Permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration and design method thereof

Abstract

The invention discloses a permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration and a design method thereof, and belongs to the technical field of permanent magnet motors. According to the structure, air gap magnetic conductance can be optimized, and a flat inverted V-shaped groove which is symmetrical about a center line is formed in a stator tooth part; then, a vertical inverted V-shaped groove is formed in the stator tooth part flat inverted V-shaped groove foundation, the opening of the groove is smaller than that of the flat inverted V-shaped groove, and the depth of the groove is larger than that of the flat inverted V-shaped groove; the deeper the grooves are closer to the central line of the stator tooth part, and the shallower the grooves close to the notches are until the grooves coincide with the edges of the stator teeth; the larger the transverse size of the auxiliary groove is, the better the optimization of air gap magnetic conductance is, and each tooth part of the stator iron core is provided with the same auxiliary groove structure; the stator core auxiliary slot structure can effectively suppress electromagnetic vibration of the motor. Compared with a traditional stator iron core rectangular auxiliary groove structure, the stator iron core rectangular auxiliary groove structure has the advantages that the electromagnetic vibration suppression effect is better, the sacrifice torque is less, and meanwhile, the torque pulsation can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet motors, and in particular to a permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration and a design method thereof. Background Art

[0002] Permanent magnet synchronous motors have become the core drive components of modern industrial equipment due to their technical advantages such as excellent power density, high-efficiency conversion characteristics, compact structural design, operational stability and precise controllability.

[0003] Torque ripple and electromagnetic vibration noise, key defects affecting the power quality of permanent magnet motors, are primarily caused by cogging torque and current harmonics. For permanent magnet motors, excessive torque ripple and electromagnetic vibration noise can significantly reduce the motor's low-speed performance and control accuracy, and can even cause system resonance. While advanced control strategies can alleviate these deficiencies to a certain extent, torque ripple and electromagnetic vibration noise can be more easily reduced by changing the motor topology and adjusting key parameters. As a key factor restricting the performance improvement of permanent magnet motors, the influencing mechanism and control strategies of motor vibration have become a research hotspot in recent years.

[0004] From an application perspective, the impact of vibration on permanent magnet motor systems exhibits significant multi-dimensional effects: in industrial production, excessive mechanical vibration not only leads to a reduction in machining accuracy but also accelerates fatigue failure of key equipment components. In civilian products, long-term exposure to vibration environments can cause disorders in the human nervous system, resulting in reduced work efficiency and potential health risks. In military equipment applications, the frequent occurrence of vibration noise significantly increases the strength of the equipment's characteristic signal, directly threatening the combat system's concealed effectiveness and battlefield survivability. Based on this, vibration suppression technology has become a core issue in breaking through the performance bottleneck of permanent magnet motors, and its innovative research results will directly promote the development of the next generation of high-precision permanent magnet drive systems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects existing in the above-mentioned background technology. The present invention proposes a surface-mounted permanent magnet motor stator tooth auxiliary slot structure and its design method for suppressing electromagnetic vibration. The structure uses double V-shaped new auxiliary slots on the teeth of the stator core to weaken the 2nd frequency radial electromagnetic force, thereby suppressing the 2nd frequency electromagnetic vibration caused by it.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

[0007] A permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration specifically includes:

[0008] The stator teeth are provided with inverted double V-shaped auxiliary slots to weaken the double frequency radial electromagnetic force and the electromagnetic vibration caused by it. The specific slotting steps include: providing a flat inverted V-shaped auxiliary slot 1 on the stator teeth, wherein the auxiliary slots are symmetrical about the stator tooth centerline; providing a vertical inverted V-shaped auxiliary slot 2 on the basis of the flat inverted V-shaped auxiliary slot 1 on the stator teeth, wherein the auxiliary slots are symmetrical about the stator tooth centerline;

[0009] The opening of the vertical inverted V-shaped groove 2 of the stator tooth is smaller than the opening of the flat inverted V-shaped groove 1; the depth of the vertical inverted V-shaped groove 2 is greater than the depth of the flat inverted V-shaped groove 1.

[0010] Furthermore, the closer the stator tooth auxiliary slot is to the center, the deeper the slot is, and the closer the auxiliary slot is to the slot opening, the shallower the slot is, until it coincides with the edge line of the stator tooth.

[0011] Furthermore, the larger the transverse dimension of the stator tooth auxiliary slot is, the greater the degree of weakening of the double frequency radial electromagnetic force and the electromagnetic vibration caused by it.

[0012] A method for designing a stator tooth auxiliary slot structure of a permanent magnet motor for suppressing electromagnetic vibration comprises the following steps:

[0013] Step S1, optimizing the stator topology of the motor to reduce the amplitude of the first-order permeance harmonic;

[0014] Step S2: Optimize the auxiliary slot structure to completely fit the total permeance waveform after weakening the first-order permeance, thereby suppressing motor vibration;

[0015] Step S3: adopting an inverted double V-shaped superimposed auxiliary groove structure so that the tooth surface edge shape approaches the total magnetic permeance waveform shape after reducing the first-order magnetic permeance harmonic, thereby specifically reducing the first-order magnetic permeance harmonic.

[0016] Furthermore, the novel auxiliary slot can effectively weaken the double frequency radial electromagnetic force without affecting the torque.

[0017] Furthermore, the principle of the design method is:

[0018] By optimizing the stator topology of the motor, the amplitude of the first-order magnetic permeance harmonic can be reduced. If the amplitude of the fundamental magnetic permeance wave is reduced, the magnetic permeance waveform will be concave in the middle of the tooth surface. The longer the air gap, the smaller the magnetic permeance. If the tooth surface shape is modified so that the tooth surface edge shape approaches the total magnetic permeance waveform shape after reducing the first-order magnetic permeance harmonic, the corresponding magnetic permeance harmonic can be reduced in a targeted manner. By using a new auxiliary slot in the middle of the stator tooth, the local air gap length is increased, causing the magnetic permeance waveform in the middle of the tooth surface to be concave, thereby reducing the amplitude of the fundamental magnetic permeance wave.

[0019] Furthermore, the design method principles specifically include:

[0020] According to the parity and periodicity of the permanent magnet potential, the permanent magnet potential of the surface-mounted rotor can be expressed by a Fourier series containing only odd harmonics:

[0021]

[0022] The stator winding is powered by a sinusoidal wave, and the stator armature reaction magnetomotive force can be expressed as:

[0023]

[0024] F p is the magnetomotive force generated by the permanent magnet; P is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle; F s is the armature reaction magnetomotive force generated by the stator winding; μ is the harmonic order of the permanent magnet magnetomotive force; v is the harmonic order of the armature magnetomotive force; F μ is the amplitude of the permanent magnet magnetomotive force of the μth harmonic; F v is the armature magnetomotive force amplitude of the vth harmonic; is the phase angle of the vth armature harmonic magnetic potential;

[0025] After considering the effect of stator slotting, the air gap permeance of the motor is no longer a constant, so it is necessary to introduce a permeance function to measure the effect of stator slotting.

[0026] Furthermore, the permeability function includes two parts: a constant component and a harmonic component, which can be expressed as:

[0027]

[0028] The air gap permeance of the motor is calculated using the magnetic potential permeance method. The permeance can be expressed as

[0029]

[0030] Where Λ(θ) is the air gap permeability; Λ0 is the constant component of the air gap permeability; δ(θ) is the equivalent air gap length; Z is the number of teeth of the motor; μ0 is the vacuum permeability; k is the harmonic order of the permeability; θ is the circumferential angle; Λ k is the permeability amplitude of the kth harmonic;

[0031] The constant part of the permeance is much larger than the harmonic part, and the air gap permeance is inversely proportional to the air gap length.

[0032] Furthermore, the design method principle specifically includes:

[0033] When the motor is unloaded, the permanent magnet potential generated by the permanent magnet is the only excitation source inside the motor. The no-load air gap flux density can be expressed as:

[0034] B r (θ,t)=F p(θ,t)·Λ(θ)

[0035] When the motor is loaded, the excitation sources inside the motor include the permanent magnet magnetic potential and the armature magnetic potential; the load air gap magnetic flux density can be expressed as:

[0036] B r (θ,t)=[F p (θ,t)+F s (θ,t)]·Λ(θ)

[0037] According to Maxwell tensor law, the radial electromagnetic force per unit area of the motor stator can be expressed as:

[0038]

[0039] Where B r is the radial air gap magnetic flux density; f r is the radial electromagnetic force density per unit area; f s is the electromagnetic force wave generated by the armature winding magnetic field; f ps is the electromagnetic force wave generated by the interaction between the permanent magnet and the winding; f p is the electromagnetic force wave generated by the permanent magnet; μ0 is the magnetic permeability of vacuum; θ is the circular angle; t is the time.

[0040] Furthermore, the electromagnetic force wave f generated by the permanent magnet p It can be further expressed as:

[0041] f p (θ,t)=f p1 (θ,t)+f p2 (θ,t)+f p3 (θ,t)

[0042] in

[0043]

[0044] Where, f p is the electromagnetic force wave generated by the permanent magnet; μ1 and μ2 are the harmonic orders of the permanent magnet potential; F u1 、F u2 is the amplitude of the permanent magnet magnetomotive force of the μ1th and μ2th harmonics; Λ0 is the constant component of the air gap permeance; k is the permeance harmonic order; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle;

[0045] The electromagnetic force wave f generated by the armature winding magnetic field s It can be further expressed as:

[0046] f s (θ,t)=f s1 (θ,t)+f s2 (θ,t)+f s3 (θ,t)

[0047] in

[0048]

[0049] Where, f s is the electromagnetic force wave generated by the armature winding magnetic field; v1 and v2 are the harmonic orders of the armature magnetic potential; F v1 、F v2 is the armature magnetomotive force amplitude of the v1th and v2th harmonics; is the phase angle of the v1th and v2th harmonic armature magnetic potential; Λ0 is the constant component of the air gap magnetic permeance; k is the harmonic order of magnetic permeance; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle;

[0050] where f s1 、f s2 and f s3 They are composed of two parts. The electromagnetic force component of the latter part does not change with time and will not produce vibration. Therefore, the electromagnetic force component of the first part of these three items is the effective component that produces vibration in the armature magnetic field.

[0051] The electromagnetic force wave f generated by the interaction between the permanent magnet and the winding ps It can be further expressed as:

[0052] f ps (θ,t)=f ps1 (θ,t)+f ps2 (θ,t)+f ps3 (θ,t)

[0053] in

[0054]

[0055] Where, f ps is the electromagnetic force wave generated by the interaction between the permanent magnet and the winding; μ is the harmonic order of the permanent magnet potential; F u is the amplitude of the permanent magnet magnetomotive force of the μth harmonic; v is the harmonic order of the armature magnetomotive force; F v is the armature magnetomotive force amplitude of the vth harmonic; is the phase angle of the vth armature harmonic magnetic potential; Λ0 is the constant component of the air gap magnetic permeance; k is the harmonic order of magnetic permeance; Λk1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circular angle.

[0056] Compared with the prior art, the present invention adopts the above technical solution, and has the following beneficial effects:

[0057] (1) The present invention proposes a permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration, which makes the tooth surface edge shape approach the total magnetic permeance waveform after reducing the first-order magnetic permeance harmonic. By optimizing the air gap magnetic track to weaken the 2nd frequency radial electromagnetic force, the motor vibration is suppressed.

[0058] (2) The present invention proposes a permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration, which has a simple structure, is easy to implement, has a better magnetic vibration suppression effect, sacrifices less torque, and can reduce torque pulsation.

[0059] (3) The present invention proposes a method for designing a stator tooth auxiliary slot structure for a permanent magnet motor for suppressing electromagnetic vibration. The method can accurately locate the electromagnetic force wave vibration excitation source and specifically reduce the amplitude of the first-order magnetic permeability harmonic. Under the condition that the area of the auxiliary slot is the same as that of the traditional auxiliary slot, it can effectively weaken the double-frequency radial electromagnetic force and avoid the parameter trade-off problem of suppressing vibration and maintaining average torque in the traditional method.

[0060] (4) The present invention proposes a method for designing a stator tooth auxiliary slot structure for a permanent magnet motor that suppresses electromagnetic vibration. This method is easier to manufacture than a complex structure that completely fits the magnetic permeability waveform. It takes into account the vibration suppression effect, torque performance and process feasibility, and provides a scientific, efficient, practical and reliable solution for the low-vibration design of permanent magnet motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a schematic diagram of the novel double V-shaped auxiliary slot structure of the permanent magnet motor stator teeth of the present invention;

[0062] Figure 2 This is a structural diagram of the permanent magnet motor of the present invention using a new double V-shaped auxiliary slot;

[0063] Figure 3 This is a schematic diagram showing the principle of slotting stator teeth to reduce air gap magnetic permeability in the present invention;

[0064] Figure 4 Schematic diagram of stator teeth without auxiliary slots;

[0065] Figure 5 Schematic diagram of stator teeth with traditional auxiliary slots;

[0066] Figure 6 Schematic diagram of stator teeth with new double V-shaped auxiliary slots;

[0067] Figure 7 It is a cross-sectional view of the permanent magnet motor structure without auxiliary slots;

[0068] Figure 8 It is a cross-sectional view of the permanent magnet motor structure with traditional auxiliary slots;

[0069] Figure 9 This is a cross-sectional view of the permanent magnet motor structure with a new double V-shaped auxiliary slot;

[0070] Figure 10 Air gap permeability and 2f for new auxiliary slot motor e Effect comparison chart;

[0071] Figure 11 This is the output torque diagram of the permanent magnet motor with double V-shaped new auxiliary slots;

[0072] Figure 12 This is the vibration acceleration spectrum of the motor with auxiliary slots in the stator teeth under no-load conditions;

[0073] Figure 13 New auxiliary slot motor 2f under multiple load conditions e Vibration acceleration spectrum;

[0074] Among them: 1. stator teeth; 1-1. flat V-shaped groove; 1-2. vertical V-shaped groove; 2. stator yoke; 3. winding coil; 4. permanent magnet assembly; 5. rotor core. DETAILED DESCRIPTION

[0075] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0076] A surface-mounted permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration can optimize air gap permeance. This structure involves creating a flat, inverted V-shaped slot symmetrically about the centerline of the stator tooth. A vertical inverted V-shaped slot is then created based on the flat, inverted V-shaped slot. This slot has a smaller opening than the flat, inverted V-shaped slot and a greater depth than the flat, inverted V-shaped slot. The slot deepens closer to the centerline of the stator tooth and becomes shallower near the slot opening until it coincides with the stator tooth edge. The larger the lateral dimension of the auxiliary slot, the better the optimization of the air gap permeance. The above describes the characteristics of a single stator tooth. For a permanent magnet motor, each stator tooth has the same structural features.

[0077] A permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration specifically includes:

[0078] The stator teeth are provided with inverted double V-shaped auxiliary slots to weaken the double frequency radial electromagnetic force and the electromagnetic vibration caused by it. The specific slotting steps include: providing a flat inverted V-shaped auxiliary slot 1 on the stator teeth, wherein the auxiliary slots are symmetrical about the stator tooth centerline; providing a vertical inverted V-shaped auxiliary slot 2 on the basis of the flat inverted V-shaped auxiliary slot 1 on the stator teeth, wherein the auxiliary slots are symmetrical about the stator tooth centerline;

[0079] The opening of the vertical inverted V-shaped groove 2 of the stator tooth is smaller than the opening of the flat inverted V-shaped groove 1; the depth of the vertical inverted V-shaped groove 2 is greater than the depth of the flat inverted V-shaped groove 1.

[0080] Furthermore, the closer the stator tooth auxiliary slot is to the center, the deeper the slot is, and the closer the auxiliary slot is to the slot opening, the shallower the slot is, until it coincides with the edge line of the stator tooth.

[0081] Furthermore, the larger the transverse dimension of the stator tooth auxiliary slot is, the greater the degree of weakening of the double frequency radial electromagnetic force and the electromagnetic vibration caused by it.

[0082] A method for designing a stator tooth auxiliary slot structure of a permanent magnet motor for suppressing electromagnetic vibration comprises the following steps:

[0083] Step S1, optimizing the stator topology of the motor to reduce the amplitude of the first-order permeance harmonic;

[0084] Step S2: Optimize the auxiliary slot structure to completely fit the total permeance waveform after weakening the first-order permeance, thereby suppressing motor vibration;

[0085] Step S3: adopting an inverted double V-shaped superimposed auxiliary groove structure so that the tooth surface edge shape approaches the total magnetic permeance waveform shape after reducing the first-order magnetic permeance harmonic, thereby specifically reducing the first-order magnetic permeance harmonic.

[0086] Furthermore, the novel auxiliary slot can effectively weaken the double frequency radial electromagnetic force without affecting the torque.

[0087] Furthermore, the principle of the design method is:

[0088] By optimizing the stator topology of the motor, the amplitude of the first-order magnetic permeance harmonic can be reduced. If the amplitude of the fundamental magnetic permeance wave is reduced, the magnetic permeance waveform will be concave in the middle of the tooth surface. The longer the air gap, the smaller the magnetic permeance. If the tooth surface shape is modified so that the tooth surface edge shape approaches the total magnetic permeance waveform shape after reducing the first-order magnetic permeance harmonic, the corresponding magnetic permeance harmonic can be reduced in a targeted manner. By using a new auxiliary slot in the middle of the stator tooth, the local air gap length is increased, causing the magnetic permeance waveform in the middle of the tooth surface to be concave, thereby reducing the amplitude of the fundamental magnetic permeance wave.

[0089] Furthermore, the design method principles specifically include:

[0090] According to the parity and periodicity of the permanent magnet potential, the permanent magnet potential of the surface-mounted rotor can be expressed by a Fourier series containing only odd harmonics:

[0091]

[0092] The stator winding is powered by a sinusoidal wave, and the stator armature reaction magnetomotive force can be expressed as:

[0093]

[0094] F p is the magnetomotive force generated by the permanent magnet; P is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle; F s is the armature reaction magnetomotive force generated by the stator winding; μ is the harmonic order of the permanent magnet magnetomotive force; v is the harmonic order of the armature magnetomotive force; F μ is the amplitude of the permanent magnet magnetomotive force of the μth harmonic; F v is the armature magnetomotive force amplitude of the vth harmonic; is the phase angle of the vth armature harmonic magnetic potential.

[0095] After considering the effect of stator slotting, the air gap permeance of the motor is no longer a constant, so it is necessary to introduce a permeance function to measure the effect of stator slotting.

[0096] Furthermore, the permeability function includes two parts: a constant component and a harmonic component, which can be expressed as:

[0097]

[0098] The air gap permeance of the motor is calculated using the magnetic potential permeance method. The permeance can be expressed as

[0099]

[0100] Where Λ(θ) is the air gap permeability; Λ0 is the constant component of the air gap permeability; δ(θ) is the equivalent air gap length; Z is the number of teeth of the motor; μ0 is the vacuum permeability; k is the harmonic order of the permeability; θ is the circumferential angle; Λ k is the permeability amplitude of the kth harmonic.

[0101] The constant part of the permeance is much larger than the harmonic part, and the air gap permeance is inversely proportional to the air gap length.

[0102] Furthermore, the design method principle specifically includes:

[0103] When the motor is unloaded, the permanent magnet potential generated by the permanent magnet is the only excitation source inside the motor. The no-load air gap flux density can be expressed as:

[0104] B r (θ,t)=F p(θ,t)·Λ(θ)

[0105] When the motor is loaded, the excitation sources inside the motor include the permanent magnet magnetic potential and the armature magnetic potential; the load air gap magnetic flux density can be expressed as:

[0106] B r (θ,t)=[F p (θ,t)+F s (θ,t)]·Λ(θ)

[0107] According to Maxwell tensor law, the radial electromagnetic force per unit area of the motor stator can be expressed as:

[0108]

[0109] Where B r is the radial air gap magnetic flux density; f r is the radial electromagnetic force density per unit area; f s is the electromagnetic force wave generated by the armature winding magnetic field; f ps is the electromagnetic force wave generated by the interaction between the permanent magnet and the winding; f p is the electromagnetic force wave generated by the permanent magnet; μ0 is the magnetic permeability of vacuum; θ is the circular angle; t is the time.

[0110] Furthermore, the electromagnetic force wave f generated by the permanent magnet p It can be further expressed as:

[0111] f p (θ,t)=f p1 (θ,t)+f p2 (θ,t)+f p3 (θ,t)

[0112] in

[0113]

[0114] Where, f p is the electromagnetic force wave generated by the permanent magnet; μ1 and μ2 are the harmonic orders of the permanent magnet potential; F u1 、F u2 is the amplitude of the permanent magnet magnetomotive force of the μ1th and μ2th harmonics; Λ0 is the constant component of the air gap permeance; k is the permeance harmonic order; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circular angle.

[0115] The electromagnetic force wave f generated by the armature winding magnetic field s It can be further expressed as:

[0116] f s (θ,t)=f s1 (θ,t)+f s2 (θ,t)+f s3 (θ,t)

[0117] in

[0118]

[0119]

[0120] Where, f s is the electromagnetic force wave generated by the armature winding magnetic field; v1 and v2 are the harmonic orders of the armature magnetic potential; F v1 、F v2 is the amplitude of the armature magnetomotive force at times v1 and v2; is the phase angle of the v1th and v2th harmonic armature magnetic potential; Λ0 is the constant component of the air gap magnetic permeance; k is the harmonic order of magnetic permeance; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circular angle.

[0121] where f s1 、f s2 and f s3 They are composed of two parts. The electromagnetic force component of the latter part does not change with time and will not produce vibration. Therefore, the electromagnetic force component of the first part of these three items is the effective component that produces vibration in the armature magnetic field.

[0122] The electromagnetic force wave f generated by the interaction between the permanent magnet and the winding ps It can be further expressed as:

[0123] f ps (θ,t)=f ps1 (θ,t)+f ps2 (θ,t)+f ps3 (θ,t)

[0124] in

[0125]

[0126] Where, f ps is the electromagnetic force wave generated by the interaction between the permanent magnet and the winding; μ is the harmonic order of the permanent magnet potential; F u is the amplitude of the permanent magnet magnetomotive force of the μth harmonic; v is the harmonic order of the armature magnetomotive force; F v is the armature magnetomotive force amplitude of the vth harmonic; is the phase angle of the vth armature harmonic magnetic potential; Λ0 is the constant component of the air gap magnetic permeance; k is the harmonic order of magnetic permeance; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circular angle.

[0127] As shown in Table 1, (-2,2f e ) mainly comes from ①, ③, ④, ⑥, ⑦, and ⑧. Among them, ①, ④, and ⑦ are only affected by the constant component of magnetic permeability. The effect of these three components on (-2,2f e ) contribution, but changing the air gap length of the motor will greatly affect the performance of the motor. In order not to affect the performance of the motor, it is necessary to reduce (-2,2f e ). ③, ⑥, ⑧, which are generated by the participation of magnetic permeance harmonics, should be the focus of analysis. In ③, when k=1, (-2,2f e ); in ⑥, when k=1, it can produce (-2,2f e ); in ⑧, when k=1,2……, it can produce (-2,2f e ). Therefore, by reducing the amplitude of the first-order permeability harmonic, (-2,2f e ), thereby suppressing the motor 2f e vibration.

[0128] Table 1 Radial electromagnetic force

[0129]

[0130] The simulation verification steps of the present invention are as follows:

[0131] The original stator tooth structure is as follows Figure 4 As shown, a combined structure is Figure 5 As shown, it includes traditional auxiliary slots, and another combination structure is as follows Figure 6 As shown, the finished structure of the present invention has double V-shaped new auxiliary slots with the same slot area on the stator teeth;

[0132] The amplitude of the first-order permeance harmonic is reduced by optimizing the motor's stator topology. Reducing the amplitude of the fundamental permeance wave causes a depression in the permeance waveform in the middle of the tooth surface. The longer the air gap, the smaller the permeance. By modifying the tooth surface shape so that the tooth edge shape approximates the total permeance waveform after reducing the first-order permeance harmonic, the first-order permeance harmonic can be specifically reduced.

[0133] Therefore, the method of grooving the middle of the tooth surface can be used to increase the local air gap length, so that the magnetic permeance waveform in the middle of the tooth surface is concave, thereby reducing the amplitude of the magnetic permeance fundamental wave.

[0134] The traditional rectangular slot in the middle of the tooth surface cannot effectively fit the total permeance waveform after weakening the first-order permeance, and it is difficult to select the appropriate slot depth and slot width parameters. A trade-off must be made between suppressing the double-frequency radial electromagnetic force and maintaining the average torque.

[0135] If a new auxiliary slot with the same area as the traditional auxiliary slot is opened on the stator tooth, it can more effectively fit the total magnetic permeability waveform, and at the expense of less torque, effectively weaken the double-frequency radial electromagnetic force and reduce torque pulsation.

[0136] The simulation results are shown in Table 2:

[0137] Table 2 Comparison of auxiliary slot motor effects

[0138]

[0139] Taking the stator teeth without auxiliary slots as a reference, the traditional rectangular auxiliary slots of the stator teeth weakened the magnetic permeance by 43.2% and reduced the double-frequency radial electromagnetic force by 31.2%; while the new double V-shaped auxiliary slots on the stator teeth weakened the magnetic permeance by 33.9% and reduced the double-frequency radial electromagnetic force by 46.4% based on the traditional rectangular auxiliary slots.

[0140] Finite element simulation results show that the stator tooth structure designed in this paper has a significant inhibitory effect on the motor's second-harmonic frequency vibration. Figure 11 This graph shows the output torque of a permanent magnet motor with the new double V-shaped auxiliary slots. Without the auxiliary slot structure, the motor's torque ripple is 2.23%, with conventional auxiliary slots, it's 2.05%, and with the new auxiliary slots, it's 1.52%. The average torque of the motor with the new auxiliary slots is essentially the same as with conventional auxiliary slots, but with lower torque ripple. The new auxiliary slots offer a more effective optimization of torque performance.

[0141] Figure 12 This is the vibration acceleration spectrum of the motor with auxiliary slots in the stator teeth under no-load conditions. When no-load, the new auxiliary slots enhance the 2f e The vibration suppression effect makes 2f e Vibration accumulation was reduced by 52.1%.

[0142] Figure 13 New auxiliary slot motor 2f under multiple load conditions e Vibration acceleration spectrum, opening double V-shaped auxiliary grooves can effectively suppress the motor 2f e Vibration acceleration.

[0143] The above verification proves that the stator tooth structure provided by the present invention has an obvious and reliable vibration reduction effect.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A permanent magnet motor stator tooth auxiliary slot structure for suppressing electromagnetic vibration, characterized in that: The auxiliary slot structure specifically includes: The stator teeth are provided with inverted double V-shaped auxiliary slots to weaken the double frequency radial electromagnetic force and the electromagnetic vibration caused by it. The specific slotting steps include: providing a flat inverted V-shaped auxiliary slot 1 on the stator teeth, wherein the auxiliary slots are symmetrical about the stator tooth centerline; providing a vertical inverted V-shaped auxiliary slot 2 on the basis of the flat inverted V-shaped auxiliary slot 1 on the stator teeth, wherein the auxiliary slots are symmetrical about the stator tooth centerline; The opening of the vertical inverted V-shaped groove 2 of the stator tooth is smaller than the opening of the flat inverted V-shaped groove 1; the depth of the vertical inverted V-shaped groove 2 is greater than the depth of the flat inverted V-shaped groove 1.

2. The stator tooth auxiliary slot structure of a permanent magnet motor for suppressing electromagnetic vibration according to claim 1, characterized in that: The closer the stator tooth auxiliary slot is to the center, the deeper the slot is, and the closer the auxiliary slot is to the slot opening, the shallower the slot is, until it coincides with the edge line of the stator tooth.

3. The stator tooth auxiliary slot structure of a permanent magnet motor for suppressing electromagnetic vibration according to claim 1, characterized in that: The larger the transverse dimension of the stator tooth auxiliary slot is, the greater the degree of weakening of the double frequency radial electromagnetic force and the electromagnetic vibration caused by it.

4. A method for designing a stator tooth auxiliary slot structure for a permanent magnet motor for suppressing electromagnetic vibration, characterized in that: The design method is applied to the stator tooth auxiliary slot structure of a permanent magnet motor for suppressing electromagnetic vibration as claimed in any one of claims 1 to 3, comprising the following steps: Step S1, optimizing the stator topology of the motor to reduce the amplitude of the first-order permeance harmonic; Step S2: Optimize the auxiliary slot structure to completely fit the total permeance waveform after weakening the first-order permeance, thereby suppressing motor vibration; Step S3: adopting an inverted double V-shaped superimposed auxiliary groove structure so that the tooth surface edge shape approaches the total magnetic permeance waveform shape after reducing the first-order magnetic permeance harmonic, thereby specifically reducing the first-order magnetic permeance harmonic.

5. The method for designing a stator tooth auxiliary slot structure for suppressing electromagnetic vibration of a permanent magnet motor according to claim 4, characterized in that: The novel auxiliary slot can effectively weaken the double frequency radial electromagnetic force without affecting the torque.

6. The method for designing a stator tooth auxiliary slot structure for suppressing electromagnetic vibration of a permanent magnet motor according to claim 4, characterized in that: The principle of the design method is: By optimizing the stator topology of the motor, the amplitude of the first-order magnetic permeance harmonic can be reduced. If the amplitude of the fundamental magnetic permeance wave is reduced, the magnetic permeance waveform will be concave in the middle of the tooth surface. The longer the air gap, the smaller the magnetic permeance. If the tooth surface shape is modified so that the tooth surface edge shape approaches the total magnetic permeance waveform shape after reducing the first-order magnetic permeance harmonic, the corresponding magnetic permeance harmonic can be reduced in a targeted manner. By using a new auxiliary slot in the middle of the stator tooth, the local air gap length is increased, causing the magnetic permeance waveform in the middle of the tooth surface to be concave, thereby reducing the amplitude of the fundamental magnetic permeance wave.

7. The method for designing a stator tooth auxiliary slot structure for a permanent magnet motor for suppressing electromagnetic vibration according to claim 4, characterized in that: The design method principles specifically include: According to the parity and periodicity of the permanent magnet potential, the permanent magnet potential of the surface-mounted rotor can be expressed by a Fourier series containing only odd harmonics: The stator winding is powered by a sinusoidal wave, and the stator armature reaction magnetomotive force can be expressed as: F p is the magnetomotive force generated by the permanent magnet; P is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle; F s is the armature reaction magnetomotive force generated by the stator winding; μ is the harmonic order of the permanent magnet magnetomotive force; v is the harmonic order of the armature magnetomotive force; F μ is the amplitude of the permanent magnet magnetomotive force of the μth harmonic; F v is the armature magnetomotive force amplitude of the vth harmonic; is the phase angle of the vth armature harmonic magnetic potential; After considering the effect of stator slotting, the air gap magnetic permeance of the motor is no longer a constant, and it is necessary to introduce a magnetic permeance function to measure the effect of stator slotting.

8. The method for designing a stator tooth auxiliary slot structure for a permanent magnet motor for suppressing electromagnetic vibration according to claim 7, characterized in that: The permeability function consists of two parts: a constant component and a harmonic component, which can be expressed as: The air gap permeance of the motor is calculated using the magnetic potential permeance method. The permeance can be expressed as Where Λ(θ) is the air gap permeability; Λ0 is the constant component of the air gap permeability; δ(θ) is the equivalent air gap length; Z is the number of teeth of the motor; μ0 is the vacuum permeability; k is the harmonic order of the permeability; θ is the circumferential angle; Λ k is the permeability amplitude of the kth harmonic; The constant part of the permeance is much larger than the harmonic part, and the air gap permeance is inversely proportional to the air gap length.

9. The method for designing a stator tooth auxiliary slot structure for suppressing electromagnetic vibration of a permanent magnet motor according to claim 4, characterized in that: The design method principle specifically includes: When the motor is unloaded, the permanent magnet potential generated by the permanent magnet is the only excitation source inside the motor. The no-load air gap flux density can be expressed as: B r (θ,t)=F p (θ,t)·Λ(θ) When the motor is loaded, the excitation sources inside the motor include the permanent magnet magnetic potential and the armature magnetic potential; the load air gap magnetic flux density can be expressed as: B r (θ,t)=[F p (θ,t)+F s (θ,t)]·Λ(θ) According to Maxwell tensor law, the radial electromagnetic force per unit area of the motor stator can be expressed as: Where B r is the radial air gap magnetic flux density; f r is the radial electromagnetic force density per unit area; f s is the electromagnetic force wave generated by the armature winding magnetic field; f ps is the electromagnetic force wave generated by the interaction between the permanent magnet and the winding; f p is the electromagnetic force wave generated by the permanent magnet; μ0 is the magnetic permeability of vacuum; θ is the circular angle; t is the time.

10. The method for designing a stator tooth auxiliary slot structure of a permanent magnet motor for suppressing electromagnetic vibration according to claim 9, characterized in that: The electromagnetic force wave f generated by the permanent magnet p It can be further expressed as: f p (θ,t)=f p1 (θ,t)+f p2 (θ,t)+f p3 (θ,t) in Where, f p is the electromagnetic force wave generated by the permanent magnet; μ1 and μ2 are the harmonic orders of the permanent magnet potential; F u1 、F u2 is the amplitude of the permanent magnet magnetomotive force of the μ1th and μ2th harmonics; Λ0 is the constant component of the air gap permeance; k is the permeance harmonic order; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle; The electromagnetic force wave f generated by the armature winding magnetic field s It can be further expressed as: f s (θ,t)=f s1 (θ,t)+f s2 (θ,t)+f s3 (θ,t) in Where, f s is the electromagnetic force wave generated by the armature winding magnetic field; v1 and v2 are the harmonic orders of the armature magnetic potential; F v1 、F v2 is the armature magnetomotive force amplitude of the v1th and v2th harmonics; is the phase angle of the v1th and v2th harmonic armature magnetic potential; Λ0 is the constant component of the air gap magnetic permeance; k is the harmonic order of magnetic permeance; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circumferential angle; where f s1 、f s2 and f s3 They are composed of two parts. The electromagnetic force component of the latter part does not change with time and will not produce vibration. Therefore, the electromagnetic force component of the first part of these three items is the effective component that produces vibration in the armature magnetic field. The electromagnetic force wave f generated by the interaction between the permanent magnet and the winding ps It can be further expressed as: f ps (θ,t)=f ps1 (θ,t)+f ps2 (θ,t)+f ps3 (θ,t) in Where, f ps is the electromagnetic force wave generated by the interaction between the permanent magnet and the winding; μ is the harmonic order of the permanent magnet potential; F u is the amplitude of the permanent magnet magnetomotive force of the μth harmonic; v is the harmonic order of the armature magnetomotive force; F v is the armature magnetomotive force amplitude of the vth harmonic; is the phase angle of the vth armature harmonic magnetic potential; Λ0 is the constant component of the air gap magnetic permeance; k is the harmonic order of magnetic permeance; Λ k1 , Λ k2 is the amplitude of the k1th and k2th permeability harmonics; μ0 is the vacuum magnetic permeability; Z is the number of teeth of the motor; p is the number of motor pole pairs; t is time; ω is the electrical angular velocity; θ is the circular angle.

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