's sampling interval to ensure that sufficient and continuous data points can be collected during the motor rotation process.

[0042] (4) Data collection and processing:

[0043] When the motor is stationary, the position data of the resolver is used as a reference, and the difference between the data after the photoelectric encoder is converted to a certain resolution and the data of the resolver is used as the deviation value. Specifically, the deviation value = the position data after the photoelectric encoder is converted - the position data of the rotary encoder, thereby ensuring that the position data of the photoelectric encoder and the resolver are consistent at the starting point.

[0044] The driver controls the motor to rotate at a speed of 10 rpm. The low-speed rotation ensures the stability and accuracy of data acquisition and facilitates the analysis and processing of feedback signals.

[0045] The driver reads the single-turn position data of the feedback photoelectric encoder and resolver and creates an array containing 4096 elements. The array index corresponds to the position of the resolver (0 to 4095, representing 0 to 360 degrees or 0 to 2π radians of the resolver). The data corresponding to each position is the position data of the photoelectric encoder. Due to data fluctuations, the position of the photoelectric encoder corresponding to each resolver needs to be averaged after multiple samplings and then filled into the deviation array to form the linearity deviation database of the resolver. The specific average value is calculated as follows:

[0046] Average =

[0047] Where N is the number of photoelectric encoder position data corresponding to each resolver position (i.e., the number of sampling times).

[0048] (5) Compensation amendment:

[0049] After the driver calculates the compensation data, it generates a deviation array. During the operation of the motor, the driver obtains the compensation value corresponding to the position from the deviation array based on the position feedback from the resolver, and compensates the actual motor position in real time.

[0050] (6) Calibration result verification:

[0051] After the compensation is implemented, data collection can be performed again. By controlling the motor to rotate at a low and stable speed, the position data of the resolver and the photoelectric encoder can be recorded for comparison. The fluctuation of the rotation speed before and after compensation can also be compared. Figure 3 and Figure 4 shown.

[0052] Through linear compensation, a linearity line close to a straight line can be obtained, which means that the position feedback of the resolver is more accurate and can better meet the application requirements of high-precision motor control systems.

[0053] This embodiment performs linearity calibration of the rotary transformer by directly controlling the motor based on the driver, without the need for additional configuration of the host computer and related equipment, reducing hardware procurement and maintenance costs, and simplifying the operation process, omitting complex communication configuration and host computer software operation, making system construction and calibration execution more convenient and efficient, helping to improve system stability, data transmission stability, enhanced anti-interference ability, and reduced calibration errors caused by communication delays and interference. In addition, the method has strong compatibility and a wide range of applications. It can flexibly adjust calibration parameters according to different motors and working conditions, enhances real-time performance, and can quickly respond to and correct the linearity deviation of the rotary transformer, ensuring the high precision and stability of the motor control system.

[0054] Example 2:

[0055] This application needs to handle data overflow when processing the data of the photoelectric encoder after matching the resolution, so as to ensure that the position data of the photoelectric encoder and the resolver are consistent at the starting point. The specific processing method is as follows:

[0056] Because the position range of the photoelectric encoder after matching the resolution is from 0 to 4095, the data is subtracted from the deviation value obtained when it is stationary (the deviation value range is also 0 to 4095). When the calculated result is less than 0, 4095 needs to be added to the result to ensure that the result range after subtracting the deviation value is still 0 to 4095.

[0057] Example 3:

[0058] In this application, the resolution of the single-turn position of the rotary transformer is 4096, and the resolution of the single-turn position of the photoelectric encoder is 131072. In order to keep the resolutions of the two consistent for effective linearity calibration, the resolution of the photoelectric encoder can be divided by 32 to achieve resolution matching between the two to ensure the accuracy and effectiveness of the calibration.

[0059] Unified resolution ensures that each resolver position accurately corresponds to the position of the photoelectric encoder, improving calibration accuracy. It also simplifies the data matching and processing process, facilitates the generation of deviation arrays and subsequent deviation calculation and compensation, and improves the linearity and position feedback accuracy of the resolver.

[0060] This application effectively improves the linearity and position feedback accuracy of the resolver by compensating for the linear deviation of the photoelectric encoder and resolver at each position, ensuring the high precision and stability of the motor control system.

[0061] This application realizes real-time compensation of the position feedback of the rotary transformer through software adjustment, and the adjustment can be achieved by simply integrating the corresponding control software into the existing motor control system, which reduces the difficulty and cost of adjusting the linearity of the rotary transformer and has wide applicability and compatibility.

[0062] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be included within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0063] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for calibrating the linearity of a rotary transformer, the method being used in a motor test system consisting of a driver, a motor, a rotary transformer, and a photoelectric encoder, characterized in that: The method comprises: S1, data acquisition step: the driver collects position data of each position of the rotary transformer and the photoelectric encoder in a rotation cycle in real time; S2, a deviation calculation step: the driver controls the motor shaft to rotate slowly and calculates the deviation between the position data of the photoelectric encoder at each position and the position data of the corresponding position of the resolver; and integrates the calculated linear deviation data of each position to generate a deviation array, wherein the data corresponding to the deviation array index is the position data of the resolver, and the data corresponding to each position is the position data of the photoelectric encoder; S3, compensation correction step: construct a compensation difference table based on the generated deviation array, the driver reads the real-time position of the resolver, and searches for the corresponding compensation value according to the compensation difference table, applies the compensation value to the output signal of the resolver, and corrects the real-time position of the resolver.

2. The method for calibrating the linearity of a rotary transformer according to claim 1, wherein: The rotary transformer is arranged on the motor, the motor is connected to the photoelectric encoder through a coupling, and the driver is connected to the motor and the photoelectric encoder respectively.

3. The method for calibrating the linearity of a rotary transformer according to claim 2, wherein: The driver analyzes the position data of the photoelectric encoder and the rotary transformer collected in real time, and controls the rotation of the motor.

4. The method for calibrating the linearity of a rotary transformer according to claim 1, wherein: In S1, the driver simultaneously collects data of the resolver and the photoelectric encoder at each position of a single turn at a sampling interval of 62.5 μs.

5. The method for calibrating the linearity of a rotary transformer according to claim 4, wherein: The resolution of the rotary transformer is 4096, and the resolution of the photoelectric encoder is 131072. The resolutions of the two are kept consistent through conversion.

6. The method for calibrating the linearity of a rotary transformer according to claim 1, wherein: In S2 , the motor rotates at a speed of 8-12 rpm.

7. The method for calibrating the linearity of a rotary transformer according to claim 1, wherein: In S2, the deviation array contains 4096 data.

8. The method for calibrating the linearity of a rotary transformer according to claim 1, wherein: The position data of each rotary transformer corresponds to the position data of the photoelectric encoder after multiple sampling and averaging.

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