Stator slotted non-uniform tooth double-sided permanent magnet vernier motor and modeling method thereof

Abstract

The application discloses a stator slotted non-uniform tooth double-sided permanent magnet vernier motor and a modeling method thereof, a rotor adopts a U-shaped alternating pole permanent magnet topological structure, a stator permanent magnet adopts a ladder-shaped permanent magnet topological structure and a stator tooth adopts a split tooth structure, the stator tooth is designed in a non-uniform distribution mode, and small grooves with specific structures are formed in the split tooth at the end of the stator tooth; the amplitude and phase of air gap magnetic flux density harmonics are changed by changing the wave peak and wave trough of the stator magnetic conductance. For the wave peak of the stator magnetic conductance, the amplitude of the air gap magnetic flux density is changed by the slotted design of the stator tooth, the torque ripple of the motor is greatly reduced, and the high torque performance of the motor is maintained; for the wave trough of the stator magnetic conductance, the phase of the air gap magnetic flux density is changed by the non-uniform distribution of the stator tooth, and the torque is improved. The above two factors jointly act on the stator magnetic conductance, so that the motor has the characteristics of high torque density and low torque ripple.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electric machines, and particularly relates to a stator slotted non-uniform tooth double-sided permanent magnet Vernier motor and a modeling method thereof. The stator slotted non-uniform tooth structure design is adopted to make the motor have the performance advantages of high torque and low torque ripple. BACKGROUND

[0002] In recent years, with the continuous upgrading of the demand for electric vehicles, the design requirements for the performance of driving motors are becoming more and more stringent, including high output torque, low torque ripple and low loss of the motor. In the magnetic field modulation motor, the double-sided permanent magnet Vernier motor has higher torque density than the ordinary permanent magnet Vernier motor because of the distribution of permanent magnets on the stator and the rotor. However, due to its unique structure, the torque ripple of the double-sided permanent magnet Vernier motor is usually relatively high. Therefore, in order to meet the requirements of the superior performance of the driving motor, reducing the torque ripple and maintaining the high torque are the primary performance goals of the double-sided permanent magnet Vernier motor.

[0003] Permanent magnet motor low torque ripple research is relatively less, the existing research mainly adopts the method of skew pole, in Chinese patent application number 201811641206.7, a skew rotor permanent magnet synchronous motor is proposed, which has low noise and low vibration performance, and reduces the cogging torque, thereby reducing the torque ripple, but the motor needs to be improved in high torque. In Chinese patent application number 201910891338.3, a non-uniform tooth topology permanent magnet vernier motor is proposed, which changes the tooth width and position of specific stator teeth to eliminate specific tooth slot torque harmonics, thereby reducing torque ripple, but it fails to maintain the high torque performance of the motor. The document of Chinese patent application number 201510688205.8 proposes a harmonic injection method, specifically sinusoidal harmonic injection, sinusoidal plus third harmonic injection, inverse cosine harmonic injection, and inverse cosine plus third harmonic injection. By using the above harmonic injection methods alone on the stator or rotor, or by combining several harmonic injection methods and applying them to the stator and rotor for harmonic injection, the torque ripple is reduced, and the performance of the motor in stability, noise and vibration is improved, but it also affects the output torque to some extent. The document of Chinese patent application number 202210439032.6 proposes a multi-gear main and auxiliary tooth type alternating pole permanent magnet vernier motor, which uses the structure of main and auxiliary teeth to introduce more effective harmonics to improve torque. The motor has high torque density, high power density and multi-mode operation performance, but the motor has some shortcomings in low torque ripple. The document of Chinese patent application number 202011227689.3 proposes a vernier permanent magnet motor with a coded auxiliary tooth stator. The motor stator adopts a coded auxiliary tooth structure, which interacts with the rotor permanent magnet and the ferromagnetic body on the rotor, respectively, and the generated magnetic fields are superimposed to form more working harmonics with larger amplitude, making the motor have higher torque. However, the motor stator and rotor permanent magnets are on both sides of the air gap, and the motor has high torque ripple, which brings challenges to the practical application of the motor.

[0004] In summary, through the research on the structure design of the motor, the torque of the motor can be improved or the torque ripple of the motor can be reduced, but it is impossible to guarantee that the motor has high torque and low torque ripple performance at the same time. Therefore, how to realize the permanent magnet vernier motor with high torque and low torque ripple performance is a key technical problem that needs to be solved in the design of permanent magnet vernier motor. SUMMARY

[0005] The purpose of this invention is to address the problem that existing bilateral magnetic field modulation permanent magnet motors struggle to simultaneously maintain high torque and low torque ripple performance. From the perspective of motor model design, this invention proposes a bilateral permanent magnet vernier motor with a "slotted stator non-uniform tooth" topology, ensuring that motor torque performance can be improved while reducing torque ripple. This invention provides the structural design of the stator slotted non-uniform tooth bilateral permanent magnet vernier motor model, including the structural design of the stator permanent magnet and rotor permanent magnet, the stator slotted structure design, and the non-uniform tooth structure design.

[0006] To achieve the above objectives, the technical solution of the stator slotted non-uniform toothed double-sided permanent magnet vernier motor provided by this invention is as follows: The motor adopts an external rotor structure, and the rotor permanent magnets are arranged in a U-shape around the rotor. The U-shaped rotor permanent magnets consist of three rectangular permanent magnets, magnetized from the outside inwards along the thickness. A triangular magnetic barrier is designed between the horizontally arranged permanent magnets and the two spoke-shaped permanent magnets to reduce internal magnetic leakage. A rotor core of a certain width exists between adjacent rotor permanent magnets. The magnetic circuit of this rotor core is opposite to that of the U-shaped rotor permanent magnets. Therefore, the rotor core and the U-shaped permanent magnets form alternating poles, and the number of pole pairs of the U-shaped rotor permanent magnets is P. r =19.

[0007] The stator structure of this invention adopts a split tooth structure and a stator slotted non-uniform tooth structure. The stator slotting mainly involves creating three small slots on the split teeth, while the non-uniform teeth are formed by adding N... s Each tooth is paired up into N groups. s The stator has two sets of teeth, each with a mechanical angle difference of 2*PI / 6. Within each set, the mechanical angle difference between the two teeth is 2*PI / 12.35. The stator permanent magnets adopt a trapezoidal permanent magnet structure, located in the stator slots between the two split teeth, distributed circumferentially. The stator trapezoidal permanent magnets have a structure that is wider on the outside and narrower on the inside, and are magnetized inwards along the thickness. The stator armature winding adopts a double-layer concentrated winding, according to armature winding P... a =2N s -P r Winding, N s This represents the number of stator slots.

[0008] For the aforementioned stator slotted non-uniform toothed double-sided permanent magnet vernier motor, the modeling method proposed in this invention is as follows:

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

[0010]

[0011] represents the stator permanent magnet magnetomotive force, represents the rotor permanent magnet magnetomotive force, r represents the rotor magnetic permeability, represents the stator magnetic permeability.

[0012] Further, the air-gap flux density generated by the stator permanent magnet is obtained by the following modeling steps:

[0013] Step 1: Assuming the magnetic permeability of the core is infinite and ignoring the leakage, only considering the number of pole pairs of the stator trapezoidal permanent magnet, the expression of the stator trapezoidal permanent magnet magnetomotive force F s (θ) can be obtained according to Fourier decomposition:

[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: The expression of the rotor magnetic permeability Λ r (θ, t) can be obtained according to Fourier decomposition:

[0017]

[0018] Λ rj is the amplitude of the j-th harmonic of the rotor magnetic permeability; Ω r is the rotor angular velocity; θ is the air-gap circumferential mechanical angle; t is time;

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

[0020] .

[0021] Further, the air-gap flux density generated by the rotor permanent magnet is obtained by the following modeling steps:

[0022] Step 1: Assuming the magnetic permeability of the core is infinite and ignoring the leakage, only considering the number of pole pairs of the rotor U-shaped permanent magnet, the expression of the U-shaped rotor permanent magnet magnetomotive force F r (θ, t) can be obtained according to Fourier decomposition:

[0023]

[0024]

[0025] In the formula, F rr is the amplitude of the nth harmonic of the rotor permanent magnet magnetic motive force; P r is the pole pair number of the U-shaped rotor permanent magnet; F M , F N are the amplitudes of the peak and trough of the rotor permanent magnet magnetic motive force respectively; alpha1 is the angle of the spoke type permanent magnet in the U-shaped rotor permanent magnet; alpha2 is the width between the two spoke type permanent magnets in the U-shaped rotor permanent magnet;

[0026] Step 2: respectively introducing the stator slotting type design effect at the peak of the stator magnetic permeability, and adopting the non-uniform tooth design effect at the trough of the stator magnetic permeability, the peak of the stator will change with the change of the angle, the angles of the two troughs will be different, and the period of the stator magnetic permeability is 4*PI / N s ; according to Fourier decomposition, the expression of the stator magnetic permeability Lambda s (theta) can be obtained:

[0027]

[0028]

[0029]

[0030] In the formula, Lambda0 is a direct current component; Lambda1 is the air gap magnetic permeability of the trapezoidal slot of the stator tooth; Lambda4 is the air gap magnetic permeability of the second stator tooth; theta7 is the angle of the trapezoidal hypotenuse; Lambda si is the amplitude of the ith harmonic of the stator magnetic permeability; N s is the number of slots of the motor stator; r g is the air gap radius of the motor; delta g (theta) is the air gap radius changing with the mechanical angle; l ef is the shaft length of the motor; mu0 is the vacuum permeability; theta m is the angle of the slot or tooth on the stator slotting structure; Lambda m is the stator magnetic permeability amplitude of the slot and tooth on the stator slotting structure;

[0031] Step 3: ignoring the magnetic field generated by the armature winding on the stator, according to the magnetic field modulation principle, the air gap magnetic flux density B rpm generated by the U-shaped rotor permanent magnet has the following expression:

[0032] .

[0033] The beneficial effects of the present application are:

[0034] 1. The motor rotor of the present application adopts a U-shaped alternating pole permanent magnet topology structure, wherein the U-shaped permanent magnet structure has a magnetic concentration effect, so that more magnetic lines pass through the air gap, the air gap flux density harmonic amplitude is increased, and the motor torque performance is improved, and the utilization rate of the permanent magnet is effectively improved.

[0035] 2. The motor stator permanent magnet of the present application adopts a ladder-shaped permanent magnet topology structure and the stator tooth adopts a split tooth structure, wherein compared with the ordinary sector-shaped permanent magnet structure, the ladder-shaped permanent magnet structure has higher air gap flux density harmonic amplitude and permanent magnet utilization rate, thereby improving the motor torque performance; the split tooth can provide more slot area, thereby improving the heat dissipation problem of the armature winding, and the split tooth can also increase the frequency of the tooth slot torque fundamental wave, thereby reducing the tooth slot torque amplitude and reducing the motor torque ripple.

[0036] 3. The present application proposes a stator slot design, i.e. changing the wave peak of the stator magnetic permeance, analyzing the modulation effect of the stator slot on the permanent magnet magnetic field, reducing the main air gap flux density harmonic amplitude contributing to the torque ripple, and increasing the 55th air gap flux density harmonic amplitude, thereby ensuring that the motor has low torque ripple and high torque performance.

[0037] 4. The present application proposes a stator tooth non-uniform distribution design, i.e. changing the wave trough of the stator magnetic permeance, analyzing the modulation effect of the stator tooth non-uniform distribution on the permanent magnet magnetic field, changing the air gap flux density harmonic phase contributing to the torque under the condition that the air gap flux density harmonic amplitude contributing to the torque ripple changes little, thereby improving the motor torque performance. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a stator slot type non-uniform tooth double-sided permanent magnet vernier motor diagram of the present application;

[0039] Figure 2 is a rotor permanent magnet vernier motor diagram of the present application;

[0040] Figure 3 is a stator slot type structure of the present application;

[0041] Figure 4 is a stator permanent magnet vernier motor of the present application;

[0042] Figure 5 is a rotor permanent magnet magnetic motive force distribution diagram of the present application;

[0043] Figure 6 is a stator magnetic permeability distribution diagram of the present application without stator slot;

[0044] Figure 7 is a stator magnetic permeability distribution diagram of the stator slot type of the present application;

[0045] Figure 8is the air gap flux harmonic wave comparison chart of the rotor permanent magnet of the conventional double-sided permanent magnet Vernier motor and the stator slotted non-uniform tooth double-sided permanent magnet Vernier motor of the present application;

[0046] Figure 9 is the air gap flux harmonic wave comparison and harmonic wave to torque and torque ripple contribution distribution chart of the conventional double-sided permanent magnet Vernier motor and the stator slotted double-sided permanent magnet Vernier motor of the present application;

[0047] Figure 10 is the air gap flux harmonic wave comparison and harmonic wave phase comparison and torque contribution distribution chart 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 application;

[0048] Figure 11 is the air gap flux comparison chart of the conventional double-sided permanent magnet Vernier motor and the stator slotted non-uniform tooth double-sided permanent magnet Vernier motor of the present application;

[0049] Figure 12 is the air gap flux harmonic wave amplitude comparison chart of the conventional double-sided permanent magnet Vernier motor and the stator slotted non-uniform tooth double-sided permanent magnet Vernier motor of the present application;

[0050] Figure 13 is the torque and torque ripple comparison chart of the conventional double-sided permanent magnet Vernier motor and the stator slotted non-uniform tooth double-sided permanent magnet Vernier motor of the present application.

[0051] In the figure: 1-rotor; 2-stator tooth; 3-U-shaped rotor permanent magnet; 4-ladder-shaped stator permanent magnet; 5-armature winding; 6-stator slotted structure; 1.1-triangle 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

[0052] The present application will be further described below in conjunction with the drawings.

[0053] As shown in the present application Figures 1-4 is a stator slotted non-uniform tooth double-sided permanent magnet Vernier motor of the present application. Among them, the motor structure includes an external rotor 1, an internal stator tooth 2, the rotor 1 is provided with a U-shaped rotor permanent magnet 3 along the circumferential direction, the U-shaped opening of the U-shaped rotor permanent magnet 3 faces the center direction, the stator tooth 2 is a left-right symmetrical structure along the radial center line, the radial end is provided with symmetrical split teeth, the ladder-shaped stator permanent magnet 4 is arranged between the two split teeth, the armature winding 5 is arranged on the stator tooth 2, the end of each split tooth is slotted, the structure of the slot is as shown in the stator slotted structure 6, and the stator tooth 2 is non-uniformly distributed along the circumferential direction.

[0054] The rotor 1 and the stator tooth 2 are respectively provided with 19 pairs of pole rotor permanent magnets and 12 pairs of pole stator permanent magnets, two triangular magnetic barriers 1.1 are arranged at the two ends of the U bottom of the U-shaped rotor permanent magnet 3, and the internal leakage can be reduced; the U-shaped rotor permanent magnet 3 is composed of three rectangular permanent magnets and is magnetized from outside to inside along the thickness; there is an iron core with an angle of γ3=8.38° between adjacent rotor permanent magnets, the magnetic circuit of the iron core is opposite to the U-shaped rotor permanent magnet 3, and therefore the iron core and the U-shaped rotor permanent magnet 3 form an alternating pole; the stator ladder-shaped permanent magnet is in a structure of wide at the top and narrow at the bottom, and is magnetized downward along the thickness; the armature winding 5 adopts a concentrated double-layer winding distribution; there are 24 modulation teeth (slit teeth), and there are 12 stator slots.

[0055] The present application is a double-sided permanent magnet vernier motor, and the working principle of the motor can be divided into the working principles of a rotor permanent magnet vernier motor and a stator permanent magnet vernier motor, as shown in the present application Figure 2 and 4 The rotor permanent magnet vernier motor is shown in the present application Figure 2 , and the rotor is provided with permanent magnets to generate permanent magnet magnetic motive force, and then the permanent magnet magnetic motive force is modulated through a stator slotted non-uniform tooth structure to obtain air gap magnetic density. Figure 2 In the present application, the width of the U-shaped rotor permanent magnet 3 is w pm , and the lengths of the U-shaped rotor permanent magnets 3 are as follows: 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 , and the stator tooth 2 is non-uniformly distributed at angles γ1 and γ2, that is, the included angles of adjacent stator teeth 2 are γ1, γ2, γ1, γ2, …, in the present application, γ2=8.6302deg, and γ1=6.9298deg; the specific structure of the stator slit slotted design is shown in the present application Figure 3 , and the specific structure of the slot is as follows: 2.1 is a first stator slot, the slot width is 0.11deg, and the slot depth is 2.5mm; 2.2 is a second stator slot, the slot width is 2.5deg, and the slot depth is 1mm; 2.3 is a first stator tooth, the tooth width is 4.5deg, and the tooth height is 1mm; 2.4 is a third stator slot, the slot depth and the slot width are 3.5mm and 1.1deg respectively; and 2.5 is a second stator tooth, the tooth width is 0.22deg, and the tooth height is 2.5mm.

[0056] The stator permanent magnet vernier motor is shown in the present application Figure 4 , and the stator tooth is provided with permanent magnets to generate permanent magnet magnetic motive force, and then the permanent magnet magnetic motive force is modulated through a rotor magnetic guide to obtain air gap magnetic density. Figure 4 In the present application, the ladder-shaped stator permanent magnet 4 is in an isosceles trapezoidal structure, the top width of the trapezoid is w pm2 , the bottom width is w pm3 , the height is l pm2 , and the width of the straight tooth part of the stator tooth 2 is w st .

[0057] The modeling method of the double-sided permanent magnet vernier motor of the stator slotted non-uniform tooth design of the application is as follows:

[0058] The air gap magnetic flux density B of the double-sided permanent magnet vernier motor of the application is rk approximately equal to the sum of the air gap magnetic flux density generated by the U-shaped rotor permanent magnet 3 and the air gap magnetic flux density generated by the trapezoidal stator permanent magnet 4 :

[0059]

[0060] F represents the magnetomotive force of the trapezoidal stator permanent magnet 4, Λ represents the magnetomotive force of the U-shaped rotor permanent magnet 3, r (θ, t) represents the rotor permeance, and Φ represents the stator permeance.

[0061] wherein the air gap magnetic flux density generated by the trapezoidal stator permanent magnet 4 is composed of the following three steps:

[0062] Step 1: Assuming that the core permeability is infinite and ignoring the leakage magnetic flux, only the pole pair number of the trapezoidal stator permanent magnet 4 is considered, and the expression of the magnetomotive force F s (θ) of the trapezoidal stator permanent magnet 4 can be obtained according to Fourier decomposition as follows:

[0063]

[0064] wherein i is the i-th harmonic; F ssi is the amplitude of the i-th harmonic of the magnetomotive force of the trapezoidal stator permanent magnet 4; P s is the pole pair number of the trapezoidal stator permanent magnet 4.

[0065] Step 2: Under ideal conditions, the expression of the rotor permeance Λ r (θ, t) can be obtained according to Fourier decomposition as follows:

[0066]

[0067] Λ rj is the amplitude of the j-th harmonic of the rotor permeance; Ω r is the rotor angular velocity; θ is the air gap circumferential mechanical angle; and t is the time.

[0068] On the basis of Step 1 and Step 2, Step 3 is as follows: ignoring the magnetic field generated by the armature winding on the stator, according to the magnetic field modulation principle, the expression of the air gap magnetic flux density B spm generated by the trapezoidal stator permanent magnet 4 is as follows:

[0069]

[0070] The air-gap flux density generated by the U-shaped rotor permanent magnet 3 is related to the magnetic motive force of the U-shaped rotor permanent magnet 3 and the stator magnetic permeability. The motor of the present application adopts a structure of the stator slotted non-uniform tooth, and the design is made aiming at the wave crest and wave trough of the stator magnetic permeability. Therefore, the design method of the present application is introduced in the stator magnetic permeability part in step 2 of generating the air-gap flux density by the U-shaped rotor permanent magnet. The air-gap flux density generated by the U-shaped rotor permanent magnet is composed of the following three steps, wherein the design method of the stator slotted non-uniform tooth of the present application is introduced in step 2:

[0071] Step 1: In the case of assuming the magnetic permeability of the core to be infinite and ignoring the leakage magnetic flux, only the pole pair number of the U-shaped rotor permanent magnet 3 is considered, and the magnetic motive force F of the U-shaped rotor permanent magnet 3 can be obtained according to Fourier decomposition r The expression of F (θ, t) is as follows:

[0072]

[0073]

[0074] In the formula, F rr is the amplitude of the nth harmonic of the magnetic motive force of the U-shaped rotor permanent magnet 3; P r is the pole pair number of the U-shaped rotor permanent magnet 3; F M , F N are the amplitudes of the wave crest and wave trough of the rotor permanent magnet magnetic motive force, respectively; α1 is the angle of the spoke type permanent magnet in the U-shaped rotor permanent magnet; α2 is the width between two spoke type permanent magnets in the 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, and the ideal wave form of the magnetic motive force of the U-shaped rotor permanent magnet 3 is shown in the Figure 5 of the present application.

[0075] Step 2: In the case of no stator slotting and non-uniform tooth design, the distribution diagram of the stator magnetic permeability is shown in the Figure 6 of the present application. At this time, the wave crest and wave trough of the stator magnetic permeability remain unchanged with the change of the angle, and the period of the stator magnetic permeability is 2*PI / N s . Then the stator slotted design is introduced at the wave crest of the stator magnetic permeability, and the non-uniform tooth design is adopted at the wave trough of the stator magnetic permeability, and the wave form of the stator magnetic permeability is changed from the Figure 6 of the present application to the Figure 7As shown, the peaks of the stator change with the angle, and the angles of the two troughs are different. Therefore, the period of the entire stator magnetic permeability becomes 4*PI / N. s The specific structure of the stator slot is as described in this invention. Figure 3 As shown, Figure 3 In the diagram, 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 through Fourier decomposition. s The expression for (θ) is as follows:

[0076]

[0077]

[0078]

[0079] In the formula, Λ0 is the DC component; Λ1 is the air gap permeability of the trapezoidal slot; Λ4 is the air gap permeability of the second stator tooth; θ7 is the angle of the hypotenuse of the trapezoid; Λ si N is the amplitude of the i-th harmonic of the stator magnetic permeability; s It is the number of stator slots of the motor; r g It is the air gap radius of the motor; δ g (θ) is the air gap radius that varies with the mechanical angle; l ef θ is the shaft length of the motor; μ0 is the permeability of free space; θ m The angle of the slots and teeth on the stator slotted structure is indicated by the subscript m. Figure 7 The individual teeth or grooves shown; Λ m It is the stator magnetic permeability amplitude of the slots and teeth on the stator slotted structure.

[0080] Based on steps 1 and 2, step 3 is as follows: Ignoring the magnetic field generated by the armature winding on the stator, according to the principle of magnetic field modulation, the air gap magnetic flux density B generated by the U-shaped rotor permanent magnet 3 is... rpm The expression is as follows:

[0081]

[0082] Based on the formula for the air gap magnetic flux density generated by the U-shaped rotor permanent magnet 3, the air gap magnetic flux density after designing a slotted stator structure and non-uniform teeth at the peaks and troughs of the stator magnetic flux density can be calculated. Figure 8 The figure shown is a comparison of the air gap magnetic flux density amplitude generated by the rotor permanent magnet before and after the stator magnetic permeability design. It can be seen that the 19th, 43rd and 57th harmonics of the air gap magnetic flux density generated by the U-shaped rotor permanent magnet 3 are significantly reduced, which leads to a reduction in motor torque pulsation. At the same time, the 55th harmonic is significantly increased, maintaining the high torque performance of the motor.

[0083] The present invention Figure 9As shown, the middle figure is a comparison of the air gap magnetic flux density harmonics of a conventional double-sided permanent magnet vernier motor and the stator slotted double-sided permanent magnet vernier motor of this invention. It can be seen that after slotting the stator teeth, the 19th, 36th, and 57th harmonics of the motor's air gap magnetic flux density decrease significantly. According to... Figure 9 The comparison diagram on the left, showing the contribution of air gap magnetic flux density harmonics to torque ripple, reveals a significant reduction in the torque ripple contribution of these harmonics. Therefore, the stator slot design reduces the motor's torque ripple. Specifically, the air gap magnetic flux density harmonic torque ripple λ... k The expression:

[0084]

[0085] In the formula: T avg It is the average value of the total electromagnetic torque; max(T) k (t) is the maximum value of each harmonic across all times; min(T) k (t) is the minimum value of each harmonic across all times.

[0086] At the same time, it can be seen from Figure 9 As shown in the middle figure, after implementing the stator slotted design, the 55th air gap magnetic flux density harmonic significantly increases. Figure 9 The torque contribution comparison diagram on the right shows a significant increase in torque contributed by the 55th air gap magnetic flux density harmonic. Therefore, the stator slotted design allows the motor to maintain high torque performance. The torque T of each air gap magnetic flux density harmonic is... k The expression:

[0087]

[0088] In the formula, μ0 is the free permeability; B rk (t), B tk (t) represent the radial and tangential amplitudes of each air gap magnetic flux density harmonic, respectively; θ rk (t), θ tk (t) represents the radial and tangential phases of each air gap magnetic flux density harmonic, respectively.

[0089] Based on the above Figure 9 The description shows that after slotting the stator in the motor, by changing the peak of the stator magnetic permeability, the amplitude of the 19th, 36th, and 57th air gap magnetic flux density harmonics is reduced, thereby reducing the torque ripple of the motor; at the same time, the amplitude of the 55th air gap magnetic flux density harmonic is increased to maintain the high torque performance of the motor, so that the motor has both low torque ripple and high torque performance.

[0090] The present invention Figure 10As shown, the middle figure is a comparison of the air gap magnetic flux density harmonic amplitude of a stator slotted double-sided permanent magnet vernier motor and a stator slotted non-uniform tooth double-sided permanent magnet vernier motor of the present invention. It can be observed that after introducing non-uniformly distributed stator teeth, the amplitudes of the 5th and 19th air gap magnetic flux density harmonics increase, while the amplitudes of the 43rd and 57th air gap magnetic flux density harmonics decrease; however, from... Figure 10 The torque increment graph of the air gap magnetic flux density harmonics on the right shows that regardless of whether the amplitude of the air gap magnetic flux density harmonics increases or decreases, the torque of the 5th, 19th, 43rd, and 57th air gap magnetic flux density harmonics all increase, thus improving the motor's torque performance; furthermore, it can be seen from... Figure 10 The harmonic phase comparison diagram on the left shows that the phases of the 43rd and 57th air gap magnetic flux density harmonics change. This explains why, although the amplitudes of the 43rd and 57th air gap magnetic flux density harmonics decrease, the torque-providing capability increases. Specifically, in this motor, the 5th air gap magnetic flux density harmonic provides negative torque, although from... Figure 10 The middle graph shows that the amplitude of the 5th air gap magnetic flux density harmonic has increased, but the negative torque it provides has decreased. Figure 10 As shown in the diagram on the left, this is because its phase changes, which reduces the negative torque it provides, thereby improving the motor's torque performance.

[0091] Based on the above Figure 10 The description shows that, based on the slotted stator design, and in conjunction with the non-uniform distribution of stator teeth, the amplitude and phase of the air gap magnetic flux density harmonics are changed by altering the troughs of the stator magnetic permeability. This results in an increase in the torque provided by the 5th, 19th, 43rd, and 57th air gap magnetic flux density harmonics, thereby improving the motor torque.

[0092] This invention Figure 11 and Figure 12 These are comparison diagrams of the air gap magnetic flux density waveform and harmonic waveform of a conventional double-sided permanent magnet vernier motor and a stator slotted non-uniform tooth double-sided permanent magnet vernier motor designed in this invention. The air gap magnetic flux density waveforms of the two are similar. As shown in this article... Figure 12 As shown, the amplitudes of the 19th, 43rd, and 57th air gap magnetic flux density harmonics decrease, while the amplitudes of the 12th and 55th air gap magnetic flux density harmonics increase. The former reduces motor torque ripple, while the latter increases motor torque. Therefore, the slotted non-uniform tooth design of the stator enables this motor to simultaneously exhibit high torque and low torque ripple performance.

[0093] This invention Figure 13The average torque and torque ripple contrast chart of the conventional double-sided permanent magnet Vernier motor and the stator slotted type non-uniform tooth double-sided permanent magnet Vernier motor designed by the application is shown, and due to the stator slotted type design and the non-uniform design of the stator teeth, the torque ripple is reduced from 5.41% to 4.56%, which is effectively inhibited; the average torque is increased from 59.94 Nm to 60.66 Nm, which increases the torque and keeps the motor with high torque performance; the above analysis and results verify that the stator slotted type design method cooperates with the non-uniform design method of the stator teeth to realize the effectiveness of the motor design with high torque and low ripple performance.

[0094] In summary, the application provides a stator slotted type non-uniform tooth double-sided permanent magnet Vernier motor and a modeling method thereof. According to the working principle of the double-sided permanent magnet Vernier motor, the motor can be divided into a rotor permanent magnet Vernier motor and a stator permanent magnet Vernier motor, and the application mainly designs the wave crest and wave trough of the stator magnetic conductance in the rotor permanent magnet Vernier motor, so as to change the air gap magnetic density of the motor. The wave crest of the stator magnetic conductance is changed by the stator slotted type design, and the wave trough of the stator magnetic conductance is changed by the non-uniform teeth, wherein the stator slotted type structure reduces the air gap magnetic density harmonic amplitude which mainly contributes to the torque ripple, thereby reducing the torque ripple of the motor, and increasing the 55th air gap magnetic density harmonic amplitude to maintain high torque of the motor; at the same time, the non-uniform distribution of the stator teeth changes the amplitude and phase of the air gap magnetic density harmonic, thereby increasing the torque and ensuring the high torque performance of the motor. Therefore, under the action of the stator slotted type structure and the non-uniform distribution of the stator teeth, the stator slotted type non-uniform tooth double-sided permanent magnet Vernier motor has the performance of high torque and low torque ripple.

[0095] The above series of detailed descriptions are only specific descriptions of the feasible embodiments of the application, and are not used to limit the protection scope of the application, and any equivalent means or changes without departing from the technology of the application should be included in the protection scope of the application.

Claims

1. A stator slotted non-uniform tooth double-sided permanent magnet Vernier motor comprising an outer rotor and inner stator teeth, characterized by, The rotor (1) is provided with U-shaped rotor permanent magnets (3) in the circumferential direction, and the U-shaped openings of the U-shaped rotor permanent magnets (3) face the circumferential direction; there is a certain width of rotor cores between adjacent U-shaped rotor permanent magnets (3), the magnetic circuit of the rotor cores is opposite to the U-shaped rotor permanent magnets (3), and the rotor cores and the U-shaped rotor permanent magnets (3) constitute alternating poles, and the pole pair number of the U-shaped rotor permanent magnets (3) is P r . The stator tooth (2) is symmetrical along the radial center line, comprising straight teeth and two symmetrical split teeth arranged at the radial ends of the straight teeth, a ladder type stator permanent magnet (4) is arranged in the stator slot between the two split teeth, the ladder type stator permanent magnet (4) has a structure of wide outside and narrow inside in the radial direction, and is magnetized inward along the thickness, an armature winding (5) is arranged on the stator tooth (2), the armature winding (5) adopts a double-layer concentrated winding, and is wound according to P a =2N s -P r , N s is the number of stator slots, P r is the number of pole pairs of the U-shaped rotor permanent magnet; each split tooth is slotted at the radial end, the stator teeth (2) are non-uniformly distributed in the circumferential direction, N s stator teeth are taken as a group two by two, and are divided into N s / 2 groups, the mechanical angle of the slot width difference of the two teeth in each group is γ2, and the mechanical angle of the slot width difference of the two teeth in one group is γ1.

2. A stator slotted non-uniform tooth double-sided permanent magnet Vernier motor as claimed in claim 1, characterized in that, The single U-shaped rotor permanent magnet (3) comprises three rectangular permanent magnets and is magnetized from outside to 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 edges.

3. The dual-sided vernier motor of claim 1 or 2, wherein, The rotor core between the adjacent U-shaped rotor permanent magnets (3) has an angle of γ3=8.38°.

4. A stator slotted non-uniform tooth double-sided permanent magnet Vernier motor as claimed in claim 1, characterized in that, The pole pair number of the U-shaped rotor permanent magnet (3) is P r = 19, the stator tooth N s = 12, and the number of split teeth is 24.

5. A stator slotted non-uniform tooth double-sided permanent magnet Vernier motor as claimed in claim 4, characterized in that, γ2=8.6302; γ1=6.9298.

6. A stator slotted non-uniform tooth double-sided permanent magnet Vernier motor as claimed in claim 1, characterized in that, The slot structure at the end of the split tooth is as follows: With the radial center line of the stator tooth (2) as the boundary, the left split tooth is sequentially provided from right to left as: the first stator slot (2.1), the second stator slot (2.2), the first stator tooth (2.3), the third stator slot (2.4), and the second stator tooth (2.5); the structure of the right split tooth is symmetrical to that of the left split tooth; The slot width of the first stator slot (2.1) is 0.11 deg, and the slot depth is 2.5 mm; the slot width of the second stator slot (2.2) is 2.5 deg, and the slot depth is 1 mm; the tooth width of the first stator tooth (2.3) is 4.5 deg, and the tooth height is 1 mm; the slot depth and the slot width of the third stator slot (2.4) are 3.5 mm and 1.1 deg respectively; the tooth width of the second stator tooth (2.5) is 0.22 deg, and the tooth height is 2.5 mm.

7. A stator slotted non-uniform tooth double-sided permanent magnet Vernier motor as claimed in claim 1 characterized by, The ladder-shaped stator permanent magnet (4) is an isosceles ladder-shaped structure.

8. The method for modeling a stator slotted non-uniform tooth double-sided permanent magnet Vernier motor as defined in claim 1, wherein, Air-gap flux density B of the electric machine rk is equal to the air-gap flux density generated by the U-shaped rotor permanent magnet (3) and the air-gap flux density generated by the ladder-shaped stator permanent magnet (4) together: denotes the magnetic motive force of the ladder stator permanent magnets, denotes the magnetic motive force of the U-shaped rotor permanent magnets, r (θ, t) denotes the rotor permeance, denotes the stator permeance.

9. The method of modeling a stator slotted non-uniform tooth double-sided permanent magnet Vernier motor according to claim 8, characterized in that, The air-gap flux density generated by the ladder stator permanent magnet (4) By the following steps: Step 1: Assuming the core permeability is infinite and ignoring leakage, only considering the pole pair number of the trapezoidal stator permanent magnet (4), the trapezoidal stator permanent magnet magnetic motive force F is obtained according to Fourier decomposition 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 stator permanent magnet (4); P s is the number of pole pairs of the trapezoidal stator permanent magnet (4); Step 2: The rotor permeance Λ is obtained from the Fourier decomposition r The expression for (θ, t): Λ rj is the amplitude of the jth rotor flux harmonic; Ω r is the rotor angular velocity; θ is the air gap circumferential mechanical angle; t is time; Step 3: Ignoring the magnetic field generated by the armature winding on the stator, according to the principle of magnetic field modulation, the air gap magnetic flux density B spm generated by the trapezoidal stator permanent magnet (4) is expressed as follows: 。 10. The method of modeling a stator slotted non-uniform tooth double-sided permanent magnet Vernier motor of claim 8, wherein, The U-shaped rotor permanent magnet (3) generates an air-gap flux density By the following steps: Step 1: Assuming the core permeability is infinite and ignoring leakage, only considering the rotor U-shaped permanent magnet pole pairs, the U-shaped rotor permanent magnet (3) magnetic motive force F is obtained according to Fourier decomposition r The expression of (θ, t): In the formula, F rr is the amplitude of the n-th harmonic of the magnetic motive force of the U-shaped rotor permanent magnet (3); P r is the pole pair number of the U-shaped rotor permanent magnet (3); F M , F N are the amplitudes of the peak and trough of the magnetic motive force of the U-shaped rotor permanent magnet (3), respectively; 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 the U-shaped rotor permanent magnet (3); Step 2: respectively introduce the stator slotting type design effect at the peak of the stator magnetic permeability, and adopt the non-uniform tooth design effect at the trough of the stator magnetic permeability, the peak of the stator will change with the change of the angle, the angles of the two troughs will be different, and the period of the stator magnetic permeability is 4*PI / N s ; the expression of the stator magnetic permeability Λ s (θ) is obtained according to Fourier decomposition: where Λ0is the DC component; Λ1is the air-gap permeance of the stator tooth with trapezoidal slot; Λ4is the air-gap permeance of the second stator tooth (2.5); θ7is the angle of the trapezoidal slope; Λ si is the amplitude of the i-th harmonic of the stator permeance; N s is the number of slots of the motor stator; r g is the air-gap radius of the motor; δ g (θ) is the air-gap radius as a function of the mechanical angle; l ef is the shaft length of the motor; μ0is the vacuum permeability; θ m is the angle of the slot or tooth on the stator slotted structure; Λ m is the amplitude of the stator permeance of the slot and tooth on the stator slotted structure; Step 3: Ignoring the magnetic field generated by the armature winding on the stator, according to the principle of magnetic field modulation, the air gap magnetic flux density B generated by the U-shaped rotor permanent magnet (3) is rpm The expression is as follows: 。

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