Stator-rotor structure, motor and eccentric design method

Abstract

This invention discloses a stator-rotor structure, a motor, and an eccentric design method, relating to the field of motor technology. It includes: a stator structure comprising a stator core, wherein the axial centerline of the inner circle of the stator core is offset from the axial centerline of the outer circle of the stator core; a rotor structure disposed inside the stator structure, wherein the axial centerline of the rotor structure coincides with the axial centerline of the outer circle of the stator core; the stator core has multiple stator teeth distributed circumferentially, and the crowns of several stator teeth corresponding to the eccentric side of the stator core have notches, which are recessed towards the tooth root; wherein the eccentric side of the stator core is the side where the axial centerline of the inner circle is offset, resulting in a smaller air gap. The above-described stator-rotor structure can solve the problems of insufficient minimum bearing load and uneven stator-rotor air gap.

Description

Technical Field

[0001] This invention relates to the field of electric motor technology, and more specifically, to a stator-rotor structure. Furthermore, this invention also relates to an electric motor comprising the above-described stator-rotor structure and an eccentric design method applied to the above-described electric motor. Background Technology

[0002] With the continuous development of rail transit vehicles, traction motors, as key core components of rail transit vehicles, are iterating towards miniaturization, lightweighting, and environmental protection technologies. In particular, permanent magnet traction motors have technical advantages such as high efficiency, high power density, and good controllability, and are expected to become the mainstream of the next generation of rail transit traction motors.

[0003] Under the condition that the existing mechanical installation interface and bearing selection configuration remain unchanged, as the rotor weight continues to decrease, the radial base load of the bearing will decrease significantly. During the motor design process, there will be a problem of insufficient minimum bearing load at high speeds, which may easily lead to bearing scratches and shortened service life.

[0004] In related technologies, an eccentric stator-rotor structure is used to address the problem of insufficient minimum bearing load. However, this method typically results in the bearing housing on the end cover being eccentric relative to the center line of the stator core's inner circle. This not only increases the machining difficulty of the bearing housing but also places high demands on the assembly process. Furthermore, the eccentricity of the stator and rotor leads to uneven air gaps, causing relative changes in the air gap magnetic flux density. This, in turn, affects the electromagnetic vibration performance of the motor and adversely impacts system reliability.

[0005] In summary, how to solve the problems of insufficient minimum bearing load and uneven air gap between stator and rotor is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a stator-rotor structure that can solve the problems of insufficient minimum bearing load and uneven air gap between the stator and rotor. Another object of the present invention is to provide a motor including the above-described stator-rotor structure and an eccentric design method applied to the above-described motor.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A stator-rotor structure, comprising: A stator structure, including a stator core, wherein the axial center line of the inner circle of the stator core is offset from the axial center line of the outer circle of the stator core; The rotor structure is located inside the stator structure, and the axial center line of the rotor structure coincides with the axial center line of the outer circle of the stator core. The stator core has a plurality of stator teeth distributed circumferentially. The crowns of several stator teeth corresponding to the eccentric side of the stator core are provided with notches, and the notches are recessed toward the root of the stator teeth. The eccentric side of the stator core is the side where the axial center line of the inner circle deviates, resulting in a smaller air gap.

[0008] Preferably, two adjacent stator teeth are separated by stator slots, and among the stator teeth corresponding to the eccentric side of the stator core, the two edges of the notch portion are respectively connected to the slot walls of the corresponding two stator slots.

[0009] Preferably, the distance between the inner axial center line of the stator core and the outer axial center line of the stator core is the deviation distance. The inner circumferential surface of the stator core on the eccentric side forms the minimum air gap distance with the side of the rotor structure facing the stator structure, and the inner circumferential surface of the stator core on the non-eccentric side forms the maximum air gap distance with the side of the rotor structure facing the stator structure. The difference between the maximum air gap distance and the minimum air gap distance is twice the deviation distance.

[0010] Preferably, the notch has any one of an arc-shaped profile, a crescent-shaped profile, or an angular profile.

[0011] Preferably, the number of stator teeth with the notch is less than or equal to half the number of stator teeth included in the stator core.

[0012] Preferably, the stator core includes a plurality of stacked stator laminations, wherein the inner circle center of any stator lamination is offset relative to the outer circle center of the stator lamination, and the offset is equal to the distance between the inner circle axial centerline of the stator core and the outer circle axial centerline of the stator core.

[0013] The present invention also provides an electric motor, comprising: The stator and rotor structure is any one of the stator and rotor structures described above; The bearing structure includes a front bearing and a rear bearing, wherein the rotor structure is supported on the inner side of the stator structure by the front bearing and the rear bearing; The axial centerline of the front bearing, the axial centerline of the rear bearing, and the axial centerline of the outer circle of the stator core coincide.

[0014] The present invention also provides an eccentric design method, applied to the motor described in any of the above claims, the eccentric design method comprising: The required unilateral magnetic pull force is determined based on the difference between the minimum load required by the bearing structure and the actual working load; the unilateral magnetic pull force is the force generated by the uneven radial air gap between the stator structure and the rotor structure; The deviation distance is calculated based on the unilateral magnetic pull force and magnetic pull force stiffness. The deviation distance is the distance between the inner axial center line of the stator core and the outer axial center line of the stator core.

[0015] Preferably, after calculating the deviation distance based on the unilateral magnetic pull force and magnetic pull force stiffness, the method further includes: If the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure caused by centrifugal force at high speed is less than the original air gap distance, then it is determined that the rotor can operate normally. If the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure caused by centrifugal force at high speed is greater than or equal to the original air gap distance, then the bearing structure is inspected.

[0016] Preferably, after calculating the deviation distance based on the unilateral magnetic pull force and magnetic pull force stiffness, the method further includes: The non-uniformity of the air gap magnetic field intensity and harmonic components corresponding to the first and second motor models are analyzed by finite element simulation method to determine the attenuation of higher harmonic amplitude. The first motor model is a simulation model without the notch, and the second motor model is a simulation model with the notch.

[0017] The stator-rotor structure provided by this invention includes a stator structure and a rotor structure. The stator structure includes a stator core, wherein the axial center line of the inner circle of the stator core is offset from the axial center line of the outer circle of the stator core. This causes a resultant force to be generated on the rotor structure towards the eccentric side when the motor is working, thereby meeting the minimum load requirement of the bearing. The eccentric side is specifically the side where the axial center line of the inner circle is offset, resulting in a smaller air gap. In addition, the stator core has multiple stator teeth distributed circumferentially. The crowns of several stator teeth corresponding to the eccentric side are provided with notches, which are recessed towards the tooth root. This weakens the higher-order harmonic components in the air gap magnetic field, thereby improving the motor's operating performance and the system's reliability.

[0018] The beneficial effects of this invention are as follows: it can not only effectively solve the problem of insufficient minimum bearing load in motor design and improve the manufacturability of the product; but also, in response to the problem of uneven air gap, it can reduce the air gap harmonic content by optimizing the tooth crown structure of the stator teeth, thereby improving the motor's operating performance and the system's reliability, and providing key technical support for motor design. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the installation of the stator and rotor structure provided by the present invention; Figure 2 This is a schematic diagram of the static eccentricity of the stator and rotor structure provided by the present invention; Figure 3 This is a schematic diagram of the structural shape of the notch provided by the present invention; Figure 4 This is a schematic diagram of the static eccentricity design of the motor stator and rotor provided by the present invention; Figure 5 for Figure 4 A schematic diagram of the area with a notch; Figure 6 This is a schematic diagram showing the comparison of air gap magnetic flux density optimization before and after rated operating conditions for two experimental groups provided by the present invention. Figure 7 This is a schematic diagram showing the comparison of air gap magnetic flux density harmonics before and after optimization under rated operating conditions for two experimental groups provided by the present invention. Figure 8 This is a schematic diagram comparing the output torque fluctuation of the motor under the same current and rated operating conditions in two test groups provided by the present invention. Figure 9 This is a flowchart illustrating the eccentric design method provided by the present invention.

[0021] Figures 1-9 In the accompanying drawings, the reference numerals include: 1-Stator structure; 11-Stator winding; 12-Stator housing; 13-Stator core; 2-Rotor structure; 131-Stator teeth; 132-Stator slot; 133-Notch; 3-Front end cover; 4-Rear end cover; 5-Front end bearing; 6-Rear end bearing; 01-Inner circle axial center line; 02-Outer circle axial center line. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The core of this invention is to provide a stator-rotor structure that solves the problems of insufficient minimum bearing load and uneven air gap between the stator and rotor. Another core aspect of this invention is to provide a motor comprising the above-described stator-rotor structure and an eccentric design method applied to the above-described motor.

[0024] The present invention provides a stator-rotor structure, comprising: a stator structure 1 and a rotor structure 2, please refer to the following for details. Figure 1 .

[0025] The stator structure 1 includes a stator core 13, and the axial center line 01 of the inner circle of the stator core 13 is offset from the axial center line 02 of the outer circle of the stator core 13. Here, the inner circle and the outer circle of the stator core 13 are relative, and specifically, the inner circle is closer to the center of the stator structure 1 than the outer circle.

[0026] The stator structure 1 also includes a stator housing 12 and a stator winding 11, wherein the stator core 13 is disposed inside the stator housing 12 and the stator winding 11 is embedded in the stator slot 132 of the stator core 13.

[0027] The rotor structure 2 is located inside the stator structure 1. The axial centerline of the rotor structure 2 coincides with the axial centerline O2 of the outer circle of the stator core 13. This coincidence means that the outer circles of the rotor structure 2 and the stator core 13 are coaxial, while their inner circles are not. This arrangement generates a resultant magnetic pull on the rotor structure 2 towards the eccentric side during motor operation, thus meeting the minimum bearing load requirements. Specifically, the eccentric side refers to the side of the stator core 13 where the axial centerline O1 of the inner circle deviates, resulting in a smaller air gap. Figure 2 The eccentric side is the lower side.

[0028] The eccentric design of the stator and rotor structure is easy to manufacture, which not only ensures that the working load of the bearing meets the minimum required load and improves the manufacturability of the product, but also avoids the risk of abnormal working clearance caused by adjusting the interference fit of the shaft and bearing inner ring, thus improving the service life and reliability of the bearing.

[0029] Specifically, when designing an eccentric motor, the direction of the eccentric side is determined based on actual needs and the motor mounting method, such as vertical, horizontal, or inclined motor mounting. Figure 2 The eccentric side shown is only one example. In reality, it can be set horizontally or inclined relative to the axial center line 01 of the inner circle, or it can be positioned on the upper or lower side. The eccentric design can be flexibly made according to the actual situation.

[0030] In addition, the rotor structure 2 specifically includes a rotating shaft, a rotor core, and a rotor pressure ring. The rotor core is fixedly mounted on the rotating shaft, and the rotor pressure ring is pressed and set at the axial end of the rotor core.

[0031] Please refer to Figure 3 The stator core 13 has multiple stator teeth 131 distributed circumferentially. The crowns of several stator teeth 131 corresponding to the eccentric side of the stator core 13 are provided with notches 133, which are recessed towards the root of the stator teeth 131. The eccentric side of the stator core 13 is the side with a smaller air gap due to the deviation of the inner axial center line O1 from the outer axial center line O2. Figure 2 The eccentric side is the lower part of the stator core 13.

[0032] Among them, the stator teeth 131 corresponding to the eccentric side of the stator core 13 specifically refers to one, two or more stator teeth 131 included on the eccentric side having notches 133. The number of stator teeth 131 with notches 133 can be flexibly changed according to the actual situation without too much restriction.

[0033] By ensuring that the bearing's working load meets the minimum required load through eccentric design, the notch 133 can weaken the higher-order harmonic components in the air gap magnetic field, thereby improving the motor's operating performance and reliability. Specifically, the notch 133 can be in the form of an angled bevel, an arc surface, etc., without specific limitations, and can be flexibly set according to actual needs.

[0034] In this embodiment, the crown of the stator tooth 131 is provided with a notch 133. The notch 133 is recessed toward the root of the stator tooth 131. The crown is specifically relative to the root. By providing the notch 133 at least partially on the crown, the effect of effectively weakening the harmonic components of a specific order in the air gap magnetic field can be achieved.

[0035] The specific form of the notch 133 can be determined based on actual needs, combined with theoretical or simulation techniques, and is not restricted.

[0036] The notch 133 in the stator tooth crown of the stator tooth 131 can weaken the higher harmonic components in the air gap magnetic field. Since the tooth harmonics that are most harmful in permanent magnet motors are usually of a higher order, the notch 133 is particularly effective in suppressing these specific harmonics. Specifically, the principle by which the notch 133 can reduce air gap harmonics is as follows: 1. Idealized magnetic permeability model for the unprocessed notch 133: The air gap permeability Λ(θ) within one tooth pitch can be considered as a rectangular wave function: ; In the formula: For mechanical angles, This refers to the mechanical angle corresponding to a stator tooth pitch of 131. This is the mechanical angle corresponding to the slot width. For the air gap magnetic permeability at the center of stator tooth 131, The air gap magnetic permeability is located at the center of stator slot 132.

[0037] This rectangular wave function exhibits abrupt changes in both the time and spatial domains, and contains a rich array of higher harmonics.

[0038] Fourier series decomposition of rectangular wave permeability: Assuming the origin of the coordinate system is at the center of the tooth, for an ideal rectangular wave permeability, its Fourier series contains only cosine terms; but, ; For average permeability, ; Let be the amplitude of the nth harmonic permeability. ; α is the ratio of the slot width to the tooth pitch of stator slot 132. ; From the above formula, we can see that for a rectangular wave, the amplitude of the nth harmonic... It is proportional to 1 / n, which means that the harmonic amplitude decays more slowly with increasing order, and higher harmonics still have considerable amplitude.

[0039] 2. Idealized magnetic permeability model when machining notch 133: After the stator tooth 131's crown is notched, the magnetic permeability no longer abruptly transitions from the center of the crown to the center of the stator slot 132, but rather forms a smooth transition. The magnetic permeability model is idealized as a trapezoidal wave function. In the trapezoidal wave model, the magnetic permeability remains constant at the center of the crown and the center of the stator slot 132. and There is a linear sloping region at the boundary, and this trapezoidal wave function is much smoother than a rectangular wave.

[0040] Decomposition of trapezoidal wave permeability:

[0041] The notch 133 increases the width of the transition zone. Let β be the angle corresponding to the width of the transition zone (expressed in per unit value). The width of the transition zone refers to the gradually changing path of the magnetic flux from the tooth crown to the notch 133 and then to the slot opening of the stator slot 132 due to the notch 133. The width occupied by the notch 133 in the air gap direction is the width of the transition zone between the magnetic permeability at the tooth tip and the magnetic permeability at the slot opening of the stator tooth 131.

[0042] For a trapezoidal wave, the amplitude of the nth harmonic of its Fourier series is: ; or, ,in, ; .

[0043] 3. Generation of air gap magnetic field

[0044] Radial magnetic flux density in the air gap Magnetomotive force generated by permanent magnet With air gap permeability Multiplying them together gives: .

[0045] 3.1 Decomposition of permanent magnet magnetomotive force

[0046] The permanent magnet magnetomotive force itself also contains a series of spatial harmonics. To simplify the calculation, considering only its fundamental and main harmonics, then: ; In the formula: It is the spatial harmonic order of the permanent magnet magnetomotive force ( (fundamental wave) It is an extreme logarithm. It is the electric angular frequency. The harmonic order is Magnetic flux.

[0047] 3.2 Mathematical expression of magnetic field modulation

[0048] Substituting the Fourier series of magnetomotive force and magnetic permeability into: ; In the formula: Z represents the number of stator slots 132, and the relationship between the number of stator slots 132 and the tooth pitch of stator teeth 131 is as follows: .

[0049] According to the trigonometric identities The above product will produce a series of new spatial harmonic components.

[0050] The harmonic order of the newly generated magnetic field is: In particular, when When (the fundamental wave of the permanent magnet magnetomotive force) is generated, the number of the tooth harmonics is: The amplitude of these tooth harmonics Proportional to: , where F1 is the amplitude of the fundamental magnetomotive force.

[0051] 4. Harmonic suppression effect

[0052] Rectangular wave permeability: ; Trapezoidal wave permeability: ; Combining the two formulas above, the ratio of the harmonic amplitudes before and after processing the notch 133 is: .

[0053] 5. Conclusions and Analysis This is key to analyzing the principle behind the notch 133 on the crown. The properties of the function are as follows: The function is in It reaches a maximum value of 1 at time, and then as The oscillations decrease as the magnitude increases. hour, .

[0054] For a given transition width Harmonic number The higher, The larger, The smaller the value, the better. This means that the notch 133 of the stator tooth crown is more sensitive to higher-order magnetic permeability harmonics. The suppression effect is far stronger than the suppression of low-order harmonics. Number of slots Typically much larger than the number of pole pairs. The most important tooth harmonic (i.e. hour The frequency is very high, so adding a notch 133 to the crown of the stator tooth 131 can very effectively suppress these most harmful tooth harmonics. In some cases, it can even be achieved through careful design. This makes it possible for specific , specifically , Thus allowing This almost completely eliminates the magnetic permeability harmonic and its corresponding tooth harmonic magnetic field.

[0055] As can be seen from the above, the notch in the stator tooth 131 smooths the waveform of the air gap magnetic permeability from a rectangular wave to a trapezoidal wave, introducing a [missing information] into the Fourier series. The attenuation factor significantly reduces the amplitude of higher-order magnetic permeability harmonics, thereby effectively suppressing the higher-order harmonics generated by the modulation of these magnetic permeability harmonics and the permanent magnet magnetomotive force. The air gap magnetic field harmonics.

[0056] Based on the above embodiment, two adjacent stator teeth 131 are separated by stator slots 132. Among the several stator teeth 131 corresponding to the eccentric side of the stator core 13, the two edges of the notch portion 133 are respectively connected to the slot walls of the corresponding two stator slots 132.

[0057] The stator slot 132 is specifically used to set the stator winding 11, and the number of stator slots 132 corresponds to the number of stator teeth 131.

[0058] Among the stator teeth 131 corresponding to the eccentric side of the stator core 13, it refers to the stator teeth 131 that need to be provided with notches 133 on the eccentric side. The two edges of the notches 133 are respectively connected to the groove walls of the corresponding two stator slots 132. That is, the notches 133 are an integral notch of the crown part of the stator teeth 131. Specifically, the notches 133 can be in the form of a whole arc surface, a slope surface, or other combinations, which can be designed according to the actual situation.

[0059] Specifically, the gap 133 is as follows: Figure 3 The crescent-shaped notch shown has its two edges connected to the slot walls of the two stator slots 132 at their corresponding positions. Thus, magnetic conduction transition can be achieved through the notch 133, which can effectively reduce the harmonic components of a specific order in the air gap magnetic field during motor operation, making the air gap magnetic field waveform closer to a sine wave.

[0060] In this embodiment, among the stator teeth 131 corresponding to the eccentric side of the stator core 13, the notch 133 of the tooth crown of each stator tooth 131 is in the same form.

[0061] Based on any of the above embodiments, please refer to Figure 2 , Figure 4 The distance between the inner axial center line 01 of the stator core 13 and the outer axial center line 02 of the stator core 13 is the deviation distance L1. The inner circumference surface of the stator core 13 on the eccentric side forms the minimum air gap distance L3 with the side of the rotor structure 2 facing the stator structure 1. The inner circumference surface of the stator core 13 on the non-eccentric side forms the maximum air gap distance L2 with the side of the rotor structure 2 facing the stator structure 1. The difference between the maximum air gap distance L2 and the minimum air gap distance L3 is twice the deviation distance L1.

[0062] The inner circular surface of the stator core 13 on the eccentric side forms the minimum air gap distance with the side of the rotor structure 2 facing the stator structure 1, while the non-eccentric side forms the maximum air gap distance L2. This generates a corresponding unilateral magnetic pull in the direction of the minimum air gap L3 to meet the minimum radial load requirements of the motor's rolling bearings.

[0063] Please refer to Figure 4 , Figure 5 Taking a three-phase 12-pole 72-slot double-end drive permanent magnet traction motor as an example, both the front bearing 5 and the rear bearing 6 need to use bearings of specific models and specifications, such as the front bearing 5 model being NU214 and the rear front bearing 5 model being 6016, and an eccentric design is required.

[0064] Specifically, assuming the air gap between the stator and rotor is uniformly 1.5mm when the motor is not eccentric, to meet the minimum load requirement of the bearing, calculations show that the outer axial center line 02 of the stator core 13 and the inner axial center line 01 of the stator core 13 are offset by 0.15mm relative to each other. This makes the center line of the rotor structure 2 concentric with the outer axial center line of the stator core 13, thus causing the center line of the rotor structure 2 to be vertically offset downward by 0.15mm relative to the inner axial center line 01 of the stator core 13. The resulting unilateral magnetic pull is directed towards the direction with the smaller air gap, i.e., downward. This unilateral magnetic pull is superimposed in the same direction as the rotor's own weight and working load, thus ensuring that the bearing's working load meets the required minimum load.

[0065] The formula for calculating the unilateral magnetic pull F is as follows: ; In the formula: For magnetic tensile stiffness, The eccentricity distance affects the magnetic pull stiffness at different speeds, due to variations in magnetic flux density. Based on the formula above, calculations show that after static eccentricity, the single-sided magnetic pull is 1.57 kN at the rated speed of 2000 r / min and 0.85 kN at the maximum speed of 3500 r / min. The single-sided magnetic pull decreases with increasing speed, but the actual working load of the bearing at the maximum speed is still greater than the minimum radial load required by the bearings at both ends. Therefore, the bearings at both ends can meet the minimum load requirements without affecting the normal operation of the motor. These bearings are the front bearing 5 and the rear bearing 6.

[0066] Based on any of the above embodiments, the notch 133 has any one of an arc-shaped profile, a crescent-shaped profile, or an angular profile. Specifically, the angular profile corresponds to a notch in the form of a bend. The notch 133 can be formed by punching or cutting, and there are no limitations.

[0067] Please refer to Figure 5 The crowns of the 11 stator teeth 131 located on the lower side of the stator core 13 are provided with crescent-shaped notches, while the shape of the remaining 61 stator teeth 131 remains unchanged.

[0068] like Figure 6 As shown, finite element simulation calculations reveal that, under rated operating conditions, the addition of notch 133 to the stator tooth crown makes the air gap magnetic flux density variation more uniform and the waveform closer to a sine wave. Figure 6 S1 is the test group with only eccentric design, and S2 is the test group with both eccentric design and notch 133 design.

[0069] As shown in Table 1, S1 represents the test group with only eccentric design, and S2 represents the test group with both eccentric design and notch 133 design. Figure 7It can be seen that, without affecting the fundamental amplitude of the air gap magnetic flux density, it can effectively reduce the 3rd, 5th, 7th, 11th, and 13th harmonics in the air gap during motor operation; and, as Figure 8 As shown, under rated operating conditions, compared with the stator tooth 131 before the tooth crown notch treatment, the motor's output performance remains unchanged, and the torque fluctuation is basically the same.

[0070] Table 1. Comparison of air gap magnetic flux density harmonic order and amplitude for different experimental groups

[0071] In one specific embodiment, the number of stator teeth 131 with notches 133 is less than or equal to half the number of stator teeth 131 included in the stator core 13.

[0072] The number of stator teeth 131 included in the stator core 13 refers to the total number of all stator teeth 131 included in the entire stator core 13.

[0073] The number of stator teeth 131 with notches 133 is less than half of the total number, and can be determined according to the actual situation. The specific actual situation here is based on the size of the area to be set on the eccentric side.

[0074] Alternatively, it can be said that the number of stator teeth 131 with notches 133 is less than half the total number of stator slots 132 included in the entire stator core 13.

[0075] Based on any of the above embodiments, the stator core 13 includes a plurality of stacked stator laminations, wherein the inner circle center of any stator lamination is offset relative to the outer circle center of the stator lamination, and the offset is equal to the distance between the inner circle axial center line O1 of the stator core 13 and the outer circle axial center line O2 of the stator core 13.

[0076] In this embodiment, the stator core 13 is formed by stacking multiple stator laminations of the same shape and size axially. Each stator lamination has an inner circle and an outer circle, and the center of the inner circle of a single stator lamination is offset relative to the center of the outer circle. The offset directions of each stator lamination are kept consistent, and during the stacking process, the offset directions of all stator laminations are aligned with each other, forming an integral stator core 13 after stacking. The axial center line O1 of the inner circle of the stator core 13 formed after stacking is offset by the same distance relative to the axial center line O2 of the outer circle of the stator core 13.

[0077] Therefore, the formed stator core 13 has a stable eccentric structure, and the center of the inner circle of the stator lamination is offset from the center of the outer circle of the stator lamination by a predetermined amount. This offset is set according to the magnitude of the unilateral magnetic pull required by the motor, so that an uneven radial air gap is formed between the stator core 13 and the rotor structure 2, generating the required unidirectional radial electromagnetic attraction in the direction of the minimum air gap. This provides sufficient radial preload for the rolling bearing, ensuring that the rolling bearing meets the minimum load requirement at all operating speeds and avoiding slippage and abnormal wear under light load.

[0078] In this embodiment, the stator core is in the form of a straight slot or an inclined slot; when the stator core is an inclined slot, the stator slot 132 is inclined along the axial direction, and its inclination direction is clockwise or counterclockwise when viewed from the winding parallel end.

[0079] In addition to the stator and rotor structures described above, please refer to... Figure 1 The present invention also provides an electric motor, comprising: The stator and rotor structure is any one of the stator and rotor structures mentioned above; The bearing structure includes a front bearing 5 and a rear bearing 6. The rotor structure 2 is supported on the inner side of the stator structure 1 by the front bearing 5 and the rear bearing 6. The front bearing 5 is installed on the front cover 3 and the rear bearing 6 is installed on the rear cover 4.

[0080] The axial centerline of the front bearing 5, the axial centerline of the rear bearing 6, and the axial centerline 02 of the outer circle of the stator core 13 coincide; the axial centerlines of the front bearing 5 and the rear bearing 6 are both deviated from the axial centerline 01 of the inner circle of the stator core 13.

[0081] The bearing in this embodiment can be lubricated by grease or by oil.

[0082] Because the eccentric design of the stator and rotor structure in this embodiment is achieved through eccentricity during the stator lamination manufacturing process; in some special scenarios or under certain usage requirements, if static eccentricity is not required, a non-eccentric structure design can be achieved by offsetting the end cover bearing chamber relative to the inner axial center line 01 of the stator structure 1 by the same distance, or by offsetting the end cover and the mounting stop of the frame relative to the inner axial center line 01 of the stator structure 1 by the same distance. Specifically, the aforementioned end cover refers to the front end cover 3 and the rear end cover 4. The offset by the same distance refers to the same distance as the offset between the inner axial center line 01 of the stator core 13 and the outer axial center line 02 of the stator core 13.

[0083] By using an eccentric design and setting a notch 133, the odd-order harmonics in the air gap can be significantly weakened while meeting the minimum load required by the bearing, making the air gap magnetic field waveform closer to a sine wave and improving the reliability of motor operation.

[0084] The motors addressed in this embodiment include, but are not limited to, permanent magnet synchronous traction motors and asynchronous traction motors used in rail transit vehicles.

[0085] In addition to the stator and rotor structures described above, please refer to... Figure 9 The present invention also provides an eccentric design method, applied to the motor described in any of the above claims, the eccentric design method comprising: The required unilateral magnetic pull force is determined based on the difference between the minimum load required by the bearing structure and the actual working load; the unilateral magnetic pull force is the force generated by the uneven radial air gap between stator structure 1 and rotor structure 2. The deviation distance is calculated based on the unilateral magnetic pull force and magnetic pull force stiffness. The deviation distance is the distance between the inner circle axial center line 01 of the stator core 13 and the outer circle axial center line 02 of the stator core 13.

[0086] The deviation distance is calculated based on the unilateral magnetic pull force and the stiffness of the magnetic pull force. Specifically, the calculation formula for the unilateral magnetic pull force F is as follows: This calculation formula allows us to obtain the theoretical value of the deviation distance, providing a theoretical basis for subsequent design and manufacturing.

[0087] The deviation distance obtained by the above calculation formula can reliably guarantee the provision of the required unilateral magnetic force, ensuring that the bearing can meet the minimum load requirements after this design.

[0088] Based on the above embodiments, after calculating the deviation distance based on the unilateral magnetic pull force and the magnetic pull force stiffness, the method further includes: If the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure caused by centrifugal force at high speed is less than the original air gap distance, then it is determined that the machine can operate normally. If the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure caused by centrifugal force at high speed is greater than or equal to the original air gap distance, then the bearing structure should be inspected.

[0089] The inspection of the bearing structure refers to any problems with the selected bearings. This includes the front bearing 5 and the rear bearing 6. If the bearings are faulty, such as having an unsuitable model or inappropriate lubrication method, they need to be replaced and matched before implementing the eccentric design. This ensures the effectiveness and reliability of the eccentric design.

[0090] In this embodiment, the non-deviation state refers to the situation where, without adopting an eccentric design, the axial center line of the front bearing 5, the axial center line of the rear bearing 6, the axial center line 02 of the outer circle of the stator core 13, the axial center line 01 of the inner circle of the stator core 13, and the axial center line of the rotor structure 2 all coincide.

[0091] Only when the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure caused by centrifugal force at high speed is less than the original air gap distance, can the motor be determined to operate normally. The determined deviation distance does not affect the normal operation of the motor at high speed, indicating that the value of the determined deviation distance can be used for subsequent design.

[0092] Based on any of the above embodiments, please refer to Figure 9 After calculating the deviation distance based on the unilateral magnetic pull force and magnetic pull force stiffness, it also includes: The non-uniformity of the air gap magnetic field intensity and harmonic components corresponding to the first and second motor models are analyzed by finite element simulation method to determine the attenuation of higher harmonic amplitude. The first motor model is a simulation model without the notch 133, and the second motor model is a simulation model with the notch 133.

[0093] Among them, by analyzing the non-uniformity of the air gap magnetic field strength and harmonic components of the first motor model through finite element simulation, the harmonics that have a significant impact on the vibration and noise performance of the motor can be identified; while by analyzing the non-uniformity of the air gap magnetic field strength and harmonic components of the second motor model through finite element simulation, the attenuation of the higher harmonic amplitude after the notch 133 is set is verified, and the designed model is tested.

[0094] The design of the notch 133 has been verified to reduce the amplitude of certain higher harmonics and their effects, thereby improving the motor's operating performance and system reliability. Only then can the design be considered effective.

[0095] Furthermore, based on an effective design, the offset distance and the number and shape of the crown notch 133 of the stator tooth 131 can be ultimately determined.

[0096] Furthermore, the actual load on the bearing at different operating speeds is calculated. If the actual load is greater than or equal to the minimum load of the bearing structure, the final verification is completed, indicating that the design can be put into industrial production. This step is to recalculate and verify the actual load on the bearing at different operating speeds to ensure that the minimum load required by the bearing is met, thus guaranteeing the reliability and effectiveness of the finally determined stator and rotor structure design.

[0097] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0098] The stator-rotor structure, motor, and eccentric design method provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A stator-rotor structure, characterized in that, include: The stator structure (1) includes a stator core (13), wherein the axial center line (01) of the inner circle of the stator core (13) is offset from the axial center line (02) of the outer circle of the stator core (13); The rotor structure (2) is located inside the stator structure (1), and the axial center line of the rotor structure (2) coincides with the axial center line (02) of the outer circle of the stator core (13). The stator core (13) has a plurality of stator teeth (131) distributed circumferentially. The crowns of a plurality of stator teeth (131) corresponding to the eccentric side of the stator core (13) are provided with notches (133), and the notches (133) are recessed toward the root of the stator teeth (131). The eccentric side of the stator core (13) is the side where the axial center line (01) of the inner circle deviates so that the air gap is smaller.

2. The stator and rotor structure according to claim 1, characterized in that, The two adjacent stator teeth (131) are separated by stator slots (132). Among the stator teeth (131) corresponding to the eccentric side of the stator core (13), the two edges of the notch (133) are respectively connected to the slot walls of the two corresponding stator slots (132).

3. The stator and rotor structure according to claim 1, characterized in that, The distance between the inner axial center line (01) of the stator core (13) and the outer axial center line (02) of the stator core (13) is the deviation distance. The inner circumferential surface of the stator core (13) on the eccentric side forms the minimum air gap distance with the side of the rotor structure (2) facing the stator structure (1). The inner circumferential surface of the stator core (13) on the non-eccentric side forms the maximum air gap distance with the side of the rotor structure (2) facing the stator structure (1). The difference between the maximum air gap distance and the minimum air gap distance is twice the deviation distance.

4. The stator and rotor structure according to claim 1, characterized in that, The notch (133) has any one of the following: arc-shaped profile, crescent-shaped profile, or angular profile.

5. The stator and rotor structure according to claim 2, characterized in that, The number of stator teeth (131) with the notch (133) is less than or equal to half the number of stator teeth (131) included in the stator core (13).

6. The stator and rotor structure according to claim 1, characterized in that, The stator core (13) includes a plurality of stacked stator laminations, wherein the inner circle center of any stator lamination is offset relative to the outer circle center of the stator lamination, and the offset is equal to the distance between the inner circle axial center line (01) of the stator core (13) and the outer circle axial center line (02) of the stator core (13).

7. An electric motor, characterized in that, include: The stator and rotor structure is the stator and rotor structure as described in any one of claims 1 to 6; The bearing structure includes a front bearing (5) and a rear bearing (6), and the rotor structure (2) is supported on the inner side of the stator structure (1) by the front bearing (5) and the rear bearing (6); The axial centerline of the front bearing (5), the axial centerline of the rear bearing (6), and the axial centerline (02) of the outer circle of the stator core (13) coincide.

8. An eccentric design method, characterized in that, The eccentric design method, applied to the motor of claim 7, comprises: The required unilateral magnetic pull force is determined based on the difference between the minimum load required by the bearing structure and the actual working load; the unilateral magnetic pull force is the force generated by the uneven radial air gap between the stator structure (1) and the rotor structure (2); The deviation distance is calculated based on the unilateral magnetic pull force and magnetic pull force stiffness. The deviation distance is the distance between the inner circle axial center line (01) of the stator core (13) and the outer circle axial center line (02) of the stator core (13).

9. The eccentric design method according to claim 8, characterized in that, After calculating the deviation distance based on the unilateral magnetic pull force and magnetic pull force stiffness, the method further includes: If the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure (2) under high speed caused by centrifugal force is less than the original air gap distance, then it is determined that it can operate normally. If the sum of the deviation distance, the radial clearance of the bearing structure, and the radial deformation of the rotor structure (2) under high speed caused by centrifugal force is greater than or equal to the original air gap distance, then the bearing structure is inspected.

10. The eccentric design method according to claim 9, characterized in that, After calculating the deviation distance based on the unilateral magnetic pull force and magnetic pull force stiffness, the method further includes: The non-uniformity of the air gap magnetic field intensity and harmonic components corresponding to the first and second motor models are analyzed by finite element simulation method to determine the attenuation of higher harmonic amplitude. The first motor model is a simulation model without the notch (133), and the second motor model is a simulation model with the notch (133).

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