A position servo control system and method based on a dual-channel resolver

Abstract

The present invention relates to a position servo control system and method based on a dual-channel resolver, comprising the following steps: dividing the angular position of a permanent magnet synchronous motor into N partitions, where N = 32; obtaining the output signals of the dual-channel rotary motor and performing position compensation calculation on them; performing position correction on the output signals of the dual-channel rotary motor after position compensation. The proposed compensation calculation methods for the coarse and fine channels in the present invention effectively prevent the "code skipping" phenomenon and improve the angle measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of angle measurement signal processing, and particularly relates to a position servo control system and method based on a two-channel resolver. Background Art

[0002] As a high-precision position sensor, the resolver has the characteristics of strong anti-shock ability, resistance to high and low temperatures, high precision, and high reliability. Moreover, it has low requirements for installation accuracy and can be widely used in the high-precision position detection of rotating bodies in various harsh environments. In order to solve the problem of high-precision angle measurement under extremely harsh working conditions, the method of multi-pole subdivision of the rotation angle is used to improve the angle measurement accuracy. Although the multi-channel method can improve the angle measurement accuracy, there will be incorrect carry between channels with different resolutions, resulting in the phenomenon of "code skipping", which instead deteriorates the angle measurement accuracy and increases the angle measurement error. Summary of the Invention

[0003] The purpose of the present invention is to improve the existing "code skipping" phenomenon and provide a position servo control system and method based on a two-channel resolver.

[0004] In order to achieve the above invention purpose, the embodiments of the present invention provide the following technical solutions:

[0005] A position servo control system based on a two-channel resolver includes: a two-channel resolver, a decoder, a main control unit, an isolation amplifier, a driver IGBT, a permanent magnet synchronous motor, and a phase current detector;

[0006] The output end of the main control unit is connected to the input end of the isolation amplifier, the output end of the isolation amplifier is connected to the driver IGBT, and the driver IGBT is respectively connected to the input end of the permanent magnet synchronous motor and the input end of the phase current detector; the output end of the permanent magnet synchronous motor is connected to the input end of the decoder, and the output ends of the decoder and the phase current detector are respectively connected to the input end of the main control unit;

[0007] The main control unit is used to perform position compensation calculation and position correction calculation on the output signal of the two-channel rotating motor.

[0008] Furthermore, the way for the main control unit to perform position compensation calculation on the output signal of the two-channel rotating motor is:

[0009] Divide the one-week angular position of the rotor of the permanent magnet synchronous motor into N partitions, where N = 32;

[0010] After performing position compensation calculation on the output signal of the two-channel rotating motor, the output of the two-channel rotating motor is:

[0011] θ = 11.25 × N + θ2 × σ(1)

[0012] In Equation (1), θ is the angular position finally measured by the coarse and fine dual-channel resolver, N is the number of partitions, θ2 is the binary code output by the fine channel, and σ is the minimum resolution of the fine channel.

[0013] Furthermore, the way for the master control unit to perform position correction calculation on the output signal of the dual-channel rotating motor is as follows:

[0014] When |θ1 - θ| ≤ 5.625°, no position correction is performed, where θ1 is the binary code output by the coarse channel;

[0015] When |θ1 - θ| > 5.625°, make N + 1, and then perform position compensation calculation until |θ1 - θ| ≤ 5.625°;

[0016] When |θ1 - θ| < -5.625°, make N - 1, and then perform position compensation calculation until |θ1 - θ| ≤ 5.625°.

[0017] A position servo control method based on a dual-channel resolver includes the following steps:

[0018] Step 1: Divide the angular position of the permanent magnet synchronous motor into N partitions, where N = 32;

[0019] Step 2: Obtain the output signal of the dual-channel rotating motor and perform position compensation calculation on it;

[0020] Step 3: Perform position correction on the output signal of the dual-channel rotating motor after position compensation.

[0021] Furthermore, Step 2 specifically includes the following steps:

[0022] The output signal of the dual-channel rotating motor includes θ1 and θ2, where θ1 is the binary code output by the coarse channel and θ2 is the binary code output by the fine channel;

[0023] After performing position compensation calculation on the output signal of the dual-channel rotating motor, the output of the dual-channel rotating motor is:

[0024] θ = 11.25 × N + θ2 × σ (1)

[0025] In Equation (1), θ is the angular position finally measured by the coarse and fine dual-channel resolver, N is the number of partitions, and σ is the minimum resolution of the fine channel.

[0026] Furthermore, Step 3 specifically includes the following steps:

[0027] When |θ1 - θ| ≤ 5.625°, no position correction is performed;

[0028] When |θ1 - θ| > 5.625°, set N + 1, and then perform position compensation calculation until |θ1 - θ| ≤ 5.625°;

[0029] When |θ1 - θ| < -5.625°, set N - 1, and then perform position compensation calculation until |θ1 - θ| ≤ 5.625°.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] For dual-channel resolvers, the existing compensation calculation method has the phenomenon of "code skipping". In view of this problem, the present invention proposes a compensation calculation method for the coarse and fine channels, which effectively prevents the "code skipping" phenomenon, improves the angle measurement accuracy, and finally uses the angle measurement result in the position servo control system. The vector control of the permanent magnet synchronous motor realizes high-precision position feedback information, achieves an angle measurement accuracy of arcseconds, and effectively improves the low-speed stability of the permanent magnet synchronous motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a block diagram of the system module of the present invention;

[0034] Figure 2 It is a flowchart of the method of the present invention;

[0035] Figure 3 It is a schematic diagram of the principle of a prior art dual-channel resolver;

[0036] Figure 4 It is the binary bits and their weights of a prior art dual-channel resolver;

[0037] Figure 5 is an output waveform diagram of a prior art permanent magnet synchronous motor. In Figure 5, a is the speed waveform diagram of the permanent magnet synchronous motor, and b in Figure 5 is the angular position waveform diagram of the permanent magnet synchronous motor;

[0038] Figure 6 is an output waveform diagram of the dual-channel resolver of the present invention. In Figure 6, a is the continuous angle measurement waveform diagram of the dual-channel resolver, and b in Figure 6 is the static angle measurement waveform diagram of the dual-channel resolver;

[0039] Figure 7 is an output waveform diagram of the permanent magnet synchronous motor of the present invention. In Figure 7, a is the speed waveform diagram of the permanent magnet synchronous motor, and b in Figure 7 is the angular position waveform diagram of the permanent magnet synchronous motor. Detailed implementation mode

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but only represents the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present invention, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance, or implying any such actual relationship or order between these entities or operations. In addition, terms such as "connected" and "coupled" can be directly connected between components or indirectly connected through other components.

[0042] Embodiment:

[0043] For the existing dual-channel resolver with a combination of 1 pole pair and 32 pole pairs, the angle measurement principle is analyzed. For the convenience of explanation, the angle measurement channel corresponding to 1 pole pair is marked as the coarse channel, and the angle measurement channel corresponding to 32 pole pairs is marked as the fine channel. The principle of the dual-channel resolver is as Figure 3 shown. The coupling method of the coarse channel and the fine channel is that the coarse channel encodes 0° to 360° into a 16-bit binary code (i.e., 0 - 65536), and its minimum resolution is 0.0055°; the fine channel encodes 0° to 11.25° into a 16-bit binary code (i.e., 0 - 65536), and its minimum resolution is 0.618 arcseconds. That is, bits 0 - 10 of the coarse channel and bits 5 - 15 of the fine channel have the same resolution.

[0044] In order to improve the angle measurement accuracy, by fusing the data of the coarse and fine channels, an angle measurement accuracy of 21 bits can be achieved. For the convenience of explanation, please refer to Figure 4 , and record the angle value corresponding to each binary digit as the weight of this binary digit. From Figure 4As can be seen, the weights represented by the 10th bit of the coarse channel and the 15th bit of the fine channel are the same, both being 5.625°. If the weight of the 10th bit of the coarse channel is represented by B, the weight of the 11th bit of the coarse channel is represented by A, and at the same time, the weight of the 15th bit of the fine channel is represented by C, and the weight of the 14th bit of the fine channel is represented by D. At this time, in order to obtain the angular measurement accuracy of 21 bits, only the weight of C can be directly carried over to A, which will result in an incorrect carry and cause the "jump code" phenomenon.

[0045] Reasons for obtaining incorrect carry: 1. The measurement error of the coarse channel is too large; 2. During the assembly process of the resolver, the relative positions of the coarse and fine conduction can be fixed. Considering the uncertainty of the subsequent processing circuit, the initial position of the decoding chip is a random value each time it is powered on, resulting in incorrect carry. For the incorrect carry, correction is required. The existing correction methods are shown in Table 1, where e is the weight of the 10th bit of the coarse channel:

[0046] Table 1 Existing correction methods for incorrect carry

[0047] Serial number Judgment method Correction method 1 B - C ≤ e Do not correct 2 B - C > e A+1 3 B - C ≤ -e A-1

[0048] Using the correction method for incorrect carry in Table 1, the obtained 21-bit angular measurement result of the permanent magnet synchronous motor is used in the position servo control system. At this time, the speed waveform of the permanent magnet synchronous motor is shown in Figure 5(a), where the abscissa is time (unit: second) and the ordinate is speed (unit: rad / s); the angular position waveform is shown in Figure 5(b), where the abscissa is time (unit: second) and the ordinate is angular position (unit: rad). It can be seen that in order to obtain the high-precision motor rotor position detection result of 21 bits, using the existing method to correct the incorrect carry, the low-speed stability index of the motor is reduced at this time, the angular position of the motor jumps, and the "jump code" phenomenon appears.

[0049] To solve the above technical problems, the present invention proposes the following solution. A position servo control system based on a dual-channel resolver, as Figure 1 shown, the system includes a dual-channel resolver, a decoder, a main control unit, an isolation amplifier, a drive IGBT, a permanent magnet synchronous motor, and a phase current detector. The output end of the main control unit is connected to the input end of the isolation amplifier, the output end of the isolation amplifier is connected to the drive IGBT, and the drive IGBT is respectively connected to the input end of the permanent magnet synchronous motor and the input end of the phase current detector; the output end of the permanent magnet synchronous motor is connected to the input end of the decoder, and the output ends of the decoder and the phase current detector are respectively connected to the input end of the main control unit.

[0050] The main control unit uses a DSP28335 chip from TI to output 6 PWM waves to the isolation amplifier. After being amplified by the isolation amplifier, the driver IGBT ensures that the input to the permanent magnet synchronous motor is a sine wave with a 120° phase difference in three phases. To meet the high-precision angle measurement requirements for the permanent magnet synchronous motor, a phase current detector is used to detect the three-phase current in real time to improve the current detection accuracy. The output signal of the dual-channel resolver is demodulated using a decoder model AD2S80 to generate two groups of 16-bit binary codes. After being calculated by the main control unit, 21-bit position data can be obtained.

[0051] In order to eliminate the "code skipping" phenomenon in this solution, the compensation calculation method of the main control unit for the output signal of the dual-channel resolver is improved. First, the angular position of the rotor of the permanent magnet synchronous motor is divided into 32 partitions. The relationship between the number of partitions and the 15-11 bits of the coarse channel is shown in Table 2.

[0052] Table 2 Partition of the Rotor Angular Position of the Permanent Magnet Synchronous Motor

[0053]

[0054] As shown in Table 2, the 360° angular position in one week is divided into 32 sectors. At this time, the outputs of the coarse and fine dual-channel resolvers are:

[0055] θ = 11.25×N + θ2×σ (1)

[0056] In formula (1), θ is the angular position finally measured by the coarse and fine dual-channel resolvers, N is the number of partitions, θ2 is the binary code output by the fine channel, and σ is the minimum resolution of the fine channel.

[0057] Accordingly, in order to prevent the "code skipping" phenomenon in this solution, the position correction method adopted is shown in Table 3, where θ1 is the binary code output by the coarse channel.

[0058] Table 3 Position Correction Method of this Solution

[0059]

[0060]

[0061] Using the position correction method in Table 3, the obtained angular measurement results of the 21-pole permanent magnet synchronous motor are used in the position servo control system. At this time, the continuous angular measurement waveforms output by the dual-channel resolver during the rotation of the permanent magnet synchronous motor are shown in Fig. 6(a). Among them, the abscissa is time (unit: millisecond), the ordinate is the partition, waveform A is the angular measurement result of the coupled output of the coarse channel and the fine channel, waveform B is the sector selection result, and waveform C represents the rotor rotation angle. It can be seen that the new correction method will not produce incorrect sector selection. Fig. 6(b) shows the angular measurement results when the rotor of the permanent magnet synchronous motor is stationary. The abscissa is time (unit: second), and the ordinate is the angular position (unit: rad / s). It can be seen that the angular measurement accuracy can reach the arcsecond level.

[0062] Figure 1 In the given system, the permanent magnet synchronous motor adopts vector control. Under the condition of using a dual-channel resolver to achieve high-precision angular measurement, when the given speed of the permanent magnet synchronous motor is 0.0001 rad / s, the speed waveform of the permanent magnet synchronous motor is shown in Fig. 7(a). The abscissa is time (unit: second), and the ordinate is speed (unit: rad / s); the angular position waveform is shown in Fig. 7(b). The abscissa is time (unit: second), and the ordinate is angular position (unit: rad). It can be seen that, first, the new multi-pole compensation calculation method proposed in this scheme can provide accurate feedback information for the rotor position of the permanent magnet synchronous motor, laying a foundation for improving the system accuracy; second, the position correction method proposed in this scheme can not only obtain high-precision position detection results, but also has good dynamic response characteristics of the detection results, meeting the requirements of rapid position detection.

[0063] Based on the above system, please refer to Figure 2 , this scheme also proposes a position servo control method based on a dual-channel resolver, including the following steps:

[0064] Step 1: Divide the angular position of the permanent magnet synchronous motor into N partitions, where N = 32.

[0065] Step 2: Obtain the output signals of the dual-channel rotating motor and perform position compensation calculation on them.

[0066] The output signals of the dual-channel rotating motor include θ1 and θ2, where θ1 is the binary code output by the coarse channel and θ2 is the binary code output by the fine channel;

[0067] After performing position compensation calculation on the output signals of the dual-channel rotating motor, the output of the dual-channel rotating motor is: [[ID=2^{2}]]

[0068] θ = 11.25 × N + θ2 × σ(1)

[0069] In formula (1), θ is the angular position finally measured by the coarse and fine dual-channel resolver, N is the number of partitions, and σ is the minimum resolution of the fine channel.

[0070] Step 3: Perform position correction on the output signal after position compensation of the dual-channel rotating motor.

[0071] When |θ1 - θ| ≤ 5.625°, no position correction is performed;

[0072] When |θ1 - θ| > 5.625°, set N + 1, and then perform position compensation calculation until |θ1 - θ| ≤ 5.625°;

[0073] When |θ1 - θ| < -5.625°, set N - 1, and then perform position compensation calculation until |θ1 - θ| ≤ 5.625°.

[0074] In summary, for the dual-channel resolver, the existing compensation calculation method has the phenomenon of "skipping codes". In response to this problem, the compensation calculation method for the coarse and fine channels proposed in this solution effectively prevents the "skipping codes" phenomenon, improves the angle measurement accuracy, and finally uses the angle measurement result in the position servo control system. The vector control of the permanent magnet synchronous motor realizes high-precision position feedback information, achieves an angle measurement accuracy of arcseconds, and effectively improves the low-speed stability of the permanent magnet synchronous motor.

[0075] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A position servo control system based on a dual-channel resolver, characterized in that: Including: Two-channel resolver, decoder, main control unit, isolation amplifier, IGBT driver, permanent magnet synchronous motor, phase current detector; The output end of the main control unit is connected to the input end of the isolation amplifier, the output end of the isolation amplifier is connected to the IGBT driver, and the IGBT driver is respectively connected to the input end of the permanent magnet synchronous motor and the input end of the phase current detector; The output end of the permanent magnet synchronous motor is connected to the input end of the decoder, and the output ends of the decoder and the phase current detector are respectively connected to the input end of the main control unit; The main control unit is used to perform position compensation calculation and position correction calculation on the output signal of the two-channel rotating motor; The position compensation calculation is as follows: The one-week angular position of the rotor of the permanent magnet synchronous motor is divided into N partitions, N = 32; After performing position compensation calculation on the output signal of the two-channel rotating motor, the output of the two-channel rotating motor is: （1） In Equation (1), is the angular position finally measured by the coarse and fine dual-channel resolver, N is the number of partitions, is the binary code output by the fine channel, is the minimum resolution of the fine channel; The position correction calculation is as follows: When no position correction is performed, is the binary code output by the coarse channel; When occurs, increment N by 1 and then perform position compensation calculation until ; When make N - 1, and then perform position compensation calculation until .

2. A position servo control method based on a dual-channel resolver, characterized in that: Including the following steps: Step 1, divide the angular position of the permanent magnet synchronous motor into N partitions, N = 32; Step 2, obtain the output signal of the two-channel rotating motor and perform position compensation calculation on it; The output signals of the dual-channel rotating motor include , , where is the binary code output by the coarse channel, is the binary code output by the fine channel; After performing position compensation calculation on the output signal of the two-channel rotating motor, the output of the two-channel rotating motor is: （1） In Equation (1), is the finally measured angular position of the coarse and fine dual-channel resolver, N is the number of partitions, is the minimum resolution of the fine channel; Step 3, perform position correction on the output signal of the two-channel rotating motor after position compensation; When there is no position correction When occurs, increment N by 1 and then perform position compensation calculation until ; When , set N - 1 and then perform position compensation calculation until .

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