Stator slotting type non-uniform tooth bilateral permanent magnet vernier motor and modeling method thereof

Abstract

The invention discloses a stator slotting type non-uniform tooth bilateral permanent magnet vernier motor and a modeling method thereof, a rotor adopts a U-shaped consequent pole permanent magnet topological structure, stator permanent magnets adopt a trapezoidal permanent magnet topological structure, stator teeth adopt split tooth structures, and the stator teeth are designed in a non-uniform distribution manner. The split teeth at the tail ends of the stator teeth are provided with small grooves with specific structures; the amplitude and the phase of the air gap flux density harmonic wave are changed by changing the wave crest and the wave trough of the stator magnetic conductance. Aiming at a wave crest of stator magnetic conductance, stator teeth are subjected to slotting design, the amplitude of air gap flux density is changed, the torque pulsation of the motor is greatly reduced, and the high torque performance of the motor is maintained; aiming at a stator magnetic conductance trough, the phase of air gap flux density is changed through non-uniform distribution of stator teeth, so that the torque is improved. The above two act on stator magnetic conductance together, so that the motor has the characteristics of high torque density and low torque pulsation.

Description

Technical Field

[0001] The present invention belongs to the field of motors, and specifically relates to a stator slotted non-uniform tooth bilateral permanent magnet vernier motor and a modeling method thereof. The structural design of the stator slotted non-uniform teeth is adopted to enable the motor to have the performance advantages of high torque and low torque pulsation at the same time. Background Art

[0002] In recent years, with the continuous upgrading of the demand for electric vehicles, the design requirements for the performance of drive motors have become increasingly stringent, including high output torque, low torque pulsation and low loss of the motor. Among the magnetic field modulation motors, the bilateral permanent magnet vernier motor has a higher torque density than the ordinary permanent magnet vernier motor because of the permanent magnet distribution on both its stator and rotor. However, due to its unique structure, the torque pulsation of the bilateral permanent magnet vernier motor is usually relatively high. Therefore, in order to meet the requirements of superior performance of the drive motor, reducing torque pulsation and maintaining high torque are the primary performance goals of the bilateral permanent magnet vernier motor.

[0003] There are relatively few studies on low torque pulsation of permanent magnet motors. Existing studies mainly use methods such as skewed poles. In Chinese Patent Application No. 201811641206.7, a skewed pole rotor permanent magnet synchronous motor is proposed. The motor has low noise and low vibration performance, while reducing the cogging torque, thereby reducing torque pulsation, but the motor needs to be improved in terms of high torque. In Chinese Patent Application No. 201910891338.3, a non-uniform tooth topology permanent magnet vernier motor is proposed. By changing the tooth width and position of specific stator teeth, the specific sub-cogging torque harmonics are eliminated to reduce torque pulsation, but the high torque performance of the motor is not well maintained. The document with Chinese patent application number 201510688205.8 proposes a harmonic injection method, including sine harmonic injection, sine plus third harmonic injection, inverse cosine harmonic injection and inverse cosine plus third harmonic injection. By using the above harmonic injection methods on the stator or rotor alone, or by applying a combination of several harmonic injection methods to the stator and rotor for harmonic injection, the torque pulsation is reduced and the motor performance in terms of stability, noise and vibration is improved, but the output torque is also affected to a certain extent. The document with Chinese patent application number 202210439032.6 proposes a multi-speed main and auxiliary tooth alternating pole permanent magnet vernier motor, which adopts the structure of main and auxiliary teeth, introduces more effective harmonics to improve the torque, and the motor has high torque density, high power density and multi-mode operation performance, but the motor is insufficient in low torque pulsation. The document with Chinese patent application number 202011227689.3 proposes a vernier permanent magnet motor with a stator having coded auxiliary teeth. The motor stator adopts a coded auxiliary tooth structure. The coded auxiliary tooth structure and the stator permanent magnet interact with the rotor permanent magnet and the ferromagnet on the rotor respectively. The generated magnetic fields are superimposed on each other to form more working harmonics with a larger harmonic amplitude, which makes the motor have a higher torque. However, the stator and rotor permanent magnets of the motor are on both sides of the air gap, and the motor torque pulsation is relatively high, which brings challenges to the practical application of the motor.

[0004] In summary, through the study of motor structure design, the motor torque can be increased or the motor torque pulsation can be reduced, but it is impossible to ensure that the motor has both high torque and low torque pulsation performance. Therefore, how to achieve the advantages of both high torque and low torque pulsation performance of permanent magnet vernier motor is a key technical problem that needs to be solved in the design of permanent magnet vernier motor. Summary of the invention

[0005] The purpose of the present invention is to address the problem that the existing bilateral magnetic field modulation permanent magnet motor is difficult to maintain the advantages of high torque and low torque pulsation performance at the same time. From the perspective of motor model design, a bilateral permanent magnet vernier motor with a "stator slotted non-uniform teeth" topology is proposed to ensure that the motor torque performance can be improved while reducing the motor torque pulsation performance. The present invention provides a structural design of a stator slotted non-uniform teeth bilateral permanent magnet vernier motor model, including the structural design of stator permanent magnets and rotor permanent magnets, the stator slotted structure design, and the non-uniform teeth structure design.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the stator slotted non-uniform tooth bilateral permanent magnet vernier motor provided by the present invention is: the motor adopts an outer rotor structure, and the rotor permanent magnets are arranged regularly in a U-shaped structure around the rotor. The U-shaped rotor permanent magnet is composed of three rectangular permanent magnets and is magnetized from the outside to the inside along the thickness. A triangular magnetic barrier is designed between the horizontally arranged permanent magnets and the two spoke-type permanent magnets to reduce internal magnetic leakage. There is a rotor core of a certain width between adjacent rotor permanent magnets. The magnetic circuit of the rotor core is opposite to that of the U-shaped rotor permanent magnet. Therefore, the rotor core and the U-shaped permanent magnet form alternating poles. The number of pole pairs of the U-shaped rotor permanent magnet is P. r =19.

[0007] The stator structure of the present invention adopts a split tooth structure and a stator slotted non-uniform tooth structure, wherein the stator slots mainly open three small slots on the split teeth, and the non-uniform teeth are N s The teeth are grouped in pairs, divided into N s / 2 groups, the mechanical angle difference between each group is 2*PI / 6, and the mechanical angle difference between the two teeth in a group is 2*PI / 12.35. The stator permanent magnet adopts a trapezoidal permanent magnet structure, located in the stator slot between the two split teeth, and distributed along the circumference. The stator trapezoidal permanent magnet is a structure that is wide outside and narrow inside, and is magnetized inward along the thickness. The stator armature winding adopts a double-layer concentrated winding, according to the armature winding P a =2N s -P r Winding, N s is the number of stator slots.

[0008] For the above-mentioned stator slotted non-uniform tooth bilateral permanent magnet vernier motor, the modeling method proposed by the present invention is as follows:

[0009] Air gap flux density B of stator slotted non-uniform tooth double-sided permanent magnet vernier motor rk Equal to the air gap flux B generated by the rotor permanent magnet rpm The air gap flux B generated by the stator permanent magnet spm sum:

[0010] B rk =B spm+B rpm =F s (θ)Λ r (θ,t)+F r (θ,t)Λ s (θ)

[0011] F s (θ) represents the magnetomotive force of the stator permanent magnet, F r (θ, t) represents the magnetomotive force of the rotor permanent magnet, Λr(θ, t) represents the rotor permeance, Λ s (θ) represents the stator permeability.

[0012] Furthermore, the air gap flux density B generated by the stator permanent magnet spm The modeling steps are as follows:

[0013] Step 1: Assuming that the magnetic permeability of the iron core is infinite and the leakage flux is ignored, only the pole pairs of the stator trapezoidal permanent magnet are considered. According to Fourier decomposition, the magnetomotive force F of the stator trapezoidal permanent magnet can be obtained. s The expression of (θ) is:

[0014]

[0015] Where i is the i-th harmonic; F ssi is the amplitude of the i-th harmonic of the stator trapezoidal permanent magnet magnetomotive force; P s is the number of pole pairs of the stator trapezoidal permanent magnet;

[0016] Step 2: According to Fourier decomposition, the rotor magnetic permeability Λ can be obtained r The expression of (θ,t) is:

[0017]

[0018] Λ rj is the amplitude of the jth harmonic of the rotor permeance; Ω r is the rotor angular velocity; θ is the air gap circumferential mechanical angle; t is the time;

[0019] Step 3: Ignore the magnetic field generated by the armature winding on the stator. According to the magnetic field modulation principle, the air gap flux density B generated by the stator trapezoidal permanent magnet is spm The expression is as follows:

[0020]

[0021] Furthermore, the air gap flux density B generated by the rotor permanent magnet is rpm The modeling steps are as follows:

[0022] Step 1: Assuming that the magnetic permeability of the core is infinite and the leakage flux is ignored, only the pole pairs of the U-shaped permanent magnet of the rotor are considered. According to Fourier decomposition, the magnetomotive force F of the U-shaped rotor permanent magnet can be obtained.r The expression of (θ,t) is:

[0023]

[0024] In the formula, F rr is the amplitude of the nth harmonic of the rotor permanent magnet magnetomotive force; P r is the number of pole pairs of the permanent magnet of the U-shaped rotor; F M 、F N are the peak and trough amplitudes of the magnetomotive force of the rotor permanent magnet, respectively; α1 is the angle of the spoke permanent magnet in the U-shaped rotor permanent magnet; α2 is the width between two spoke permanent magnets in a U-shaped rotor permanent magnet;

[0025] Step 2: Introduce the stator slot design effect at the stator permeance peak, and use the non-uniform tooth design effect at the stator permeance trough. The stator peak will change with the change of angle, and the angles of the two troughs will be different. The period of the stator permeance is 4*PI / N s ; According to Fourier decomposition, the stator permeability Λ can be obtained s The expression of (θ) is:

[0026]

[0027] Where Λ0 is the DC component; Λ1 is the air gap permeance of the trapezoidal slot of the stator tooth; Λ4 is the air gap permeance of the second stator tooth; θ7 is the angle of the trapezoidal hypotenuse; Λ si is the amplitude of the i-th harmonic of the stator permeance; N s is the number of stator slots of the motor; r g is the motor air gap radius; δ g (θ) is the air gap radius that varies with the mechanical angle; l ef is the shaft length of the motor; μ0 is the magnetic permeability of vacuum; θ m is the angle of the slot or tooth on the stator slot structure; Λ m is the stator permeability amplitude of the slots and teeth on the stator slotted structure;

[0028] Step 3: Ignore the magnetic field generated by the armature winding on the stator. According to the magnetic field modulation principle, the air gap flux density B generated by the U-shaped rotor permanent magnet is rpm The expression is as follows:

[0029]

[0030] Beneficial effects of the present invention:

[0031] 1. The motor rotor of the present invention adopts a U-shaped alternating pole permanent magnet topology structure, wherein the U-shaped permanent magnet structure has a magnetic field concentration effect, allowing more magnetic lines of force to pass through the air gap, increasing the air gap magnetic flux harmonic amplitude, thereby improving the motor torque performance, and effectively improving the utilization rate of the permanent magnet.

[0032] 2. The stator permanent magnet of the motor of the present invention adopts a trapezoidal permanent magnet topology structure and the stator teeth adopt a split tooth structure. Compared with the ordinary fan-shaped permanent magnet structure, the trapezoidal permanent magnet structure has higher air gap magnetic flux harmonic amplitude and permanent magnet utilization rate, thereby improving the motor torque performance; the split teeth can provide more slot area, thereby improving the heat dissipation problem of the armature winding, and the split teeth can also increase the frequency of the tooth slot torque fundamental wave, thereby reducing the tooth slot torque amplitude and reducing the motor torque pulsation.

[0033] 3. The present invention proposes a stator slot design, that is, changing the peak of the stator magnetic permeability, analyzing the modulation effect of the stator slot on the permanent magnet magnetic field, reducing the amplitude of the main air gap magnetic flux harmonic that contributes to the torque pulsation, and at the same time increasing the amplitude of the 55th air gap magnetic flux harmonic, to ensure that the motor has low torque pulsation and high torque performance.

[0034] 4. The present invention proposes a non-uniform distribution design of stator teeth, that is, changing the trough of the stator magnetic permeability, analyzing the modulation effect of the non-uniform distribution of stator teeth on the permanent magnetic field, and changing the phase of the air gap magnetic density harmonics that contribute to the torque while ensuring that the amplitude of the air gap magnetic density harmonics that contribute to the torque pulsation changes little, thereby improving the torque performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a diagram of a stator slotted non-uniform tooth bilateral permanent magnet vernier motor of the present invention;

[0036] Figure 2 It is a diagram of a rotor permanent magnet vernier motor of the present invention;

[0037] Figure 3 The stator slotted structure of the present invention;

[0038] Figure 4 It is the stator permanent magnet vernier motor of the present invention;

[0039] Figure 5 It is the magnetomotive force distribution diagram of the rotor permanent magnet of the present invention;

[0040] Figure 6 This is a stator magnetic permeability distribution diagram of the present invention without stator slots;

[0041] Figure 7 It is a stator magnetic permeability distribution diagram of the slotted stator of the present invention;

[0042] Figure 8 It is a comparison diagram of the air gap magnetic flux harmonics generated by the rotor permanent magnets of the conventional bilateral permanent magnet vernier motor and the stator slotted non-uniform tooth bilateral permanent magnet vernier motor of the present invention;

[0043] Fig. 9It is a comparison of the air gap magnetic flux harmonics of the conventional bilateral permanent magnet vernier motor and the stator slotted bilateral permanent magnet vernier motor of the present invention, and a distribution diagram of the contribution of the harmonics to the torque and torque ripple;

[0044] Fig.10 It is a comparison of air gap magnetic flux harmonics and harmonic phases and a torque contribution distribution diagram between the stator slotted double-sided permanent magnet vernier motor and the stator slotted non-uniform tooth double-sided permanent magnet vernier motor of the present invention;

[0045] Fig.11 It is a comparison diagram of the air gap magnetic flux density between the conventional bilateral permanent magnet vernier motor and the stator slotted non-uniform tooth bilateral permanent magnet vernier motor of the present invention;

[0046] Fig.12 It is a comparison diagram of the air gap magnetic flux harmonic amplitudes of the conventional bilateral permanent magnet vernier motor and the stator slotted non-uniform tooth bilateral permanent magnet vernier motor of the present invention;

[0047] Fig.13 It is a comparison diagram of torque and torque pulsation of the conventional bilateral permanent magnet vernier motor and the stator slotted non-uniform tooth bilateral permanent magnet vernier motor of the present invention.

[0048] In the figure: 1—rotor; 2—stator tooth; 3—U-shaped rotor permanent magnet; 4—trapezoidal stator permanent magnet; 5—armature winding; 6—stator slot structure; 1.1—triangular magnetic barrier; 2.1—first stator slot; 2.2—second stator slot; 2.3—first stator tooth; 2.4—third stator slot; 2.5—second stator tooth. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the accompanying drawings.

[0050] As the present invention Figure 1-4 As shown, it is a stator slotted non-uniform tooth bilateral permanent magnet vernier motor of the present invention. The motor structure includes an external rotor 1 and internal stator teeth 2. The rotor 1 is provided with U-shaped rotor permanent magnets 3 along the circumferential direction, and the U-shaped opening of the U-shaped rotor permanent magnets 3 faces the center of the circle. The stator teeth 2 are left-right symmetrical structures along the radial center line, and symmetrical split teeth are provided at the radial ends. A trapezoidal stator permanent magnet 4 is provided between the two split teeth. An armature winding 5 is provided on the stator teeth 2, and each split tooth end is slotted. The structure of the slot is like a stator slotted structure 6. The stator teeth 2 are non-uniformly distributed along the circumferential direction.

[0051] There are 19 pairs of rotor permanent magnets and 12 pairs of stator permanent magnets on the rotor 1 and stator teeth 2 respectively. There are two triangular magnetic barriers 1.1 at both ends of the U bottom of the U-shaped rotor permanent magnet 3, which can reduce internal leakage magnetic flux; the U-shaped rotor permanent magnet 3 is composed of three rectangular permanent magnets and is magnetized from the outside to the inside along the thickness; there is an iron core with an angle of γ3=8.38° between adjacent rotor permanent magnets, and the magnetic circuit of the iron core is opposite to that of the U-shaped permanent magnet 3, so the iron core and the U-shaped permanent magnet 3 form alternating poles; the stator trapezoidal permanent magnet is a structure that is wide at the top and narrow at the bottom, and is magnetized downward along the thickness; the armature winding 5 adopts a centralized double-layer winding distribution; there are 24 modulation teeth (split teeth) and 12 stator slots.

[0052] The present invention is a bilateral permanent magnet vernier motor, so the working principle of the motor can be divided into the working principle of the rotor permanent magnet vernier motor and the stator permanent magnet vernier motor. Figure 2 and 4 As shown. Figure 2 The figure shows a rotor permanent magnet vernier motor, on which permanent magnets are mounted to generate permanent magnet magnetomotive force, which is then modulated by a stator slotted non-uniform tooth structure to obtain air gap flux density. Figure 2 In the figure, the width of the U-shaped rotor permanent magnet 3 is w pm , the lengths of the U-shaped rotor permanent magnets 3 are: the length of the bottom permanent magnet of the U-shaped rotor permanent magnet 3 is l pm , the length of the side permanent magnet is l pm1 The uneven distribution angles of the stator teeth 2 are γ1 and γ2, that is, the angles of adjacent stator teeth 2 are γ1, γ2, γ1, γ2, ..., in the present invention, γ2 = 8.6302 degrees, γ1 = 6.9298 degrees; the specific structure of the stator tooth slot design is as shown in the present invention Figure 3 As shown, the specific structure of the slot is as follows: 2.1 is the first stator slot, with a slot width of 0.11deg and a slot depth of 2.5mm; 2.2 is the second stator slot, with a slot width of 2.5deg and a slot depth of 1mm; 2.3 is the first stator tooth, with a tooth width of 4.5deg and a tooth height of 1mm; 2.4 is the third stator slot, with a slot depth and slot width of 3.5mm and 1.1deg respectively; 2.5 is the second stator tooth, with a tooth width of 0.22deg and a tooth height of 2.5mm.

[0053] in Figure 4 The figure shows a stator permanent magnet vernier motor. Permanent magnets are mounted on the stator teeth to generate permanent magnet magnetomotive force, which is then modulated by the rotor magnetic permeance to obtain the air gap magnetic flux density. Figure 4 In the figure, the trapezoidal stator permanent magnet 4 is an isosceles trapezoidal structure, and the width of the trapezoidal top is w. pm2 , the width below is w pm3 , height l pm2 , the width of the straight tooth part of stator tooth 2 is w st .

[0054] The modeling method of the bilateral permanent magnet vernier motor with stator slotted non-uniform teeth design of the present invention is as follows:

[0055] The air gap magnetic flux density B of the bilateral permanent magnet vernier motor of the present invention rk It can be approximately equal to the air gap flux B generated by the U-shaped rotor permanent magnet 3 rpm The air gap flux B generated by the ladder-shaped stator permanent magnet 4 spm sum:

[0056] B rk =B spm +B rpm =F s (θ)Λ r (θ,t)+F r (θ,t)Λ s (θ)

[0057] F s (θ) represents the magnetomotive force of the ladder-type stator permanent magnet 4, F r (θ, t) represents the magnetomotive force of the U-shaped rotor permanent magnet 3, Λr(θ, t) represents the rotor permeance, Λ s (θ) represents the stator permeability.

[0058] Among them, the air gap flux density B generated by the ladder-shaped stator permanent magnet 4 spm It consists of the following three steps:

[0059] Step 1: Assuming that the core magnetic permeability is infinite and the leakage flux is ignored, only the number of pole pairs of the ladder-type stator permanent magnet 4 is considered. According to Fourier decomposition, the magnetomotive force F of the ladder-type stator permanent magnet 4 can be obtained. s The expression of (θ) is:

[0060]

[0061] Where i is the i-th harmonic; F ssi is the amplitude of the i-th harmonic of the magnetomotive force of the ladder-type stator permanent magnet 4; P s is the number of pole pairs of the ladder-type stator permanent magnet 4 .

[0062] Step 2: Under ideal conditions, the rotor magnetic permeability Λ can be obtained according to Fourier decomposition r The expression of (θ,t) is as follows:

[0063]

[0064] Λ rj is the amplitude of the jth harmonic of the rotor permeance; Ω r is the rotor angular velocity; θ is the air gap circular mechanical angle; t is the time.

[0065] Based on step 1 and step 2, step 3 is as follows: Ignore the magnetic field generated by the armature winding on the stator. According to the magnetic field modulation principle, the air gap flux density B generated by the ladder-shaped stator permanent magnet 4 is spm The expression is as follows:

[0066]

[0067] The air gap flux generated by the U-shaped rotor permanent magnet 3 is related to the magnetomotive force and stator permeance of the U-shaped rotor permanent magnet 3. The motor of the present invention adopts a structure of non-uniform teeth in the stator slot type, and is designed for the peaks and troughs of the stator permeance. Therefore, the design method of the present invention mainly changes the air gap flux of the rotor permanent magnet by directionally changing the peaks and troughs of the stator permeance, thereby changing the total air gap flux and improving the performance of the motor. Therefore, the design method of the present invention is introduced into the stator permeance part in step 2 of the U-shaped rotor permanent magnet generating air gap flux. Air gap flux B generated by the U-shaped rotor permanent magnet rpm The method comprises the following three steps, wherein step 2 introduces the design method of the stator slotted non-uniform teeth of the present invention:

[0068] Step 1: Assuming that the core magnetic permeability is infinite and the leakage flux is ignored, only the pole pairs of the U-shaped rotor permanent magnet 3 are considered. According to Fourier decomposition, the magnetomotive force F of the U-shaped rotor permanent magnet 3 can be obtained. r The expression of (θ,t) is as follows:

[0069]

[0070] In the formula, F rr is the amplitude of the nth harmonic of the magnetomotive force of the U-shaped rotor permanent magnet 3; P r is the number of pole pairs of the U-shaped rotor permanent magnet 3; F M 、F N are the peak and trough amplitudes of the magnetomotive force of the rotor permanent magnet respectively; α1 is the angle of the spoke permanent magnet in the U-shaped rotor permanent magnet; α2 is the width between two spoke permanent magnets in a U-shaped rotor permanent magnet 3; α3 is the angle between two adjacent U-shaped rotor permanent magnets 3, and the period T satisfies α3=(T-α2-2α1) / 2. The ideal waveform of the magnetomotive force of the U-shaped rotor permanent magnet 3 is as shown in the present invention. Figure 5 shown.

[0071] Step 2: When there is no stator slotting and non-uniform tooth design, the distribution diagram of the stator magnetic flux is as shown in the present invention Figure 6 As shown, at this time, the peaks and troughs of the stator flux permeance remain unchanged with the change of angle, and the period of the stator flux permeance is 2*PI / N sThen, a stator slot design is introduced at the stator permeance wave crest, and a non-uniform tooth design is adopted at the stator permeance wave trough. The stator permeance waveform is formed by the present invention. Figure 6 Become the present invention Figure 7 As shown, the stator peak changes with the angle, the angles of the two troughs are different, and the period of all stator flux becomes 4*PI / N s The specific structure of the stator slot is as shown in the present invention. Figure 3 As shown, Figure 3 In the figure, 2.1, 2.2, and 2.4 are stator slots, and 2.3 and 2.5 are stator teeth. Finally, the stator permeability Λ can be obtained according to Fourier decomposition. s The expression of (θ) is as follows:

[0072]

[0073] Where Λ0 is the DC component; Λ1 is the air gap permeance of the trapezoidal slot; Λ4 is the air gap permeance of the second stator tooth; θ7 is the angle of the trapezoidal hypotenuse; Λ si is the amplitude of the i-th harmonic of the stator permeance; N s is the number of stator slots of the motor; r g is the motor air gap radius; δ g (θ) is the air gap radius that varies with the mechanical angle; l ef is the shaft length of the motor; μ0 is the magnetic permeability of vacuum; θ m is the angle between the slot and the tooth on the stator slot structure, and the subscript m indicates that Figure 7 Each tooth or groove shown; Λ m is the stator permeability amplitude of the slots and teeth on the stator slotted structure.

[0074] Based on step 1 and step 2, step 3 is as follows: Ignore the magnetic field generated by the armature winding on the stator. According to the magnetic field modulation principle, the air gap magnetic flux B generated by the U-shaped rotor permanent magnet 3 is rpm The expression is as follows:

[0075]

[0076] According to the air gap flux formula generated by the U-shaped rotor permanent magnet 3, the air gap flux after the stator slotted structure and non-uniform teeth are designed at the peak and trough of the stator flux can be calculated, as shown in FIG. Figure 8 As shown, it is a comparison diagram of the air gap flux amplitude generated by the rotor permanent magnet before and after the stator flux permeability design. It can be seen that the 19th, 43rd, and 57th harmonics of the air gap flux generated by the U-shaped rotor permanent magnet 3 are significantly reduced, which leads to a reduction in the motor torque pulsation. At the same time, the 55th harmonic is significantly increased, maintaining the high torque performance of the motor.

[0077] The present invention Fig. 9As shown, the middle figure is a comparison diagram of the air gap magnetic flux harmonics of the conventional bilateral permanent magnet vernier motor and the stator slotted bilateral permanent magnet vernier motor of the present invention. It can be seen that after the stator teeth are slotted, the 19th, 36th and 57th harmonics of the air gap magnetic flux harmonics of the motor are significantly reduced. Fig. 9 The torque pulsation comparison chart of the air gap magnetic flux harmonic contribution on the left shows that the torque pulsation contribution of these air gap magnetic flux harmonics is significantly reduced. Therefore, after the stator slot design, the torque pulsation of the motor is reduced. Among them, the air gap magnetic flux harmonic torque pulsation λ k The expression is:

[0078]

[0079] Where: T avg is the total electromagnetic torque average value; max(T k (t)) is the maximum value of each harmonic in all time periods; min(T k (t)) is the minimum value of all times for each harmonic.

[0080] At the same time, you can Fig. 9 As shown in the middle figure, it can be found that after the stator is slotted, the 55th air gap magnetic flux harmonic increases significantly. Fig. 9 From the torque contribution comparison diagram on the right, it can be found that the torque contributed by the 55th air gap flux harmonic has increased significantly. Therefore, after the stator slot design, the motor maintains high torque performance. k The expression is:

[0081]

[0082] Where μ0 is the magnetic permeability of vacuum; B rk (t), B tk (t) are the radial and tangential amplitudes of each air gap magnetic flux harmonic; θ rk (t),θ tk (t) are the radial and tangential phases of each air gap magnetic flux harmonic.

[0083] According to the above Fig. 9 From the description, it can be found that after the stator is slotted in the motor, the amplitudes of the 19th, 36th and 57th air gap magnetic flux harmonics are reduced by changing the peak of the stator magnetic permeability, thereby reducing the torque pulsation of the motor; at the same time, the amplitude of the 55th air gap magnetic flux harmonic is increased to maintain the high torque performance of the motor, so that the motor has both low torque pulsation and high torque performance.

[0084] The present invention Fig.10As shown, the middle figure is a comparison diagram of the air gap flux harmonic amplitude of the stator slotted double-sided permanent magnet vernier motor and the stator slotted non-uniform tooth double-sided permanent magnet vernier motor of the present invention. It can be found that after the introduction of non-uniformly distributed stator teeth, the 5th and 19th air gap flux harmonic amplitudes increase, and the 43rd and 57th air gap flux harmonic amplitudes decrease; but from Fig.10 From the torque increment diagram of the air gap flux harmonic on the right, it can be found that no matter whether the amplitude of the air gap flux harmonic increases or decreases, the torque of the 5th, 19th, 43rd, and 57th air gap flux harmonics increases, thereby improving the torque performance of the motor. Fig.10 From the harmonic phase comparison diagram on the left, we know that the phases of the 43rd and 57th air gap flux harmonics have changed, which is why the ability to provide torque has increased despite the decrease in the amplitude of the 43rd and 57th air gap flux harmonics. Among them, the 5th air gap flux harmonic provides negative torque in this motor. Fig.10 The middle figure shows that the amplitude of the 5th air gap magnetic flux harmonic has increased, but the negative torque it provides has decreased. Fig.10 In the figure on the left, it can be seen that this is because its phase changes, so the negative torque it provides is reduced, thereby improving the motor torque performance.

[0085] According to the above Fig.10 From the description, it can be found that on the basis of the stator slotted design, the non-uniform distribution of stator teeth is coordinated, and the amplitude and phase of the air gap magnetic flux harmonics are changed by changing the trough of the stator magnetic permeance, so that the torque provided by the 5th, 19th, 43rd and 57th air gap magnetic flux harmonics is increased, thereby improving the motor torque.

[0086] The present invention Fig.11 and Fig.12 The air gap flux density waveform comparison diagram and air gap flux density harmonic comparison diagram of the conventional bilateral permanent magnet vernier motor and the stator slotted non-uniform tooth bilateral permanent magnet vernier motor designed by the present invention are similar in air gap flux density waveform changes. Fig.12 As shown in the figure, the amplitudes of the 19th, 43rd, and 57th harmonics of the air gap flux density are reduced, while the amplitudes of the 12th and 55th harmonics of the air gap flux density are increased. The former reduces the torque pulsation of the motor, while the latter increases the torque of the motor. Therefore, the stator slotted non-uniform tooth design enables the motor to have both high torque and low torque pulsation performance.

[0087] The present invention Fig.13As shown, it is a comparison diagram of the average torque and torque pulsation of a conventional bilateral permanent magnet vernier motor and a stator slotted non-uniform tooth bilateral permanent magnet vernier motor designed by the present invention. Due to the coordinated stator slotted design and the stator tooth non-uniform design, the torque pulsation is reduced from 5.41% to 4.56%, which is effectively suppressed; the average torque is increased from 59.94Nm to 60.66Nm, which improves the torque and enables the motor to maintain high torque performance; the above analysis and results verify the effectiveness of the motor design based on the stator slotted design method and the stator tooth non-uniform design method to achieve high torque and low pulsation performance.

[0088] In summary, the present invention proposes a stator slotted non-uniform tooth bilateral permanent magnet vernier motor and a modeling method thereof. According to the working principle of the bilateral permanent magnet vernier motor, the motor can be divided into a rotor permanent magnet vernier motor and a stator permanent magnet vernier motor. The present invention mainly designs the peaks and troughs of the stator magnetic permeance in the rotor permanent magnet vernier motor, thereby changing the air gap magnetic flux of the motor. The peaks of the stator magnetic permeance are changed by the stator slotted design, and the troughs of the stator magnetic permeance are changed by the non-uniform teeth. Among them, the stator slotted structure reduces the amplitude of the air gap magnetic flux harmonics that mainly contribute to the torque pulsation, thereby reducing the torque pulsation of the motor, and at the same time increases the amplitude of the 55th air gap magnetic flux harmonic to maintain the high torque of the motor; at the same time, the non-uniform distribution of the stator teeth is coordinated to change the amplitude and phase of the air gap magnetic flux harmonics, thereby improving the torque and ensuring the high torque performance of the motor. In summary, under the action of the stator slotted structure and the non-uniform distribution of the stator teeth, the stator slotted non-uniform tooth bilateral permanent magnet vernier motor has the performance of high torque and low torque pulsation.

[0089] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent methods or changes that do not deviate from the technical creation of the present invention should be included in the scope of protection of the present invention.

Claims

1. A stator slotted non-uniform tooth bilateral permanent magnet vernier motor, comprising an external rotor and internal stator teeth, characterized in that: The rotor (1) is provided with U-shaped rotor permanent magnets (3) along the circumferential direction, and the U-shaped opening of the U-shaped rotor permanent magnets (3) faces the center of the circle; a rotor core of a certain width is present between adjacent U-shaped rotor permanent magnets (3), the magnetic circuit of the rotor core is opposite to that of the U-shaped rotor permanent magnets (3), the rotor core and the U-shaped permanent magnets (3) form alternating poles, and the number of pole pairs of the U-shaped rotor permanent magnets (3) is P r ; The stator teeth (2) are symmetrically structured along the radial centerline, including straight teeth and two symmetrical split teeth arranged at the radial ends of the straight teeth. A trapezoidal stator permanent magnet (4) is arranged in the stator slot between the two split teeth. The trapezoidal stator permanent magnet (4) is a radially wide outer and narrow inner structure, and is magnetized inward along the thickness. An armature winding (5) is arranged on the stator teeth (2). The armature winding (5) adopts a double-layer concentrated winding. According to the armature winding P a =2N s -P r Winding; each tooth has a slot at the radial end, and the stator teeth (2) are unevenly distributed along the circumferential direction. s The stator teeth are grouped in pairs, divided into N s / 2 groups, the mechanical angle of the slot width difference between each group is γ2, and the mechanical angle of the slot width difference between two teeth in a group is γ1.

2. The stator slotted non-uniform tooth double-sided permanent magnet vernier motor according to claim 1, characterized in that: The single U-shaped rotor permanent magnet (3) comprises three rectangular permanent magnets and is magnetized from the outside to the inside along the thickness, and a triangular magnetic barrier (1.1) is arranged between the permanent magnet at the bottom of the U-shape and the two spoke-shaped permanent magnets at the side.

3. A stator slotted non-uniform tooth double-sided permanent magnet vernier motor according to claim 1 or 2, characterized in that: There is a rotor core with an angle of γ3=8.38° between the adjacent U-shaped rotor permanent magnets (3).

4. The stator slotted non-uniform tooth double-sided permanent magnet vernier motor according to claim 1, characterized in that: The number of pole pairs of the U-shaped rotor permanent magnet (3) is P r =19, stator teeth N s =12, the number of cracked teeth is 24.

5. The stator slotted non-uniform tooth double-sided permanent magnet vernier motor according to claim 4, characterized in that: γ2=8.6302; γ1=6.9298.

6. The stator slotted non-uniform tooth double-sided permanent magnet vernier motor according to claim 1, characterized in that: The slotted structure at the end of the split tooth is as follows: Taking the radial center line of the stator tooth (2) as the boundary, the left split tooth is arranged from right to left in sequence as follows: a first stator slot (2.1), a second stator slot (2.2), a first stator tooth (2.3), a third stator slot (2.4), and a second stator tooth (2.5); the structure of the right split tooth is symmetrical to that of the left split tooth; The first stator slot (2.1) has a slot width of 0.11 degrees and a slot depth of 2.5 mm; the second stator slot (2.2) has a slot width of 2.5 degrees and a slot depth of 1 mm; the first stator tooth (2.3) has a tooth width of 4.5 degrees and a tooth height of 1 mm; the third stator slot (2.4) has a slot depth and a slot width of 3.5 mm and 1.1 degrees respectively; the second stator tooth (2.5) has a tooth width of 0.22 degrees and a tooth height of 2.5 mm.

7. The stator slotted non-uniform tooth double-sided permanent magnet vernier motor according to claim 1, characterized in that: The ladder-shaped stator permanent magnet (4) is an isosceles ladder-shaped structure.

8. The modeling method of a stator slotted non-uniform tooth bilateral permanent magnet vernier motor according to claim 1, characterized in that: Air gap magnetic flux density B of the motor rk It can be equal to the air gap flux B generated by the U-shaped rotor permanent magnet (3) rpm The air gap flux B generated by the trapezoidal stator permanent magnet (4) spm sum: B rk =B spm +B rpm =F s (i)L r (θ,t)+F r (θ,t)Λ s (i) F s (θ) represents the magnetomotive force of the ladder-type stator permanent magnet, F r (θ, t) represents the magnetomotive force of the permanent magnet of the U-shaped rotor, Λr(θ, t) represents the rotor permeability, Λ s (θ) represents the stator permeability.

9. The modeling method of the stator slotted non-uniform tooth bilateral permanent magnet vernier motor according to claim 8, characterized in that: The air gap magnetic flux B generated by the trapezoidal stator permanent magnet (4) spm Obtained through the following steps: Step 1: Assuming that the magnetic permeability of the iron core is infinite and the leakage flux is ignored, only the pole pairs of the trapezoidal permanent magnet (4) of the trapezoidal stator are considered. According to Fourier decomposition, the magnetomotive force F of the trapezoidal stator permanent magnet can be obtained. s The expression of (θ) is: Where i is the i-th harmonic; F ssi is the amplitude of the i-th harmonic of the magnetomotive force of the trapezoidal permanent magnet (4) of the trapezoidal stator; P s is the number of pole pairs of the ladder-type stator permanent magnet (4); Step 2: According to Fourier decomposition, the rotor magnetic permeability Λ can be obtained r The expression of (θ,t) is: Λ rj is the amplitude of the jth harmonic of the rotor permeance; Ω r is the rotor angular velocity; θ is the air gap circumferential mechanical angle; t is the time; Step 3: Ignore the magnetic field generated by the armature winding on the stator. According to the magnetic field modulation principle, the air gap flux density B generated by the ladder-shaped stator permanent magnet (4) is spm The expression is as follows:

10. The modeling method of the stator slotted non-uniform tooth bilateral permanent magnet vernier motor according to claim 8, characterized in that: The air gap magnetic flux B generated by the U-shaped rotor permanent magnet (3) rpm Obtained through the following steps: Step 1: Assuming that the magnetic permeability of the core is infinite and the leakage flux is ignored, only the pole pairs of the U-shaped permanent magnet of the rotor are considered. According to Fourier decomposition, the magnetomotive force F of the U-shaped rotor permanent magnet (3) can be obtained. r The expression of (θ,t) is: In the formula, F rr is the amplitude of the nth harmonic of the magnetomotive force of the U-shaped rotor permanent magnet (3); P r is the number of pole pairs of the U-shaped rotor permanent magnet (3); F M 、F N are respectively the peak and trough amplitudes of the magnetomotive force of the U-shaped rotor permanent magnet (3); α1 is the angle of the spoke-type permanent magnet in the U-shaped rotor permanent magnet (3); α2 is the width between two spoke-type permanent magnets in a U-shaped rotor permanent magnet (3); Step 2: Introduce the stator slot design effect at the stator permeance peak, and use the non-uniform tooth design effect at the stator permeance trough. The stator peak will change with the change of angle, and the angles of the two troughs will be different. The period of the stator permeance is 4*PI / N s ; According to Fourier decomposition, the stator permeability Λ can be obtained s The expression of (θ) is: Where Λ0 is the DC component; Λ1 is the air gap permeance of the trapezoidal slot of the stator tooth; Λ4 is the air gap permeance of the second stator tooth (2.5); θ7 is the angle of the trapezoidal hypotenuse; Λ si is the amplitude of the i-th harmonic of the stator permeance; N s is the number of stator slots of the motor; r g is the motor air gap radius; δ g (θ) is the air gap radius that varies with the mechanical angle; l ef is the shaft length of the motor; μ0 is the magnetic permeability of vacuum; θ m is the angle of the slot or tooth on the stator slot structure; Λ m is the stator permeability amplitude of the slots and teeth on the stator slotted structure; Step 3: Ignore the magnetic field generated by the armature winding on the stator. According to the magnetic field modulation principle, the air gap flux density B generated by the U-shaped rotor permanent magnet (3) is rpm The expression is as follows:

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