Variable bias current control method and system for magnetic bearing under high load working condition

Abstract

The application discloses a variable bias current control method and system of a magnetic suspension bearing under high load conditions, and belongs to the field of magnetic suspension bearings, and comprises the following steps: S1, multi-dimensional state sensing; S2, constructing a radial rotor force model based on real-time operation data of a rotor and hardware parameters of the magnetic suspension bearing; S3, solving the radial rotor force model to obtain a radial current; S4, superimposing a radial dynamic bias current and a radial dynamic control current to obtain a target driving current of a radial electromagnet; and S5, outputting the target driving current to a power amplifier to generate a bearing force. The variable bias current control method and system of the magnetic suspension bearing under high load conditions realize the dual goals of low energy consumption, low heat generation and stable suspension.

Description

Technical Field

[0001] This invention relates to the field of magnetic bearing technology, and in particular to a method and system for controlling the variable bias current of magnetic bearings under high load conditions. Background Technology

[0002] In industrial equipment such as turbine vacuum pumps and high-speed motors, high-load magnetic levitation bearings, with their contactless support characteristics, effectively avoid the friction and wear problems of traditional mechanical bearings, becoming a core component for increasing equipment operating speed and extending service life. Their working principle involves an electromagnet array formed by the stator windings generating controllable electromagnetic force under the coordination of a controller, achieving stable levitation and high-speed rotation of the rotor without mechanical contact, fundamentally eliminating the mechanical losses and vibration interference caused by contact supports.

[0003] Furthermore, the supporting force of magnetic levitation bearings possesses the core advantage of being "controllable and adjustable": through the design and optimization of the controller algorithm, the magnitude and direction of the electromagnetic force can be adjusted in real time, thereby dynamically regulating the dynamic characteristics of the bearing system, such as stiffness and damping. This flexibility allows the magnetic levitation bearing system to adaptively adjust its performance parameters according to the equipment's operating conditions (such as load fluctuations and speed changes), effectively suppressing rotor vibration, compensating for installation errors, and ultimately ensuring the stable operation of the entire equipment under high load and high speed conditions, significantly outperforming the fixed performance characteristics of traditional bearings.

[0004] However, current mainstream magnetic levitation bearing control technologies generally adopt a composite current mode of "constant bias current + variable control current". The original design intention of this mode was to linearize the nonlinear relationship between electromagnetic force and control current by introducing a constant bias current, thereby reducing the difficulty of controller algorithm design and real-time calculation. However, in practical applications, this design has significant technical defects: on the one hand, the constant bias current is only used to linearize the electromagnetic force characteristics and cannot enhance the bearing's active control capability against load fluctuations and external disturbances, which is a "functional redundancy" of energy consumption; on the other hand, the continuous flow of the constant bias current through the electromagnet coil will generate a large amount of Joule heat, causing the coil temperature to rise. In closed operating conditions such as turbine vacuum pumps where cooling conditions are limited, excessive temperature rise will not only accelerate the aging of the coil insulation material and shorten the bearing's service life, but may also cause problems such as current drift and electromagnetic force attenuation. In severe cases, it may even lead to levitation instability and threaten the safe operation of the equipment.

[0005] In summary, the inherent disadvantages of the existing constant bias current control mode in terms of energy consumption and heat dissipation have become a key bottleneck restricting the further application of high-load magnetic levitation bearings in energy-sensitive and cooling-limited industrial equipment. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for controlling the variable bias current of magnetic levitation bearings under high load conditions, thereby solving the aforementioned technical problems.

[0007] To achieve the above objectives, this invention provides a method for controlling the variable bias current of a magnetic levitation bearing under high load conditions, comprising the following steps: S1. Multi-dimensional state perception: Synchronously collect real-time operating data of the magnetic levitation bearing rotor, including the radial magnetic levitation rotor position, initial rotor load, external disturbance force on the rotor, rotor force, rotor displacement deviation, and air gap length between the rotor and stator; at the same time, acquire the hardware parameters of the magnetic levitation bearing, including the vacuum permeability of the electromagnet, magnetic pole area, number of coil turns, and maximum allowable current threshold of the coil. S2. Based on the real-time rotor operation data collected in step S1 and the hardware parameters of the magnetic levitation bearing, construct a radial rotor force model. S3. Solve the radial rotor force model constructed in step S2 to obtain the radial current, which includes the radial dynamic bias current used to offset the load force during buoyancy and the radial dynamic control current used to offset the external disturbance force. S4. Superimpose the radial dynamic bias current obtained in step S3 with the radial dynamic control current to obtain the target driving current of the radial electromagnet. S5. The target drive current obtained in step S4 is output to the power amplifier. The power amplifier amplifies the current signal and transmits it to the radial electromagnet of the stator assembly. The generated electromagnetic force is the bearing force for buoyancy, counteracting external interference forces, and stabilizing the rotor in the desired position.

[0008] A system for implementing a variable bias current control method for magnetic levitation bearings under high load conditions includes: The multi-dimensional state perception module is used to synchronously collect real-time operating data of the rotor of the magnetic levitation bearing, and at the same time obtain the hardware parameters of the magnetic levitation bearing. The force model construction module is used to construct a radial rotor force model based on the collected real-time rotor operation data and the hardware parameters of the magnetic levitation bearing. The model solving module is used to solve the radial rotor force model to obtain the radial current, which includes the radial dynamic bias current used to offset the load force during buoyancy and the radial dynamic control current used to offset the external disturbance force. The target drive current calculation module is used to superimpose the solved radial dynamic bias current and the radial dynamic control current to obtain the target drive current of the radial electromagnet. The power amplifier module is used to output the acquired target drive current to the power amplifier. The power amplifier amplifies the current signal and transmits it to the radial electromagnet of the stator assembly. The generated electromagnetic force is the bearing force for buoyancy, counteracting external interference forces, and stabilizing the rotor in the desired position.

[0009] Therefore, the present invention employs the above-mentioned variable bias current control method and system for magnetic levitation bearings under high load conditions, and has the following beneficial effects: 1. Ensure stable suspension under high load: Through load ratio optimization (such as rotor gravity 130%), external disturbance force vector decomposition, magnetic pole weight distribution and other designs, the rotor can still accurately counteract the load and external disturbances and remain stable in the desired position under high load and multiple external disturbance scenarios. 2. Improve control accuracy: Construct a radial force model and consider current distribution, magnetic pole angle, and load direction to achieve precise matching of current, magnetic field force, and expected bearing force, thus avoiding rotor misalignment; 3. Wide range of applications: It is suitable for applications with limited cooling and where energy utilization efficiency is important (such as turbine vacuum pumps), and it balances stability and economy, making it highly practical for engineering applications.

[0010] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0011] Figure 1 This is a flowchart of the variable bias current control method for magnetic levitation bearings under high load conditions according to the present invention. Figure 2 This is a block diagram of the radial magnetic levitation bearing variable bias current control closed-loop system described in Example 1; Figure 3 This is the current distribution diagram of each magnetic pole as described in Example 1; Figure 4 As described in Example 1, there exists a single , At that time, a schematic diagram of the decomposition of external disturbance force; Figure 5 This is a schematic diagram illustrating the principle of external disturbance force decomposition and magnetic pole current distribution of the radial magnetic levitation bearing described in Example 1. Figure 6 This is a schematic diagram illustrating the principle of external disturbance force decomposition and magnetic pole current distribution of the radial magnetic levitation bearing described in Example 2. Figure 7 This is the current distribution diagram of each magnetic pole as described in Example 2; Figure 8 This is a schematic diagram illustrating the principle of external disturbance force decomposition and magnetic pole current distribution of the radial magnetic levitation bearing described in Example 2. Figure 9This is a schematic diagram illustrating the principle of external disturbance force decomposition and magnetic pole current distribution of the radial magnetic levitation bearing described in Example 3; Figure 10 This is the current distribution diagram of each magnetic pole as described in Example 3; Figure 11 This is a schematic diagram illustrating the principle of external disturbance force decomposition and magnetic pole current distribution of the radial magnetic levitation bearing described in Example 3. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0013] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0014] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0015] like Figure 1 As shown, the variable bias current control method for magnetic levitation bearings under high load conditions includes the following steps: S1. Multi-dimensional state perception: Synchronously collect real-time operating data of the magnetic levitation bearing rotor, including the radial magnetic levitation rotor position, initial rotor load, external disturbance force on the rotor, rotor force, rotor displacement deviation, and air gap length between the rotor and stator; at the same time, acquire the hardware parameters of the magnetic levitation bearing, including the vacuum permeability of the electromagnet, magnetic pole area, number of coil turns, and maximum allowable current threshold of the coil. S2. Based on the real-time rotor operation data collected in step S1 and the hardware parameters of the magnetic levitation bearing, construct a radial rotor force model. The steps for constructing the radial rotor force model described in step S2 are as follows: Step 1: Based on the hardware parameters of the radial electromagnet and the radial air gap length, calculate the magnetic force of a pair of radial magnetic poles (NS) on the rotor using a magnetic force model: ; in, ; ; ; In the formula, Indicates the first The magnetic force of each radial magnetic pole on the rotor; Represents static magnetic force; Indicates the increment of dynamic magnetic field force; Represents the dynamic bias current of a single radial magnetic pole; Indicates the current stiffness of a single radial magnetic pole; Indicates the first Dynamic control current for each radial magnetic pole; , , and The vacuum permeability, pole area, number of coil turns, and air gap length of the radial electromagnets are determined respectively. Step 2, Orthogonal decomposition of magnetic field forces: Decompose the magnetic field forces of all radial electromagnets in the X and Y orthogonal directions; Step 3: Matching the expected bearing force: Match the decomposed magnetic field force with the expected radial bearing force to form a radial rotor force model: ; In the formula, and These represent the X and Y components of the radial expected bearing force, respectively; This indicates the total number of radial magnetic poles.

[0016] The steps for calculating the radial expected bearing force are as follows: First, based on the actual weight of the rotor For reference, the static load borne by a single radial magnetic levitation bearing is set to the actual weight of the rotor. Half of this is used to obtain the component of rotor gravity borne by a single radial magnetic levitation bearing. ; Then, based on the balance between energy consumption and stability, the actual weight of the rotor is selected. 130% is used as the bias force reference; Then calculate the total lifting offset load force. : In the formula, This represents the load percentage coefficient; Based on the total buoyancy offset load force The weights of the magnetic poles corresponding to the opposite direction of the load force are successively decreased, so that the resultant force of the decomposed forces of each magnetic pole in the horizontal and vertical directions is zero, thus obtaining the load component force of each magnetic pole. ; Then, external interference force External disturbance forces that can be decomposed into individual magnetic poles according to the direction of each magnetic pole: ; In the formula, Indicates the first External disturbance component of each radial magnetic pole; Indicates the pole angle of a magnetic pole; Indicates the angle of external disturbance force; Finally, the expected bearing force for a single magnetic pole is calculated: ; In the formula, Indicates the first The expected bearing force of each radial magnetic pole.

[0017] S3. Solve the radial rotor force model constructed in step S2 to obtain the radial current, which includes the radial dynamic bias current used to offset the load force during buoyancy and the radial dynamic control current used to offset the external disturbance force. The strategy for solving the radial dynamic bias current in step S3 is as follows: Establish a radial magnetic pole bias current weight allocation based on the principle of minimizing the required current, and calculate the radial dynamic bias current used to offset the load force during buoyancy, in conjunction with the radial force model: ; The strategy for solving the radial dynamic control current is as follows: decompose the external disturbance force into each radial magnetic pole direction, and calculate the radial dynamic control current for each radial magnetic pole to counteract the external disturbance force in the corresponding direction based on the radial force model; .

[0018] S4. Superimpose the radial dynamic bias current obtained in step S3 with the radial dynamic control current to obtain the target driving current of the radial electromagnet. The target driving current of the radial electromagnet mentioned in step S4 The calculation formula is as follows: .

[0019] S5. The target drive current obtained in step S4 is output to the power amplifier. The power amplifier amplifies the current signal and transmits it to the radial electromagnet of the stator assembly. The generated electromagnetic force is the bearing force for buoyancy, counteracting external interference forces, and stabilizing the rotor in the desired position.

[0020] Electromagnetic force synthesized in step S5 The expression is as follows: .

[0021] A system for implementing a variable bias current control method for magnetic levitation bearings under high load conditions includes: The multi-dimensional state perception module is used to synchronously collect real-time operating data of the rotor of the magnetic levitation bearing, and at the same time obtain the hardware parameters of the magnetic levitation bearing. The force model construction module is used to construct a radial rotor force model based on the collected real-time rotor operation data and the hardware parameters of the magnetic levitation bearing. The model solving module is used to solve the radial rotor force model to obtain the radial current, which includes the radial dynamic bias current used to offset the load force during buoyancy and the radial dynamic control current used to offset the external disturbance force. The target drive current calculation module is used to superimpose the solved radial dynamic bias current and the radial dynamic control current to obtain the target drive current of the radial electromagnet. The power amplifier module is used to output the acquired target drive current to the power amplifier. The power amplifier amplifies the current signal and transmits it to the radial electromagnet of the stator assembly. The generated electromagnetic force is the bearing force for buoyancy, counteracting external interference forces, and stabilizing the rotor in the desired position.

[0022] Example 1: Verification of current distribution for external disturbance force cancellation in an 8-pole C-type magnetic levitation bearing; like Figure 2 As shown, the test conditions were: rotor gravity. A single radial magnetic levitation bearing bears half of the total load, i.e., 204.5 kg; Number of radial magnetic poles: 8 (arranged evenly in a circle on the outside of the rotor as poles 1, 2, 3, 4, 5, 6, 7, and 8, with poles N, S paired and adjacent poles spaced 45° apart; pole 1 has an angle of...). (The angle between counterclockwise and the X-axis), the angles of each magnetic pole are... Test load percentages: 120%, 130%, and 140% of rotor weight (In this embodiment, the bias force benchmark of 130% of rotor weight can simultaneously meet the requirements of low energy consumption and high buoyancy stability, so the bias force benchmark of 130% of rotor weight is selected).

[0023] Assume the following single external disturbance exists: , ;or , ;or , ;in, and These represent the external disturbance force and its direction of action in the second quadrant, respectively. and These represent the external disturbance force and its direction of action in the third quadrant, respectively. and These represent the external disturbance force and its direction of action in the fourth quadrant, respectively.

[0024] External interference force decomposition and current adjustment rules: External interference force... Decomposed into components of the magnetic poles according to their directions. The magnitude of the component force and Proportional; Current adjustment logic: Magnetic poles in the same direction as the external disturbance force control the current to decrease; magnetic poles in the opposite direction control the current to increase.

[0025] Based on the principle of maximizing the weight of the opposite-direction magnetic pole and decreasing it progressively to the other two poles, the bias current percentages for each magnetic pole are allocated as follows: opposite-direction magnetic pole: 40% of the rotor weight; adjacent magnetic pole: 35% of the rotor weight; next adjacent magnetic pole: 10% of the rotor weight; farthest magnetic pole: 5% of the rotor weight. In this embodiment, then... .

[0026] Table 1. Current and force distribution at each magnetic pole under external disturbance force (100N, 40°)

[0027] Table 2 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0028] Table 3 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0029] Table 4 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0030] As shown in Table 1, the traditional scheme fixes the bias current to half of the maximum coil current. The magnetic pole bias current distribution scheme in this embodiment requires less total current and reduces static energy consumption. See Tables 2-4 and... Figures 3-5 As shown, a single existence , At that time, the incremental forces of each magnetic pole are symmetrically distributed, and the total canceling force is 150N, with the direction opposite to 110°; only when it exists , At that time, the total canceling force is equal to 175N, and the direction is opposite to 210°; only when it exists , At that time, the total counteracting force is 160N, and the direction is opposite to 290°. It can be seen that the radial magnetic pole current distribution strategy described in this invention can accurately decompose external interference forces, achieve complete cancellation of external interference forces by dynamically adjusting the control current, and keep the rotor displacement fluctuation within the allowable range, demonstrating excellent anti-disturbance stability.

[0031] Example 2: Verification of current distribution for external disturbance force cancellation in a 6-pole C-type magnetic levitation bearing; The test conditions were: rotor gravity A single radial magnetic levitation bearing bears half of the total load, i.e., 2045N; Number of radial magnetic poles: 6 (poles 1, 2, 3, 4, 5, and 66 are evenly arranged in a circle on the outside of the rotor, with poles N, S, and H paired and adjacent poles spaced 60° apart; the angle of pole 1 is... (The angle between counterclockwise and the X-axis), the angles of each magnetic pole are... ).

[0032] Assume the following single external disturbance exists: , ;or , ;or , ;in, and These represent the external disturbance force and its direction of action in the second quadrant, respectively. and These represent the external disturbance force and its direction of action in the third quadrant, respectively. and These represent the external disturbance force and its direction of action in the fourth quadrant, respectively.

[0033] External interference force decomposition and current adjustment rules: External interference force... Decomposed into components of the magnetic poles according to their directions. The magnitude of the component force and Proportional; Current adjustment logic: Magnetic poles in the same direction as the external disturbance force control the current to decrease; magnetic poles in the opposite direction control the current to increase.

[0034] Based on the principle of maximizing the weight of the opposite-direction magnetic poles and decreasing it progressively to the other two poles, the bias current percentages for each magnetic pole are allocated as follows: 65% of the rotor weight for each of the two opposite-direction magnetic poles; 40% of the rotor weight for each of the two adjacent horizontal magnetic poles; and 15% of the rotor weight for each of the farthest magnetic poles. The percentage for the magnetic poles in the direction of the load is to ensure the system's stiffness. In this embodiment, there is... .

[0035] Table 5. Current and force distribution at each magnetic pole under external disturbance force (100N, 40°)

[0036] Table 6 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0037] Table 7 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0038] Table 8 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0039] As shown in Table 5, the traditional scheme fixes the bias current to half of the maximum coil current. The magnetic pole bias current distribution scheme in this embodiment requires less total current and reduces static energy consumption. (See Tables 5-8 and...) Figures 6-8 As shown, a single existence , At that time, the incremental forces of each magnetic pole are symmetrically distributed, and the total canceling force is 150N, with the direction opposite to 110°; only when it exists , At that time, the total canceling force is equal to 175N, and the direction is opposite to 220°; only when it exists , At that time, the total counteracting force is 160N, and the direction is opposite to 290°. It can be seen that the radial magnetic pole current distribution strategy described in this invention can accurately decompose external interference forces, achieve complete cancellation of external interference forces by dynamically adjusting the control current, and keep the rotor displacement fluctuation within the allowable range, demonstrating excellent anti-disturbance stability.

[0040] Example 3: Verification of current distribution for external disturbance force cancellation in a 4-pole C-type magnetic levitation bearing; The test conditions were: rotor gravity A single radial magnetic bearing bears half of the total load, i.e., 2045N; Number of radial magnetic poles: 4 (pole 1, pole 2, pole 3, and pole 4 are evenly arranged in a circle on the outside of the rotor, with poles N, N, and S paired, and adjacent poles spaced 90° apart; pole 1 has an angle of... (The angle between counterclockwise and the X-axis), the angles of each magnetic pole are... .

[0041] Assume the following single external disturbance exists: , ;or , ;or , ;in, and These represent the external disturbance force and its direction of action in the second quadrant, respectively. and These represent the external disturbance force and its direction of action in the third quadrant, respectively. and These represent the external disturbance force and its direction of action in the fourth quadrant, respectively.

[0042] External interference force decomposition and current adjustment rules: External interference force... Decomposed into components of the magnetic poles according to their directions. The magnitude of the component force and Proportional; Current adjustment logic: Magnetic poles in the same direction as the external disturbance force control the current to decrease; magnetic poles in the opposite direction control the current to increase.

[0043] Based on the principle of maximizing the weight of the magnetic poles in the opposite direction of the load and decreasing it gradually on both sides, the bias current ratio of each magnetic pole is allocated as follows: the two magnetic poles in the opposite direction of the load each account for 120% of the rotor weight; the two adjacent magnetic poles, i.e., the two magnetic poles in the horizontal direction, each account for 50% of the rotor weight; the farthest magnetic pole each accounts for 30% of the rotor weight; the reason for the proportion of magnetic poles in the direction of the load is to ensure the stiffness of the system. In this embodiment, it is as follows: .

[0044] Table 9. Current and force distribution at each magnetic pole under external disturbance force (100N, 40°)

[0045] Table 10 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0046] Table 11 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0047] Table 12 Current and Force Distribution for Each Magnetic Pole (Single) and interference)

[0048] As shown in Table 9, the traditional scheme fixes the bias current to half of the maximum coil current. The magnetic pole bias current distribution scheme in this embodiment requires less total current and reduces static energy consumption. (See Tables 9-12 and...) Figures 9-11 As shown, a single existence , At that time, the incremental forces of each magnetic pole are symmetrically distributed, and the total canceling force is 150N, with the direction opposite to 110°; only when it exists , At that time, the total canceling force is equal to 175N, and the direction is opposite to 220°; only when it exists , At that time, the total counteracting force is 160N, and the direction is opposite to 290°. It can be seen that the radial magnetic pole current distribution strategy described in this invention can accurately decompose external interference forces, achieve complete cancellation of external interference forces by dynamically adjusting the control current, and keep the rotor displacement fluctuation within the allowable range, demonstrating excellent anti-disturbance stability.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for controlling the variable bias current of a magnetic levitation bearing under high load conditions, characterized in that: Includes the following steps: S1. Multi-dimensional state perception: Synchronously collect real-time operating data of the magnetic levitation bearing rotor, including the radial magnetic levitation rotor position, initial rotor load, external disturbance force on the rotor, rotor force, rotor displacement deviation, and air gap length between the rotor and stator; at the same time, acquire the hardware parameters of the magnetic levitation bearing, including the vacuum permeability of the electromagnet, magnetic pole area, number of coil turns, and maximum allowable current threshold of the coil. S2. Based on the real-time rotor operation data collected in step S1 and the hardware parameters of the magnetic levitation bearing, construct a radial rotor force model. S3. Solve the radial rotor force model constructed in step S2 to obtain the radial current, which includes the radial dynamic bias current used to offset the load force during buoyancy and the radial dynamic control current used to offset the external disturbance force. S4. Superimpose the radial dynamic bias current obtained in step S3 with the radial dynamic control current to obtain the target driving current of the radial electromagnet. S5. The target drive current obtained in step S4 is output to the power amplifier. The power amplifier amplifies the current signal and transmits it to the radial electromagnet of the stator assembly. The generated electromagnetic force is the bearing force for buoyancy, counteracting external interference forces, and stabilizing the rotor in the desired position. The steps for constructing the radial rotor force model described in step S2 are as follows: Step 1: Based on the hardware parameters of the radial electromagnet and the radial air gap length, calculate the magnetic force of a pair of radial magnetic poles on the rotor using a magnetic force model: ； in, ； ； ； In the formula, Indicates the first The magnetic force of each radial magnetic pole on the rotor; Represents static magnetic force; Indicates the increment of dynamic magnetic field force; Represents the dynamic bias current of a single radial magnetic pole; Indicates the current stiffness of a single radial magnetic pole; Indicates the first Dynamic control current for each radial magnetic pole; , , and The vacuum permeability, pole area, number of coil turns, and air gap length of the radial electromagnets are determined respectively. Step 2, Orthogonal decomposition of magnetic field forces: Decompose the magnetic field forces of all radial electromagnets in the X and Y orthogonal directions; Step 3: Matching the expected bearing force: Match the decomposed magnetic field force with the expected radial bearing force to form a radial rotor force model. ； In the formula, and These represent the X and Y components of the radial expected bearing force, respectively; This indicates the total number of radial magnetic poles.

2. The variable bias current control method for magnetic levitation bearings under high load conditions according to claim 1, characterized in that: The steps for calculating the radial expected bearing force are as follows: First, based on the actual weight of the rotor For reference, the static load borne by a single radial magnetic levitation bearing is set to the actual weight of the rotor. Half of this is used to obtain the component of rotor gravity borne by a single radial magnetic levitation bearing. ; Then, based on the balance between energy consumption and stability, the actual weight of the rotor is selected. 130% is used as the bias force reference; Then calculate the total lifting offset load force. : In the formula, This represents the load percentage coefficient; Based on the total buoyancy offset load force The weights of the magnetic poles corresponding to the opposite directions of the load force are successively decreased, so that the resultant force of each magnetic pole in the horizontal and vertical directions is zero, thus obtaining the load component force of each magnetic pole. ; Then, external interference force External disturbance forces that can be decomposed into individual magnetic poles according to the direction of each magnetic pole: ； In the formula, Indicates the first External disturbance component of each radial magnetic pole; Indicates the pole angle of a magnetic pole; Indicates the angle of external disturbance force; Finally, the expected bearing force for a single magnetic pole is calculated: ； In the formula, Indicates the first The expected bearing force of each radial magnetic pole.

3. The variable bias current control method for magnetic levitation bearings under high load conditions according to claim 2, characterized in that: The strategy for solving the radial dynamic bias current in step S3 is as follows: Establish a radial magnetic pole bias current weight allocation based on the principle of minimizing the required current, and calculate the radial dynamic bias current used to offset the load force during buoyancy, in conjunction with the radial force model: ； The strategy for solving the radial dynamic control current is as follows: decompose the external disturbance force into each radial magnetic pole direction, and calculate the radial dynamic control current for each radial magnetic pole to counteract the external disturbance force in the corresponding direction based on the radial force model; 。 4. The variable bias current control method for magnetic levitation bearings under high load conditions according to claim 3, characterized in that: The target driving current of the radial electromagnet mentioned in step S4 The calculation formula is as follows: 。 5. The variable bias current control method for magnetic levitation bearings under high load conditions according to claim 4, characterized in that: Electromagnetic force synthesized in step S5 The expression is as follows: 。 6. A system for executing the variable bias current control method for magnetic levitation bearings under high load conditions as described in any one of claims 1-5, characterized in that: include: The multi-dimensional state perception module is used to synchronously collect real-time operating data of the rotor of the magnetic levitation bearing, and at the same time obtain the hardware parameters of the magnetic levitation bearing. The force model construction module is used to construct a radial rotor force model based on the collected real-time rotor operation data and the hardware parameters of the magnetic levitation bearing. The model solving module is used to solve the radial rotor force model to obtain the radial current, which includes the radial dynamic bias current used to offset the load force during buoyancy and the radial dynamic control current used to offset the external disturbance force. The target drive current calculation module is used to superimpose the solved radial dynamic bias current and the radial dynamic control current to obtain the target drive current of the radial electromagnet. The power amplifier module is used to output the acquired target drive current to the power amplifier. The power amplifier amplifies the current signal and transmits it to the radial electromagnet of the stator assembly. The generated electromagnetic force is the bearing force for buoyancy, counteracting external interference forces, and stabilizing the rotor in the desired position.

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