A magnetic levitation stirrer and stirring method

Abstract

This invention belongs to the field of stirrers, specifically relating to a magnetic levitation stirrer and stirring method. The magnetic levitation stirrer includes a container, a stirring shaft assembly, a stirring shaft positioning assembly, and a power assembly. The container includes an upper main cavity and a lower stirring shaft mounting cavity that are interconnected. The stirring shaft assembly includes an impeller and a rotating shaft that are interconnected. The impeller is disposed without contact within the main cavity, and the rotating shaft is disposed without contact within the stirring shaft mounting cavity. The stirring shaft positioning assembly includes at least two sets of axially arranged suspension bearings disposed outside the stirring shaft mounting cavity of the container, with the at least two sets of suspension bearings levitizing the rotating shaft axially and radially. The power assembly is used to drive the rotating shaft to rotate without contact. This invention truly achieves zero contact between the stirring shaft assembly and the container, and is convenient to install, has a larger capacity, and provides better stirring effect.

Description

Technical Field

[0001] This invention belongs to the field of stirrers, specifically relating to a magnetic levitation stirrer and a stirring method. Background Technology

[0002] Agitators are a common production equipment in the biopharmaceutical industry, used to stir mixed drug solutions to ensure uniform mixing. Traditional medical agitators use a stirring shaft to stir the mixed drug solution in a mixing tank. The stirring shaft is driven by a motor through mechanical transmission, without the need for suspension control, and the mixing tank cannot be sealed. During the operation of the agitator, friction and wear of the mechanical transmission device can easily cause fine dust to mix into the drug solution, which can adversely affect the quality of the finished product.

[0003] Existing magnetic stirrers use permanent magnet materials to make small stirrers. The stirrers are driven to rotate by the rotating magnetic field of the base. This allows for stirring of the liquid medicine in a sealed environment, but it does not provide static buoyancy. At low speeds, the stirrers will come into contact with the mixing tank, which also poses a risk of micro-dust pollution due to wear.

[0004] For the reasons mentioned above, magnetic levitation stirrers using active magnetic levitation bearings are currently a research hotspot and have broad application prospects in the biopharmaceutical industry. Taking the Chinese patent "CN202223219180.1 A Horizontal Fully Sealed Single-Axis High-Temperature Superconducting Magnetic Levitation Sterile Stirrer" as an example, this type of magnetic levitation stirrer also adopts a "bearing + motor" structure. The motor is used to control the axial rotational degree of freedom, while the other five degrees of freedom are controlled by magnetic levitation bearings. Its basic structure is similar to that of a five-degree-of-freedom magnetic levitation bearing. However, in order to meet the requirements of non-contact stirring, the axial length of the rotating shaft is limited and must be within the space of the stirring tank. There is no base to provide axial support force, so axial bearings cannot be used. If it is changed to a vertical stirrer, an axial bearing or a central axial suspension bearing must be installed between the inner magnet and the inner wall of the left side of the stirrer housing to achieve this. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a magnetic levitation stirrer and stirring method that has a non-contact stirring shaft assembly, is easy to install, and has a better stirring effect.

[0006] This invention provides a magnetic levitation stirrer, comprising a container, a stirring shaft assembly, a stirring shaft positioning assembly, and a power assembly;

[0007] The container includes an upper main cavity and a lower stirring shaft mounting cavity that are interconnected.

[0008] The stirring shaft assembly includes an impeller and a rotating shaft connected to each other. The impeller is disposed in the main cavity without contact, and the rotating shaft is disposed in the stirring shaft mounting cavity without contact.

[0009] The stirring shaft positioning assembly includes at least two sets of suspension bearings arranged along the axis, located outside the stirring shaft mounting cavity of the container, and the at least two sets of suspension bearings suspend the rotating shaft in the axial and radial directions.

[0010] The power unit is used to drive the shaft to rotate without contact.

[0011] Furthermore, the outer wall of the rotating shaft is provided with blades, which are used to guide the liquid medicine in the stirring shaft mounting cavity to the main cavity, or the blades are used to generate lift.

[0012] Furthermore, the outer walls of the main cavity, the lower stirring shaft mounting cavity, and the stirring shaft assembly are coated with an anti-fouling coating.

[0013] Furthermore, the two sets of suspension bearings are respectively installed at the upper and lower ends of the rotating shaft.

[0014] Furthermore, the power assembly includes a stator disposed on the outside of the container's stirring shaft mounting cavity and a rotor disposed on the rotating shaft, the stator and rotor being positioned between two sets of suspension bearings.

[0015] Furthermore, it also includes a suspension bearing control system, which includes a shaft speed sensor, a shaft position sensor, and a controller;

[0016] A shaft speed sensor is used to detect the shaft speed.

[0017] The shaft position sensor is used to detect the axial and radial position of the shaft;

[0018] The controller is used to adjust the current of the two sets of suspension bearings based on the weight of the stirring shaft assembly, the rotation speed of the shaft, and the position of the shaft, thereby adjusting the axial and radial suspension positions of the two sets of suspension bearings relative to the shaft.

[0019] Furthermore, the controller is used to:

[0020] The required axial magnetic force of the rotating shaft is calculated based on the rotational speed of the shaft and the self-weight of the stirring shaft assembly, including:

[0021] The axial force exerted by the liquid on the shaft is calculated based on the shaft rotation speed.

[0022] The required axial magnetic force of the stirring shaft assembly is calculated based on the axial force and the self-weight of the stirring shaft assembly:

[0023] F c =F1+G1

[0024] Among them, F c F1 is the required axial magnetic force, G1 is the axial force, and G1 is the weight of the stirring shaft assembly.

[0025] Furthermore, the required current value for the suspension bearing is calculated based on the axial position deviation of the shaft and the required axial magnetic force, including:

[0026] Finite element models of the suspension bearing and the shaft were established using electromagnetic field simulation software. The axial magnetic force values ​​corresponding to various axial position deviations under specific current ampere-turns were calculated, and multiple axial position deviation-axial magnetic force value curves were plotted.

[0027] Set the axial position deviation of the shaft, and calculate the required radial and axial current values ​​based on the set axial position deviation, the required axial magnetic force, and the axial position deviation-axial magnetic force value curve by looking up a table or fitting.

[0028] Furthermore, it also includes a support, with the bottom of the main cavity located at the top of the support, the stirring shaft mounting cavity located inside the support, and the support located outside the stirring shaft mounting cavity having a mounting cavity for mounting the suspension bearing and power component structure.

[0029] The present invention also provides a stirring method using a magnetically levitated stirrer with blades, comprising the following steps:

[0030] S1, Install the stirring shaft assembly into the container;

[0031] S2, Pour the liquid to be mixed into the container, filling the gap between the stirring shaft mounting cavity and the rotating shaft and part of the main cavity;

[0032] S3, the stirring shaft positioning component starts working, suspending the stirring shaft component in the container without contact;

[0033] S4, the power unit starts working, and the stirring shaft assembly starts rotating. The impeller performs the main stirring of the liquid in the main chamber, and the blades guide the liquid in the gap between the stirring shaft mounting cavity and the rotating shaft to the main chamber for auxiliary stirring.

[0034] The beneficial effects of this invention are that the magnetic levitation stirrer provided by this invention can truly achieve zero contact between the stirring shaft assembly and the container. By setting the stirring shaft mounting cavity in the lower part of the main container, at least the following four effects are achieved: 1. The gap between the stirring shaft assembly and the container is filled with the liquid to be stirred, therefore the stirring shaft mounting cavity also contains the liquid, which can increase the capacity of the liquid in the container; 2. The stirring shaft mounting cavity is easy to install; installation is completed simply by placing the rotating shaft into the stirring shaft mounting cavity; 3. The liquid fills the space between the container and the stirring shaft assembly, and when the mixing temperature of the liquid is lower than the heat generated by the levitation bearing and the power component, the stirring of the liquid is not sensitive to temperature. In addition, the liquid can also cool the suspension bearing and power components, improving driving performance; Fourth, the space between the stirring shaft mounting cavity and the rotating shaft is filled with liquid. By simply installing blades on the rotating shaft to guide the liquid in the stirring shaft mounting cavity to the main cavity, auxiliary stirring can be achieved, improving the stirring effect and further enhancing the heat dissipation effect on the suspension bearing and power components (the liquid in the stirring shaft mounting cavity is heated after heat exchange. The blades can guide the heated liquid into the main cavity for continued stirring. The liquid in the main cavity flows back into the stirring shaft mounting cavity for heat exchange again, and this cycle is repeated to ensure the temperature of the liquid in the stirring shaft mounting cavity). Attached Figure Description

[0035] Appendix Figure 1 This is a schematic diagram of the structure of the present invention;

[0036] Appendix Figure 2 This is a top view of the present invention;

[0037] Appendix Figure 3 for Figure 2 Sectional view along line AA;

[0038] Appendix Figure 4 This is a schematic diagram of the container structure in this invention;

[0039] Appendix Figure 5 This is a schematic diagram of the support structure in this invention;

[0040] Appendix Figure 6 This is a schematic diagram of the rotating shaft portion in this invention;

[0041] Appendix Figure 7 This is a schematic diagram of the structure of the rotating shaft with blades in this invention;

[0042] Appendix Figure 8 This is a schematic diagram of the connection relationship in this invention;

[0043] Appendix Figure 9 This is a top view of the upper suspension bearing in this invention;

[0044] Appendix Figure 10This is a top view of the lower suspension bearing in this invention;

[0045] Appendix Figure 11 Simulation results of the variation curves of axial magnetic force and axial position deviation of the suspension bearing under different current ampere-turns;

[0046] Appendix Figure 12 This is a block diagram of the decoupling control of the upper and lower suspension bearings in this invention.

[0047] In the diagram, 1-container; 11-main cavity; 12-stirring shaft mounting cavity; 2-stirring shaft assembly; 21-impeller; 22-rotating shaft; 23-blade; 24-suspended fitting ring; 3-stirring shaft positioning assembly; 31-suspended bearing; 31a-upper suspended bearing; 310a-first stator core; 311a~318a-first coil; 31b-lower suspended bearing; 310b-second stator core; 311a~318a-second coil; 4-power assembly; 41-stator; 42-rotor; 5-support; 51-outer shell; 52-upper ring plate; 53-lower fixed plate; 54-mounting cavity; 6-radial Hall sensor; 61-permanent magnet array; 7-axial Hall sensor; 8-displacement sensor; 8a-upper displacement sensor; 8b-lower displacement sensor. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0050] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0053] As attached Figure 1-12 As shown, the present invention provides a magnetic levitation stirrer, including a container 1, a stirring shaft assembly 2, a stirring shaft positioning assembly 3, and a power assembly 4;

[0054] The container 1 includes an upper main cavity 11 and a lower stirring shaft mounting cavity 12 that are interconnected. The stirring shaft mounting cavity 12 is located in the lower part of the main cavity 11, which can increase the volume of the container 1 to a certain extent. More importantly, this arrangement can simplify the installation of the stirring shaft assembly 2. During installation, the rotating shaft 22 only needs to be placed in the stirring shaft mounting cavity 12 by gravity. On the other hand, it provides a basis for the auxiliary stirring of the blades.

[0055] The stirring shaft assembly 2 includes an impeller 21 and a rotating shaft 22 connected to each other. The impeller 21 is disposed in the main cavity 11 without contact, and the rotating shaft 22 is disposed in the stirring shaft mounting cavity 12 without contact. Specifically, the non-contact is achieved by the stirring shaft positioning assembly 3. With this configuration, the rotation of the stirring shaft assembly 2 will not have friction and wear because there is no mechanical transmission device, and will not generate fine dust due to friction that will mix into the liquid medicine, thereby ensuring the quality of the finished liquid medicine.

[0056] The stirring shaft positioning assembly 3 includes at least two sets of suspension bearings 31 arranged along the axis, located outside the stirring shaft mounting cavity 12 of the container 1. The at least two sets of suspension bearings 31 suspend the rotating shaft 22 axially and radially. The suspension bearings 31 provided by the present invention can suspend and limit the rotating shaft 22 axially and radially. This is different from existing suspension stirrers (e.g., Chinese patent "CN202223219180.1 A horizontal fully sealed single-axis high temperature superconducting magnetic levitation sterile stirrer". If it is changed to a vertical stirrer, an axial bearing or a central axial suspension bearing must be installed between the inner magnet and the inner wall of the left side of the stirrer shell to achieve this). The axial bearing can be eliminated, achieving true zero-contact rotation.

[0057] The power component 4 is used to drive the rotating shaft 22 to rotate without contact.

[0058] The magnetic levitation stirrer provided by this invention can truly achieve zero contact between the stirring shaft assembly 2 and the container 1. By setting the stirring shaft mounting cavity 12 at the lower part of the main container 11, it achieves at least the following four effects: 1. The gap between the stirring shaft assembly 2 and the container 1 is filled with the liquid to be stirred, therefore the stirring shaft mounting cavity 12 also contains the liquid, increasing the capacity of the liquid in the container; 2. The stirring shaft mounting cavity 12 is easy to install; installation is completed simply by placing the rotating shaft into the stirring shaft mounting cavity 12; 3. The liquid fills the space between the container 1 and the stirring shaft assembly 2. When the mixing temperature of the liquid is lower than the heat generated by the suspension bearing 31 and the power assembly 4, and the stirring of the liquid is not sensitive to temperature, the liquid can still... To cool down the suspension bearing 31 and the power assembly 4 and improve driving performance; Fourth, the space between the stirring shaft mounting cavity 12 and the rotating shaft 22 is filled with liquid medicine. By simply setting blades 23 on the rotating shaft 22 to guide the liquid medicine in the stirring shaft mounting cavity 12 to the main cavity 11, auxiliary stirring can be achieved, which can improve the stirring effect and further improve the heat dissipation effect on the suspension bearing 31 and the power assembly 4 (the liquid medicine in the stirring shaft mounting cavity 12 is heated after heat exchange. Setting blades 23 can guide the heated liquid medicine into the main cavity 11 to continue stirring. The liquid medicine in the main cavity 11 flows back into the stirring shaft mounting cavity 12 for heat exchange again. This cycle is repeated to ensure the temperature of the liquid medicine in the stirring shaft mounting cavity 12).

[0059] refer to Figure 7 In one embodiment, the outer wall of the rotating shaft 22 is provided with blades 23. The blades 23 are used to guide the liquid medicine in the stirring shaft mounting cavity 12 to the main cavity 11, or the blades 23 are used to generate lift. In this embodiment, there is a certain gap between the outer wall of the blades 23 and the stirring shaft mounting cavity 12 to ensure that the stirring shaft assembly 2 and the container 1 do not contact each other, while ensuring that the liquid medicine circulates in the stirring shaft mounting cavity 12.

[0060] When the blade 23 guides the liquid medicine in the stirring shaft mounting cavity 12 to the main cavity 11, the blade 23, installed on the outer wall of the rotating shaft 22, guides the liquid medicine in the stirring shaft mounting cavity 12 to the main cavity 11, thereby achieving an axial jet in the main cavity 11 (due to the small gap between the rotating shaft 22 and the stirring shaft mounting cavity 12, a jet of a certain intensity can be formed, ensuring the effect of auxiliary mixing). This jet mixes with the radial rotational flow of the liquid medicine achieved by the impeller 21, greatly improving the mixing degree of the liquid medicine. Under the same stirring power and the same stirring time, the stirring effect of the liquid medicine can be improved. In addition, when the liquid medicine can dissipate heat from the suspension bearing 31 and the power component 4, the impeller 21 can also ensure the heat dissipation effect. That is, the liquid medicine in the stirring shaft mounting cavity 12 is heated after heat exchange. The blades 23 can guide the heated liquid medicine into the main cavity 11 for continued stirring. The liquid medicine in the main cavity 11 flows back into the stirring shaft mounting cavity 12 for heat exchange again. This cycle is repeated to ensure the temperature of the liquid medicine in the stirring shaft mounting cavity 12. Under normal circumstances, the stirring of the liquid medicine is completed before all the liquid medicine is heated to near the heat output of the suspension bearing 31 and the power component 4.

[0061] In this embodiment, the stirring effect and the heat dissipation effect on the suspension bearing 31 and the power component 4 can be improved by using only a simple blade 23 structure.

[0062] Specifically, the blades 23 can be a spiral guide structure arranged at intervals. As long as the rotating shaft 22 rotates, the blades 23 can guide the liquid medicine located in the stirring shaft mounting cavity 12 into the main cavity 11.

[0063] The blade 23 is used to generate lift. The installation direction of the blade 23 is opposite to that used for guiding the flow. The effect of auxiliary stirring is small, but it can reduce the electromagnetic force required by the suspension bearing, thereby reducing energy consumption.

[0064] In this embodiment, the rotating shaft 22 is covered with a layer of material on the outside of the rotor 42, so that the overall shape of the rotating shaft 22 is a cylinder, and the blades 23 are arranged on the outside of the cylinder.

[0065] In one embodiment, the outer walls of the main cavity 11, the lower stirring shaft mounting cavity 12, and the stirring shaft assembly 2 are coated with an anti-pollution coating, or are made of materials such as stainless steel or PE, which can prevent contamination of the liquid medicine and further improve the stirring quality of the liquid medicine.

[0066] refer to Figure 3 In one embodiment, the two sets of suspension bearings 31 are respectively disposed at the upper and lower ends of the rotating shaft 22, thereby improving the axial and radial suspension positioning effect of the suspension bearings 31 on the rotating shaft.

[0067] In one embodiment, the upper and lower ends of the rotating shaft 22 are provided with two sets of suspension bearings 31, and the suspension rings 24 are made of Q235 material. In a preferred embodiment, the rotating shaft 22 and the suspension rings 24 are integrally machined from Q235 material. In addition, considering the suspension capacity of the suspension bearings 31, the weight of the rotating shaft 22 is limited to within 0.5 kg. Therefore, the rotating shaft 22 is designed as a hollow structure.

[0068] In another embodiment, the suspension bearing 31 includes a stator core arranged in a ring and magnetic pole coils wound on the stator core. The suspension bearing 31 contains 8 magnetic poles, divided into 4 groups for control, with 2 coils connected in series in each group; by controlling the current in the magnetic pole coils, an electromagnetic force is generated, thereby making the rotating shaft 22 stably levitate at a designated position.

[0069] In one embodiment, the power assembly 4 includes a stator 41 disposed on the outside of the stirring shaft mounting cavity 12 of the container 1 and a rotor 42 disposed on the rotating shaft 22. The stator 41 and the rotor 42 are disposed between two sets of suspension bearings 31. In this embodiment, the power assembly 4 adopts the principle of a permanent magnet synchronous motor to drive the rotating shaft 22 to rotate at high speed.

[0070] Specifically, the stator 41 includes a stator core arranged in a ring and a coil wound on the stator core;

[0071] The rotor 42 consists of several permanent magnet blocks arranged circumferentially along the shaft 22. The permanent magnet blocks are magnetized in parallel in the thickness direction. The surface magnetic flux uniformity of each permanent magnet block is ≤3%, and the polarization angle deviation is less than 3 degrees. Furthermore, the N and S poles of adjacent permanent magnet blocks are arranged alternately.

[0072] By energizing the coil, an electromagnetic force is generated, which in turn causes the rotating shaft 22 to rotate.

[0073] In one embodiment, the present invention further includes a suspension bearing control system, which includes a shaft speed sensor, a shaft position sensor, and a controller;

[0074] The shaft speed sensor is used to detect the rotational speed of shaft 22. The shaft speed sensor can be a radial Hall sensor 6 mounted on support 5. (Refer to...) Figure 6 Preferably, a permanent magnet array 61 is set at the location corresponding to the radial Hall sensor 6 on the rotating shaft 22 to facilitate rotational speed measurement;

[0075] The shaft position sensor is used to detect the axial and radial positions of the shaft 22. The shaft position sensor includes an axial Hall sensor 7 mounted on the support 5 for detecting the axial position of the shaft and a displacement sensor 8 mounted on the support 5 for detecting the radial position of the shaft.

[0076] The controller is used to adjust the current of the two sets of suspension bearings 31 according to the weight of the stirring shaft assembly 2, the rotation speed of the rotating shaft 22 and the position data of the rotating shaft 22, thereby adjusting the axial and radial suspension positions of the two sets of suspension bearings 31 relative to the rotating shaft 22 to ensure the suspension stability of the rotating shaft 22.

[0077] refer to Figure 8 Specifically, the entire agitator also includes a host computer control system for controlling the suspension bearing control system and the power component 4. The host computer control system realizes the operation control of the system application. During use, the shaft position sensor detects the shaft position signal and sends the position signal to the controller. The controller processes the signal according to the control strategy and then controls the current of the electromagnet coil in the suspension bearing 31 through the power amplifier, thereby generating electromagnetic force and making the shaft stably suspend at the specified position. The host computer control system can also control the motor controller, which controls the motor driver to adjust the current of the coil in the rotor 42 and adjust the rotation of the shaft 22.

[0078] In one embodiment, the controller is used to:

[0079] The required axial magnetic force of the rotating shaft is calculated based on the rotational speed of the rotating shaft 22 and the self-weight of the stirring shaft assembly 2, including:

[0080] The axial force exerted by the liquid on the rotating shaft 22 is calculated based on the rotational speed of the rotating shaft 22.

[0081] The required axial magnetic force of the stirring shaft assembly 2 is calculated based on the axial force and the self-weight of the stirring shaft assembly 2:

[0082] F c =F1+G1

[0083] Among them, F c F1 is the required axial magnetic force, G1 is the axial force, and G1 is the weight of the stirring shaft assembly 2.

[0084] In one embodiment, the required current value of the suspension bearing 31 is calculated based on the axial position deviation of the rotating shaft 22 and the required axial magnetic force, including:

[0085] Finite element models of the suspension bearing 31 and the rotating shaft 22 were established using electromagnetic field simulation software. The axial magnetic force values ​​corresponding to each axial position deviation under a specific current ampere-turns were calculated, and multiple axial position deviation-axial magnetic force value curves were plotted.

[0086] Set the axial position deviation of the rotating shaft 22. Based on the set axial position deviation of the rotating shaft 22, the required axial magnetic force, and the axial position deviation-axial magnetic force value curve, calculate the required radial and axial current values ​​by looking up a table or by fitting.

[0087] In one embodiment, the controller is used to:

[0088] Obtain the rotational speed and weight data of the stirring shaft assembly 2, and calculate the required axial magnetic force of the rotating shaft 22 based on the rotational speed and weight of the stirring shaft assembly 2;

[0089] The required current values ​​of the two sets of suspension bearings 31 are calculated based on the axial position deviation of the rotating shaft 22 and the required axial magnetic force, and the required current values ​​of the suspension bearings 31 are taken as the current zero point.

[0090] An XOY coordinate system is constructed along the same radial direction of the upper suspension bearing 31a and the lower suspension bearing 31b, respectively; in the XOY coordinate system, the positive X direction and the positive Y direction are both located on the axis of symmetry of the adjacent coils;

[0091] The X-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the rotating shaft 22 in the X-direction of the upper suspension bearing 31a, and the Y-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the rotating shaft 22 in the Y-direction of the upper suspension bearing 31a.

[0092] The X-direction current correction value of the lower suspension bearing 31b is calculated based on the radial position deviation of the rotating shaft 22 in the X-direction of the lower suspension bearing 31b, and the Y-direction current correction value of the lower suspension bearing 31b is calculated based on the radial position deviation of the rotating shaft 22 in the Y-direction of the lower suspension bearing 31b.

[0093] The current of the upper suspension bearing 31a is controlled based on the X-direction current correction value and the Y-direction current correction value of the upper suspension bearing 31a and the current zero point. At the same time, the current of the lower suspension bearing 31b is controlled based on the X-direction current correction value and the Y-direction current correction value of the lower suspension bearing 31b and the current zero point.

[0094] Specifically, refer to Figures 8-12 In one embodiment, the present invention also provides a decoupling control method for an axial bearingless active magnetic levitation stirrer.

[0095] This can be applied to the magnetic levitation stirrer of this application. Specifically, an upper suspension bearing 31a and a lower suspension bearing 31b are arranged on the outer side of the rotating shaft 22. The upper suspension bearing 31a is equipped with an upper position sensor 8a, and the lower suspension bearing 31b is equipped with a lower position sensor 8b. The stator 41 is arranged between the upper suspension bearing 31a and the lower suspension bearing 31b, and the three are coaxial. A rotor 42 is arranged on the rotating shaft 22, and the rotor 42 consists of multiple magnets arranged in an array, maintaining the same height as the stator 41. A rotating shaft speed sensor is arranged at the bottom; in one specific embodiment, the rotating shaft speed sensor is a radial Hall sensor 6.

[0096] The structure of the upper suspension bearing 31a is as follows Figure 9 As shown, eight first coils, numbered 311a to 318a, are sequentially wound on the first stator core 310a. An XOY coordinate system is defined, with the positive X-axis located on the axis of symmetry between first coils 311a and 312a, and the positive Y-axis located on the axis of symmetry between first coils 313a and 314a. Similarly, the structure of the lower suspension bearing 31b is as follows... Figure 10 As shown, eight second coils, numbered 311b to 318b, are wound sequentially on the second stator core 310b, and they use the same coordinate system XOY as the upper suspension bearing 31a.

[0097] The specific implementation of this invention is as follows: based on the measurement results of the shaft speed sensor, the corresponding current zero point is calculated; based on the detection results of the upper position sensor 8a, the current correction values ​​in the X and Y directions of the upper suspension bearing 31a are calculated, and differential control is performed on the corresponding actual current; based on the detection results of the lower position sensor 8b, the current correction values ​​in the X and Y directions of the lower suspension bearing 31b are calculated, and differential control is performed on the corresponding actual current.

[0098] In one embodiment, a decoupling control method for an axial bearing-free active magnetic levitation stirrer is provided, comprising the following steps:

[0099] Step 402: Obtain the rotational speed and weight of the active magnetic levitation stirrer's shaft 22, and calculate the required axial magnetic force of the shaft 22 based on the rotational speed and weight of the shaft 22.

[0100] Specifically, based on the rotational speed and weight of the agitator shaft 22, the corresponding axial load is calculated, and the required axial magnetic force value is determined so that the axial magnetic force value is equal to the corresponding axial load.

[0101] The active magnetic levitation stirrer has a suspension bearing 31 on the outside of the rotating shaft 22. The suspension bearing 31 includes an upper suspension bearing 31a and a lower suspension bearing 31b.

[0102] As the stirrer shaft 22 rotates in the liquid medicine, it experiences a reaction force from the liquid, manifested as an axial force, which varies with the rotational speed. For a specific shaft 22 structure, the relationship between this force and rotational speed can be obtained through testing. Therefore, the required axial magnetic force, in addition to overcoming the shaft 22's own weight, must also counteract the axial force.

[0103] Step 404: Calculate the required current value of the suspension bearing based on the axial position deviation of the rotating shaft 22 and the required axial magnetic force, and take the required current value of the suspension bearing as the current zero point.

[0104] When the axial load remains constant, the current zero point remains constant; when the rotational speed of the shaft 22 changes, causing the axial load to change, or when the axial load fluctuates due to uneven stirring liquid, the current zero point will automatically adjust to the corresponding value according to the control algorithm.

[0105] For a specific structure of the suspension bearing 31 and the rotating shaft 22, the magnitude of the axial magnetic force is affected by the ampere-turns of the current and the axial position deviation. The axial position deviation is typically set according to the specific application scenario and denoted as Δz0. Once set, the axial position deviation remains unchanged during the operation of the magnetic levitation stirrer. The axial position deviation is selected based on the top-level requirements; for example, when the suspension bearing core height is 8mm, a 2mm axial position deviation is sufficient. Given the axial magnetic force, the required zero current can be calculated using table lookup and fitting methods.

[0106] Step 406: Construct XOY coordinate systems along the same radial direction of the upper suspension bearing 31a and the lower suspension bearing 31b respectively.

[0107] In the XOY coordinate system, the positive X and positive Y directions are both located on the axis of symmetry of the adjacent coils.

[0108] Step 408: The X-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the rotating shaft 22 in the X-direction of the upper suspension bearing 31a. At the same time, the Y-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the rotating shaft 22 in the Y-direction of the upper suspension bearing 31a. The X-direction current correction value of the lower suspension bearing 31b is calculated based on the radial position deviation of the rotating shaft 22 in the X-direction of the lower suspension bearing 31b. At the same time, the Y-direction current correction value of the lower suspension bearing 31b is calculated based on the radial position deviation of the rotating shaft 22 in the Y-direction of the lower suspension bearing 31b.

[0109] Radial position deviation refers to the distance from the central axis.

[0110] Based on the radial position deviation of the shaft 22 corresponding to the upper suspension bearing 31a, the current correction value is calculated in two independent radial directions. Combined with the current zero point mentioned in 2, the corresponding current of the upper suspension bearing 31a is controlled so that: (1) when the position of the shaft 22 deviates from the central axis in a certain radial direction, the generated current can make the shaft 22 move towards the central axis and will not affect the movement in the other direction; (2) the greater the distance of the shaft 22 from the central axis, the greater the restoring force generated; (3) when the shaft 22 does not deviate from the central axis, the current correction value is 0; (4) in the radial direction, the sum of the axial magnetic forces generated after the current correction is basically equal to the sum of the axial magnetic forces before correction, and the total axial magnetic force generated will not be affected by the current correction.

[0111] Based on the radial position deviation of the shaft 22 corresponding to the lower suspension bearing 31b, the current correction value is calculated in the two independent radial directions that are the same as those mentioned above. Combined with the current zero point mentioned above, the corresponding current of the lower suspension bearing 31b is controlled in the same way as the above method.

[0112] Step 410: Control the current of the upper suspension bearing 31a according to the X positive direction current correction value, the Y positive direction current correction value, and the current zero point of the upper suspension bearing 31a; at the same time, control the current of the lower suspension bearing 31b according to the X positive direction current correction value, the Y positive direction current correction value, and the current zero point of the lower suspension bearing 31b.

[0113] In the above-mentioned decoupling control method for an axial bearingless active magnetic levitation stirrer, the required zero-current position for the suspension bearings is first calculated based on the rotational speed and the weight of the shaft 22. Secondly, the required current correction values ​​are calculated based on the radial position deviations of the upper suspension bearing 31a and the lower suspension bearing 31b in the X and Y directions, respectively. Finally, the required target current value is generated based on the zero-current position and the current correction value, and the actual current in the corresponding direction is rapidly adjusted to match the target current value. This method has the following technical advantages: 1. The required axial magnetic force and current value are calculated based on the rotational speed and weight of the shaft 22, resulting in good matching between the control parameters and the model, and a fast start-up response. 2. The zero-current position can be adjusted in real time according to changes and fluctuations in the axial load, providing good adaptability to working conditions and strong anti-interference capability. 3. The suspension bearings are divided into upper suspension bearing 31a and lower suspension bearing 31b, which share the same radial direction, enabling coordinated control of the radial degree of freedom. 4. In the agreed radial direction, both the upper suspension bearing 31a and the lower suspension bearing 31b use differential control to correct the current, so that within a small deviation range, the sum of the axial magnetic forces generated after the current correction is basically equal to the sum of the axial magnetic forces before correction. The total axial magnetic force generated will not be affected by the current correction, thus achieving decoupling between radial control and axial control.

[0114] In one embodiment, the required axial magnetic force of the rotating shaft 22 is calculated based on the rotational speed of the rotating shaft 22 and the self-weight of the rotating shaft 22, including:

[0115] The axial force exerted by the liquid on the rotating shaft 22 in the active magnetic levitation stirrer is calculated based on the rotational speed of the rotating shaft 22.

[0116] The required axial magnetic force of shaft 22 is calculated based on the axial force and the weight of shaft 22:

[0117] F c =F1+G1

[0118] Among them, F c F1 is the required axial magnetic force, G1 is the axial force, and G1 is the weight of the rotating shaft 22.

[0119] In one embodiment, the required current value of the suspension bearing is calculated based on the axial position deviation of the shaft 22 and the required axial magnetic force, including:

[0120] Finite element models of the suspension bearing and shaft 22 were established using electromagnetic field simulation software. The axial magnetic force values ​​corresponding to various axial position deviations under specific current ampere-turns were calculated, and multiple axial position deviation-axial magnetic force value curves were plotted. Figure 11 As shown, simulation results of the variation curves of axial magnetic force and axial position deviation of the suspension bearing under different current ampere-turns are provided.

[0121] Set the axial position deviation of the rotating shaft 22. Based on the set axial position deviation of the rotating shaft 22, the required axial magnetic force, and the axial position deviation-axial magnetic force value curve, calculate the required radial and axial current values ​​by looking up a table or by fitting.

[0122] In one embodiment, the required radial and axial current values ​​are calculated by looking up a table or fitting based on the pre-defined axial position deviation of the rotating shaft 22 and the axial position deviation-axial magnetic force value curve, including:

[0123] When the set axial position deviation of the rotating shaft 22 and the position corresponding to the required axial magnetic force are located on the axial position deviation-axial magnetic force value curve, the required ampere-turns of current can be obtained by looking up the table. Based on the ratio of the required ampere-turns of current to the number of coil turns, the required current value of the suspension bearing can be obtained.

[0124] I0 = NI0 / N

[0125] Where I0 is the required current value of the suspension bearing, NI0 is the required ampere-turns, and N is the number of coil turns;

[0126] When the set axial position deviation of the rotating shaft 22 and the corresponding position of the required axial magnetic force are not on the axial position deviation-axial magnetic force value curve, the axial position deviation value and current ampere-turn value on the two adjacent axial position deviation-axial magnetic force value curves of the corresponding position are read respectively, and then the required current value of the suspension bearing is calculated by linear interpolation:

[0127]

[0128] Wherein, NI1 and NI2 are the current ampere-turn values ​​on the two adjacent axial position deviation-axial magnetic force value curves, respectively; Δz0 is the set axial position deviation of the rotating shaft 22; and Δz1 and Δz2 are the axial position deviation values ​​on the two adjacent axial position deviation-axial magnetic force value curves, respectively.

[0129] In one embodiment, the X-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the shaft 22 in the X-direction of the upper suspension bearing 31a, and the Y-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the shaft 22 in the Y-direction of the upper suspension bearing 31a, including:

[0130] The X-direction current correction value of the upper suspension bearing 31a is calculated based on the radial position deviation of the rotating shaft 22 in the X-direction of the upper suspension bearing 31a. Considering the requirements for stability and anti-interference capability, a PID control algorithm can be adopted according to relevant knowledge of control theory. Its expression is as follows:

[0131]

[0132] Where, ΔI xu k is the correction value for the positive X-direction current of the upper suspension bearing 31a. p k is the positional scaling factor. d Here are the position differential coefficients, Δx u k represents the radial position deviation of the shaft 22 in the positive X direction of the upper suspension bearing 31a. i For position integral coefficients, For Δx u The differential;

[0133] The correction value of the current in the positive Y direction of the upper suspension bearing 31a is calculated based on the radial position deviation of the rotating shaft 22 in the positive Y direction of the upper suspension bearing 31a:

[0134]

[0135] Where, ΔI yu The correction value for the positive Y-direction current of the upper suspension bearing 31a is Δy. u This refers to the radial position deviation of the rotating shaft 22 in the positive Y direction of the upper suspension bearing 31a. For Δy u The differential.

[0136] In one embodiment, the X-direction current correction value of the lower suspension bearing 31b is calculated based on the radial position deviation of the shaft 22 in the X-direction of the lower suspension bearing 31b, and the Y-direction current correction value of the lower suspension bearing 31b is calculated based on the radial position deviation of the shaft 22 in the Y-direction of the lower suspension bearing 31b, including:

[0137] The correction value for the current in the positive X direction of the lower suspension bearing 31b is calculated based on the radial position deviation of the rotating shaft 22 in the positive X direction.

[0138]

[0139] Where, ΔI xl The current correction value in the positive X direction for the lower suspension bearing 31b is Δx. l This refers to the radial position deviation of the shaft 22 in the positive X direction of the lower suspension bearing 31b. For Δx l The differential;

[0140] The correction value of the current in the positive Y direction of the lower suspension bearing 31b is calculated based on the radial position deviation of the rotating shaft 22 in the positive Y direction.

[0141]

[0142] where, ΔI yl is the Y positive direction current correction value of the lower suspension bearing 31b, and Δy l is the radial position deviation of the rotating shaft 22 in the Y positive direction of the lower suspension bearing 31b, is the differential of Δy l .

[0143] According to the deviation of the position of the rotating shaft 22 at the upper / lower suspension bearing 31b, in the X direction and the Y direction, the current correction value is calculated separately by the position regulator, and the control block diagram is as Figure 12 shown.

[0144] In one embodiment, the differential of the radial position deviation is calculated by filtering, and the specific steps include:

[0145] Obtain the filter transfer function according to the type and parameters of the filter:

[0146]

[0147] where, T1 is the first time constant of the filter, T2 is the first time constant, T1 < T2, this filter has a good approximate differential effect in the low frequency band and can quickly attenuate high frequency noise, which is beneficial to obtaining better improve the control performance of the system;

[0148] Determine the closed-loop transfer coefficient of the control system according to the filter transfer function:

[0149]

[0150] Calculate the Laplace transform of the closed-loop position response according to the closed-loop transfer function:

[0151] Y(s) = H(s)X(s)

[0152] where, X(s) is the Laplace transform of the unit step input, and Y(s) is the Laplace transform of the closed-loop position response;

[0153] Differentiate the closed-loop position response Y(s) to obtain the differential of the radial position deviation.

[0154] In one embodiment, the expression of the position proportional coefficient is:

[0155]

[0156] where, k p (n) is the position proportional coefficient when the rotational speed of the rotating shaft 22 is n, k p0 is the position proportional coefficient when the rotational speed of the rotating shaft 22 is 0, n maxFor the maximum shaft rotation speed of 22, k pmax Position proportionality coefficient at maximum shaft rotation speed of 22;

[0157] The expression for the position differential coefficient is:

[0158]

[0159] Where, k d (n) is the position differential coefficient of shaft 22 when the rotational speed is n, k d0 The position differential coefficient, k, when the rotational speed of shaft 22 is 0. dmax The position differential coefficient at the maximum shaft rotation speed of 22.

[0160] Considering that the current zero point will adjust in real time with the change of rotation speed, and different current zero points will cause changes in the linearization model of the control system, in order to ensure the rapid dynamic response and the basic unchanged damping characteristics of the system, an adaptive law is introduced into the position proportional coefficient and the position differential coefficient.

[0161] In one embodiment, controlling the current of the upper suspension bearing 31a based on the X-direction positive current correction value and the Y-direction positive current correction value of the upper suspension bearing 31a and the current zero point includes:

[0162] The target current value of the X-direction coil on the upper suspension bearing 31a is calculated based on the X-direction current correction value of the upper suspension bearing 31a and the aforementioned current zero point:

[0163]

[0164] Among them, I eu1 The target current value of the coil in the X direction on the upper suspension bearing 31a, Δx u >0 indicates that the rotating shaft 22 has a positional deviation along the positive X direction at the upper suspension bearing 31a, Δx u <0 indicates that the rotating shaft 22 has a positional deviation in the negative X direction at the upper suspension bearing 31a;

[0165] Based on the target current value of the X-direction coil on the upper suspension bearing 31a and the current zero point, the X-direction control voltage of each coil is calculated, and then the current of the X-direction coil on the upper suspension bearing 31a is controlled.

[0166] u xu =I0·T1+k pc ·(I eu1 -I u1 )+k ic ·∫(I eu1 -I u1 )dt

[0167] Among them, uxu R is the control voltage of the two adjacent coils in the X direction on the upper suspension bearing 31a, and I is the total resistance of the two adjacent coils in the X direction. u1 k represents the actual current in two adjacent coils in the X direction. pc k represents the current proportionality coefficient. ic Indicates the differential coefficient of the current;

[0168] Calculate the target Y-direction current value of each coil on the upper suspension bearing 31a based on the Y-direction current correction value of the upper suspension bearing 31a and the current zero point:

[0169]

[0170] Among them, I eu2 The target current value of the Y-direction coil on the upper suspension bearing 31a is Δy. u >0 indicates that the rotating shaft 22 has a positional deviation along the positive Y direction at the upper suspension bearing 31a, Δy u <0 indicates that the rotating shaft 22 has a positional deviation in the negative Y direction at the upper suspension bearing 31a;

[0171] The control voltage of the Y-direction coil is calculated based on the target current value of the Y-direction coil on the upper suspension bearing 31a and the zero current value, thereby controlling the current of the Y-direction coil on the upper suspension bearing 31a:

[0172] u yu =I0·R2+k pc ·(I eu2 -I u2 )+k ic ·∫(I eu2 -I u2 )dt

[0173] Among them, u yu R2 is the control voltage of the two adjacent coils in the Y direction on the upper suspension bearing 31a, and R2 is the total resistance of the two adjacent coils in the Y direction. u2 This represents the actual current in two adjacent coils in the Y direction.

[0174] In one embodiment, controlling the current of the lower suspension bearing 31b based on the X-direction positive current correction value and the Y-direction positive current correction value of the lower suspension bearing 31b and the current zero point includes:

[0175] The current of the lower suspension bearing 31b is controlled based on the X-direction positive current correction value and the Y-direction positive current correction value of the lower suspension bearing 31b, as well as the current zero point, including:

[0176] The target current value of the X-direction coil on the lower suspension bearing 31b is calculated based on the X-direction current correction value of the lower suspension bearing 31b and the aforementioned current zero point:

[0177]

[0178] Among them, I eu1 The target current value of the coil in the X direction on the lower suspension bearing 31b is Δx. u >0 indicates that the rotating shaft 22 has a positional deviation along the positive X direction at the lower suspension bearing 31b, Δx u <0 indicates that the shaft 22 has a positional deviation in the negative X direction at the lower suspension bearing 31b;

[0179] Based on the target current value of the X-direction coil on the lower suspension bearing 31b and the current zero point, the X-direction control voltage of each coil is calculated, and the current of the X-direction coil on the lower suspension bearing 31b is controlled accordingly.

[0180] u xu =I0·R1+k pc ·(I eu1 -I u1 )+k ic ·∫(I eu1 -I u1 )dt

[0181] Among them, u xu R is the control voltage of the two adjacent coils in the X direction on the lower suspension bearing 31b, and R is the total resistance of the two adjacent coils in the X direction. u1 k represents the actual current in two adjacent coils in the X direction. pc k represents the current proportionality coefficient. ic Indicates the differential coefficient of the current;

[0182] Calculate the target Y-direction current value of each coil on the lower suspension bearing 31b based on the Y-direction current correction value of the lower suspension bearing 31b and the current zero point:

[0183]

[0184] Among them, I eu2 The target current value of the Y-direction coil on the lower suspension bearing 31b is Δy. u >0 indicates that the rotating shaft 22 has a positional deviation along the positive Y direction at the lower suspension bearing 31b, Δy u <0 indicates that the shaft 22 has a positional deviation in the negative Y direction at the lower suspension bearing 31b;

[0185] The control voltage of the Y-direction coil is calculated based on the target current value of the Y-direction coil on the lower suspension bearing 31b and the zero current value, thereby controlling the current of the Y-direction coil on the lower suspension bearing 31b:

[0186] u yu =I0·R2+k pc ·(I eu2 -I u2 )+k ic ·∫(I eu2 -I u2 )dt

[0187] Among them, u yu R2 is the control voltage of two adjacent coils in the Y direction on the lower suspension bearing 31b, and I is the total resistance of the two adjacent coils in the Y direction. u2 This represents the actual current in two adjacent coils in the Y direction.

[0188] Taking the upper side suspension bearing 31a as an example, in the X direction, coils 31 and 32 are located in the positive X direction, and the resulting electromagnetic attraction force points in the positive X direction, denoted as F. xu+ Coil 35 and coil 36 are located in the negative X direction, and the resulting electromagnetic attraction force points in the negative X direction, denoted as F. xu- When the rotating shaft 22 has a positional deviation along the positive X direction at the upper suspension bearing 31a, Δx u >0; at this time, the target currents corresponding to coil 31 and coil 32 are I0-ΔI xu The trend is to make the electromagnetic attraction F generated by the coil xu+ Reduce; simultaneously, the target currents corresponding to coils 35 and 36 are I0 + ΔI xu The trend is to make the electromagnetic attraction F generated by the coil xu- The magnitude of the resultant force increases, therefore, the magnitude of the resultant force is F. xu- -F xu+ Its direction is along the negative X direction, so that the rotating shaft 22 returns to the central axis position, forming a differential return control effect.

[0189] The function of the current regulator is to make the actual current quickly track the target current value. A PI type regulator can be used. Taking coils 31 and 32 in the positive X direction as an example, its current regulation law is as follows:

[0190] u xu+ =I0·R+k pc ·(I eu1 -I u1 )+k ic ·∫(I eu1 -I u1 )dt (13)

[0191] Where R represents the total resistance of coil 31 and coil 32, k pc k represents the current proportionality coefficient. ic U represents the differential coefficient of the current. xu+ I represents the control voltage applied to coils 31 and 32. u1 This represents the actual current in coils 31 and 32. Similarly, for coils 35 and 36 in the negative X direction, the current adjustment rule is as follows:

[0192] u xu- =I0·R+k pc ·(I eu1 -I u1 )+k ic ·∫(I eu1 -I u1 )dt (13)

[0193] Among them, u xu- I represents the control voltage applied to coils 35 and 36. u1 This indicates the actual current in coils 35 and 36.

[0194] When the rotating shaft 22 has a positional deviation along the negative X direction at the upper suspension bearing 31a, Δx u <0; Current correction value ΔI xu The sign will change, correcting the current zero position, which also has the effect of returning the rotating shaft 22 to the central axis position.

[0195] In the Y direction, the current regulation is similar to that in the X direction, also achieving a differential recovery control effect. The difference lies in that the input is the position deviation in the Y direction, while the output control voltage is applied to the coil in the Y direction.

[0196] In one embodiment, a decoupling control device for an axial bearingless active magnetic levitation stirrer is provided, comprising: an axial magnetic force calculation module for the rotating shaft 22, a current zero-position calculation module, a coordinate system establishment module, a current correction value calculation module, and a current control module, wherein:

[0197] The axial magnetic force calculation module required for the rotating shaft 22 is used to obtain the rotation speed and weight of the rotating shaft 22 of the active magnetic levitation stirrer, and calculate the required axial magnetic force of the rotating shaft 22 based on the rotation speed and weight of the rotating shaft 22; a suspension bearing is provided on the outside of the rotating shaft 22 of the active magnetic levitation stirrer; the suspension bearing includes an upper suspension bearing 31a and a lower suspension bearing 31b;

[0198] The zero-current calculation module is used to calculate the required current value of the suspension bearing based on the axial position deviation of the rotating shaft 22 and the required axial magnetic force, and to use the required current value of the suspension bearing as the zero current value.

[0199] The coordinate system establishment module is used to construct XOY coordinate systems along the same radial direction of the upper suspension bearing 31a and the lower suspension bearing 31b respectively; in the XOY coordinate system, the positive X direction and the positive Y direction are both located on the axis of symmetry of the adjacent coils.

[0200] The current correction value calculation module is used to calculate the X-direction current correction value of the upper suspension bearing 31a based on the radial position deviation of the rotating shaft 22 in the X-direction of the upper suspension bearing 31a, and simultaneously calculate the Y-direction current correction value of the upper suspension bearing 31a based on the radial position deviation of the rotating shaft 22 in the Y-direction of the upper suspension bearing 31a; and to calculate the X-direction current correction value of the lower suspension bearing 31b based on the radial position deviation of the rotating shaft 22 in the X-direction of the lower suspension bearing 31b, and simultaneously calculate the Y-direction current correction value of the lower suspension bearing 31b based on the radial position deviation of the rotating shaft 22 in the Y-direction of the lower suspension bearing 31b.

[0201] The current control module is used to control the current of the upper suspension bearing 31a according to the X-direction current correction value and Y-direction current correction value of the upper suspension bearing 31a and the current zero point, and at the same time, to control the current of the lower suspension bearing 31b according to the X-direction current correction value and Y-direction current correction value of the lower suspension bearing 31b and the current zero point.

[0202] Specific limitations regarding the decoupling control device for a bearingless active magnetic levitation stirrer can be found in the above description of the decoupling control method for a bearingless active magnetic levitation stirrer, and will not be repeated here. Each module in the aforementioned decoupling control device for a bearingless active magnetic levitation stirrer can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0203] In one embodiment, the present invention further includes a support 5, which simplifies the arrangement of the container 1, the suspension bearing 31, and the stator 41. The bottom of the main cavity 11 is located at the top of the support 5, and the stirring shaft mounting cavity 12 is located inside the support 5. The support 5 is provided with a mounting cavity 54 for mounting the suspension bearing 31 and the power assembly 4 on the outside of the stirring shaft mounting cavity 12. The suspension bearing 31, the stator 41, the radial Hall sensor 6, the axial Hall sensor 7, and the displacement sensor 8 are all located inside the mounting cavity 54. In addition, preferably, the outer wall of the stirring shaft mounting cavity 12 is used as the inner wall of the mounting cavity 54, which can avoid affecting the suspension effect of the suspension bearing 31 and the driving effect of the stator 41 on the rotor 42.

[0204] In one specific embodiment, the container 1 is detachably mounted on the support 5. The support 5 includes a housing 51, an upper ring plate 52 detachably mounted on the upper end of the housing 51, and a lower fixing plate 53 detachably mounted on the lower end of the housing 51. The stirring shaft mounting cavity 12 is inserted into the housing 51 through the upper ring plate 52, which simplifies the disassembly, assembly, and maintenance of the suspension bearing 31, stator 41, radial Hall sensor 6, axial Hall sensor 7, and displacement sensor 8.

[0205] The present invention also provides a stirring method using a magnetic levitation stirrer, characterized in that a magnetic levitation stirrer with blades 23 is used, comprising the following steps:

[0206] S1, Install the stirring shaft assembly 2 into the container 1;

[0207] S2, pour the medicine to be mixed into the container 1, and fill the gap between the stirring shaft mounting cavity 12 and the rotating shaft 22 and part of the main cavity 11 with the medicine;

[0208] S3, the stirring shaft positioning component 3 starts working, suspending the stirring shaft component 2 in the container 1 without contact;

[0209] S4, the power unit 4 starts working, and the stirring shaft assembly 2 starts rotating. The impeller 21 performs the main stirring of the liquid medicine in the main cavity 11, and the blades 23 guide the liquid medicine in the gap between the stirring shaft mounting cavity 12 and the rotating shaft 22 to the main cavity 11 for auxiliary stirring.

[0210] Compared to conventional mixers, this method offers superior mixing performance and product quality, while also improving positioning and driving efficiency.

[0211] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A magnetically levitated stirrer, characterized in that, It includes a container (1), a stirring shaft assembly (2), a stirring shaft positioning assembly (3), and a power assembly (4). The container (1) includes an upper main cavity (11) and a lower stirring shaft mounting cavity (12) that are interconnected. The stirring shaft assembly (2) includes an impeller (21) and a rotating shaft (22) connected to each other. The impeller (21) is disposed in the main cavity (11) without contact, and the rotating shaft (22) is disposed in the stirring shaft mounting cavity (12) without contact. The stirring shaft positioning assembly (3) includes at least two sets of suspension bearings (31) arranged along the axis, which are located outside the stirring shaft mounting cavity (12) of the container (1). The at least two sets of suspension bearings (31) suspend the rotating shaft (22) in the axial and radial directions. The power assembly (4) is used to drive the rotating shaft (22) to rotate without contact; The outer wall of the rotating shaft (22) is provided with blades (23), and there is a certain gap between the outer wall of the blades (23) and the stirring shaft mounting cavity (12). The blades (23) are used to generate lift. The two sets of suspension bearings (31) are respectively installed at the upper and lower ends of the rotating shaft (22); The power assembly (4) includes a stator (41) located outside the stirring shaft mounting cavity (12) of the container (1) and a rotor (42) located on the rotating shaft (22), wherein the stator (41) and the rotor (42) are arranged between two sets of suspension bearings (31).

2. The magnetic levitation stirrer as described in claim 1, characterized in that, The outer walls of the main cavity (11), the lower stirring shaft mounting cavity (12), and the stirring shaft assembly (2) are coated with an anti-pollution coating.

3. The magnetic levitation stirrer as described in claim 1, characterized in that, It also includes a suspension bearing control system, which includes a shaft speed sensor, a shaft position sensor, and a controller; The shaft speed sensor is used to detect the rotational speed of the shaft (22); The shaft position sensor is used to detect the axial and radial positions of the shaft (22); The controller is used to adjust the current of the two sets of suspension bearings (31) according to the weight of the stirring shaft assembly (2), the rotation speed of the shaft (22) and the position data of the shaft (22), thereby adjusting the axial and radial suspension positions of the two sets of suspension bearings (31) relative to the shaft (22).

4. The magnetic levitation stirrer as described in claim 3, characterized in that, The controller is used for: The required axial magnetic force of the rotating shaft is calculated based on the rotational speed of the rotating shaft (22) and the self-weight of the stirring shaft assembly (2), including: The axial force exerted by the liquid on the rotating shaft (22) is calculated based on the rotational speed of the rotating shaft (22); The required axial magnetic force of the stirring shaft assembly (2) is calculated based on the axial force and the self-weight of the stirring shaft assembly (2): in, For the required axial magnetic force, It is an axial force. The weight of the stirring shaft assembly (2) is the weight of itself.

5. The magnetic levitation stirrer as described in claim 4, characterized in that, The required current value of the suspension bearing (31) is calculated based on the axial position deviation of the shaft (22) and the required axial magnetic force, including: Finite element models of the suspension bearing (31) and the shaft (22) were established using electromagnetic field simulation software, and the axial magnetic force values ​​corresponding to each axial position deviation under a specific current ampere-turns were calculated. Multiple axial position deviation-axial magnetic force value curves were plotted. Set the axial position deviation of the rotating shaft (22), and calculate the required radial and axial current values ​​by looking up a table or fitting the set axial position deviation of the rotating shaft (22), the required axial magnetic force, and the axial position deviation-axial magnetic force value curve.

6. The magnetic levitation stirrer as described in any one of claims 1-5, characterized in that, It also includes a support (5), the bottom of the main cavity (11) is located at the top of the support (5), the stirring shaft mounting cavity (12) is located inside the support (5), and the support (5) is located outside the stirring shaft mounting cavity (12) and has a mounting cavity (54) for mounting the suspension bearing (31) and the power assembly (4) part structure.

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