A bearingless asynchronous motor structure and winding optimization method for reducing harmonic suspension force

Abstract

The application discloses a bearingless asynchronous motor structure and a winding optimization method for reducing harmonic suspension force, and aims to improve the suspension performance by optimizing the short pitch angle of the suspension winding. First, the distribution factor and the pitch factor of the winding are considered, and a harmonic suspension force equation of the bearingless asynchronous motor is established; second, the full-pitch structure is adopted for the torque winding, and the short-pitch structure is adopted for the suspension force winding, the first four harmonic suspension force coefficients under different short pitch angles of the suspension winding are compared, and the optimal short pitch angle of the suspension force winding is selected according to the principle that the sum of the harmonic suspension force coefficients is minimum; and finally, a winding design scheme of the bearingless asynchronous motor is formulated, in which the suspension winding is embedded in the inner layer, the torque winding is embedded in the outer layer, and the suspension winding is embedded.

Description

Technical Field

[0001] This invention belongs to the field of asynchronous motor technology, and specifically relates to a bearingless asynchronous motor structure and winding optimization method for reducing harmonic levitation force. Background Technology

[0002] With the development of modern industry, the application of electric motors is becoming increasingly widespread. Traditional mechanical bearing-supported motor systems suffer from friction and wear, which shortens the service life of the motor system and limits the upper limit of motor speed. In addition, the dust generated by friction and wear causes environmental pollution, limiting the application of motors in certain special fields. However, by utilizing the similarity between magnetic bearings and motor stator structures, bearingless motors embed an additional set of suspension windings to generate magnetic tension that balances the rotor's gravity, achieving self-levitation. They have advantages such as no friction and wear, no need for lubrication, and long service life. Among many bearingless motors, bearingless asynchronous motors also have the advantages of reliable operation and low torque ripple, making them very suitable for ultra-high-speed precision operation and possessing profound research value in ultra-high-speed fields such as flywheel energy storage.

[0003] However, bearingless asynchronous motors typically have a small air gap, making them prone to stator-rotor collisions under external disturbances, which can lead to equipment damage or even safety accidents in severe cases. Therefore, suppressing rotor chattering and improving suspension control accuracy have become key issues in the research and development of bearingless asynchronous motors.

[0004] The main causes of vibration in bearingless asynchronous motors include rotor vibration caused by unbalanced magnetic pull and rotor vibration caused by harmonics. Several technologies are currently dedicated to solving these problems. For example, Chinese patent application CN201810153245.X, entitled "An Adaptive Suppression System for Unbalanced Vibration of a Magnetic Levitation Motor Rotor," uses real-time detection of rotor displacement signals combined with an adaptive filtering algorithm to generate a compensation current to suppress vibration caused by mass imbalance. Another patent, CN202010528936.2, entitled "A Harmonic Vibration Suppression Method for Magnetic Bearings Based on a Resonant Controller," adds a multi-frequency resonant controller to the control loop to achieve precise compensation for harmonic disturbances of specific frequencies, thereby enhancing the smoothness of rotor operation. These methods improve the response speed and accuracy of vibration suppression to a certain extent.

[0005] However, most existing research focuses on unbalanced force compensation, and systematic analysis of harmonic vibration mechanisms and their effects is still lacking. In actual operation, the air gap magnetic field of a bearingless asynchronous motor is not an ideal sine wave; its waveform is closer to a square wave containing rich harmonic components. Fourier decomposition reveals a series of higher-order harmonics in addition to the fundamental wave. As long as the difference between the number of pole pairs of the torque winding and the suspension winding is 1, these harmonics can also generate additional suspension forces, resulting in a significant deviation between the actual suspension force and the ideal model. This deviation not only affects the suspension positioning accuracy but also causes interference in the control loop, exacerbating high-frequency chattering of the rotor. Especially at high speeds, force fluctuations caused by harmonics are more easily excited, becoming a bottleneck restricting further improvement in control performance. Summary of the Invention

[0006] To address the rotor vibration problem caused by harmonics in traditional three-phase bearingless asynchronous motors, this invention proposes a bearingless asynchronous motor structure and winding optimization method to reduce harmonic levitation force. The optimal short-pitch angle of the levitation force winding is found to reduce the influence of harmonic levitation force, thereby improving the motor's levitation performance.

[0007] This invention provides a bearingless asynchronous motor structure for reducing harmonic levitation force, including a motor stator and a motor rotor; the stator slots of the motor stator are divided into inner and outer layers and adopt a pear-shaped slot structure, while the motor rotor adopts a squirrel-cage rotor, with both ends of the rotor connected by aluminum rings to form a short-circuit structure, and there is a certain air gap between the motor rotor and the motor stator.

[0008] The inner layer of the motor stator is entirely embedded with suspension windings, and the outer layer of the stator is divided into two parts: the first part is embedded with torque windings, and the second part is embedded with suspension windings.

[0009] The torque winding adopts a full-pitch structure, that is, the corresponding short-pitch angle is 0; while the suspension winding adopts a short-pitch angle structure.

[0010] This invention also provides a method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force, comprising the following steps:

[0011] Step A: Establish the harmonic levitation force equation for the bearingless asynchronous motor, and transform the nth harmonic force expression into a nonlinear function of the distribution factor and pitch factor of the torque winding and the levitation winding, respectively;

[0012] Step A1: For a specific bearingless asynchronous motor, summarize the combination of torque winding and levitation winding pole pairs that generate harmonic levitation force;

[0013] Step A2: Construct the harmonic levitation force equation. Based on the ratio between the harmonic components and the fundamental component, add the fundamental winding factor, harmonic winding factor, and harmonic pole pair number after the fundamental levitation force equation.

[0014] Step B: Compare the sum of the first few harmonic levitation forces under different short-pitch angles of the levitation winding, and find the short-pitch angle of the levitation winding that corresponds to achieving the minimum sum.

[0015] Step B1: In the case of a torque winding with a full pitch angle structure, substitute the specific stator parameters of the bearingless asynchronous motor into the harmonic levitation force equation established in step A, and simplify it.

[0016] Step B2: List the first few harmonic winding factors of the bearingless asynchronous motor, and filter out the parts that change with the harmonic order and the short-pitch angle of the suspension winding, and define them as the harmonic suspension force influence factor.

[0017] Step B3: Add up the previous harmonic levitation force influence factors and define it as the total harmonic levitation force influence factor;

[0018] Step B4: Compare the total harmonic levitation force influence factors under different short-pitch angles of the levitation windings. The short-pitch angle corresponding to the minimum total harmonic levitation force influence factor is the desired one.

[0019] Step C: After obtaining the optimal short-pitch angle of the levitation winding, design the winding wiring for the torque winding and the levitation winding.

[0020] Step C1: Perform torque winding. Number the stator slots clockwise from 12 o'clock. Select the outer layer of the even-numbered part as the torque winding slot of the motor and wind it according to the full-pitch wiring method of the asynchronous motor.

[0021] Step C2: Perform the suspension winding. The inner layer of the stator and the outer layer of the odd-numbered parts are used as the suspension winding slots of the motor, and the winding is performed according to the short-pitch winding wiring method.

[0022] Preferably, the specific steps of step A are as follows:

[0023] When the number of pole pairs in the torque winding of a bearingless asynchronous motor is 1 and the number of pole pairs in the suspension winding is 2, a pole pair combination analysis is performed: at this time, the number of pole pairs of the 12n-1 and 12n+1 harmonics of the torque winding and the number of pole pairs of the 6n-1 and 6n+1 harmonics of the suspension winding satisfy the motor suspension condition, and thus a corresponding harmonic suspension force will be formed.

[0024] Considering the winding distribution factor and pitch factor, the harmonic levitation force series is constructed by multiplying the fundamental levitation force equation by the proportion of harmonics in the torque winding and the levitation winding, respectively:

[0025] (1)

[0026] In the formula, Represents the harmonic levitation force series. represents the fundamental wave levitation force series, and n represents a natural number; and These are the 12n±1 harmonic winding factor of the torque winding and the 6n±1 harmonic winding factor of the suspension winding, respectively. and These are the fundamental winding factors of these two sets of windings, respectively.

[0027] Preferably, the specific steps of step B are as follows:

[0028] Based on the motor distribution factor and pitch factor, the harmonic winding factor related to the harmonic order in the harmonic levitation force equation (1) is rewritten to obtain:

[0029] (2)

[0030] In the formula, , These are the short-pitch angles of the torque winding and the suspension winding, respectively; and These represent the number of stator slots for the torque winding and the suspension winding, respectively; n represents a natural number; when the torque winding adopts a full-pitch structure, the result is... At this point, equation (2) can be rewritten as:

[0031] (3).

[0032] Preferably, the first four harmonic winding factors of the bearingless asynchronous motor are listed:

[0033] When n=1, 2, 3, 4, substituting into equation (3) yields:

[0034] (4)

[0035] In the formula, .

[0036] Preferably, the non-constant components of the coefficients in equation (4) are separated and defined as: harmonic levitation force influence factor. , Based on this, the specific calculation for the first item is as follows:

[0037] (5)

[0038] Substituting n=1 and β2=0 into equation (5), we can obtain the result when using a full-pitch winding structure. The specific values; similarly, substituting n=2 and β2=0 into equation (5) will yield the values ​​when using a full-pitch winding structure. The specific values ​​can be obtained by substituting n=3 and β2=0 into equation (5) when using a full-pitch winding structure. Substituting the specific values ​​n=4 and β2=0 into equation (5), we can obtain the result when using a full-pitch winding structure. The specific value;

[0039] Next, different short-pitch angles of the suspension winding within the range of 0-π are selected, with a difference of 1 / 6π in sequence, i.e., β2=1 / 6π, 2 / 6π, 3 / 6π, 4 / 6π, 5 / 6π. The steps of Equation (5) are used to calculate the four harmonic suspension force influence factors under different short-pitch angles. , , as well as Finally, the total levitation force influence factor is obtained by summing all harmonic levitation force influence factors at the short-pitch angle of the same levitation winding. That is, the total suspension force influence factor when β2=0. Factor affecting total suspension force when β2 = 1 / 6π Factor affecting total suspension force when β2 = 2 / 6π Factor affecting total suspension force when β2 = 3 / 6π Factor affecting total suspension force when β2 = 4 / 6π The total suspension force influence factor when β2=5 / 6π .

[0040] Preferably, the final step is to compare the total levitation force influence factors under different short-pitch angles of the levitation force windings, i.e. , , , , , The shortest distance angle corresponding to the minimum total levitation force influence factor is the optimal angle being sought.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1. This invention analyzes the pole pair relationship between different torque windings and levitation force windings of a bearingless asynchronous motor that can generate harmonic levitation force, and constructs a harmonic levitation force equation, thus improving the levitation theory of bearingless asynchronous motors.

[0043] 2. This invention proposes an optimization method for bearingless asynchronous motor windings to reduce harmonic levitation force. This method can obtain the optimal levitation force winding structure, thereby reducing the chattering effect of harmonic levitation force on the rotor.

[0044] 3. To achieve the optimal short-pitch angle mentioned above, while taking into account the influence of slot fill factor and manufacturing difficulty, this invention designs a winding distribution scheme suitable for full-pitch torque windings and specific-angle suspension windings for specific motor models, providing practical basis for the optimization method of bearingless asynchronous motor windings to reduce harmonic suspension force. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the A-phase winding distribution of the bearingless asynchronous motor provided by the present invention.

[0046] In the diagram: the solid line represents the torque winding, and the dashed line represents the suspension winding. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0048] In addition, the features, operations, and characteristics described in the specification can be combined in any suitable manner to form various embodiments. Similarly, the steps or actions described in the method can be rearranged in a manner that is readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the purpose of clearly describing a particular embodiment and are not necessarily required orders, unless otherwise stated that a particular order must be followed.

[0049] Example

[0050] This invention provides a bearingless asynchronous motor structure for reducing harmonic levitation force, wherein the levitation winding adopts a specific short-pitch angle; it includes a motor stator and a motor rotor; characterized in that the stator slots of the motor stator are divided into inner and outer layers and adopt a pear-shaped slot structure, while the motor rotor adopts a squirrel-cage rotor, with both ends of the rotor connected by aluminum rings to form a short-circuit structure, and there is a certain air gap between the motor rotor and the motor stator; the inner layer of the motor stator is entirely embedded with the levitation winding, and the outer layer of the stator is divided into two parts, the first part embedding the torque winding and the second part embedding the levitation winding.

[0051] The torque winding adopts a full-pitch structure, meaning the corresponding short-pitch angle is 0; while the suspension winding adopts a short-pitch angle structure.

[0052] To balance stator slot fill factor and actual manufacturing complexity, this embodiment designs a winding distribution scheme suitable for full-pitch torque windings and specific-angle suspension windings, dividing the stator slots of the bearingless asynchronous motor into three parts, such as... Figure 1 As shown.

[0053] Specifically, when winding the torque winding, let's take phase A of the motor as an example: (e.g.) Figure 1 The suspended winding shown uses a three-phase bearingless asynchronous motor core with a specific short pitch angle. Unlike traditional distributed bearingless asynchronous motors, this winding method first splits the stator slots into two parts, with odd-numbered slots in the figure representing one part and even-numbered slots representing the other part.

[0054] Furthermore, the even-numbered outer layers are selected as the torque winding slots of the motor, and the windings are wound according to the full-pitch wiring method of a conventional asynchronous motor. In this embodiment, the outer layers of stator slots 4 and 18 are embedded with the first group of windings of phase A of the torque winding; the outer layers of stator slots 6 and 16 are embedded with the second group of windings of phase A, forming a pair of magnetic fields after energization. The winding methods of phases B and C of the torque winding are the same.

[0055] Specifically, when winding the suspension winding, such as Figure 1 The suspended winding shown employs a three-phase bearingless asynchronous motor core with a specific short-pitch angle. The first set of windings for phase A of the suspended winding is embedded in the inner layers of stator slots 4 and 5, and the outer layer of stator slot 23; the second set of windings for phase A of the suspended winding is embedded in the inner layers of stator slots 10 and 11, and the outer layer of stator slot 5; the third set of windings for phase A of the suspended winding is embedded in the inner layers of stator slots 16 and 17, and the outer layer of stator slot 11; the fourth set of windings for phase A of the suspended winding is embedded in the inner layers of stator slots 22 and 23, and the outer layer of stator slot 17, forming two pairs of magnetic fields. The winding methods for phases B and C of the suspended winding are the same.

[0056] The principle of motor rotation in this embodiment is as follows: A rated current is applied to the torque winding of a three-phase bearingless asynchronous motor (with 1 and 2 pole pairs for the torque winding and levitation winding, respectively), forming a rotating magnetic field with one pole pair on the outer layer of the stator. The axial guide bars in the rotor slots cut relative to this rotating magnetic field, thereby inducing a current in the closed rotor bars. This induced current is subjected to a Lorentz force under the action of the rotating magnetic field, generating an electromagnetic torque acting on the rotor bars, driving the motor rotor to rotate.

[0057] The levitation principle is as follows: Applying a rated current to the levitation winding creates a two-pole rotating magnetic field within the stator. This magnetic field and the one-pole magnetic field generated by the torque winding satisfy the condition that their pole pairs differ by one, and their interaction forms a Maxwell force. Based on the dot product and cross product principles of vectors, the levitation winding current is decomposed into the d-axis and q-axis. By adjusting the magnitudes of the d-axis and q-axis currents respectively, stable levitation of the rotor can be achieved.

[0058] The principle of harmonic attenuation is as follows: for the entire motor, its total levitation force is linearly superimposed. As the harmonic order increases, its amplitude decreases exponentially; therefore, only the first four factors affecting the levitation force are considered. Through the optimized calculation method of this invention, a larger total levitation force influence factor indicates a greater harmonic impact; conversely, a smaller total levitation force influence factor indicates a smaller harmonic effect. By selecting the short-pitch angle corresponding to a smaller influence factor, harmonic attenuation can be effectively reduced, further improving the motor's levitation performance.

[0059] Therefore, this invention also provides a method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force; the specific steps are as follows:

[0060] Step one: First, establish the harmonic levitation force equation for the bearingless asynchronous motor, transforming the expression for the nth harmonic force into a nonlinear function of the distribution factors and pitch factors of the torque winding and the levitation winding, respectively. That is, for a specific bearingless asynchronous motor, derive the combination form of the number of pole pairs of the torque winding and the levitation winding that generates the harmonic levitation force. Then, based on the proportional relationship between the harmonic components and the fundamental component, add the fundamental winding factor, the harmonic winding factor, and the number of harmonic pole pairs to the fundamental levitation force equation to construct the harmonic levitation force equation. Next, the sums of the first few harmonic levitation forces under different short-pitch angles of the levitation windings are compared to find the short-pitch angle of the levitation winding that corresponds to the minimum sum. That is, in the case of torque windings with a full-pitch angle structure, the specific stator parameters of the bearingless asynchronous motor are substituted into the harmonic levitation force equation established above and simplified. Then, the first few harmonic winding factors of the bearingless asynchronous motor are listed, and the parts that change with the harmonic order and the short-pitch angle of the levitation winding are selected and defined as harmonic levitation force influence factors. Then, the first few harmonic levitation force influence factors are added together and defined as the total harmonic levitation force influence factor. Finally, the total harmonic levitation force influence factors under different short-pitch angles of the levitation windings are compared, and the short-pitch angle corresponding to the minimum total harmonic levitation force influence factor is the desired result.

[0061] The specific optimization method in this embodiment takes a motor model with 1 pole pair in the torque winding and 2 pole pairs in the suspension winding as an example to perform pole pair combination analysis: At this time, the 12n-1th harmonic pole pair and 12n+1th harmonic pole pair of the torque winding and the 6n-1th harmonic pole pair and 6n+1th harmonic pole pair of the suspension winding satisfy the motor suspension condition, so a corresponding harmonic suspension force will be formed;

[0062] The first step is to consider the winding distribution factor and pitch factor, and multiply the fundamental levitation force equation by the proportion of harmonics in the torque winding and the levitation winding, respectively, to construct the harmonic levitation force series (representing the algebraic sum of levitation forces under a series of n) as follows:

[0063] (1)

[0064] In the formula, Represents the harmonic levitation force series. represents the fundamental wave levitation force series (where F: force, s: suspension), and n represents a natural number; and These are the 12n±1 harmonic winding factor of the torque winding and the 6n±1 harmonic winding factor of the suspension winding, respectively. and These are the fundamental winding factors of these two sets of windings, respectively.

[0065] The second step is to find the optimal short-pitch angle of the levitation winding that can weaken the harmonic levitation force. In this embodiment, based on the motor distribution factor and pitch factor, the harmonic winding factor related to the harmonic order in the harmonic levitation force equation (1) is rewritten to obtain:

[0066] (2)

[0067] In the formula, , These are the short-pitch angles of the torque winding and the suspension winding, respectively; and These represent the number of stator slots for the torque winding and the suspension winding, respectively, where n represents a natural number; when the torque winding adopts a full-pitch structure, the result is... At this point, equation (2) can be rewritten as:

[0068] (3).

[0069] The third step is to list the first four harmonic winding factors of the bearingless asynchronous motor. As described above, the harmonic attenuation principle is followed. In this embodiment, only the first four harmonic winding factors are considered.

[0070] When n=1, 2, 3, 4, substituting into equation (3) yields:

[0071] (4)

[0072] In the formula, k has no actual physical meaning; it is only used to summarize the common part of the four expressions in formula (4) to simplify writing, and can be defined as "a variable".

[0073] The fourth step is to separate the non-constant parts of the coefficients in equation (4) and define them as:

[0074] Harmonic levitation force influencing factor , Based on this, the specific calculation for the first item is as follows:

[0075] (5)

[0076] Substituting n=1 and β2=0 into equation (5), we can obtain the result when using a full-pitch winding structure. The specific values; similarly, substituting n=2 and β2=0 into equation (5) will yield the values ​​when using a full-pitch winding structure. The specific values ​​can be obtained by substituting n=3 and β2=0 into equation (5) when using a full-pitch winding structure. Substituting the specific values ​​n=4 and β2=0 into equation (5), we can obtain the result when using a full-pitch winding structure. The specific value;

[0077] Next, different short-pitch angles of the suspension winding within the range of 0-π are selected, with a difference of 1 / 6π in sequence, i.e., β2=1 / 6π, 2 / 6π, 3 / 6π, 4 / 6π, 5 / 6π. The steps of Equation (5) are used to calculate the four harmonic suspension force influence factors under different short-pitch angles. , , as well as Finally, the total levitation force influence factor is obtained by summing all harmonic levitation force influence factors at the short-pitch angle of the same levitation winding. That is, the total suspension force influence factor when β2=0. Factor affecting total suspension force when β2 = 1 / 6π Factor affecting total suspension force when β2 = 2 / 6π Factor affecting total suspension force when β2 = 3 / 6π The total levitation force influence factor when β2=4 / 6π The total suspension force influence factor when β2=5 / 6π .

[0078] The fifth step is to compare the total levitation force influence factors under different levitation force winding short-pitch angles, i.e. , , , , , The shortest distance angle corresponding to the minimum total levitation force influence factor is the optimal angle being sought.

[0079] To achieve the optimal short-pitch angle mentioned above, while taking into account the influence of slot fill factor and manufacturing difficulty, this invention designs a winding distribution scheme suitable for full-pitch torque windings and specific-angle suspension windings for specific motor models, providing practical basis for the optimization method of bearingless asynchronous motor windings to reduce harmonic suspension force.

[0080] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A bearingless asynchronous motor structure for reducing harmonic levitation force, comprising a motor stator and a motor rotor; characterized in that, The stator slots of the motor stator are divided into inner and outer layers and adopt a pear-shaped slot structure, while the motor rotor adopts a squirrel-cage rotor. Both ends of the rotor are connected by aluminum rings to form a short-circuit structure, and there is a certain air gap between the motor rotor and the motor stator. The inner layer of the motor stator is entirely embedded with suspension windings, and the outer layer of the stator is divided into two parts: the first part is embedded with torque windings, and the second part is embedded with suspension windings.

2. The bearingless asynchronous motor structure for reducing harmonic levitation force according to claim 1, characterized in that, The torque winding adopts a full-pitch structure, that is, the corresponding short-pitch angle is 0; while the suspension winding adopts a short-pitch angle structure.

3. A method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force, characterized in that, Includes the following steps: Step A: Establish the harmonic levitation force equation for the bearingless asynchronous motor, and transform the nth harmonic force expression into a nonlinear function of the distribution factor and pitch factor of the torque winding and the levitation winding, respectively; Step A1: For a specific bearingless asynchronous motor, summarize the combination of torque winding and levitation winding pole pairs that generate harmonic levitation force; Step A2: Construct the harmonic levitation force equation. Based on the ratio between the harmonic components and the fundamental component, add the fundamental winding factor, harmonic winding factor, and harmonic pole pair number after the fundamental levitation force equation. Step B: Compare the sum of the first few harmonic levitation forces under different short-pitch angles of the levitation winding, and find the short-pitch angle of the levitation winding that corresponds to achieving the minimum sum. Step B1: In the case of a torque winding with a full pitch angle structure, substitute the specific stator parameters of the bearingless asynchronous motor into the harmonic levitation force equation established in step A, and simplify it. Step B2: List the first few harmonic winding factors of the bearingless asynchronous motor, and filter out the parts that change with the harmonic order and the short-pitch angle of the suspension winding, and define them as the harmonic suspension force influence factor. Step B3: Add up the previous harmonic levitation force influence factors and define it as the total harmonic levitation force influence factor; Step B4: Compare the total harmonic levitation force influence factors under different short-pitch angles of the levitation windings. The short-pitch angle corresponding to the minimum total harmonic levitation force influence factor is the desired one. Step C: After obtaining the optimal short-pitch angle of the levitation winding, design the winding wiring for the torque winding and the levitation winding. Step C1: Perform torque winding. Number the stator slots clockwise from 12 o'clock. Select the outer layer of the even-numbered part as the torque winding slot of the motor and wind it according to the full-pitch wiring method of the asynchronous motor. Step C2: Perform the suspension winding. The inner layer of the stator and the outer layer of the odd-numbered parts are used as the suspension winding slots of the motor, and the winding is performed according to the short-pitch winding wiring method.

4. The method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force according to claim 3, characterized in that, The specific steps of step A are as follows: When the number of pole pairs in the torque winding of a bearingless asynchronous motor is 1 and the number of pole pairs in the suspension winding is 2, a pole pair combination analysis is performed: at this time, the number of pole pairs of the 12n-1 and 12n+1 harmonics of the torque winding and the number of pole pairs of the 6n-1 and 6n+1 harmonics of the suspension winding satisfy the motor suspension condition, and thus a corresponding harmonic suspension force will be formed. Considering the winding distribution factor and pitch factor, the harmonic levitation force series is constructed by multiplying the fundamental levitation force equation by the proportion of harmonics in the torque winding and the levitation winding, respectively: （1） In the formula, Represents the harmonic levitation force series. represents the fundamental wave levitation force series, and n represents a natural number; and These are the 12n±1 harmonic winding factor of the torque winding and the 6n±1 harmonic winding factor of the suspension winding, respectively. and These are the fundamental winding factors of these two sets of windings, respectively.

5. The method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force according to claim 4, characterized in that, The specific steps of step B are as follows: Based on the motor distribution factor and pitch factor, the harmonic winding factor related to the harmonic order in the harmonic levitation force equation (1) is rewritten to obtain: （2） In the formula, , These are the short-pitch angles of the torque winding and the suspension winding, respectively; and These are the number of stator slots for the torque winding and the suspension winding, respectively, where n represents a natural number; When the torque winding adopts a full-pitch structure, the following is obtained: At this point, equation (2) can be rewritten as: （3）。 6. The method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force according to claim 5, characterized in that, List the first four harmonic winding factors of a bearingless asynchronous motor: When n=1, 2, 3, 4, substituting into equation (3) yields: （4） In the formula, .

7. The method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force according to claim 6, characterized in that, Separate the non-constant parts of the coefficients in equation (4) and define them as: Harmonic levitation force influencing factor , ; Representing the fundamental wave levitation force series, the first term is calculated as follows: （5） Substituting n=1 and β2=0 into equation (5), we can obtain the result when using a full-pitch winding structure. The specific values; similarly, substituting n=2 and β2=0 into equation (5) will yield the values ​​when using a full-pitch winding structure. The specific values ​​can be obtained by substituting n=3 and β2=0 into equation (5) when using a full-pitch winding structure. Substituting the specific values ​​n=4 and β2=0 into equation (5), we can obtain the result when using a full-pitch winding structure. The specific value; Next, different short-pitch angles of the suspension winding within the range of 0-π are selected, with a difference of 1 / 6π in sequence, i.e., β2=1 / 6π, 2 / 6π, 3 / 6π, 4 / 6π, 5 / 6π. The steps of Equation (5) are used to calculate the four harmonic suspension force influence factors under different short-pitch angles. , , as well as Finally, the total levitation force influence factor is obtained by summing all harmonic levitation force influence factors at the short-pitch angle of the same levitation winding. That is, the total suspension force influence factor when β2=0. Factor affecting total suspension force when β2 = 1 / 6π Factor affecting total suspension force when β2 = 2 / 6π Factor affecting total suspension force when β2 = 3 / 6π Factor affecting total suspension force when β2 = 4 / 6π The total suspension force influence factor when β2=5 / 6π .

8. The method for optimizing the windings of a bearingless asynchronous motor to reduce harmonic levitation force according to claim 7, characterized in that, Finally, the total levitation force influence factors under different levitation force winding short-pitch angles were compared, i.e. , , , , , The shortest distance angle corresponding to the minimum total levitation force influence factor is the optimal angle being sought.

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