阅读说明：本技术 一种基于离散磁导模型的永磁电机拓扑构造方法 (Permanent magnet motor topology construction method based on discrete magnetic conductance model ) 是由 李大伟 房莉 任翔 曲荣海 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种基于离散磁导模型的永磁电机拓扑构造方法,属于永磁电机技术领域。本发明构造电机转矩与电机关键参数(永磁体结构参数、绕组结构参数和圆周分布的每个位置气隙长度)的目标函数,并提出具有理论指导意义的离散磁导模型,通过研究周向上每个位置上的磁导微元对转矩的贡献,得到最优的磁导分布取值方法,由此设计得到电机的调制单元和相应的绕组结构。理论上,设计的电机可以实现该外形尺寸约束下,工作磁场谐波的总转矩输出最大化,达到其转矩输出能力的理论上限。基于本发明方法构造得到的电机极大可能存在区别于常规电机的结构特征,从而实现电机结构的创新突破。(The invention discloses a permanent magnet motor topology construction method based on a discrete magnetic conductance model, and belongs to the technical field of permanent magnet motors. The invention constructs a target function of motor torque and motor key parameters (permanent magnet structure parameters, winding structure parameters and the length of an air gap at each position of circumferential distribution), provides a discrete magnetic conductance model with theoretical guiding significance, and obtains an optimal magnetic conductance distribution value-taking method by researching the contribution of magnetic conductance infinitesimal at each position in the circumferential direction to the torque, thereby designing and obtaining a modulation unit of the motor and a corresponding winding structure. Theoretically, the designed motor can realize the maximization of the total torque output of the working magnetic field harmonic under the constraint of the overall dimension, and the theoretical upper limit of the torque output capacity is reached. The motor constructed based on the method of the invention has structural characteristics different from the conventional motor, thereby realizing the innovative breakthrough of the motor structure.)

1. A permanent magnet motor topology construction method based on a discrete magnetic conductance model is characterized by comprising the following steps:

s1, constructing a fundamental wave no-load counter electromotive force E of a motor₁About each magnetically-conductive harmonic wave_mjAmplitude and phase of and an objective function f (E) of winding structure parameters₁,Λ_mj,θ_w,θ_so) (ii) a The winding structure parameter comprises a span theta_wAnd notch angle theta_so；

S2, constructing a discrete magnetic conductance model, and solving spatial magnetic conductance distribution which enables an objective function to be maximum through the discrete magnetic conductance model; the construction process of the discrete magnetic conductance model comprises the following steps:

at winding structure parameter theta_w,θ_soUnder the fixed premise, a fundamental wave no-load back electromotive force micro-element dE generated by the magnetic conductance micro-element at each position on the inner circumference of the air gap is established₁The value of magnetic conductance with the position is Λ_iObtaining a discrete magnetic conductance model according to the functional relation;

s3, aiming at different winding structure parameters theta_w,θ_soObtaining a plurality of target function maximum values and corresponding spatial magnetic conductance distributions through step S2, and selecting the spatial magnetic conductance distribution corresponding to the maximum one of the plurality of target function maximum values as an optimal spatial magnetic conductance distribution;

s4, constructing a corresponding modulation unit structure according to the optimal space magnetic conductance distribution;

and S5, integrating the winding structure corresponding to the maximum value of the plurality of target function maximum values in the step S3 and the modulation unit obtained in the step S4 into a stator side overall structure, and combining the stator with the rotor to form an optimal motor topology.

2. The permanent magnet motor topology construction method based on the discrete magnetic conductance model according to claim 1, wherein an initial phase θ of each sub magnetic conductance harmonic wave_mjSatisfy the requirement of

Wherein the content of the first and second substances,v is the pole pair number of the working magnetic density of the air gap, P_rIs the number of pole pairs, P, of the permanent magnet array_mjRepresenting air gap permeance harmonics a_mjThe pole pair number of (g), (v) is the air gap flux density B_gvCounter-clockwise is the positive direction of rotation, sgn is + 1; clockwise negative direction of rotation, sgn-1, theta_svThe initial phase of the armature harmonic with a pole pair number v is shown.

3. The permanent magnet motor topology construction method based on the discrete magnetic conductance model according to claim 2, wherein the objective function f (E)₁,Λ_mj,θ_w,θ_so) Comprises the following steps:

K_e＝D_gLN_sω_m

D_gthe diameter is corresponding to the motor air gap; l is the effective axial length of the motor; n is a radical of_sFor the phase windings connected in series with turns, F_m1Representing the fundamental magnetomotive force, k, generated by the permanent magnet rotor_wvRepresenting the winding coefficient, spanned by the coil_wWidth of slot theta_soDetermination of Λ_0(mj)Represents a number of pole pairs of P_mjThe amplitude of the flux-guide of the air gap,ω_mis the mechanical angular velocity of rotation of the rotor, t is the time, θ_r1The initial phase of the permanent magnet fundamental excitation magnetic potential is obtained.

4. The method according to claim 3, wherein in step S2, the discrete flux guide model is used to solve the spatial flux guide distribution that maximizes the objective function, specifically, a sum of contributions of each sub-flux guide harmonic of the flux guide infinitesimal at each point in the circumferential direction to the fundamental back-emf is obtained according to the discrete flux guide model; when the sum of the contribution values is a positive value, the point magnetic conductance is assigned to a maximum value; when the sum of the contributions is negative, the point permeance is assigned a minimum value.

5. The permanent magnet motor topology construction method based on the discrete magnetic conductance model according to claim 4, wherein in step S4, the modulation unit structure corresponding to the maximum value of the magnetic conductance is a tooth, and the parameter is represented by that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is the length of the air gap; the modulation unit structure corresponding to the minimum value of the magnetic conductance is a groove, and the parameter shows that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is larger than the length of the air gap.

6. The discrete flux guide model-based permanent magnet motor topology construction method according to claim 5, wherein the slot structure of the modulation unit is parametrically embodied such that a distance between an inner edge of the modulation unit and an outer edge of the permanent magnet is greater than 7-10 times of a length of the air gap.

7. A permanent-magnet machine, characterized in that the modulation units and the winding structure that constitute the stator structure in the permanent-magnet machine are formed by the construction method according to any of claims 1-6.

8. The permanent magnet motor according to claim 7, wherein said modulation unit has different modulation tooth shapes and non-uniform slot size distribution.

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a permanent magnet motor topology construction method based on a discrete magnetic conductance model.

Background

Since the first motor of the 19 th century appeared, the motor has become an industrial door which supports the inexhaustible and scarce modern society of human beings. The motor is widely applied to various aspects of national economy from a large water wheel generator with single machine capacity of thousands of megawatts to a small special motor with a small capacity of a few microwatts. Industrial robots, chip manufacturing, numerical control machines and the like are key breakthrough fields. The motor is used as a wide and key basic part and plays a key role in improving the overall level of equipment manufacturing industry, and meanwhile, the rapid development of the manufacturing industry also puts higher requirements on the performance quality of the motor, such as torque density, response speed, torque pulsation and the like. Among them, high torque density has been a major objective of motor development, and has important significance in reducing motor volume, cost, increasing response speed, and the like.

The conventional permanent magnet motor generally relies on a single working magnetic field to realize the generation of torque, and the increase of the torque density is limited by material performance and a cooling mode. The vernier permanent magnet motor has a similar structure to a conventional permanent magnet motor, but based on a magnetic field modulation principle, two working magnetic fields are utilized to convert electromechanical energy to generate torque, so that higher torque density is obtained. However, when a conventional permanent magnet motor and a vernier permanent magnet motor are designed at present, structures of a permanent magnet rotor, a stator, an armature winding and the like in the motor are always limited in a traditional topological structure frame, no theoretical method exists how to solve the upper limit of torque density, the upper limit is solved through repeated optimization of structural parameters, the design process is irregular, and strong contingency exists. Therefore, it is difficult to achieve the innovation of the motor topology and the improvement of the torque density.

Disclosure of Invention

Aiming at the defects or the improvement requirements of the prior art, the invention provides a permanent magnet motor topological structure method based on a discrete magnetic conductance model, and aims to break through the traditional permanent magnet motor topological structure framework to design a permanent magnet motor structure so as to realize the maximization of torque output capacity.

In order to achieve the above object, according to an aspect of the present invention, there is provided a method for constructing a topology of a permanent magnet motor based on a discrete flux guide model, including:

s1, constructing a fundamental wave no-load counter electromotive force E of a motor₁About each magnetically-conductive harmonic wave_mjAnd the amplitude and phase of (d) and an objective function f (E) of the winding structure parameters₁,Λ_mj,θ_w,θ_so) (ii) a The winding structure parameter comprises a span theta_wAnd notch angle theta_so；

S2, constructing a discrete magnetic conductance model, and solving spatial magnetic conductance distribution with a maximum objective function through the discrete magnetic conductance model; the construction process of the discrete magnetic conductance model comprises the following steps:

at winding structure parameter theta_w,θ_soUnder the fixed premise, a fundamental wave no-load back electromotive force micro-element dE generated by the magnetic conductance micro-element at each position on the inner circumference of the air gap is established₁The value of magnetic conductance with the position is Λ_iObtaining a discrete magnetic conductance model according to the function relation of the magnetic conductance sensor;

s3, aiming at different winding structure parameters theta_w,θ_soObtaining a plurality of target function maximum values and corresponding spatial magnetic conductance distributions through step S2, and selecting the spatial magnetic conductance distribution corresponding to the maximum of the plurality of target function maximum values as an optimal spatial magnetic conductance distribution;

s4, constructing a corresponding modulation unit structure according to the optimal space magnetic conductance distribution;

and S5, integrating the winding structure corresponding to the maximum value of the plurality of target function maximum values in the step S3 and the modulation unit obtained in the step S4 into a stator side overall structure, and combining the stator with the rotor to form an optimal motor topology.

Further, the initial phase θ of each sub-magnetic conduction harmonic_mjSatisfy the requirement of

Wherein the content of the first and second substances,v is qiPole pair number of gap working flux density, P_rIs the number of pole pairs, P, of the permanent magnet array_mjRepresenting air gap permeance harmonics a_mjThe pole pair number of (g), sgn (v) is the air gap magnetic field B_gvCounter-clockwise is the positive direction of rotation, sgn is + 1; clockwise negative direction of rotation, sgn-1, theta_svThe initial phase of the armature harmonic with a pole pair number v is shown.

Further, the objective function f (E)₁,Λ_mj,θ_w,θ_so) Comprises the following steps:

K_e＝D_gLN_sω_m

D_gthe diameter is corresponding to the motor air gap; l is the effective axial length of the motor; n is a radical of_sFor the phase windings connected in series with turns, F_m1Representing the fundamental magnetomotive force, k, generated by the permanent magnet rotor_wvRepresenting the winding coefficient, spanned by the coil_wWidth of slot theta_soDetermination of Λ_0(mj)Represents a number of pole pairs of P_mjAmplitude of the permeance of the air gap, omega_mIs the mechanical angular velocity of rotation of the rotor, t is the time, θ_r1The initial phase of the permanent magnet fundamental excitation magnetic potential is obtained.

Further, in step S2, the discrete magnetic permeability model is used to solve the spatial magnetic permeability distribution that maximizes the objective function, specifically, the sum of the contribution values of each sub-magnetic permeability harmonic of the magnetic permeability infinitesimal at each point in the circumferential direction to the fundamental back electromotive force is obtained according to the discrete magnetic permeability model; when the sum of the contribution values is a positive value, the point magnetic conductance is assigned with a maximum value; when the sum of the contributions is negative, the point permeance is assigned a minimum value.

Further, in step S4, the modulation unit corresponding to the maximum value of the magnetic conductance is a tooth, and the parameter represents that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is the length of the air gap; the modulation unit structure corresponding to the minimum value of magnetic conductance is a slot, and the parameter shows that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is larger than the length of an air gap.

Furthermore, the slot structure of the modulation unit is parametrically embodied that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is 7-10 times larger than the length of the air gap.

According to another aspect of the present invention, there is provided a permanent magnet motor in which modulation units and winding structures constituting a stator structure are formed by the above-described construction method.

Furthermore, the modulating tooth shapes of the modulating units are different, and the sizes of the grooves are not uniformly distributed.

In general, the above technical solutions contemplated by the present invention can achieve the following advantageous effects compared to the prior art.

(1) The invention constructs a target function of motor torque and motor key parameters (permanent magnet structure parameters, winding structure parameters and the length of an air gap at each position of circumferential distribution), provides a discrete magnetic conductance model with theoretical guidance meaning, and obtains an optimal magnetic conductance distribution value-taking method by researching the contribution of magnetic conductance infinitesimal at each position in the circumferential direction to the torque, thereby designing and obtaining a modulation unit and a corresponding winding structure of the motor. Theoretically, the designed motor can realize the maximization of the total torque output of the working magnetic field harmonic under the constraint of the overall dimension, and the theoretical upper limit of the torque output capacity is reached.

(2) The motor constructed based on the method is an inverted product taking torque performance requirements as guidance, magnetic conductance harmonic waves as intermediate variables and a discrete magnetic conductance model as a theoretical basis, and has no any existing motor structure as reference, so that structural characteristics different from that of a conventional motor are greatly possible, and innovative breakthrough of the motor structure is realized.

Drawings

FIG. 1 is a flowchart of a permanent magnet motor topology construction method based on a discrete magnetic conductance model according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a modulation unit structure construction method based on a discrete magnetic conductance model;

FIG. 3 is a schematic diagram of a modulation unit constructed in an embodiment of the present invention;

fig. 4 is a schematic view of the overall structure of a stator in a permanent magnet motor of an oriented structure according to an embodiment of the present invention;

fig. 5 is a schematic view of the overall structure of the permanent magnet motor in the oriented configuration according to the embodiment of the present invention.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

1 is a modulation unit, 2 is a winding, 3 is a stator, 4 is a rotor, 5 is a permanent magnet array, and 6 is a rotating shaft.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention aims to directly construct an objective function of torque related to key structural parameters of a motor; and then solving the spatial magnetic permeability distribution which enables the objective function to be maximum through a discrete magnetic permeability model, and finally obtaining the corresponding modulation tooth structure and the corresponding winding structure. The construction method provided by the invention is expected to solve the bottleneck that the permanent magnet motor in the prior art is highly dependent on the existing motor structure, the topological innovation of the motor is difficult to realize, and the torque density is improved.

In order to achieve the purpose, the invention provides a permanent magnet motor topology construction method based on a discrete magnetic conductance model, which has the innovation points that: fundamental wave no-load counter electromotive force E of structured motor₁About each magnetically-conductive harmonic wave_vAmplitude and phase of (1) and winding structure parameters (span θ)_wAnd notch angle theta_so) Is the objective function f (E)₁, Λ_v,θ_w,θ_so). Firstly, at the winding structure parameter theta_w,θ_soUnder the fixed premise, a fundamental wave no-load counter-potential infinitesimal dE generated by the magnetic conductance infinitesimal at each position in the air gap in the circumferential direction is established₁The value of magnetic conductance with the position is Λ_iFunctional relationship f (dE)₁,Λ_i) Which satisfies:

next, f (dE) is analyzed₁,Λ_i) The function characteristic of the magnetic field is obtained, the solving method of the maximum value of the function is obtained, the value law of the optimal magnetic conductance value of any space position is further obtained, and finally the objective function f (E) can be obtained₁,Λ_v) Maximum optimal spatial permeance distribution; and finally, obtaining the specific structure of the modulation unit corresponding to the optimal magnetic conductance function according to the corresponding relation between the magnetic conductance value and the structure parameter of the modulation unit.

For different winding structure parameters theta_w,θ_so，f(E₁,Λ_v,θ_w,θ_so) The optimal values of (A) can be obtained according to the method, and the maximum f (E)₁,Λ_v,θ_w,θ_so) The modulation unit and the winding structure corresponding to the value are the optimal motor structure under the constraint of the overall dimension.

Fig. 1 is a flowchart of a permanent magnet motor topology construction method based on a discrete magnetic conductance model in an embodiment of the present invention, and fig. 2 is a schematic diagram of a modulation unit structure construction method based on a discrete magnetic conductance model. With reference to fig. 1 and 2, a topology construction method of a permanent magnet motor in the present embodiment is described in detail. The method includes steps S1-S4.

Before step S1 is executed, it is necessary to clarify the no-load fundamental back electromotive force E₁The reason for this is the following relationship with the average output torque T:

the output torque contains two components, electromagnetic torque and reluctance torque, but in permanent magnet machines, the electromagnetic torque tends to contribute>90% of the average torque, thus achieving maximization of the electromagnetic torque, and then the maximization of the total output torque can be achieved through adjustment of the later torque angle. According to the principle of electromechanical energy conversion, the electromagnetic torque can be calculated by (2), namely no-load fundamental wave back electromotive force E₁The output capability of the average torque can be directly reflected, and the maximum average torque means the maximum E₁Therefore, subsequent analysis of the invention is performed in E₁Maximum E was obtained for the study subject₁To design goals; furthermore, E₁Is represented by the working magnetic field of the air gap, through E₁The output torque can be correlated with the air gap field to make a cushion for subsequent analytical design.

Omega denotes the mechanical rotor speed, I_mRepresenting phase current magnitude;

step S1, according to the air gap flux density B_gExpression (3) of (a) and no-load fundamental wave back electromotive force E₁With respect to B_gThe analytical expression (4) shows that the initial phase of each magnetic conductance harmonic must satisfy (5), i.e., E in the expression (4), in order to achieve the design object₁When the amplitude is maximum, the phase of each sub-magnetic conductance harmonic is determined by equation (5). The specific reason is as follows: air gap field B_gv＝Pr(the number of pole pairs is P_rIs also called air-gap magnetic field fundamental wave) is determined, so the initial phase of the counter electromotive force generated by the air-gap magnetic field fundamental wave can be expressed as theta_r1-θ_sv＝PrThen the initial phase of the fundamental back-emf harmonics generated by the other air-gap field harmonics should also be such that theoretically the total fundamental back-emf E can be made₁The amplitude of (a) is maximum.

Wherein, F₁Is the permanent magnet fundamental magnetic potential, P_rIs the number of pole pairs, omega, of the permanent magnet array_mFor mechanical rotational angular velocity of rotors, Λ₀Is a constant component of the permeance function of the air gap, theta is the spatial mechanical angular position, theta_r1For the initial phase of the fundamental excitation potential of the permanent magnet, Λ_mjIs a magnetically conductive harmonic component with a number of pole pairs j, theta_mjIs Λ_mjThe initial phase of (a).

Wherein D is_gThe diameter is corresponding to the motor air gap; l is the effective axial length of the motor; n is a radical of_sThe number of turns of the phase winding is in series connection; v is the pole pair number of the working magnetic density of the air gap; k is a radical of_wvDenotes the winding factor, B_gvThe pole pair number is the air gap flux density of v; sgn (v) is the air gap flux density B_gvThe direction of rotation of (counter clockwise is positive direction of rotation, sgn is + 1; clockwise is negative direction of rotation, sgn is-1); theta_svThe initial phase of the armature field harmonic is shown as the pole pair number v.

It can be seen that the initial phase of the magnetic conduction harmonic is the initial phase theta of the permanent magnet fundamental excitation magnetic potential_r1Harmonic phase theta of sum winding_svAnd (4) jointly determining. The initial phase of the fundamental wave magnetic potential is generally determined, but the phase of the winding harmonic is changed along with the change of the winding structure parameters, so that the initial phase of the magnetic conductance harmonic is a variable related to the winding structure parameters.

Operation S2, based on the analysis in S1, fundamental unloaded back emf E₁Can be further expressed as a function (6) related to the critical structural parameters of the motor.

Wherein, F_m1Expressing the fundamental magnetomotive force generated by the permanent magnet rotor, determined by the permanent magnet pole arc coefficient and the magnet steel thickness, k_wvRepresenting the harmonic coefficient, k, of the winding with a number of pole pairs v_wv＝PrThen the number of pole pairs v is represented as P_rWinding harmonic coefficient of (2), winding coefficient k_wvFrom winding construction parameters (coil span θ)_wWidth of slot theta_so) Determination of Λ_0(mj)Represents a constant term (the number of pole pairs is P)_mj(j≠0)) The amplitude of the air gap permeance is determined by the modulation unit structure, and t is time. Wherein, the thickness and the pole arc coefficient of the magnetic steel of the permanent magnet can be optimized to obtain the optimal value in the initial stage, so F_m1Which may be considered constant in subsequent designs.

It can be seen that (6) is actually E₁Target function f (E, Lambda, theta) of magnetic conductance harmonic wave and winding structure parameter_w,θ_so). Therefore, the design objective is equivalent to solving for the maximum of (6), and the permeance harmonic distribution and winding structure parameters that maximize (6).

Before step S3, a certain constraint needs to be set on the winding structure, specifically, teeth with a certain width must be provided on both sides of the notch of the slot where the two sides of the winding coil are located, so as to fix the winding structure and ensure that the winding structure does not change in the subsequent design operation.

Step S3 is to establish the total fundamental wave back electromotive force amplitude E in the objective function (6) in the case where the winding structure parameter is determined to be a certain value₁Can be further expressed as amplitude Λ with respect to the magnetically permeable harmonic_mjThe objective function of (2):

in order to solve the permeance distribution which enables (7) to be maximum, a discrete permeance model is provided, and the basic idea is as follows: and independently researching the maximum optimal value of the target function (7) under the size constraint of the magnetic conductance infinitesimal of each point in the circumferential direction, and combining the optimal magnetic conductance values of each point into a final optimal magnetic conductance function. The specific steps are shown in fig. 2: firstly, in the circumferential direction, the magnetic conductance in an infinite small neighborhood of a certain point on the air gap side opposite to the rotor is assumed to be nonzero, and the magnetic conductance at other positions is zero, so that mutual interference is avoided; next, each sub-flux of the flux guide infinitesimal is calculated based on the characteristics of the flux guide harmonic pole pair number, phase and the like calculated in S1 and the objective function (7)Counter potential E of harmonic pair fundamental wave₁And the sum of the fundamental back-emf contributions of all the magnetically permeable harmonics at that point, as shown in equations (9) and (10), respectively:

as can be seen from the equation (10), the back electromotive force amplitude of the fundamental wave contributed by the permeance harmonic wave at each point is actually linear with the permeance amplitude of the point, and the positive and negative values thereof depend onPositive and negative. If the equation is positive, the flux guide has any mechanical angle theta in the circumferential direction_iAmplitude of (a)_i) The maximum value under the size constraint should be taken so that the total back electromotive force of all the magnetic conduction harmonic contributions at the point is maximum; if the equation is negative, the permeance is at θ_iThe amplitude Λ (θ) at that point_i) The minimum value under the size constraint should be taken so that the total negative back-emf of all the magnetically conducted harmonic contributions at that point is minimized.

According to the method, the optimal value of the magnetic conductance of each point in the circumferential direction can be calculated to achieve the goal of maximum back electromotive force of the total fundamental wave, and then the optimal values of the magnetic conductance of each point are combined together to obtain the optimal magnetic conductance function which enables the maximum magnetic conductance of the step (7).

In addition, a clear corresponding relation exists between the optimal magnetic conductance value and the modulation unit structure, namely the tooth structure of the corresponding modulation unit when the magnetic conductance is maximum, and the parameter is represented as that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is the length of an air gap; the slot structure of the corresponding modulation unit when the magnetic conductance is the minimum value is shown in the parameter that the distance between the inner edge of the modulation unit and the outer edge of the permanent magnet is larger than the length of the air gap, the larger the gap is, the better the gap is theoretically, but the infinite gap cannot be selected in consideration of the structural limit and the space limit of the slot where the winding is located, and the air gap length is generally 7-10 times. Therefore, the corresponding optimal modulation unit structure can be constructed according to the optimal magnetic conductance function obtained by calculation.

Step S4 is to execute step S3 under different winding structure. For the structural parameter theta_wAnd theta_soAnd designing a corresponding optimal modulation unit structure for each winding in the value range. The combination of structures that maximizes the objective function (6) among all the winding-modulation units is selected. And finally, integrating into a stator side integral structure according to the characteristics of the modulation unit and the winding structure, and combining with a rotor to obtain a final motor structure. Theoretically, the motor can generate the maximum fundamental wave no-load back electromotive force under the constraint of the outer diameter size, namely the theoretical upper limit of the average torque.

According to the design method provided by the invention, various motor structures can be designed, and an inner rotor permanent magnet motor with the number of pole pairs of 10 and the outer diameter of 124mm is selected as a design case. The structure of the motor is shown in fig. 3-5. Fig. 3 shows a modulation unit 1 designed based on the discrete flux guide model method, which has different shapes (with rectangular teeth and trapezoidal teeth) and non-uniform distribution (the sizes of the grooves are not all the same, and have different sizes); fig. 4 is an integrated structure of the winding 2 structure and the modulation unit 1 after simultaneously considering the structural features of the two: the winding is a concentrated winding structure, and the notches of the two side coils of the winding are corresponding to the smallest slot in the modulation unit. The teeth of the modulation unit across which the coil is wound are grouped under a wide stator tooth, and the teeth of the modulation unit between the two sides of the coil (the coil is wound around the stator tooth, namely, the coil penetrates into the slot on one side of the stator tooth and penetrates out of the slot on the other side of the stator tooth, so that the two sides of the coil refer to the coil parts in the slots on the two sides) are grouped under a narrow stator tooth. The rotor can be of a surface-mounted or built-in permanent magnet rotor structure.

It can be seen that the structure of the motor stator 3 shown in fig. 4 is greatly different from the common stator tooth structure or split tooth structure which is uniformly distributed, and the special motor structure further embodies two benefits of the invention, thereby not only improving the torque output capability of the motor, but also realizing the structural innovation of the motor.

Further, the structure of the permanent magnet motor formed by nesting the stator 3, the rotor 4 (surface-mounted or built-in structure and the like) and the permanent magnet array 5 with the rotating shaft 6 is shown in fig. 5.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.