阅读说明：本技术 针对新型不对称模块化永磁辅助同步磁阻电机及其振噪优化方法 (Novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor and vibration noise optimization method thereof ) 是由 刘国海 高阿康 陈前 毛彦欣 徐高红 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种针对新型不对称模块化永磁辅助同步磁阻电机及其振噪优化方法,包括分析该不对称结构电机的径向力分布；根据电机振动理论,得出不平衡电磁力和共振是引起较大振动的原因；建立不同电机模型得到转子相对磁导及其谐波,根据转子相对磁导分析,提出优化转子结构削弱不平衡电磁力；根据定子磁密云图,提出定子磁通间隙加辅助槽的优化定子结构削弱共振影响,从而确定最优电机模型；通过验证后得出优化后的电机能够有效地降低电机的振动和噪声。本发明针对非对称结构的模块化电机进行振噪分析和优化,所提方法为此类型电机的设计优化提供参考。(The invention discloses a novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor and a vibration noise optimization method thereof, which comprises the steps of analyzing the radial force distribution of the asymmetric structure motor; according to the motor vibration theory, the reason that unbalanced electromagnetic force and resonance are large vibration is obtained; establishing different motor models to obtain the relative magnetic conductance of the rotor and the harmonic thereof, and providing an optimized rotor structure to weaken unbalanced electromagnetic force according to the analysis of the relative magnetic conductance of the rotor; according to the magnetic flux density cloud chart of the stator, providing an optimized stator structure of a stator magnetic flux gap plus an auxiliary slot to weaken resonance influence, and determining an optimal motor model; the optimized motor obtained after verification can effectively reduce the vibration and noise of the motor. The vibration noise analysis and optimization method aims at the vibration noise analysis and optimization of the modular motor with the asymmetric structure, and the method provides reference for the design optimization of the motor of the type.)

1. The novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor is characterized by comprising an outer-layer modular stator and an inner-layer asymmetric rotor, wherein the modular stator consists of a stator core, magnetic flux gaps and coils, the coils are wound in stator teeth, and the stator core is uniformly divided into three parts by the magnetic flux gaps with different widths; the asymmetric rotor consists of a ferrite permanent magnet and three pairs of U-shaped magnetic barriers with different opening angles, each pair of magnetic barriers is two layers, the opening angle of the magnetic barrier positioned on the outer side is larger than the opening angle of the inner magnetic barrier, and the permanent magnet with different thicknesses is positioned in the center of the two layers of U-shaped magnetic barriers.

2. The novel asymmetric modular permanent magnet assisted synchronous reluctance machine according to claim 1, wherein an auxiliary slot with a length of 3mm and a width of 1mm is opened in the flux gap at a distance of 0.5mm from the air gap.

3. The new asymmetric modular permanent magnet assisted synchronous reluctance machine according to claim 1, wherein the offset angles of the U-shaped magnetic barriers with different opening angles are clockwise: beta, beta + sigma, beta-sigma; selecting: β and σ are 25 ° and 1.5 °, respectively.

4. A vibration noise optimization method for a novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor is characterized by comprising the following steps:

step 1, analyzing the radial force distribution of the motor with the asymmetric structure, and determining a radial force source which can cause large vibration according to a motor vibration theory;

step 2, establishing different motor rotor models, and indirectly obtaining the relative magnetic conductance of the rotor and the harmonic thereof in a radial magnetizing mode;

step 3, determining an optimized magnetic conductance harmonic order according to rotor relative magnetic conductance analysis, and providing a rotor optimization model by taking a magnetic barrier offset angle as a target so as to weaken unbalanced electromagnetic force;

step 4, according to the magnetic flux density cloud chart of the stator, a stator optimization model for slotting in the magnetic flux gap is provided, the radial force is further weakened, and large vibration caused by resonance is reduced, so that an optimal motor model is determined;

and 5, checking the electromagnetic performance, vibration and noise of the optimized motor.

5. The method for optimizing the vibration noise of the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor according to claim 4, wherein the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor comprises a modular stator and an asymmetric rotor, the modular stator comprises a stator core, flux gaps and coils, and the stator core is uniformly divided into three parts by the flux gaps with different widths; the asymmetric rotor consists of a ferrite permanent magnet and a U-shaped magnetic barrier with different opening angles, and the permanent magnet is positioned in the center of the U-shaped magnetic barrier.

6. The method for optimizing the vibration noise of the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor according to claim 4, wherein: in the step 1, the radial force distribution is different for different types of motors; magnetic density is obtained through magnetic potential and magnetic conductance, and then radial force is obtained, and the formula is as follows:

ignoring the current harmonics, the stator magnetomotive force can be expressed as:

where θ is the spatial position of the rotor, t is time, ω is the mechanical angular velocity, p is the number of pole pairs, F_vIs the amplitude of the v-order stator magnetomotive force, and k is a positive integer;

the rotor magnetomotive force can be expressed as:

wherein, F_μIs the amplitude of the mu-order rotor magnetomotive force, i is a natural number;

the stator permeance can be expressed as:

wherein, Λ_s0And Λ_smRespectively the average value of the stator magnetic conductance and the harmonic amplitude of the m-order stator magnetic conductance, wherein z is the number of slots, and m is a positive integer;

the rotor permeance can be expressed as:

wherein, Λ_r0And Λ_rnThe average value of the rotor permeance and the harmonic amplitude of the n-order rotor permeance are respectively, and n is a positive integer;

the air gap permeance can be expressed as: Λ (θ, t) ═ Λ_s(θ,t)·Λ_r(θ,t)

By maxwell stress-strain, the radial force density can be expressed as:

the radial force can be obtained by integrating the radial force density, so that the order and the frequency of the radial force can be obtained, the radial force harmonic of the motor with the asymmetric structure is very rich, and the motor comprises the radial force of each order of each fundamental frequency, especially comprises unbalanced electromagnetic force. And obtaining the specific amplitude of the radial force by using a finite element method, and quantitatively analyzing the contribution degree of the radial force to the vibration noise of the motor.

7. The method for optimizing the vibration noise of the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor according to claim 4, wherein in the step 1, the asymmetric structure causes the motor to generate abundant radial force harmonics, and for non-high-speed medium and small-sized motors, the resonance phenomenon is almost unavoidable; the vibrational response to radial forces of order 2 and above can be approximated as:

in the formula, F_mIs the radial force amplitude, r is the radial force order, f is the radial force frequency, f_εThe natural frequency of the motor is defined, A is the influence of the motor size and material parameters on the vibration acceleration of the motor under the mode of more than 2 orders, and the larger the amplitude of the radial force is, the larger the vibration acceleration of the motor is, and the vibration acceleration of the surface of the shell is in direct proportion to the square of the frequency of the radial force;

the vibration response to a 1 st order radial force is substantially the same as other general orders, except that the motor stiffness and mass expressions can be approximated by:

in the formula, B is the influence of the size and material parameters of the motor on the vibration acceleration of the motor in the 1-order mode, and because of the difference of the vibration modes, the value of B is smaller than that of a, so that the vibration caused by the 1-order radial force is at least 9 times that of other orders, and the unbalanced electromagnetic force in the asymmetric structure causes the motor to generate larger vibration.

8. The method for optimizing the vibration noise of the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor according to claim 4, wherein in the step 2, the rotor relative magnetic conductance analysis process is as follows:

the permanent magnet is arranged on the outer side of the rotor along the circumferential direction, a radial magnetizing mode is adopted, the ratio of air gap flux density when the rotor is a slot and the rotor is solid is a waveform distributed along the circumference of the relative flux guide of the rotor, Fourier decomposition is carried out on the waveform, space harmonic of the relative flux guide of the rotor is obtained, the asymmetric magnetic barrier enables the relative flux guide of the rotor to be rich in harmonic, under the condition that the magnetic potential is not changed, the unbalanced electromagnetic force and the asymmetric magnetic barrier are closely linked, and the unbalanced electromagnetic force can be reduced by reducing the relative flux guide harmonic of the related rotor.

9. The vibration noise optimization method for the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor according to claim 4, wherein in the rotor optimization model provided in step 3, the different offset angles of the magnetic barriers lead to different distributions of the relative magnetic conductance of the rotor, and a link between the relative magnetic conductance harmonic of the rotor and the vibration noise of the motor is established, and the optimal rotor model is determined by parametric analysis by selecting a reasonable offset angle, which can ensure the electromagnetic performance and weaken the vibration noise of the motor.

10. The vibration noise optimization method for the novel asymmetric modular permanent magnet-assisted synchronous reluctance motor according to claim 4, wherein the step 4 provides a stator optimization model, establishes the relationship between flux density harmonics and motor vibration noise, analyzes the flux density cloud distribution and the air gap flux density harmonic composition, and reduces the radial force amplitude causing larger vibration by slotting the stator flux gap to further suppress the vibration noise.

Technical Field

The invention relates to a novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor and a vibration noise optimization method thereof, belongs to the technical field of low-vibration noise motor design, and is applied to occasions such as aerospace and high-performance ships.

Background

The development of permanent magnet motors is restricted by the high price of neodymium iron boron, and researchers put forward a permanent magnet auxiliary synchronous reluctance motor in order to reduce the production cost. The advantage of this machine is that the torque density is within acceptable limits, the efficiency is high and only inexpensive ferrite is required. In recent years, there has been increasing emphasis on optimizing rotors to improve electromagnetic performance. Asymmetric stators and rotors have been proposed to suppress torque ripple, but asymmetric configurations produce unbalanced electromagnetic forces. New problems with vibration and noise will arise. The asymmetrical structure has a serious influence on vibration and noise when the motor operates at high speed. However, the mechanism has not been studied in depth, nor has the origin of vibration and noise been clearly explained. In some studies, the sources of vibration and noise of symmetric permanent magnet synchronous motors were analyzed. The slot harmonics and their multiples are the main cause of vibration, but the effect of the windings is not considered in the modal analysis. For an integer slot symmetric permanent magnet synchronous motor, the vibration of the motor is mainly caused by zero-order radial force. However, the vibration of an asymmetric motor is different from the vibration of a symmetric motor. The unbalanced electromagnetic force generated by the asymmetric motor causes the vibrations to vary significantly. The previous research on unbalanced electromagnetic force mainly comes from the eccentric or asymmetric winding of the rotor, and the influence of the unbalanced electromagnetic force generated by the asymmetric structure on the vibration and noise of the motor is not paid sufficient attention. At present, the vibration and noise of the asymmetric motor are not well optimized, so that the vibration and noise analysis of the asymmetric motor is of great significance.

Disclosure of Invention

The invention provides a novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor and a vibration noise optimization method thereof, aiming at the problem that the motor generates unbalanced electromagnetic force and new vibration noise is caused due to an asymmetric structure.

In order to meet the technical requirements, the technical scheme adopted by the invention is as follows: a novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor comprises an outer-layer modular stator and an inner-layer asymmetric rotor, wherein the modular stator consists of a stator core, magnetic flux gaps and coils, the coils are wound in stator teeth, and the stator core is uniformly divided into three parts by the magnetic flux gaps with different widths; the asymmetric rotor consists of a ferrite permanent magnet and three pairs of U-shaped magnetic barriers with different opening angles, each pair of magnetic barriers is two layers, the opening angle of the magnetic barrier positioned on the outer side is larger than the opening angle of the inner magnetic barrier, and the permanent magnet with different thicknesses is positioned in the center of the two layers of U-shaped magnetic barriers.

Furthermore, an auxiliary groove with the length of 3mm and the width of 1mm is arranged in the magnetic flux gap at a position 0.5mm away from the air gap.

Further, the offset angles of the three pairs of U-shaped magnetic barriers with different opening angles are as follows in sequence clockwise: beta, beta + sigma, beta-sigma; selecting: β and σ are 25 ° and 1.5 °, respectively.

A vibration noise optimization method for a novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor comprises the following steps:

step 1, analyzing the radial force distribution of the motor with the asymmetric structure, and determining a radial force source which can cause large vibration according to a motor vibration theory;

step 2, establishing different motor rotor models, and indirectly obtaining the relative magnetic conductance of the rotor and the harmonic thereof in a radial magnetizing mode;

step 3, determining an optimized magnetic conductance harmonic order according to rotor relative magnetic conductance analysis, and providing a rotor optimization model by taking a magnetic barrier offset angle as a target so as to weaken unbalanced electromagnetic force;

step 4, according to the magnetic flux density cloud chart of the stator, a stator optimization model for slotting in the magnetic flux gap is provided, the radial force is further weakened, and large vibration caused by resonance is reduced, so that an optimal motor model is determined;

and 5, checking the electromagnetic performance, vibration and noise of the optimized motor.

Furthermore, the novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor consists of a modular stator and an asymmetric rotor, wherein the modular stator consists of a stator core, magnetic flux gaps and coils, and the stator core is uniformly divided into three parts by the magnetic flux gaps with different widths; the asymmetric rotor consists of a ferrite permanent magnet and a U-shaped magnetic barrier with different opening angles, and the permanent magnet is positioned in the center of the U-shaped magnetic barrier.

Further, in the radial force distribution in the step 1, the radial force distribution of different types of motors is different; magnetic density is obtained through magnetic potential and magnetic conductance, and then radial force is obtained, and the formula is as follows:

ignoring the current harmonics, the stator magnetomotive force can be expressed as:where θ is the spatial position of the rotor, t is time, ω is the mechanical angular velocity, p is the number of pole pairs, F_vIs the amplitude of the v-order stator magnetomotive force, and k is a positive integer;

the rotor magnetomotive force can be expressed as:wherein, F_μIs the amplitude of the mu-order rotor magnetomotive force, i is a natural number;

the stator permeance can be expressed as:wherein, Λ_s0And Λ_smRespectively the average value of the stator magnetic conductance and the harmonic amplitude of the m-order stator magnetic conductance, wherein z is the number of slots, and m is a positive integer;

the rotor permeance can be expressed as:wherein, Λ_r0And Λ_rnThe average value of the rotor permeance and the harmonic amplitude of the n-order rotor permeance are respectively, and n is a positive integer;

the air gap permeance can be expressed as: Λ (θ, t) ═ Λ_s(θ,t)·Λ_r(θ,t)

By maxwell stress-strain, the radial force density can be expressed as:

the radial force can be obtained by integrating the radial force density, so that the order and the frequency of the radial force can be obtained, the radial force harmonic of the motor with the asymmetric structure is very rich, and the motor comprises the radial force of each order of each fundamental frequency, especially comprises unbalanced electromagnetic force. And obtaining the specific amplitude of the radial force by using a finite element method, and quantitatively analyzing the contribution degree of the radial force to the vibration noise of the motor.

Further, in the step 1, the motor generates rich radial force harmonic waves due to the asymmetric structure, and the resonance phenomenon is almost unavoidable for non-high-speed medium and small motors; the vibrational response to radial forces of order 2 and above can be approximated as:

in the formula, F_mIs the radial force amplitude, r is the radial force order, f is the radial force frequency, f_εThe natural frequency of the motor is defined, A is the influence of the motor size and material parameters on the vibration acceleration of the motor under the mode of more than 2 orders, and the larger the amplitude of the radial force is, the larger the vibration acceleration of the motor is, and the vibration acceleration of the surface of the shell is in direct proportion to the square of the frequency of the radial force;

the vibration response to a 1 st order radial force is substantially the same as other general orders, except that the motor stiffness and mass expressions can be approximated by:

in the formula, B is the influence of the size and material parameters of the motor on the vibration acceleration of the motor in the 1-order mode, and because of the difference of the vibration modes, the value of B is smaller than that of a, so that the vibration caused by the 1-order radial force is at least 9 times that of other orders, and the unbalanced electromagnetic force in the asymmetric structure causes the motor to generate larger vibration.

Further, in the step 2, the rotor relative magnetic conductance analysis process is as follows:

the permanent magnet is arranged on the outer side of the rotor along the circumferential direction, a radial magnetizing mode is adopted, the ratio of air gap flux density when the rotor is a slot and the rotor is solid is a waveform distributed along the circumference of the relative flux guide of the rotor, Fourier decomposition is carried out on the waveform, space harmonic of the relative flux guide of the rotor is obtained, the asymmetric magnetic barrier enables the relative flux guide of the rotor to be rich in harmonic, under the condition that the magnetic potential is not changed, the unbalanced electromagnetic force and the asymmetric magnetic barrier are closely linked, and the unbalanced electromagnetic force can be reduced by reducing the relative flux guide harmonic of the related rotor.

Further, in the rotor optimization model provided in step 3, the different offset angles of the magnetic barriers lead to different distributions of the relative magnetic conductance of the rotor, a relationship between the relative magnetic conductance harmonic of the rotor and the vibration noise of the motor is established, the reasonable offset angle is selected, so that the electromagnetic performance can be ensured, the vibration noise of the motor can be weakened, and the optimal rotor model is determined through parametric analysis.

Further, the step 4 provides a stator optimization model, establishes a relation between flux density harmonics and motor vibration noise, analyzes flux density cloud picture distribution and air gap flux density harmonic composition, reduces the radial force amplitude causing larger vibration through stator flux gap slotting, and further inhibits the vibration noise.

Further, step 5 verifies that the proposed optimized structure meets the design requirements through analysis of torque and mechanical stress. The vibration exciter method measures the modal parameters of the motor, and the material parameters are adjusted by the finite element method, so that the finite element result fits the experimental result as much as possible. And finally, optimizing the motor model through finite element analysis, so that the vibration noise of the motor can be weakened to a great extent.

The invention has the following beneficial effects:

1. the mechanism of radial force generated by the motor with the asymmetric modular structure is fully researched, and sufficient conditions are provided for optimizing the motor.

2. The unbalanced electromagnetic force and resonance obtained by research are main sources of motor vibration noise, and an optimization model is obtained through rotor relative magnetic conductance analysis and flux density harmonic analysis, so that a novel optimization idea is provided.

3. The vibration acceleration and the sound power level of the motor are obviously reduced by the proposed optimization model, the vibration noise performance of the optimized motor is obviously improved, and guidance is provided for the design of the motor with the future asymmetric structure.

Drawings

Fig. 1 is a structural diagram of an asymmetric modular permanent magnet assisted synchronous reluctance motor (primary motor).

Fig. 2 shows the process of finding the relative permeance of the rotor in the present invention.

Fig. 3 is a schematic diagram of selecting an offset angle of a rotor magnetic barrier according to the present invention.

Fig. 4 is a structural view of an optimized motor proposed in the present invention.

Fig. 5 is a comparison graph of output torques of the original motor and the optimized motor in the present invention.

Fig. 6 is a comparative graph of relative magnetic conductance of rotors of a primary motor and an optimized motor in the invention.

Fig. 7 is a comparison graph of relative magnetic conductance harmonics of rotors of an original motor and an optimized motor in the invention.

FIG. 8 is a graph comparing vibration acceleration of the original motor and the optimized motor in the present invention

FIG. 9 is a comparison of the acoustic power levels of the original and optimized motors of the present invention

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in fig. 1, a structure diagram of a conventional asymmetric modular permanent magnet assisted synchronous reluctance motor is shown, where 1 is a rotor, 2 is a stator, 3 is a magnetic flux gap, 4 is a stator winding, 5 is a magnetic barrier, and 6 is a ferrite permanent magnet. Taking a 36-slot 6-pole asymmetric modular permanent magnet assisted synchronous reluctance motor as an example, the method steps are as follows.

Step 1, analyzing the radial force distribution of the motor with the asymmetric structure;

magnetic density is obtained through magnetic potential and magnetic conductance, and further radial force is obtained, and the analysis process is as follows:

ignoring the current harmonics, the stator magnetomotive force can be expressed as:where θ is the spatial position of the rotor, t is time, ω is the mechanical angular velocity, p-3 is the number of pole pairs, and F_vAnd k is the amplitude of the v-order stator magnetomotive force and is a positive integer.

The rotor magnetomotive force can be expressed as:mu-2 i +1 wherein, F_μIs the amplitude of the mu-order rotor magnetomotive force, i is a natural number.

The stator permeance can be expressed as:wherein, Λ_s0And Λ_smThe average value of the stator permeance and the harmonic amplitude of the m-order stator permeance are respectively, wherein z is 36 is the number of slots, and m is a positive integer.

The rotor permeance can be expressed as:wherein, Λ_r0And Λ_rnRespectively the average value of the rotor permeance and the harmonic amplitude of the n-order rotor permeance, n being a positive integer.

The air gap permeance can be expressed as: Λ (θ, t) ═ Λ_s(θ,t)·Λ_r(θ,t)

By maxwell stress-strain, the radial force density can be expressed as:

the radial force can be obtained by integrating the radial force densitySo that there are orders of radial force … … of 0, 1, 2, 3; frequency existence f_r、2f_r、3f_r、4f_r… … are provided. The radial force harmonics of the motor with the asymmetric structure are very rich, and the motor comprises radial forces of various orders of fundamental frequencies, particularly unbalanced electromagnetic forces. And obtaining the specific amplitude of the radial force by using a finite element method, and quantitatively analyzing the contribution degree of the radial force to the vibration noise of the motor. It can be found by analysis that the 1 st order radial force is mainly caused by rotor and stator asymmetry.

Step 1, obtaining a radial force source which can possibly cause large vibration according to a motor vibration theory;

the asymmetric structure causes the motor to generate rich radial force harmonic waves, and the resonance phenomenon is almost inevitable for non-high-speed medium and small motors; the vibrational response to radial forces of order 2 and above can be approximated as:

in the formula, F_mIs the radial force amplitude, r is the radial force order, f is the radial force frequency, f_εThe natural frequency of the motor is A, and A is the influence of the motor size and material parameters on the vibration acceleration of the motor under the mode of more than 2 orders.

The vibration response to a 1 st order radial force is substantially the same as other general orders, except that the motor stiffness and mass expressions can be approximated by:

in the formula, B is the influence of the size and material parameters of the motor on the vibration acceleration of the motor under the 1-order mode, and the value of B is smaller than that of A due to the difference of the vibration modes, so that the vibration caused by the 1-order radial force is at least 9 times of that of other orders; therefore, the unbalanced electromagnetic force in the asymmetric structure causes the motor to generate larger vibration, which is an important direction for vibration and noise optimization.

Step 2, establishing different motor models to obtain the relative magnetic conductance of the rotor and the harmonic thereof, wherein the analysis process of the relative magnetic conductance of the rotor is as follows:

the permanent magnet is arranged on the outer side of the rotor along the circumferential direction, and a radial magnetizing mode is adopted. When the rotor is a slot and the rotor is solid, the ratio of the air gap flux density is the waveform of the rotor relative flux guide distributed along the circumference, and the Fourier decomposition is carried out on the waveform to obtain the rotor relative flux guide space harmonic; according to the analysis result of the radial force, under the condition that the magnetic potential is not changed, the 1-order radial pressure is closely related to the relative magnetic conductance of the rotor. An asymmetric rotor results in the rotor having orders other than 3n with respect to the magnetically permeable harmonics, where n is a positive integer, and these harmonics are the main sources of unbalanced electromagnetic forces. By reducing the amplitude of these harmonics, the unbalanced electromagnetic forces will be reduced. Thus, the rotor may be optimized to reduce associated rotor relative permeance harmonics, thereby reducing vibration and noise of the machine. Fig. 2 shows the process of determining the relative permeance of the rotor. Establishing motor models of rotor slotting and solid, respectively simulating to obtain corresponding air gap flux density, and obtaining B_{r_slotting}And B_{r_solid}The ratio of the flux to the flux is the corresponding rotor air gap permeance Λ_{r_relative}In which B is_{r_slotting}Air gap flux density with rotor slotted, B_{r_solid}Air gap flux density, Λ, for rotors being solid_{r_relative}The rotor relative permeance is defined.

Step 3, providing a rotor optimization model according to the relative magnetic conductance analysis of the rotor;

the different deviation angles of the magnetic barriers lead to different distribution of the relative magnetic conductance of the rotor, and the relation between the relative magnetic conductance harmonic wave of the rotor and the vibration noise of the motor is established. The reasonable offset angle not only ensures the electromagnetic performance, but also can weaken the vibration noise of the motor.

Fig. 3 is a schematic diagram of selecting an offset angle of a rotor magnetic barrier according to the present invention. The difference between the angle beta and the angle sigma affects the distribution of the relative permeance of the rotor. Finite element analysis selects 2, 4, 5 and 7 rotor relative flux guide harmonics as reduction targets, and in order to select a proper offset angle, multi-parameter optimization is adopted. There is a conflicting relationship between rotor relative permeance and torque ripple. Therefore, a comprehensive consideration is required for optimization. Finally, β and σ are chosen to be 25 ° and 1.5 °, respectively.

Step 4, according to the stator flux density cloud picture, a stator optimization model is provided, and an optimal motor model is determined;

the method comprises the steps of establishing a relation between flux density harmonic waves and motor vibration noise, analyzing a flux density cloud chart, and reducing the amplitude of radial force causing larger vibration by slotting a stator flux gap to further suppress the vibration noise. Analysis shows that an auxiliary groove with the length of 3mm and the width of 1mm is arranged in the magnetic flux gap at a position 0.5mm away from the air gap, and the auxiliary groove is helpful for reducing relevant radial force.

Fig. 4 is a structural view of an optimized motor finally determined in the present invention, 7 is an auxiliary groove, and 8 is a magnetic barrier offset. The novel asymmetric modular permanent magnet auxiliary synchronous reluctance motor consists of a modular stator and an asymmetric rotor, wherein the modular stator consists of a stator core, magnetic flux gaps and coils, and the stator core is uniformly divided into three parts by the magnetic flux gaps with different widths; the asymmetric rotor consists of a ferrite permanent magnet and three pairs of U-shaped magnetic barriers with different opening angles, each pair of magnetic barriers is two layers, the opening angle of the magnetic barrier positioned on the outer side is larger than the opening angle of the inner magnetic barrier, and the permanent magnet with different thicknesses is positioned in the center of the two layers of U-shaped magnetic barriers.

Step 5, checking and optimizing the performance of the motor;

step 5.1: checking and optimizing the electromagnetic performance and the mechanical stress of the motor;

as can be seen from the comparison graph of the output torques of the original motor and the optimized motor in the invention shown in FIG. 5, the torque performance of the motors is not sacrificed, the average torque is maintained at about 9.8Nm, the torque ripple is basically the same, and the electromagnetic performance is not sacrificed.

Fig. 6 and 7 are comparative graphs of relative magnetic permeability of rotors of the original motor and the optimized motor and harmonics thereof, and it can be seen from the graphs that relative magnetic permeability harmonics of rotors of 2 th, 4 th, 5 th and 7 th orders are reduced, fundamental waves are increased, and expected effects are achieved.

Step 5.2: and the finite element method completes the analysis of relevant modal parameters, considers the anisotropies of the stator material and the equivalent winding material and verifies the anisotropies through experimental tests.

The modal frequency, the damping and the vibration mode of the motor are measured by a vibration exciter method, the material parameters and the winding equivalent model are adjusted, and the finite element result is consistent with the experimental result as much as possible, so that the accuracy of the subsequent vibration noise analysis result is ensured.

Step 5.3: checking optimizes the vibration and noise of the motor.

FIGS. 8 and 9 are graphs comparing vibration acceleration and sound power level of the original motor and the optimized motor in the invention, and compared with the original motor, the vibration acceleration and sound power level of the optimized motor are obviously reduced, and the maximum value of the vibration acceleration is from 0.53m/s²Down to 0.35m/s²The reduction is 38.6%; the effective value of the sound power level is reduced from 32 db to 21 db by 34%. The optimized motor greatly improves the vibration and noise performance of the motor.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.