Control methods, computer equipment, storage media, magnetic bearings and compressors
By measuring the rotor center coordinates and calculating the same-direction adjustment displacement and force, and using the resultant force control of multiple coils, the problem of low adjustment accuracy when the magnetic levitation bearing rotor deviates is solved, achieving higher adjustment accuracy and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GREE ELECTRIC APPLIANCE INC OF ZHUHAI
- Filing Date
- 2023-12-25
- Publication Date
- 2026-07-17
Smart Images
Figure CN117780789B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of magnetic bearing technology, and particularly to a control method, computer equipment, storage medium, magnetic bearing, and compressor for magnetic bearings. Background Technology
[0002] In magnetic levitation bearings, the rotor passes inside the stator, and the rotor is disengaged from the positioning system via coils during rotation, reducing the loss of rotational energy. However, the rotor may occasionally deviate from its preset position during rotation, thus getting too close to the inner wall of the stator and affecting the rotor's rotational accuracy.
[0003] In related technologies, in order to adjust the position of the rotor and move it quickly to a preset position, the rotor's offset in the front radial direction (x-direction) and the offset in the rear radial direction (y-direction) are measured. A coil arranged in the front radial direction is controlled to generate an adjusting force in the x-direction, and a coil arranged in the rear radial direction is controlled to generate an adjusting force in the y-direction, thereby adjusting the rotor's position.
[0004] However, in reality, the rotor's offset direction can be in any direction. When the rotor's offset direction has an angle with both the x and y directions, the direction of the adjustment force applied to the rotor will have an angle with the rotor's offset direction, resulting in low adjustment accuracy of the magnetic levitation bearing. Summary of the Invention
[0005] This invention provides a control method, a magnetic levitation bearing, and a compressor, which provide a control method with high adjustment accuracy.
[0006] In a first aspect, the present invention provides a control method for a magnetic levitation bearing, comprising the following steps: calculating the center coordinates of a rotor based on a measurement signal from a measuring device, wherein the center coordinates are the polar coordinates of the rotor's center in a first polar coordinate system with the stator center as the pole;
[0007] The adjustment displacement is determined based on the center coordinates and the polar coordinates of the rotor's preset position.
[0008] The adjusting force is calculated based on the adjusting displacement, and the adjusting force is in the same direction as the adjusting displacement.
[0009] The adjustment force is calculated based on the center offset displacement, and the direction of the adjustment force is the same as the direction of the center offset displacement.
[0010] The adjusting force is applied to the rotor, and the rotor is moved so that the center of the rotor coincides with the preset position.
[0011] In one embodiment, calculating the center coordinates of the rotor based on the measurement signal from the measuring device includes the following sub-steps: establishing a first function X = f(θ) based on the measurement signal, where X is the gap between the inner profile of the stator and the outer profile of the rotor along the stator radial direction at an angle θ in the first polar coordinate system;
[0012] Calculate the coordinates of the maximum and minimum values of the first function in θ∈[0,2π];
[0013] The center coordinates are obtained based on the maximum and minimum coordinates.
[0014] In one embodiment, the measuring device includes at least three displacement sensors for measuring θ along the first polar coordinate system. 测 The gap X between the outer profile of the rotor and the inner profile of the stator in the radial direction of the stator. 测 The corresponding θ of the displacement sensor 测 They are all different.
[0015] In one embodiment, the measuring device includes at least four displacement sensors, each corresponding to θ. 测 They are 0, Π / 2, Π, and 3Π / 2, respectively.
[0016] In one embodiment, the first function X = f(θ) established in the first polar coordinate system based on the measurement signal includes the following sub-steps: establishing a second function X = g(θ, a, b) based on the stator inner diameter and the rotor outer diameter, where a and b are the abscissa and ordinate of the rotor center in a rectangular coordinate system established with the stator center as the origin, respectively;
[0017] Multiple groups (θ) 测i X 测i Substituting these values into the second function yields multiple sets of (a) i b i );
[0018] For multiple groups (a) i b i Calculate the average and substitute the average into the second function to obtain the first function.
[0019] In one implementation, the second function X = g(θ, a, b) satisfies the following expression:
[0020]
[0021] Where r1 is the inner diameter of the stator and r2 is the outer diameter of the rotor.
[0022] In one embodiment, obtaining the center coordinates based on the maximum and minimum coordinates includes the following sub-steps: determining the polar angle of the center coordinates based on the polar angle of the minimum coordinates;
[0023] The polar radius of the center coordinates is determined based on the polar radius of the minimum coordinates and the polar radius of the maximum coordinates.
[0024] In one embodiment, after calculating the adjusting force based on the center offset displacement, the method further includes the following step:
[0025] Determine whether there is an adjustment coil in the same direction as the adjustment displacement direction. If so, control the adjustment coil to generate the adjustment force. If not, select at least two adjustment coils with an adjustment direction similar to the adjustment displacement direction for adjustment, and control the resultant force generated by each control adjustment coil to be equal to the adjustment force.
[0026] In a second aspect, a computer device is also provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of a control method.
[0027] Thirdly, a computer-readable storage medium is also provided, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the steps of the above-described control method.
[0028] Fourthly, a magnetic levitation bearing is also provided, comprising:
[0029] stator;
[0030] A rotor that passes through the stator;
[0031] A measuring device, which is mounted on the stator and generates a measuring signal;
[0032] An adjustment component, installed on the stator, is used to implement the control method described above, so as to control the center of the rotor to coincide with a preset position.
[0033] Fifthly, a compressor is also provided, which includes the aforementioned magnetic levitation bearing.
[0034] Compared with the prior art, the advantage of the present invention is that, since the center coordinates of the rotor are obtained by first using the measurement signal of the measuring device through relevant calculations, the adjustment displacement and adjustment direction of the rotor for subsequent adjustment can be obtained.
[0035] Compared to directly adjusting the rotor by offsetting in only two directions, this method better ensures that the subsequent adjustment force and the rotor's center offset direction are aligned on the same straight line. This improves the adjustment accuracy of the magnetic levitation bearing. Attached Figure Description
[0036] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.
[0037] Figure 1 This is a flowchart of the control method in an embodiment of the present invention;
[0038] Figure 2 This is a schematic diagram of the stator and rotor in the first coordinate system.
[0039] Figure 3 Let be the graph of the first function in θ∈[0, 2π].
[0040] Figure 4 Another schematic diagram of the stator and rotor in the first coordinate system;
[0041] Figure 5 This is a schematic diagram of one arrangement of displacement sensors in the measuring device according to an embodiment of the present invention;
[0042] Figure 6 This is a control block diagram of a control method in a related technology;
[0043] Figure 7 This is a control block diagram of the control method in an embodiment of the present invention.
[0044] Reference numerals in the attached figures: 1. Stator; 2. Rotor; 3. First displacement sensor; 4. Second displacement sensor; 5. Third displacement sensor; 6. Fourth displacement sensor. Detailed Implementation
[0045] The invention will now be further described with reference to the accompanying drawings.
[0046] See Figure 1 as well as Figure 2 As shown, in a first aspect, embodiments of the present invention provide a control method for a magnetic levitation bearing, comprising the following steps:
[0047] S1: Calculate the center coordinates of rotor 2 based on the measurement signal of the measuring device, wherein the center coordinates are the polar coordinates of the center of rotor 2 in the first polar coordinate system with the center of stator 1 as the pole; compared with the control scheme that directly obtains the deviation displacement in the x-direction by using the sensor to measure, this application first integrates the measurement information of the measuring device and obtains the center coordinates of rotor 2 in the first coordinate system.
[0048] The position of the center coordinates can be determined by multiple sets of measurement data, which avoids large errors in the entire adjustment scheme due to large deviations in displacement in a single direction, and reduces the impact of measurement errors of a single sensor on adjustment accuracy.
[0049] S2: The adjustment displacement is determined based on the center coordinates and the polar coordinates of the preset position of rotor 2. In this application, the adjustment displacement is calculated by the difference between the center coordinates and the polar coordinates of the preset position. Since both the center coordinates and the polar coordinates of the preset position are polar coordinates, the calculated adjustment displacement with direction can be obtained, which reduces the difficulty of selecting the adjustment coil in the subsequent process.
[0050] In this application, the preset position is the optimal rotation center of rotor 2, which is generally the center of stator 1. Since the calculation is performed using the first polar coordinate system, the coordinates of the preset position are (0, 0). Therefore, the adjustment displacement is a vector with the same magnitude as the center coordinates and a polar angle difference of Π. After obtaining the center coordinates, the adjustment displacement can be easily obtained.
[0051] S3: Calculate the adjusting force based on the adjusting displacement, and the adjusting force is in the same direction as the adjusting displacement; S4: Calculate the adjusting force based on the center offset displacement, and the direction of the adjusting force is in the same direction as the center offset displacement; Apply the adjusting force to the rotor 2 to move the rotor 2 so that the center of the rotor 2 coincides with the preset position.
[0052] Since the adjusting force is in the same direction as the adjusting displacement of rotor 2, it can better ensure that rotor 2 moves along the adjusting displacement. Compared with directly using the offset in the x-direction to determine the adjusting force in the x-direction, it can satisfy the adjusting displacement in more directions.
[0053] It should be noted that, in order to avoid shaking during the adjustment process, a PID control algorithm is used to calculate the adjustment force. In other words, the magnitude of the adjustment force and the magnitude of the required adjustment displacement are not necessarily linear. This also causes the resultant force of the adjustment force calculated directly from the adjustment displacements offset in two directions to deviate from the direction of the resultant displacement, making it difficult to achieve precise levitation of the magnetic levitation bearing.
[0054] In this application, since the adjustment displacement is calculated first based on the measurement signal, and then the adjustment force is obtained by adjusting the displacement, it can better ensure that the adjustment force and the adjustment displacement are in the same direction, thereby improving the precise suspension of the magnetic levitation bearing.
[0055] In some embodiments, step S1 calculates the center coordinates of the rotor based on the measurement signal of the measuring device, including the following sub-steps: S101, establish a first function X = f(θ) based on the measurement signal, where X is the gap between the inner contour of the stator 1 and the outer contour of the rotor 2 along the radial direction of the stator 1 at angle θ in the first polar coordinate system.
[0056] like Figure 2 as well as Figure 4 As shown, X = ρ 1-ρ2 and X are values measured by the measuring device, where ρ1 is the distance from the point with polar angle θ on the outer contour of rotor 2 to the center of stator 1, and ρ2 is the distance from the point with polar angle θ on the inner contour of stator 1 to the center of stator 1. Since the inner contour of stator 1 is circular, ρ1 is equal to the radius of stator 1. That is, f(θ) = r1 - ρ2, where r1 is the inner diameter of stator 1. ρ2 is actually a function of θ. Assuming that the coordinates of the center of rotor 2 in the rectangular coordinate system established with the center of stator 1 are (a, b), we can obtain...
[0057]
[0058] Converting the rectangular coordinate system to the first coordinate system, we get a = ρ²cosθ and b = ρ²sinθ. Substituting these coordinates into equation (1), we obtain...
[0059]
[0060] In other words,
[0061]
[0062] Specifically, the values of a and b can be obtained by setting a sensor at the center of stator 1.
[0063] S102, calculate the coordinates of the maximum and minimum values of the first function in θ∈[0,2π];
[0064] From equation (3), we know that X = f(θ) is a periodic function of θ with a period of 2π. (See also...) Figure 3 As shown, this is a curve of X = f(θ). Based on the practical meaning of X, it can be seen that X changes continuously and smoothly with θ, exhibiting both a maximum and a minimum value. The maximum value is the largest gap between the outer contour of rotor 2 and the inner contour of stator 1, while the minimum value is the smallest gap between the outer contour of rotor 2 and the inner contour of stator 1.
[0065] By finding the extreme value of the function, we can obtain the coordinates of the point in the outer contour of rotor 2 that is furthest from the inner contour of stator 1, and the coordinates of the point in the outer contour of rotor 2 that is closest to the inner contour of stator 1.
[0066] S103, the center coordinates are obtained based on the maximum and minimum coordinates.
[0067] refer to Figure 2 as well as Figure 3 It can be seen that the point corresponding to the maximum value and the point corresponding to the minimum value form a straight line passing through the center of rotor 2. The polar coordinates of the center can be obtained from the coordinates of the two points.
[0068] like Figure 5As shown, in some embodiments, the measuring device includes at least three displacement sensors for measuring θ along the first polar coordinate system. 测 The gap X between the outer contour of rotor 2 and the inner contour of stator 1 in the radial direction of stator 1. 测 The corresponding θ of the displacement sensor 测 They are all different.
[0069] In other words, when arranging displacement sensors, it is necessary to adjust the detection direction of the displacement sensors to ensure that the measurement result is θ. 测 The gap in the direction.
[0070] Three sets of (X) can be measured using at least three displacement sensors. 测 θ 测 The coordinates can be substituted into equation (3) to find a and b.
[0071] Compared to measuring the offset in the x-direction and the offset in the y-direction, this method requires the sensor to be accurate not only in the measurement direction but also in the position of the position sensor.
[0072] In the scheme of this application, during installation, it is only necessary to ensure that the measuring direction of the displacement sensor points to the center of stator 1. The actual θ can be measured after the displacement sensor is installed. 测 Compared to other measurement methods, it has lower requirements for sensor installation accuracy.
[0073] In some embodiments, the measuring device includes at least four displacement sensors, the four displacement sensors corresponding to θ. 测 They are 0, Π / 2, Π, and 3Π / 2, respectively.
[0074] like Figure 5 As shown, the corresponding θ of the first displacement sensor 3 测 The value is 0, and the corresponding θ of the second displacement sensor 4 is 0. 测 For Π / 2, the corresponding θ of the third displacement sensor 5 测 For Π, the corresponding θ of the fourth displacement sensor 6 测 The value is 3π / 2. That is, the first displacement sensor 3 and the third displacement sensor 5 are arranged along the first direction and facing each other toward the center of the stator 1, and the second displacement sensor 4 and the fourth displacement sensor 6 are arranged along the second direction and facing each other toward the center of the stator 1, with the first direction perpendicular to the second direction.
[0075] It is more convenient to substitute it into equation (3), which reduces the calculation difficulty of the first function.
[0076] In some embodiments, step S101, establishing a first function X = f(θ) in the first polar coordinate system based on the measurement signal, includes the following sub-steps:
[0077] Based on the inner diameter of stator 1 and the outer diameter of rotor 2, a second function X = g(θ, a, b) is established, where a and b are the abscissa and ordinate of the center of rotor 2 in a rectangular coordinate system established with the center of stator 1 as the origin.
[0078] Multiple groups (θ) 测i X 测i Substituting these values into the second function yields multiple sets of (a) i b i );
[0079] For multiple groups (a) i b i Calculate the average and substitute the average into the second function to obtain the first function.
[0080] In other words, the coordinates of the center of rotor 2 can be measured by the displacement sensor of the measuring device, and the accuracy of the average value can be improved by increasing the number of displacement sensors.
[0081] The second function satisfies equation (3).
[0082] In some embodiments, obtaining the center coordinates based on the maximum and minimum coordinates includes the following sub-steps:
[0083] The polar angle of the center coordinates is determined based on the polar angle of the minimum value coordinates;
[0084] The polar radius of the center coordinates is determined based on the polar radius of the minimum coordinates and the polar radius of the maximum coordinates.
[0085] As can be seen from the above, the point corresponding to the maximum value coordinate is the point on the outer contour of rotor 2 that is furthest from the inner contour of stator 1. Figure 2 , Figure 4 It can be seen that the polar angle θ of its polar coordinates differs from that of the center coordinates by Π. The point corresponding to the minimum coordinate is the point on the outer contour of rotor 2 that is closest to the inner contour of stator 1, and its polar angle θ is equal to that of the center coordinate. Furthermore, the average of the polar radius of the minimum coordinate and the polar radius of the maximum coordinate is equal to the polar radius of the center coordinate.
[0086] In this application, the function can be obtained by differentiating X = f(θ).
[0087]
[0088] By setting X' = 0, we can obtain two θ values. Substituting these two θ values into equation (3) will give us two extreme values, the larger of which is the maximum and the other is the minimum.
[0089] In some embodiments, after calculating the adjusting force based on the center offset displacement, step S3 further includes the following step:
[0090] Determine whether there is an adjustment coil in the same direction as the adjustment displacement in the adjustment direction; if so, control the adjustment coil to generate the adjustment force.
[0091] If not, select at least two adjusting coils with an adjusting direction similar to the adjusting displacement direction for adjustment, and control the resultant force generated by each adjusting coil to be equal to the adjusting force.
[0092] In other words, when a single coil cannot achieve the adjustment force along the direction of the offset displacement, two adjacent adjustment coils can be selected to achieve the resultant force of the adjustment force along the direction of the offset displacement.
[0093] like Figure 6 As shown, this is a control method for a magnetic levitation bearing provided in related technologies, in which the same adjustment coil is used each time. Figure 7 The control method for a magnetic levitation bearing provided in this application, compared to Figure 6 Regarding the control method provided in this application, the displacement is not directly provided by the displacement sensor, but the output coil is selected based on the displacement vector.
[0094] Thanks to the aforementioned processing steps, the unidirectional gap measurement obtained from the displacement sensor can be converted into the center coordinates of rotor 2, further yielding the required adjustment displacement of rotor 2. This maximizes the alignment of the adjustment displacement direction with the output force direction, thereby improving the control accuracy of the magnetic levitation bearing.
[0095] In this application, after calculating the regulating force, the coil force is controlled based on the PWM ratio of the control coil. Furthermore, the regulation process incorporates two layers of PID control. Specifically, after each coil output, the coil current is measured, and the coil is further controlled based on the current to ensure the coil's PWM meets the calculation requirements. In the displacement loop, the displacement offset is constantly measured and compared with the adjusted displacement to obtain the next adjustment displacement, enabling rotor 2 to quickly and stably adjust to coincide with the preset position.
[0096] An embodiment of the present invention also provides a magnetic levitation bearing, comprising: a stator 1; a rotor 2 disposed within the stator 1; a measuring device installed on the stator 1 and generating a measuring signal; and an adjusting assembly installed on the stator 1 and generating an adjusting force according to the control method described above, so as to control the center of the rotor 2 to coincide with a preset position.
[0097] The adjustment component includes multiple sets of adjustment coils. When a single coil cannot meet the adjustment force along the adjustment displacement direction, multiple coils generate a resultant force along the adjustment displacement direction.
[0098] This application also provides a computer device including a memory and a processor. The memory stores a computer program. In one embodiment, when the computer program is executed by the processor, it further performs the following steps: calculating the center coordinates of the rotor based on the measurement signal from the measuring device; determining an adjustment displacement based on the center coordinates and the polar coordinates of a preset position of the rotor; calculating an adjustment force based on the adjustment displacement, wherein the adjustment force is in the same direction as the adjustment displacement; calculating an adjustment force based on the center offset displacement, wherein the direction of the adjustment force is in the same direction as the center offset displacement; applying the adjustment force to the rotor to move the rotor so that the center of the rotor coincides with the preset position. This improves the control accuracy of the layered magnetic levitation bearing.
[0099] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this disclosure can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.
[0100] This application also provides a magnetic levitation bearing, which includes a stator; a rotor passing through the stator; a measuring device installed on the stator and generating a measuring signal; and an adjusting assembly installed on the stator for implementing the above-described control method to control the center of the rotor to coincide with a preset position.
[0101] This application also provides a compressor that includes the aforementioned magnetic levitation bearing.
[0102] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A control method for magnetic levitation bearings, characterized in that, It includes the following steps: The center coordinates of the rotor are calculated based on the measurement signals from the measuring device; wherein, the center coordinates are the polar coordinates of the rotor's center in a first polar coordinate system with the stator center as the pole; The adjustment displacement is determined based on the center coordinates and the polar coordinates of the rotor's preset position; The adjusting force is calculated based on the adjusting displacement, and the adjusting force is in the same direction as the adjusting displacement. The adjusting force is applied to the rotor to move the rotor so that the center of the rotor coincides with the preset position; The calculation of the rotor's center coordinates based on the measurement signal from the measuring device includes the following sub-steps: Based on the measured signal, establish the first function X=f( ), where X is along the first polar coordinate system The gap between the inner profile of the stator and the outer profile of the rotor in the radial direction of the stator at an angle; Calculate the first function in The coordinates of the maximum and minimum values within the range; The center coordinates are obtained based on the maximum and minimum coordinates. The measuring device includes at least three displacement sensors, which are used to measure along the first polar coordinate system. 测 The gap X between the outer profile of the rotor and the inner profile of the stator in the radial direction of the stator. 测 The corresponding displacement sensor 测 They are all different; The first function X=f(established in the first polar coordinate system based on the measurement signal) This includes the following sub-steps: Based on the stator inner diameter and the rotor outer diameter, establish the second function X=g( , a, b), where a and b are the abscissa and ordinate of the rotor center in a rectangular coordinate system established with the stator center as the origin, respectively; Multiple groups ( 测i X 测i Substituting these values into the second function yields multiple sets of (a) i b i ); For multiple groups (a) i b i Calculate the average and substitute the average into the second function to obtain the first function; The second function X=g ( (a, b) satisfy the following expression: Where r1 is the inner diameter of the stator and r2 is the outer diameter of the rotor; The step of obtaining the center coordinates based on the maximum and minimum coordinates includes the following sub-steps: The polar angle of the center coordinates is determined based on the polar angle of the minimum value coordinates; The polar radius of the center coordinates is determined based on the polar radius of the minimum coordinates and the polar radius of the maximum coordinates.
2. The control method according to claim 1, characterized in that, The measuring device includes at least four displacement sensors, the four displacement sensors corresponding to... 测 They are 0, Π / 2, Π, and 3Π / 2, respectively.
3. The control method according to claim 1, characterized in that, After calculating the adjusting force based on the adjusting displacement, the method further includes the following steps: Determine whether there is an adjustment coil in the same direction as the adjustment displacement direction. If so, control the adjustment coil to generate the adjustment force. If not, select at least two adjustment coils with an adjustment direction similar to the adjustment displacement direction for adjustment, and control the resultant force generated by each control adjustment coil to be equal to the adjustment force.
4. A computer device, characterized in that, It includes a memory and a processor, the memory storing a computer program, wherein the processor executes the computer program to implement the steps of the control method according to any one of claims 1 to 3.
5. A computer-readable storage medium, characterized in that, It stores a computer program, wherein the computer program, when executed by a processor, implements the steps of the control method according to any one of claims 1 to 3.
6. A magnetic levitation bearing, characterized in that, It includes: stator; A rotor that passes through the stator; A measuring device, which is mounted on the stator and generates a measuring signal; An adjustment component, mounted on the stator, is used to implement the control method according to any one of claims 1-3, to control the center of the rotor to coincide with a preset position.