阅读说明：本技术 电机转矩电流的优化方法及表贴式永磁电机 (motor torque current optimization method and surface-mounted permanent magnet motor ) 是由 莫为 于 2019-09-25 设计创作，主要内容包括：本发明公开一种电机转矩电流的优化方法及表贴式永磁电机,该电机转矩电流的优化方法包括：选用分数槽集中绕组的表贴式永磁电机,并利用Maxwell软件建立分数槽集中绕组永磁电机的齿槽转矩仿真模型；对表贴式永磁电机的极数和槽数进行优化,获得电机槽极比的优化结果；根据电机槽极比的优化结果对表贴式永磁电机中定子齿的宽度及铁芯轭部的厚度进行优化,获得第一优化结果；根据第一优化结果,对表贴式永磁电机中机械极弧系数进行优化,获得第二优化结果；将第一优化结果和第二优化结果输入至分数槽集中绕组永磁电机齿槽转矩仿真模型,确定永磁电机的机械结构。本发明技术方案提高了表贴式永磁电机转矩电流的线性度。(The invention discloses a motor torque current optimization method and a surface-mounted permanent magnet motor, wherein the motor torque current optimization method comprises the following steps: selecting a surface-mounted permanent magnet motor of the fractional-slot concentrated winding, and establishing a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor by using Maxwell software; optimizing the pole number and the slot number of the surface-mounted permanent magnet motor to obtain an optimization result of the motor slot pole ratio; optimizing the width of stator teeth and the thickness of an iron core yoke part in the surface-mounted permanent magnet motor according to the optimization result of the slot pole ratio of the motor to obtain a first optimization result; optimizing the mechanical pole arc coefficient in the surface-mounted permanent magnet motor according to the first optimization result to obtain a second optimization result; and inputting the first optimization result and the second optimization result into a fractional slot concentrated winding permanent magnet motor cogging torque simulation model to determine the mechanical structure of the permanent magnet motor. The technical scheme of the invention improves the linearity of the torque current of the surface-mounted permanent magnet motor.)

1. a method for optimizing a torque current of a motor, the method comprising:

Selecting a surface-mounted permanent magnet motor of the fractional-slot concentrated winding, and establishing a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor by using Maxwell software;

Optimizing the pole number and the slot number of the surface-mounted permanent magnet motor to obtain an optimization result of the motor slot pole ratio;

Optimizing the width of stator teeth and the thickness of an iron core yoke part in the surface-mounted permanent magnet motor according to the optimization result of the motor slot pole ratio to obtain a first optimization result;

Optimizing the mechanical pole arc coefficient in the surface-mounted permanent magnet motor according to the first optimization result to obtain a second optimization result;

and inputting the first optimization result and the second optimization result into the fractional slot concentrated winding permanent magnet motor cogging torque simulation model, and determining the mechanical structure of the permanent magnet motor.

2. The method for optimizing torque and current of a motor according to claim 1, wherein the step of optimizing the widths of the stator teeth and the thicknesses of the yoke parts of the iron cores in the surface-mounted permanent magnet motor according to the optimization result of the slot pole ratio of the motor to obtain a first optimization result comprises:

keeping the no-load air gap flux density of the surface-mounted permanent magnet motor consistent, and reducing the flux per pole of the surface-mounted permanent magnet motor;

According to the reduction of the magnetic flux per pole of the surface-mounted permanent magnet motor, the thickness of a yoke part of a stator core of the surface-mounted permanent magnet motor is reduced, and the width of a stator tooth of the surface-mounted permanent magnet motor is increased;

and analyzing a plurality of parameters in the cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor to obtain the first optimization result.

3. The method for optimizing motor torque current according to claim 2, wherein the step of analyzing a plurality of parameters in a fractional-slot concentrated winding permanent magnet motor cogging torque simulation model to obtain the first optimization result comprises:

analyzing a plurality of parameters in a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor; wherein the plurality of parameters include cogging torque, no-load air gap flux density, and temperature rise;

and taking the scheme that the permanent magnet motor of which the temperature rise does not exceed the highest temperature bearing temperature of the cogging torque simulation model of the fractional slot concentrated winding permanent magnet motor as the first optimization result.

4. The method of claim 3, wherein the permanent magnet machine is a neodymium-iron-boron permanent magnet.

5. a method for optimizing torque current for an electric motor as claimed in claim 3 wherein said permanent magnet motor is subjected to a maximum temperature in the range of 140 ℃ to 160 ℃.

6. The method for optimizing the torque and current of the motor according to claim 1, wherein the step of optimizing the mechanical pole arc coefficient in the surface-mount permanent magnet motor according to the first optimization result to obtain a second optimization result comprises:

determining the axial size of a rotor of the surface-mounted permanent magnet motor, and keeping the axial size consistent with the axial length of the surface-mounted permanent magnet motor;

And increasing the mechanical pole arc coefficient of the surface-mounted permanent magnet motor, weakening the cogging torque of the surface-mounted permanent magnet motor, and obtaining the second optimization result.

7. the method of claim 6, wherein the rotor axial dimension of the surface-mount permanent magnet machine comprises: axial length, pole width, and radial thickness;

When the mechanical pole arc coefficient of the surface-mounted permanent magnet motor is increased, the width of the magnetic pole is increased, and the effective magnetic flux of the surface-mounted permanent magnet motor is increased;

when the magnetic potential of the permanent magnet of the surface-mounted permanent magnet motor is increased, the radial thickness is increased.

8. the method for optimizing torque current of an electric motor according to claim 7, wherein when the magnetic potential of the permanent magnet of the surface-mount permanent magnet electric motor increases, the step of increasing the radial thickness comprises:

When the radial thicknesses of the surface-mounted permanent magnet motors are not consistent, the relationship between the armature magnetomotive force of the surface-mounted permanent magnet motors and the permanent magnet magnetomotive force is a formula: nimax is less than or equal to alpha H' chmin, wherein N is the number of single coil turns of the surface-mounted permanent magnet motor, imax is the maximum current of the surface-mounted permanent magnet motor, alpha is a process parameter of the surface-mounted permanent magnet motor, hm is the maximum thickness of a permanent magnet of the surface-mounted permanent magnet motor, hmin is the minimum thickness of the permanent magnet of the surface-mounted permanent magnet motor, R is the excircle radius of the permanent magnet of the surface-mounted permanent magnet motor, R1 is the inner circle radius of the permanent magnet of the surface-mounted permanent magnet motor, and bm is the actual width corresponding to the mechanical pole arc coefficient of the permanent magnet of the surface-mounted permanent magnet motor.

9. the method for optimizing torque and current of an electric motor according to claim 8, wherein the process parameter α of the surface-mounted permanent magnet motor is in a range of 0.7 to 0.97.

10. A surface-mounted permanent magnet electric machine, characterized in that it comprises a method for optimizing the torque current of an electric machine according to any one of claims 1 to 9.

Technical Field

the invention relates to the technical field of motors, in particular to a motor torque current optimization method and a surface-mounted permanent magnet motor.

Background

With the development of permanent magnet motors, servo motors for providing power for various robots and high-end industrial intelligent equipment are one of core functional components, and high-performance permanent magnet brushless torque servo motors are one of typical representatives. In the permanent magnet brushless torque servo motor, the rotating speed, the torque and the production cost are closely related to the number of poles, the cogging torque in the permanent magnet brushless torque servo motor can directly influence the running performance of a generator, and meanwhile, the torque and the power density are small, so that the torque current linearity is low.

Disclosure of Invention

The invention mainly aims to provide a motor torque current optimization method and a surface-mounted permanent magnet motor, aiming at improving the linearity of the torque current of the surface-mounted permanent magnet motor.

in order to achieve the purpose, the method for optimizing the torque current of the motor comprises the steps of selecting a surface-mounted permanent magnet motor with a fractional-slot concentrated winding, and establishing a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor by using Maxwell software;

Optimizing the pole number and the slot number of the surface-mounted permanent magnet motor to obtain an optimization result of the motor slot pole ratio;

optimizing the width of stator teeth and the thickness of an iron core yoke part in the surface-mounted permanent magnet motor according to the optimization result of the motor slot pole ratio to obtain a first optimization result;

Optimizing the mechanical pole arc coefficient in the surface-mounted permanent magnet motor according to the first optimization result to obtain a second optimization result;

and inputting the first optimization result and the second optimization result into the fractional slot concentrated winding permanent magnet motor cogging torque simulation model, and determining the mechanical structure of the permanent magnet motor.

Optionally, the step of optimizing the width of the stator teeth and the thickness of the core yoke in the surface-mounted permanent magnet motor according to the optimization result of the slot pole ratio of the motor to obtain a first optimization result includes:

Keeping the no-load air gap flux density of the surface-mounted permanent magnet motor consistent, and reducing the flux per pole of the surface-mounted permanent magnet motor;

According to the reduction of the magnetic flux per pole of the surface-mounted permanent magnet motor, the thickness of a yoke part of a stator core of the surface-mounted permanent magnet motor is reduced, and the width of a stator tooth of the surface-mounted permanent magnet motor is increased;

And analyzing a plurality of parameters in the cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor to obtain the first optimization result.

Optionally, the analyzing a plurality of parameters in a cogging torque simulation model of a fractional-slot concentrated winding permanent magnet motor, and the obtaining the first optimization result includes:

Analyzing a plurality of parameters in a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor; wherein the plurality of parameters include cogging torque, no-load air gap flux density, and temperature rise;

and taking the scheme that the permanent magnet motor of which the temperature rise does not exceed the highest temperature bearing temperature of the cogging torque simulation model of the fractional slot concentrated winding permanent magnet motor as the first optimization result.

optionally, the permanent magnet motor is a neodymium iron boron permanent magnet.

optionally, the maximum temperature to which the permanent magnet machine is subjected is in the range of 140 ℃ to 160 ℃.

optionally, the step of optimizing a mechanical pole arc coefficient in the surface-mount permanent magnet motor according to the first optimization result to obtain a second optimization result includes:

Determining the axial size of a rotor of the surface-mounted permanent magnet motor, and keeping the axial size consistent with the axial length of the surface-mounted permanent magnet motor;

and increasing the mechanical pole arc coefficient of the surface-mounted permanent magnet motor, weakening the cogging torque of the surface-mounted permanent magnet motor, and obtaining the second optimization result.

Optionally, the axial dimension of the rotor of the surface-mounted permanent magnet motor includes: axial length, pole width, and radial thickness;

When the mechanical pole arc coefficient of the surface-mounted permanent magnet motor is increased, the width of the magnetic pole is increased, and the effective magnetic flux of the surface-mounted permanent magnet motor is increased;

when the magnetic potential of the permanent magnet of the surface-mounted permanent magnet motor is increased, the radial thickness is increased.

Optionally, when the magnetic potential of the permanent magnet of the surface-mount permanent magnet motor increases, the step of increasing the radial thickness includes:

when the radial thicknesses of the surface-mounted permanent magnet motors are not consistent, the relationship between the armature magnetomotive force of the surface-mounted permanent magnet motors and the permanent magnet magnetomotive force is a formula: nimax is less than or equal to alpha Hc' hmin, wherein N is the number of single coil turns of the surface-mounted permanent magnet motor, imax is the maximum current of the surface-mounted permanent magnet motor, alpha is a process parameter of the surface-mounted permanent magnet motor, hm is the maximum thickness of a permanent magnet of the surface-mounted permanent magnet motor, hmin is the minimum thickness of the permanent magnet of the surface-mounted permanent magnet motor, R is the excircle radius of the permanent magnet of the surface-mounted permanent magnet motor, R1 is the inner circle radius of the permanent magnet of the surface-mounted permanent magnet motor, and bm is the actual width corresponding to the mechanical pole arc coefficient of the permanent magnet of the surface-mounted permanent magnet motor.

optionally, the numerical range of the process parameter α of the surface-mounted permanent magnet motor is 0.7-0.97.

The invention also provides a surface-mounted permanent magnet motor, which comprises the method for optimizing the torque current of the motor.

According to the technical scheme, the surface-mounted permanent magnet motor with the fractional slot concentrated winding is selected, a tooth space torque simulation model of the fractional slot concentrated winding permanent magnet motor is established by using Maxwell software, and parameters related in the tooth space torque simulation model are optimized to obtain a motor mechanical structure for reducing the motor torque current linearity. Further, after a cogging torque simulation model of the permanent magnet motor is established, the pole number and the slot number of the surface-mounted permanent magnet motor are optimized to obtain an optimized permanent magnet motor slot pole ratio; according to the optimization result of the slot pole ratio of the motor, the width of the stator teeth and the thickness of the iron core yoke part in the motor are optimized, so that high magnetic density saturation of the permanent magnet motor during overload can not be easily caused, and the requirement of better torque current linearity of the permanent magnet motor is met. Meanwhile, the mechanical pole arc coefficient of the surface-mounted permanent magnet motor is optimized so as to pass through the optimized effective magnetic flux of the permanent magnet motor. The optimized result of the width of the stator teeth, the thickness of the iron core yoke part and the mechanical pole arc coefficient is input into a fractional slot concentrated winding permanent magnet motor tooth space torque simulation model to obtain the optimized mechanical structure of the permanent magnet motor, namely the optimized mechanical structure of the permanent magnet motor with the number of poles of the fractional slot concentrated winding larger than the number of slots. The optimized mechanical structure of the permanent magnet motor improves the torque current linearity of the surface-mounted permanent magnet motor.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic flow chart illustrating an embodiment of a method for optimizing motor torque current according to the present invention;

Fig. 2 is a schematic structural diagram of an embodiment of a surface-mounted permanent magnet motor magnetic pole in the method for optimizing the torque current of the motor of the present invention.

The reference numbers illustrate:

the implementation, functional features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides a method for optimizing motor torque current, which is applied to a surface-mounted permanent magnet motor. The method comprises the following steps according to the position of the permanent magnet magnetic pole of the rotor of the permanent magnet motor on the rotor: surface mount, in-cell, and claw pole types. The surface-mounted rotor structure is simple in manufacturing process, low in cost and wide in application, for the high-speed permanent magnet motor, some motor rotors adopt the surface-mounted motor rotors, the motor rotors generally comprise sheaths, permanent magnets, iron cores, rotating shafts and end plates, the iron cores are sleeved on the rotating shafts, the permanent magnets are located on the outer sides of the iron cores, the sheaths are located on the radial outer sides of the permanent magnets and wrap the permanent magnets, and the end plates are located on the two axial sides of the permanent magnets, so that eddy current loss can be reduced, and the strength of the sheaths.

in an embodiment of the present invention, as shown in fig. 1, the method for optimizing the torque current of the motor includes:

S100, selecting a surface-mounted permanent magnet motor of the fractional-slot concentrated winding, and establishing a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor by using Maxwell software;

s200, optimizing the pole number and the slot number of the surface-mounted permanent magnet motor to obtain an optimization result of the motor slot pole ratio;

Step S300, optimizing the width of the stator teeth and the thickness of the iron core yoke part in the surface-mounted permanent magnet motor according to the optimization result of the motor slot pole ratio to obtain a first optimization result;

s400, optimizing a mechanical pole arc coefficient in the surface-mounted permanent magnet motor according to the first optimization result to obtain a second optimization result;

and S500, inputting the first optimization result and the second optimization result into a fractional slot concentrated winding permanent magnet motor cogging torque simulation model, and determining a mechanical structure of the permanent magnet motor.

In this embodiment, the permanent magnet motor includes stator and rotor, be equipped with a plurality of teeth on the stator, constitute the groove between the adjacent tooth, be equipped with a plurality of pairs of magnetic shoes on the rotor, the number of poles of permanent magnet in the magneto is for short the pole, and the number of poles is the number of magnetic shoes, and N in a magnetic shoe and S calculate two poles. It can be understood that the existing permanent magnet motor is composed of a preset number of unit motors, each unit motor is composed of a preset number of teeth, slots and magnetic shoes, and the slot pole ratio of each unit motor is 9:8, namely the number of slot poles of the unit motor in the permanent magnet motor is 9: the integer multiple of 8 may be, for example, 9 slots 8 poles, 18 slots 16 poles, 27 slots 24 poles, or the like. In the permanent magnet motor, the slot pole matching of the motor is usually periodic, for example, 8 poles are allocated to 9 slots, and then the previous allocation is repeated, so that 16-pole 18 slots, 24-pole 27 slots and the like are formed, the allocated poles and slots in each period are called "unit motor", and the number of the repeated allocation periods is called "unit motor number".

In the above embodiments, the magnetic shoe is mainly used in a permanent magnet direct current motor, and unlike an electromagnetic motor which generates a magnetic potential source through a field coil, a permanent magnet motor generates a constant magnetic potential source through a permanent magnet material. The permanent magnetic shoe has many advantages of replacing electric excitation, and can make the motor simple in structure, convenient in maintenance, light in weight, small in volume, reliable in use, less in copper consumption, low in energy consumption, etc.

In the embodiment, firstly, Maxwell software is used for establishing a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor for the surface-mounted type permanent magnet motor of the fractional-slot concentrated winding; because the number of the slot poles of the permanent magnet motor in the prior art is generally integral multiple of 9:8, or the number of the poles is smaller than the number of the slots; therefore, in the scheme, the pole number and the slot number of the surface-mounted permanent magnet motor are optimized to obtain an optimization result of a slot pole ratio of the permanent magnet motor, the width of stator teeth and the thickness of yoke parts of an iron core of the surface-mounted permanent magnet motor are optimized according to the optimization result of the slot pole ratio of the surface-mounted permanent magnet motor to obtain a first optimization result, the mechanical pole arc coefficient of the surface-mounted permanent magnet motor is optimized to obtain a second optimization result, and finally the mechanical structure of the permanent magnet motor is determined by combining the first optimization result and the second optimization result with a fractional slot concentrated winding permanent magnet motor tooth space torque simulation model.

It can be understood that the mechanical structure of the permanent magnet motor determined according to the optimization result is based on the optimized slot pole ratio of the surface-mounted permanent magnet motor, and the linearity of the torque current of the permanent magnet motor can be improved at the moment.

Furthermore, the rotating speed, the torque and the like of the surface-mounted permanent magnet motor are all related to the number of poles of the motor, the cost is lower when the number of poles of the permanent magnet motor is small, and the higher rotating speed is easier to achieve; however, the thickness of the permanent magnet motor stator and rotor core yoke is inversely proportional to the number of pole pairs of the permanent magnet motor, and the width of the stator teeth is proportional to the number of pole pairs of the permanent magnet motor. Therefore, the pole number and the slot number of the surface-mounted permanent magnet motor need to be optimized, and the width of the stator teeth and the thickness of the iron core yoke part in the permanent magnet motor need to be optimized, so that high magnetic density saturation of the motor during overload can not be easily caused, and the torque current linearity of the permanent magnet motor can be improved.

In addition, if the torque stability and the torque current linearity of the permanent magnet motor are good, a fractional slot concentrated winding slot pole matching mode can be adopted, and the cogging torque and the torque fluctuation of the permanent magnet motor need to be small, so when the pole number and the slot number of the surface-mounted permanent magnet motor are optimized, the pole number needs to be as many as possible, the pole number of the fractional slot concentrated winding slot takes a similar value, specifically, the fractional slot concentrated winding slot pole ratio can be optimized to be 8:9, 16:18, 24:27 and the like, and the method is not limited here. The number of winding slots in the fractional slot set is less than the number of poles. Therefore, the magnetic load of the permanent magnet motor can be improved, the number of cycles of cogging torque change of a permanent magnet motor rotor rotating for one circle is increased, the lowest cogging torque order is improved, the cogging torque is weakened from the angle of slot pole matching, high magnetic density saturation of the permanent magnet motor during overload is reduced, and the requirement of better torque current linearity is met.

According to the technical scheme, the surface-mounted permanent magnet motor with the fractional slot concentrated winding is selected, a tooth space torque simulation model of the fractional slot concentrated winding permanent magnet motor is established by using Maxwell software, and parameters related in the tooth space torque simulation model are optimized to obtain a motor mechanical structure for reducing the motor torque current linearity. Further, after a cogging torque simulation model of the permanent magnet motor is established, the pole number and the slot number of the surface-mounted permanent magnet motor are optimized to obtain an optimized permanent magnet motor slot pole ratio; according to the optimization result of the slot pole ratio of the motor, the width of the stator teeth and the thickness of the iron core yoke part in the motor are optimized, so that high magnetic density saturation of the permanent magnet motor during overload can not be easily caused, and the requirement of better torque current linearity of the permanent magnet motor is met. Meanwhile, the mechanical pole arc coefficient of the surface-mounted permanent magnet motor is optimized so as to pass through the optimized effective magnetic flux of the permanent magnet motor. The optimized result of the width of the stator teeth, the thickness of the iron core yoke part and the mechanical pole arc coefficient is input into a fractional slot concentrated winding permanent magnet motor tooth space torque simulation model to obtain the optimized mechanical structure of the permanent magnet motor, namely the optimized mechanical structure of the permanent magnet motor with the number of poles of the fractional slot concentrated winding larger than the number of slots. The optimized mechanical structure of the permanent magnet motor improves the torque current linearity of the surface-mounted permanent magnet motor.

In an embodiment, the step of optimizing the width of the stator teeth and the thickness of the core yoke in the surface-mounted permanent magnet motor according to the optimization result of the slot pole ratio of the motor to obtain a first optimization result includes:

keeping the no-load air gap flux density of the surface-mounted permanent magnet motor consistent, and reducing the flux per pole of the surface-mounted permanent magnet motor;

According to the reduction of the magnetic flux per pole of the surface-mounted permanent magnet motor, the thickness of a yoke part of a stator core of the surface-mounted permanent magnet motor is reduced, and the width of a stator tooth of the surface-mounted permanent magnet motor is increased;

And analyzing a plurality of parameters in the cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor to obtain the first optimization result.

in the embodiment, that is, when the torque stability and the torque current linearity of the permanent magnet motor are relatively good, the matching mode of the fractional-slot concentrated winding slot poles is adopted, and the cogging torque and the torque fluctuation of the permanent magnet motor need to be small, so that when the pole number and the slot number of the surface-mounted permanent magnet motor are optimized, the pole number of the fractional-slot concentrated winding slot takes a similar value, which may cause that magnetic flux enters the stator tooth part through the air gap at each moment but does not enter the stator yoke part, no effective magnetic circuit closed loop is formed, ineffective excitation is generated, at this time, the magnetic load of the permanent magnet motor can be increased by the pole number of the permanent magnet motor being greater than the slot number, the cycle number of cogging torque change of the permanent magnet motor rotor in one rotation cycle is increased, the lowest cogging torque order is increased, and further, the cogging torque is weakened from the angle of slot pole matching, so as to reduce, thereby meeting the requirement of better torque current linearity.

in this embodiment, the magnetic flux density refers to the magnetic flux density, specifically to the number of magnetic lines passing through a unit area perpendicularly, which is also referred to as magnetic induction intensity. It quantitatively reflects the density of the magnetic lines. The strength of the magnetic field is generally expressed by magnetic induction intensity, and the stronger the magnetic field, the larger the value of the magnetic induction intensity, the denser the magnetic lines of force. The magnetic force lines in the permanent magnet motor can penetrate through the stator and rotor cores and the air gap, and the magnetic pressure drop of the air gap occupies most of the magnetic circuit under the condition of non-deep saturation due to the large magnetic resistance of the air gap. The magnetic field in the air gap has both radial and tangential components, but is dominated by the radial component, so we refer to the air gap field and the air gap flux density as the radial component by default. In the design parameters of the permanent magnet motor, the concept of air gap flux density is not directly mentioned, but is characterized by magnetic load.

in this embodiment, the step of analyzing a plurality of parameters in a fractional-slot concentrated winding permanent magnet motor cogging torque simulation model to obtain the first optimization result includes:

Analyzing a plurality of parameters in a cogging torque simulation model of the fractional-slot concentrated winding permanent magnet motor; wherein the plurality of parameters include cogging torque, no-load air gap flux density, and temperature rise;

And taking the scheme that the permanent magnet motor of which the temperature rise does not exceed the highest temperature bearing temperature of the cogging torque simulation model of the fractional slot concentrated winding permanent magnet motor as the first optimization result.

in this embodiment, the permanent magnet motor is a neodymium iron boron permanent magnet. Neodymium-iron-boron magnet is an intermetallic compound composed of rare earth elements, iron and boron, the rare earth elements are mainly a combination of neodymium or neodymium, and some iron is replaced by cobalt, aluminum, vanadium and other elements. With the development of industries such as computers, communication and the like, the rare earth permanent magnet industry, particularly the NdFeB permanent magnet industry, has been rapidly developed. The rare earth permanent magnetic material is a permanent magnetic material with the highest comprehensive performance in the prior art, has much better performance than ferrite and alnico, and has twice higher magnetic performance than expensive platinum-cobalt alloy. Due to the use of the rare earth permanent magnetic material, the development of permanent magnetic devices towards miniaturization is promoted, and the performance of products is improved.

In the above embodiment, the maximum temperature range to which the permanent magnet motor is subjected is 140 ℃ to 160 ℃. Further, the radial thickness of the permanent magnet in the permanent magnet motor is related to the magnetic potential of the permanent magnet, especially the permanent magnet structure with inconsistent radial thickness, the minimum thickness of the permanent magnet is designed on the premise that the permanent magnet can bear the highest temperature, the demagnetization resistance of the permanent magnet is considered, under normal conditions, the highest working temperature of the high-coercivity neodymium iron boron permanent magnet is about 140-160 ℃, at this time, the intrinsic demagnetization curve and the demagnetization curve are basically coincident, and the thickness of the permanent magnet is determined by the magnitude of the armature magnetomotive force. It is understood that the maximum working temperature of the higher coercivity neodymium iron boron permanent magnet may be 140 ℃, 150 ℃, 160 ℃, etc.

in this embodiment, the demagnetization curve refers to a curve of a magnetic hysteresis loop of the magnetic alloy in the second quadrant or the fourth quadrant of the coordinate axis. Generally refers to the situation where demagnetization occurs from saturation with a magnetic field that varies by one unit. The intrinsic demagnetization curve is a part of the demagnetization curve, and the intrinsic demagnetization curve is a part inside the demagnetization curve that can be restored. It is to be understood that the magnetic alloy referred to herein is a permanent magnet in a permanent magnet machine.

it should be noted that, the magnetic hysteresis loop is a phenomenon that if the magnetization field strength is reduced after the ferromagnetic material reaches the magnetic saturation state, the magnetic induction strength of the medium is not reduced along the initial magnetization curve, and the change of the magnetic induction strength lags behind the change of the magnetization field strength, which is called magnetic hysteresis. In a magnetic field, the relationship between the magnetic induction intensity of a ferromagnet and the magnetic field intensity can be represented by a curve, and when the magnetizing magnetic field is periodically changed, the relationship between the magnetic induction intensity of the ferromagnet and the magnetic field intensity is a closed line, and the closed line is called a hysteresis loop. The area of the hysteresis loop of the magnetic induction and magnetization field strength represents the energy lost by the ferromagnet after a period of time.

in this embodiment, the coercive force refers to that the magnetic induction intensity of a magnetic material does not return to zero when an external magnetic field returns to zero after saturation magnetization, and the magnetic induction intensity can return to zero only by adding a magnetic field with a certain magnitude in the direction opposite to the original magnetic field, which is called a coercive field and is also called coercive force. The magnetized ferromagnetic substance loses magnetism and must be added with external magnetic field strength opposite to the original magnetization direction. Not only with respect to the nature of the ferromagnetic substance, but also on the original magnetization of the ferromagnetic substance. For example, in the manufacture of an iron core or an electromagnet of a transformer, it is necessary to select a material having a small coercive force (for example, soft iron, silicon steel, or the like) so that the magnetic properties disappear as soon as possible after the current is cut off. In the production of permanent magnets, it is necessary to select a material having a large coercive force (e.g., alnico or the like) in order to preserve the magnetic properties as much as possible without disappearing the same.

in an embodiment, the step of optimizing a mechanical pole arc coefficient in the surface-mount permanent magnet motor according to the first optimization result to obtain a second optimization result includes:

Determining the axial size of a rotor of the surface-mounted permanent magnet motor, and keeping the axial size consistent with the axial length of the surface-mounted permanent magnet motor;

And increasing the mechanical pole arc coefficient of the surface-mounted permanent magnet motor, weakening the cogging torque of the surface-mounted permanent magnet motor, and obtaining the second optimization result.

in this embodiment, the rotor axial dimension of the surface-mounted permanent magnet motor includes: axial length, pole width, and radial thickness;

When the mechanical pole arc coefficient of the surface-mounted permanent magnet motor is increased, the width of the magnetic pole is increased, and the effective magnetic flux of the surface-mounted permanent magnet motor is increased;

When the magnetic potential of the permanent magnet of the surface-mounted permanent magnet motor is increased, the radial thickness is increased.

in this embodiment, as shown in fig. 2, when the magnetic potential of the permanent magnet of the surface-mount permanent magnet motor increases, the step of increasing the radial thickness includes:

When the radial thicknesses of the surface-mounted permanent magnet motors are not consistent, the relationship between the armature magnetomotive force of the surface-mounted permanent magnet motors and the permanent magnet magnetomotive force is a formula: nimax is less than or equal to alpha Hc' hmin, wherein N is the number of single coil turns of the surface-mounted permanent magnet motor, imax is the maximum current of the surface-mounted permanent magnet motor, alpha is a process parameter of the surface-mounted permanent magnet motor, hm is the maximum thickness of a permanent magnet of the surface-mounted permanent magnet motor, hmin is the minimum thickness of the permanent magnet of the surface-mounted permanent magnet motor, R is the excircle radius of the permanent magnet of the surface-mounted permanent magnet motor, R1 is the inner circle radius of the permanent magnet of the surface-mounted permanent magnet motor, and bm is the actual width corresponding to the mechanical pole arc coefficient of the permanent magnet of the surface-mounted permanent magnet motor.

in this embodiment, the numerical range of the process parameter α of the surface-mounted permanent magnet motor is 0.7 to 0.97. It is understood that the value of the process parameter α of the surface-mount permanent magnet motor may be 0.7, 0.8, 0.97, etc., and is set according to the practical application, and is not limited herein.

The invention also provides a surface-mounted permanent magnet motor, which comprises the method for optimizing the motor torque current. The specific steps of the method for optimizing the torque and the current of the motor refer to the above embodiments, and the surface-mounted permanent magnet motor adopts all technical solutions of all the above embodiments, so that the method at least has all the beneficial effects brought by the technical solutions of the above embodiments, and details are not repeated herein.

The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.