High-speed bearingless stator-excited reluctance motor levitation force decoupling control method

Abstract

This invention discloses a method for decoupling the levitation force of a high-speed bearingless stator-excited reluctance motor, relating to the technical field of bearingless reluctance motors. The invention includes: real-time detection of the rotor position angle during motor operation to determine the phase winding conduction mode. Based on the obtained phase winding conduction mode, the levitation force is projected onto the corresponding stator pole direction to obtain the required levitation force for the corresponding phase winding stator pole. According to the analytical formula for levitation force and levitation current, a reference value for the levitation current can be calculated. The levitation current loop controls the on / off state of the switching transistors in the H-bridge circuit by outputting a duty cycle signal, thereby controlling the output levitation current. The control method of this invention is simple and reliable, achieving levitation force decoupling in a high-speed bearingless stator-excited reluctance motor and improving the stability of the motor's levitation system.

Description

Technical Field

[0001] This invention relates to the technical field of bearingless reluctance motors, and more particularly to a method for decoupling the levitation force of a high-speed bearingless stator-excited reluctance motor. Background Technology

[0002] The stator-excited reluctance motor has a stator and rotor structure similar to that of a switched reluctance motor, exhibiting high reliability and robustness. The motor's excitation magnetic field is provided by DC excitation current, eliminating the need for controllable rectifiers and angle / position sensors during power generation. Therefore, the stator-excited reluctance motor offers advantages such as simple and flexible power generation control and high power generation reliability.

[0003] By combining bearingless technology with a stator-excited reluctance motor, a high-speed bearingless stator-excited reluctance motor is constructed. The levitation magnetic field generated by the motor's levitation winding is superimposed on the DC excitation magnetic field, and the levitation force on the rotor can be controlled by controlling the levitation winding current. Both the levitation winding and the excitation winding are DC windings, simplifying levitation control. Furthermore, the mutual inductance between the levitation winding, the excitation winding, and the armature winding is very small, resulting in weak coupling between the windings. However, due to its salient pole structure, the high-speed bearingless stator-excited reluctance motor exhibits a cross-coupling effect in its radial levitation forces. This means that the radial levitation force is affected not only by the levitation current in the corresponding direction but also by the levitation current in the orthogonal direction. This cross-coupling in the radial levitation forces severely impacts the stability of the motor's levitation operation.

[0004] To address this issue, some research groups have proposed a scheme for decoupling control of radial levitation force in high-speed bearingless stator-excited reluctance motors based on a non-synchronous rotating coordinate system. However, this scheme treats the armature current as an ideal square wave when considering its influence. Under high-speed conditions, due to the effects of current commutation and advance angle control methods, the armature current differs significantly from the ideal square wave. This still cannot effectively solve the problem that the cross-coupling between radial levitation forces seriously affects the stability of the motor's levitation operation. Furthermore, the calculation process of this method is relatively complex, requiring high computing power from the controller, which limits its potential for use under high-speed conditions.

[0005] Therefore, how to design a method to improve the cross-coupling between radial suspension forces, which seriously affects the stability of motor suspension operation, has become a research topic. Summary of the Invention

[0006] This invention provides a method for decoupling the levitation force of a high-speed bearingless stator-excited reluctance motor. The method determines the stator pole that generates the levitation force based on the rotor position angle. According to the determined projection relationship, the levitation force in the XY stationary coordinate system is projected onto the stator pole direction corresponding to the current rotor angle, thus obtaining the levitation force that each stator pole should generate. Based on the analytical formula for levitation force and levitation current, a reference value for the levitation current can be obtained, achieving decoupling of the levitation force and ultimately improving the stability of the motor's levitation operation, which is significantly affected by the cross-coupling between radial levitation forces.

[0007] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0008] A method for decoupling the levitation force of a high-speed bearingless stator-excited reluctance motor includes:

[0009] S1. The current position of the rotor of the high-speed bearingless stator-excited reluctance motor is obtained using an eddy current sensor, and the required levitation force values ​​in the X and Y axes are determined based on the current position of the rotor. The levitation force values ​​required to achieve stable levitation correspond to the actual rotor position and can be preset.

[0010] S2. Obtaining the rotor position angle θ using a rotary transformer. r And determine the conduction mode of the three-phase winding, the conduction mode of the three-phase winding including: the current presence in the A, B, and C three-phase armature windings;

[0011] S3. Decompose the given value of the levitation force to obtain the given value of the levitation force corresponding to the stator pole in the conduction mode;

[0012] S4. Establish the mapping relationship between the given value of the levitation force corresponding to the stator pole and the levitation current, and obtain the reference values ​​of the levitation current in the X-axis and Y-axis directions; among them, the Maxwell stress tensor method can be used to express the levitation force generated by each stator pole in terms of levitation current.

[0013] S5. The actual levitation current in the X and Y axes is collected using a current Hall sensor; among which, the X-axis levitation current I is obtained using a current Hall sensor. sx Floating current I along the Y-axis sy The difference between the floating current reference value and the value is used as the input of the PI controller. The high and low voltage duty cycle analog signals output by the PI controller are used to adjust the switching of the switching transistors in the H-bridge circuit to regulate the floating current, thereby controlling the radial displacement of the rotor.

[0014] S6. The difference between the actual floating current and the reference value of the floating current is used as the value of the PI controller, and the PI controller outputs a PWM signal to the control circuit of the high-speed bearingless stator-excited reluctance motor.

[0015] In this embodiment, step S1 includes: obtaining the current position x of the rotor using an eddy current sensor, and comparing x with the rotor position reference value x. * The difference is input to the X-axis displacement PID controller, which outputs the required levitation force F in the X-axis direction. x * The current position y of the rotor is obtained using an eddy current sensor, and y is compared with the rotor position reference value y. * The difference is input to the Y-axis displacement PID controller, which outputs the required levitation force F in the Y-axis direction. y * .

[0016] Specifically, the types of the conduction modes include: AB phase conduction, BC phase conduction, and AC phase conduction; wherein, when θ r ∈[0,15°), sampling yields i mA and i mB When θ r ∈[15°, 30°), sampling yields i mB and i mC When θ r (∈[30°~45°). For example: using a rotary transformer to obtain the rotor position angle θ). r The phase winding conduction mode is determined based on the real-time rotor position angle. The conduction modes of each phase winding under different rotor position angles are shown in Table 1 (taking the rotor position mechanical angle of 0 to 45° as an example):

[0017] Table 1

[0018]

[0019] Sampled i mA and i mC i mA i mB i mC These are the instantaneous values ​​of the armature winding currents of phases A, B, and C obtained from sampling.

[0020] In this embodiment, S3 includes: dividing the levitation force generated by each phase stator pole on the rotor into a λ region and a μ region, wherein the λ region covers the six stator poles near the X-axis plane, and the μ region covers the six stator poles near the Y-axis plane; and F x * and F y * The levitation force is decomposed into a given value corresponding to the levitation force generated by each independent stator pole. In the AB phase conduction mode, when the rotor angle is between 0 and 15° (i.e., when phases A and B are conducting), the levitation force generated by the Y-axis levitation current at the stator poles of phases A and B is determined by F.A1 and F B1 This indicates that the levitation force F in the X direction... x Suspension force F in the Y direction y The decomposition is expressed as:

[0021] in:

[0022]

[0023] F A1 F B1 and F C1 F represents the levitation force generated by the Y-axis levitation current at the stator poles of phases A, B, and C. A2 F B2 and F C2 This represents the levitation force generated by the X-axis levitation current at the stator poles of phases A, B, and C. F represents the levitation force generated solely by the levitation current along the Y-axis. μA F represents the magnitude of the levitation force generated at the stator pole of phase A in the μ direction. μB The magnitude of the levitation force generated at the B-phase stator pole in the μ direction; F represents the levitation force generated solely by the levitation current along the X-axis. λA F represents the magnitude of the levitation force generated at the A-phase stator pole in the λ direction. λB Let F be the magnitude of the levitation force generated at the B-phase stator pole in the λ direction. Specifically, the direction of the levitation force generated by each stator pole on the rotor always points from the rotor center to the center of that stator pole, and the positive direction of the force is defined to be consistent with the positive direction of the coordinate axis. Based on the projection relationship determined by the motor structure, the levitation force in the X direction is given a value F. x * The given value of the levitation force F in the Y direction y * The levitation force is decomposed into the levitation force generated by each independent stator pole. The levitation force generated by each stator pole on the rotor is divided into a λ region and a μ region. The λ region covers the six stator poles near the X-axis plane, and the μ region covers the six stator poles near the Y-axis plane. Six unit direction vectors are introduced. and The specific numerical correspondences are shown in Table 2:

[0024] Table 2

[0025]

[0026] In the BC phase conduction mode, when the rotor angle is between 15° and 30° (i.e., when phases B and C are conducting), the levitation force generated by the Y-axis levitation current at the stator poles of phases B and C is determined by F. B1 and F C1 This indicates that the levitation force F in the X direction is...x Suspension force F in the Y direction y The decomposition is expressed as:

[0027] in:

[0028]

[0029] F μC F represents the magnitude of the levitation force generated at the C-phase stator pole in the μ direction. λC The magnitude of the levitation force generated at the C-phase stator pole in the λ direction;

[0030] In the AC phase conduction mode, when the rotor angle is between 30° and 45° (i.e., when phases A and C are conducting), the levitation force generated by the Y-axis levitation current in phases A and C is determined by F. A1 and F C1 This indicates that the levitation force F in the X direction is... x Suspension force F in the Y direction y The decomposition is expressed as: in:

[0031]

[0032] In this embodiment, in S4, establishing the correspondence between the levitation force and the levitation current corresponding to each stator pole includes: at any rotor position angle and The representation in the XY stationary coordinate system is as follows:

[0033] Then, using the Maxwell stress tensor method, the levitation force generated by each stator pole is expressed in terms of levitation current, thus establishing a mapping model between the levitation force and levitation current generated by each stator pole:

[0034] Where K represents the mechanical characteristic constant of the motor, i sy Indicates the Y-axis floating current, i sx L represents the X-axis levitation current, μ0 represents the air permeability, and L represents the air permeability. Fe R represents the core length, and R represents the rotor radius. gap N represents the air gap length. s Indicates the number of turns of the levitation coil, A M B M and C M There are three coupling coefficients, and their expressions are shown in Table 3:

[0035] Table 3

[0036]

[0037] Where, N f N represents the number of turns of the excitation coil. m i represents the number of turns in the armature coil. f This represents the excitation winding current. In this embodiment, in S4, obtaining the reference values ​​of the levitation current in the X and Y axes includes: the given value of the levitation force F in the X direction. x * The given value of the levitation force F in the Y direction y * expression:

[0038]

[0039] The matrix form is shown in equation (17): This allows us to further obtain the X-axis levitation current reference value i. sx * and Y-axis levitation current reference value i sy *:

[0040]

[0041] In the preferred embodiment, the high-speed bearingless stator-excited reluctance motor adopts a 12 / 8-pole bearingless double salient pole motor. The stator poles employ a parallel tooth structure, including 4 large slots and 8 small slots. The armature coil is wound on each stator pole, the excitation coil is wound in the large slots of the stator, and the X-axis and Y-axis suspension coils are wound in the large slots of the stator. The spatially radially opposite suspension coils are connected in reverse series to form the X-axis and Y-axis suspension windings, respectively. Four sets of eddy current sensors are used, which obtain the rotor position signal by measuring the distance between the probe and the reference ring of the shaft. The magnitudes of the armature current and excitation current are detected by four sets of current Hall sensors; the magnitudes of the X-axis suspension current and Y-axis suspension current are detected by two sets of current Hall sensors.

[0042] The levitation force decoupling control method for a high-speed bearingless stator-excited reluctance motor provided in this invention detects the rotor position angle in real time during motor operation to determine the phase winding conduction mode. Based on the obtained phase winding conduction mode, the levitation force is projected onto the corresponding stator pole direction, thus obtaining the required levitation force for the corresponding phase winding stator pole. According to the analytical formula for levitation force and levitation current, a reference value for the levitation current can be calculated. The levitation current loop controls the on / off state of the switching transistors in the H-bridge circuit through an output duty cycle signal, thereby controlling the output levitation current. The control method of this invention is simple and reliable, achieving levitation force decoupling for a high-speed bearingless stator-excited reluctance motor and improving the stability of the motor's levitation system. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 Block diagram for decoupling control of levitation force of high-speed bearingless stator-excited reluctance motor;

[0045] Figure 2 A schematic diagram of the levitation force projection along the X and Y axes;

[0046] Figure 3 (a) to Figure 3 (d) is a schematic diagram of the suspension force waveform before decoupling under no-load conditions;

[0047] Figure 4 (a) to Figure 4 (d) is a schematic diagram of the levitation force waveform before decoupling under load conditions;

[0048] Figure 5 (a) to Figure 5 (d) is a schematic diagram of the levitation force waveform after decoupling under no-load conditions;

[0049] Figure 6 (a) to Figure 6 (d) is a schematic diagram of the levitation force waveform after decoupling under load conditions. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Embodiments of the present invention will be described in detail below, examples of which 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. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in the specification of the present invention means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0051] Figure 1 A decoupling control box for levitation force of a high-speed bearingless stator-excited reluctance motor Figure 1 The rotor's current position x and the rotor position reference value x are obtained using an eddy current sensor. * After subtraction and adjustment by the x-direction displacement PID controller, the required suspension force F in the x-axis direction is obtained. x * The rotor's current position y and the rotor position reference value y are obtained using an eddy current sensor. * After subtraction and adjustment by a PID controller for displacement in the y-axis direction, the required levitation force F in the y-axis direction is obtained. y * .

[0052] Using a rotary transformer to obtain the rotor position angle θ r The phase winding conduction mode is determined based on the real-time rotor position angle. The conduction modes of each phase winding under different rotor position angles are shown in the table below (taking the rotor position mechanical angle of 0 to 45° as an example):

[0053]

[0054] Where i mA ,,i mB i mC These are the instantaneous values ​​of the armature winding currents of phases A, B, and C obtained from sampling.

[0055] Based on the stator pole distribution pattern, it is assumed that the direction of the levitation force generated by each stator pole on the rotor is always from the rotor...

[0056] The sub-center points to the stator pole center, and the positive direction of the force is defined to be consistent with the positive direction of the coordinate axis. Based on the projection relationship determined by the motor structure, the levitation force F in the X direction is given as a value. x * The given value of the levitation force F in the Y direction y * The levitation force is decomposed into the levitation force generated by each independent stator pole. The levitation force generated by each stator pole on the rotor is divided into a λ region and a μ region. The λ region covers the six stator poles near the X-axis plane, and the μ region covers the six stator poles near the Y-axis plane. Six unit direction vectors are introduced. and The specific numerical correspondences are shown in the table below:

[0057]

[0058] Based on the analytical formulas for levitation force and levitation current, the reference value of the levitation current can be obtained. The levitation current loop outputs high and low voltage duty cycle analog signals to control the on / off state of the switching transistors in the H-bridge circuit, thereby achieving control of the levitation current.

[0059] Figure 2 This is a schematic diagram of the levitation force projection along the X and Y axes, ensuring that the direction of the levitation force generated by each phase stator pole always points towards the center of that stator pole.

[0060] 1) When the rotor angle is between 0° and 15°, i.e., when phases A and B are conducting, the levitation force generated by the Y-axis levitation current at the stator poles of phases A and B is determined by F. A1 and F B1 express:

[0061]

[0062] In the formula, F represents the levitation force generated solely by the levitation current along the Y-axis. μA F represents the magnitude of the levitation force generated at the stator pole of phase A in the μ direction. μB The magnitude of the levitation force generated at the B-phase stator pole in the μ direction.

[0063] The levitation force generated by the X-axis levitation current at the stator poles of phases A and B is determined by F. A2 and F B2 express:

[0064]

[0065] In the formula, F represents the levitation force generated solely by the levitation current along the X-axis. λA F represents the magnitude of the levitation force generated at the A-phase stator pole in the λ direction. λB Let λ represent the magnitude of the levitation force generated at the B-phase stator pole in the λ direction.

[0066] At this moment, the levitation force F in the X direction x Suspension force F in the Y direction y It can be represented as:

[0067]

[0068] Using the Maxwell stress tensor method, the levitation forces in the X and Y directions are expressed as levitation currents in the X and Y directions, respectively.

[0069]

[0070] Matrix operations simplify to obtain:

[0071]

[0072] 2) When the rotor angle is between 15° and 30°, i.e., when phases B and C are conducting, according to the stator-rotor overlap rule, F can be... x and F y They are projected onto the stator pole directions of phase B and phase C, respectively.

[0073] The levitation force generated by the Y-axis levitation current at the stator poles of phases B and C is determined by F. B1 and F C1 express:

[0074] In the formula, F represents the levitation force generated solely by the levitation current along the Y-axis. μB F represents the magnitude of the levitation force generated at the B-phase stator pole in the μ direction. μC The magnitude of the levitation force generated at the C-phase stator pole in the μ direction.

[0075] The levitation force generated by the X-axis levitation current at the stator poles of phases B and C is determined by F. B2 and F C2 express:

[0076]

[0077] In the formula, F represents the levitation force generated solely by the levitation current along the X-axis. λB F represents the magnitude of the levitation force generated at the B-phase stator pole in the λ direction. λC The magnitude of the levitation force generated at the C-phase stator pole in the λ direction.

[0078] The levitation force F in the X direction x Suspension force F in the Y direction y It can be represented as:

[0079]

[0080] Using Maxwell's stress tensor method, the levitation force generated by each stator pole is expressed as a levitation current:

[0081]

[0082] Matrix operations can be simplified to obtain:

[0083]

[0084] 3) When the rotor angle is between 30° and 45°, i.e., phases A and C are conducting, according to the stator-rotor overlap rule, F can be... x and F y They are projected onto the stator pole directions of phase A and phase C, respectively.

[0085] The levitation force generated by the Y-axis levitation current in phases A and C is determined by F. A1 and F C1 express:

[0086]

[0087] In the formula, F represents the levitation force generated solely by the levitation current along the Y-axis. μA F represents the magnitude of the levitation force generated at the stator pole of phase A in the μ direction. μC The magnitude of the levitation force generated at the C-phase stator pole in the μ direction.

[0088] The levitation force generated by the X-axis levitation current in phases A and C is determined by F. A2 and F C2 express:

[0089]

[0090] In the formula, F represents the levitation force generated solely by the levitation current along the X-axis. λA F represents the magnitude of the levitation force generated at the A-phase stator pole in the λ direction. λC The magnitude of the levitation force generated at the C-phase stator pole in the λ direction.

[0091] Among them, the levitation force F in the X direction x Suspension force F in the Y direction y It can be represented as:

[0092]

[0093] Using Maxwell's stress tensor method, the levitation force generated by each stator pole is expressed as a levitation current:

[0094]

[0095] Matrix operations simplify to obtain:

[0096]

[0097] Figure 3 (a) to Figure 3 (d) is a schematic diagram of the levitation force waveform before decoupling under no-load conditions. When the excitation current is 2A, the Y-axis levitation current is 1A, and the X-axis levitation current is 0A, from... Figure 3 As can be seen from (d), although no X-axis levitation current is applied, the levitation force in the X-axis direction still fluctuates with the rotor position angle. The levitation force cross-coupling coefficient ζ is defined as the ratio of the levitation force in the x-direction generated by coupling to Fy when only the y-direction levitation force Fy needs to be generated. Its magnitude is shown in equation (16):

[0098]

[0099] Figure 4 (a) to Figure 4 (d) is a schematic diagram of the levitation force waveform before decoupling under load conditions. When the excitation current is 2A, the Y-axis levitation current is 1A, and the X-axis levitation current is 0A, from... Figure 4 As can be seen in (d), although no X-axis levitation current is applied, the levitation force in the X-axis direction still fluctuates with the rotor position angle under load conditions. Furthermore, due to the influence of the armature current, compared to... Figure 3 (c), Figure 4 (c) shows that the levitation force in the Y-axis direction is distorted. At this time, the maximum value of ξ in one electrical cycle is 49.8%.

[0100] Figure 5 (a) to Figure 5 (d) is a schematic diagram of the levitation force waveform after decoupling under no-load conditions. With an excitation current of 2A and an armature current of 2A, after applying the levitation current calculated using the decoupling block diagram, compared to... Figure 3 (d), Figure 5 As shown in (d), the levitation force in the X-axis direction hardly changes with the rotor position angle. At this time, the maximum value of ξ in one electric cycle is 0.6%, and the cross-coupling coefficient of the levitation force is reduced by 98% compared with before decoupling.

[0101] Figure 6 (a) to Figure 6 (d) is a schematic diagram of the levitation force waveform after decoupling under load conditions. With an excitation current of 2A and an armature current of 2A, after applying the levitation current calculated using the decoupling block diagram, compared to... Figure 4 (c), Figure 6 As shown in (d), the levitation force in the X-axis direction hardly changes with the rotor position angle. At this time, the maximum value of ξ in one electric cycle is 1.2%, and the cross-coupling coefficient of the levitation force is reduced by 97% compared with before decoupling.

[0102] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for decoupling the levitation force of a high-speed bearingless stator-excited reluctance motor, characterized in that, include: S1. The current position of the rotor of the high-speed bearingless stator-excited reluctance motor is obtained using an eddy current sensor, and the required levitation force values ​​in the X and Y axes are determined based on the current position of the rotor. S2. Obtaining the rotor position angle using a rotary transformer. r And determine the conduction modes of the three-phase windings, the conduction modes of the three-phase windings including: the current presence in the A, B, and C phase armature windings; S3. Decompose the given value of the levitation force to obtain the given value of the levitation force corresponding to the stator pole in the conduction mode; S4. Establish the mapping relationship between the given value of the levitation force corresponding to the stator pole and the levitation current, and obtain the reference values ​​of the levitation current in the X-axis and Y-axis directions; S5. Use a current Hall sensor to collect the actual floating current in the X and Y axis directions; S6. The difference between the actual floating current and the reference value of the floating current is used as the input of the PI controller, and the PI controller outputs a PWM signal to the control circuit of the high-speed bearingless stator-excited reluctance motor. In S3, the following are included: The levitation force generated by each phase stator pole to rotor is divided into Region and The region, among which, The region covers six stator poles near the X-axis plane. The region covers six stator poles close to the Y-axis plane; Give the levitation force a value and Decomposed into a given value of the levitation force generated by each independent stator pole; Suspension force F in the X direction under AB phase conduction mode x Suspension force F in the Y direction y The decomposition is expressed as ,in: , F A1 F B1 and F C1 F represents the levitation force generated by the Y-axis levitation current at the stator poles of phases A, B, and C. A2 F B2 and F C2 This represents the levitation force generated by the X-axis levitation current at the stator poles of phases A, B, and C. This represents the levitation force generated solely by the Y-axis levitation current. for The magnitude of the levitation force generated at the stator pole in direction A. for The magnitude of the levitation force generated at the stator pole of phase B; This represents the levitation force generated solely by the X-axis levitation current. for The magnitude of the levitation force generated at the stator pole in direction A. for The magnitude of the levitation force generated at the stator pole in phase B. , , , , and These represent the six unit direction vectors, i mA i mB i mC The instantaneous values ​​of the armature winding currents of phases A, B, and C obtained from sampling; N f N represents the number of turns of the excitation coil. m i represents the number of turns in the armature coil. f Represents the excitation winding current; Suspension force F in the X direction during BC phase conduction mode x Suspension force F in the Y direction y The decomposition is expressed as: ,in: , , for The magnitude of the levitation force generated at the C-phase stator pole. for The magnitude of the levitation force generated at the C-phase stator pole; The levitation force F in the X direction during AC phase conduction mode x Suspension force F in the Y direction y The decomposition is expressed as: ,in: ， 。 2. The method according to claim 1, characterized in that, S1 includes: The current position of the rotor is obtained using an eddy current sensor. , Rotor position reference value in the X-axis direction The difference is input to the X-axis displacement PID controller, which outputs the required levitation force setpoint in the X-axis direction. ; The current position of the rotor is obtained using an eddy current sensor. , Rotor position reference value in the Y-axis direction The difference is input to the Y-axis displacement PID controller, which outputs the required levitation force setpoint in the Y-axis direction. .

3. The method according to claim 1, characterized in that, The types of conduction modes include: AB phase conduction, BC phase conduction, and AC phase conduction; Among them, when r ∈[0,15 o ), sampled to obtain i mA and i mB ;when r ∈[15 o 30 o ), sampled to obtain i mB and i mC ;when r ∈[30 o ~45 o ), sampled to obtain i mA and i mC .

4. The method according to claim 1, characterized in that, In S4, establishing the correspondence between the levitation force and the levitation current for each stator pole includes: Establish a mapping model between the levitation force and levitation current generated by each stator pole: ， ， ， Where K represents the mechanical characteristic constant of the motor, i sy Indicates the Y-axis floating current, i sx L represents the X-axis levitation current, μ0 represents the air permeability, and L represents the air permeability. Fe R represents the core length, and R represents the rotor radius. N represents the air gap length. s Indicates the number of turns of the levitation coil, A M B M and C M There are three coupling coefficients.

5. The method according to claim 4, characterized in that, In S4, obtaining the reference values ​​of the levitation current in the X-axis and Y-axis directions includes: 。 6. The method according to claim 1, characterized in that, The stator poles of the high-speed bearingless stator-excited reluctance motor adopt a parallel tooth structure, including 4 large slots and 8 small slots. The armature coil is wound on each stator pole, the excitation coil is wound in the large slot of the stator, and the X-axis and Y-axis suspension coils are wound in the large slot of the stator. The suspension coils that are radially opposite in space are connected in reverse series to form the X-axis and Y-axis suspension windings respectively. Four sets of eddy current sensors are used. The eddy current sensors obtain the rotor position signal by measuring the distance between the probe and the reference ring of the rotating shaft.

7. The method according to claim 1, characterized in that, The magnitudes of armature current and excitation current are detected by four sets of current Hall sensors; The magnitudes of the X-axis and Y-axis floating currents are detected using two sets of current Hall sensors.

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