A thickness-adjustable back-emf sinusoidal permanent magnet motor and a parameter optimization method thereof

Abstract

The application relates to the field of permanent magnet motors, and particularly discloses a thickness-adjustable back electromotive force sinusoidal permanent magnet motor and a parameter optimization method thereof, which comprises a stator and a rotor; the rotor comprises a rotating shaft, a rotor iron core and combined magnetic poles; the outer layer is made of aluminum-nickel-cobalt and has a thickness of high-low-high along the center of the magnetic poles in a symmetrical mode, and the inner layer is made of neodymium-iron-boron and has a thickness of low-high-low along the center of the magnetic poles in a symmetrical mode; the adjacent magnetic poles are magnetized in opposite directions; the stator comprises an iron core and an armature winding. The specific parameter optimization method is as follows: S1 determines optimization variables and a target function; S2 globally optimizes the optimal parameters by using a lion swarm optimization algorithm; and S3 substitutes the optimal parameters into a finite element model for solving and comparison and verification with a motor air gap magnetic field modeling result. The application effectively solves the problems of a parallel wave of a back electromotive force of a traditional surface-mounted permanent magnet motor, large torque ripple, complex optimization process and low calculation efficiency, and improves the sinusoidal degree of the back electromotive force, the motor stability and the optimization efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of permanent magnet motors, in particular to a thickness-adjustable back EMF sinusoidal permanent magnet motor and a parameter optimization method thereof. BACKGROUND

[0002] Surface-mounted permanent magnet motors (SPMM) are widely used in industrial fields due to their simple structure, high power density and significant efficiency. However, due to the shape of the magnet, the back EMF of the SPMM usually presents a flat-top wave distribution, which leads to an increase in the harmonic component of the flux linkage, thereby increasing the torque ripple and affecting the stability and reliability of the motor, which is not conducive to its application in high-precision scenarios.

[0003] In order to improve this situation, researchers have tried to design specific rotor profile structures, such as using magnet pole cutting technology, to make the back EMF sinusoidal, and thus make the flux linkage sinusoidal. The magnet pole cutting technology optimizes the shape and angle of the rotor outer surface pole arc by designing the magnet into a sine or inverse cosine shape and adjusting its pole arc coefficient, thereby achieving sinusoidal back EMF. Although this technology is effective, it faces problems such as complex process, time-consuming optimization design, and high cost of magnets. Another common method is to use Halbach structure, which improves the sinusoidal degree of the flux linkage waveform through a specific magnet arrangement, but also faces problems such as complex structure and rising costs. Therefore, there is an urgent need for a permanent magnet structure design method that is easy to process and has low production cost.

[0004] At the same time, the complex structure of the magnet profile design increases the difficulty of magnetic circuit analysis and makes the performance prediction of the motor more complex. Although the traditional finite element method (FEM) can effectively analyze the electromagnetic performance, it has large calculation amount and long time consumption, and is low in optimization efficiency for the optimization design of the SPMM rotor pole, and has high demand for the host computer, which further limits the optimization efficiency.

[0005] Therefore, there is an urgent need for a thickness-adjustable back EMF sinusoidal permanent magnet motor and a parameter optimization method thereof that can balance the sinusoidal back EMF, simplify the process and reduce the cost, while reducing the difficulty of magnetic circuit analysis and optimization time, and improving the efficiency, to improve the sinusoidal degree of the motor back EMF, stability and optimization efficiency, reduce the torque ripple, adapt to high-precision scenarios, and reduce the load of the host computer. SUMMARY

[0006] The present application provides a thickness-adjustable back EMF sinusoidal permanent magnet motor and a parameter optimization method thereof to effectively solve the problems of large torque ripple caused by flat-top wave of SPMM back EMF, complex process and high cost of traditional magnet structure, difficulty of magnetic circuit analysis and low optimization efficiency, and improve the sinusoidal degree of the motor back EMF and the running stability.

[0007] In order to achieve the above object, the application provides a thickness-adjustable back electromotive force sinusoidal permanent magnet motor, which comprises a stator and a rotor.

[0008] Preferably, the permanent magnet with the highest residual magnetism is a neodymium iron boron permanent magnet, and the permanent magnet with lower residual magnetism is an alnico permanent magnet, and the residual magnetism of the alnico permanent magnet is lower than that of the neodymium iron boron permanent magnet.

[0009] Preferably, the magnetization directions of the alnico permanent magnet and the neodymium iron boron permanent magnet are radial magnetization directions.

[0010] Preferably, in the combined magnet pole, the neodymium iron boron permanent magnet is arranged above each pole, the alnico permanent magnet is arranged below each pole, the alnico permanent magnet unit corresponds to the neodymium iron boron permanent magnet unit one by one, the neodymium iron boron permanent magnet and the alnico permanent magnet of each pole are processed in a block manner, and the angles and thicknesses of the two are determined by the back electromotive force sinusoidal optimization method.

[0011] Preferably, the stator comprises a stator core and an armature winding embedded in the stator core; the stator core is provided with a slot body, and the shape and size of the slot body are matched with the arrangement of the armature winding.

[0012] Preferably, the overall thickness of each magnet pole on the rotor core is the same, and the thicknesses of the alnico permanent magnet and the neodymium iron boron permanent magnet and the pole arc coefficient are adjusted to improve the sinusoidal degree of the no-load back electromotive force of the motor.

[0013] A parameter optimization method of a thickness-adjustable back electromotive force sinusoidal permanent magnet motor, comprising the following steps:

[0014] S1, determining optimization variables and a target function, the optimization variables are the thickness of the alnico permanent magnet, the angle of the alnico permanent magnet, the thickness of the neodymium iron boron permanent magnet and the angle of the neodymium iron boron permanent magnet of each unit, and the target function is the no-load back electromotive force amplitude and the no-load back electromotive force harmonic rate of the motor;

[0015] S2. Based on the objective function, the lion swarm optimization algorithm is used to globally optimize the motor performance to obtain the optimal thickness, angle, and thickness of the sector-shaped AlNiCo permanent magnet, as well as the optimal angle of the sector-shaped NdFeB permanent magnet.

[0016] S3. Substitute the optimal parameters obtained in S2 into the finite element model to solve for the amplitude and harmonic rate of the no-load back EMF under the finite element model. Compare the solution with the back EMF parameters corresponding to the amplitude and harmonic rate of the air gap magnetic flux density obtained by the motor air gap magnetic field modeling method to verify the performance matching.

[0017] Preferably, in S1, the objective function is expressed by the following formula:

[0018] ;

[0019] In the formula, To optimize variables, To optimize variables The value of the optimization objective function corresponding to the change. i =1, 2, 3…, E 0、 THD - E 0 represents the initial back EMF amplitude and the initial back EMF harmonic rate, respectively. , Optimization variables The corresponding back electromotive force amplitude and back electromotive force harmonic rate, , These are the weighting coefficients for the back EMF amplitude and the back EMF harmonic rate, respectively, and they satisfy... .

[0020] Preferably, in S2, the specific process of using the lion pack optimization algorithm for global optimization is as follows:

[0021] S21. Divide the value range of each optimization variable into multiple intervals, and perform a random sampling of the optimization variable in each interval to obtain the thickness and angle of the fan-shaped aluminum nickel cobalt permanent magnet and the thickness and angle of the fan-shaped neodymium iron boron permanent magnet after sampling.

[0022] S22. Substitute the sampled parameters into the motor air gap magnetic field modeling method to solve for the corresponding back EMF amplitude and back EMF harmonic rate.

[0023] S23. Based on the lion pack optimization algorithm, a global search mechanism is used to iteratively update the optimization variables until the objective function value is optimal, and then the optimal parameters are output.

[0024] Preferably, in S3, the method for modeling the air gap magnetic field of the motor includes:

[0025] S31, according to the residual magnetism distribution of the motor permanent magnet and the boundary condition, the slotless no-load air gap magnetic flux density of the sector-shaped alnico permanent magnet and the sector-shaped Nd-Fe-B permanent magnet is calculated respectively when the two kinds of permanent magnets act alone;

[0026] S32, according to the stator slotting and slot opening shape, the relative permeability is calculated, combined with the slotless no-load air gap magnetic flux density, the slotting no-load air gap magnetic flux density of the two kinds of permanent magnets is calculated respectively when the two kinds of permanent magnets act alone, and the slotting no-load air gap magnetic flux density of the motor is obtained after superposition;

[0027] S33, according to the armature winding distribution, the winding function and the winding factor are calculated, combined with the slotting no-load air gap magnetic flux density, the motor no-load back electromotive force and the back electromotive force harmonic rate are calculated.

[0028] Therefore, the present application proposes a thickness-adjustable back electromotive force sinusoidal permanent magnet motor and a parameter optimization method thereof, which has the following beneficial effects:

[0029] (1) Optimize the structure to reduce the cost and improve the efficiency: the rotor adopts alnico and Nd-Fe-B block combination, without special forming process, simplifying the production and reducing the cost; by adjusting the thickness and pole arc coefficient of the two, the sine degree of back electromotive force can be improved, the flux harmonic and torque ripple can be reduced, and the defects of traditional pole cutting and Halbach structure can be avoided.

[0030] (2) High efficiency optimization and reliable verification: taking the thickness and angle of the permanent magnet as variables, and taking the amplitude and harmonic rate of the back electromotive force as targets, the lion swarm algorithm is used for global optimization, which has smaller calculation amount and shorter time consumption than the traditional finite element method; the optimal parameters are verified by comparing the results of the finite element model and the air gap magnetic field modeling, and the performance is stable.

[0031] (3) Adapt to high-precision scene: improve the back electromotive force waveform, reduce the torque ripple, and improve the motor operation stability; reduce the iron loss to maintain high efficiency operation, and adapt to high-precision operation demand.

[0032] The technical solutions of the present application will be further described in detail below with the help of the drawings and examples. DESCRIPTION OF DRAWINGS

[0033] Figure 1 is the structure diagram of the stator of the thickness-adjustable back electromotive force sinusoidal permanent magnet motor and the parameter optimization method thereof;

[0034] Figure 2 is the structure diagram of the rotor of the thickness-adjustable back electromotive force sinusoidal permanent magnet motor and the parameter optimization method thereof;

[0035] Figure 3 is the flow chart of the thickness-adjustable back electromotive force sinusoidal permanent magnet motor and the parameter optimization method thereof;

[0036] Figure 4is a structural diagram of a rotor parameterized modeling of a thickness-adjustable back-EMF sinusoidal permanent magnet motor and a parameter optimization method thereof according to the present application, wherein Figure 4 (a) is a parameterized modeling diagram of a sector-shaped Al-Ni-Co permanent magnet unit, Figure 4 (b) is a parameterized modeling diagram of a single-pole combined magnetic pole, Figure 4 (c) is a parameterized modeling diagram of a whole magnetic pole array of a rotor;

[0037] Figure 5 is a flow chart of a thickness-adjustable back-EMF sinusoidal permanent magnet motor and a parameter optimization method thereof according to the present application;

[0038] Figure 6 is a comparison diagram of an existing technology and an optimized modeling method according to the present application in an embodiment of a thickness-adjustable back-EMF sinusoidal permanent magnet motor and a parameter optimization method thereof according to the present application, wherein Figure 6 (a) is a comparison diagram of a no-load back-EMF before and after optimization, Figure 6 (b) is a comparison diagram of Fourier decomposition results of a no-load back-EMF before and after optimization.

[0039] Reference signs

[0040] 1, stator, 11, stator core, 12, motor winding, 2, motor rotor, 21, rotor core, 22, Al-Ni-Co S-pole permanent magnet with low residual magnetism, 23, Al-Ni-Co N-pole permanent magnet with low residual magnetism, 24, Nd-Fe-B S-pole permanent magnet with high residual magnetism, 25, Nd-Fe-B N-pole permanent magnet with high residual magnetism. DETAILED DESCRIPTION

[0041] In order to make the technical solutions, advantages and purposes of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0042] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the meanings commonly understood by those skilled in the art to which the present application belongs.

[0043] Embodiment One

[0044] As shown in the drawings, the present application provides a thickness-adjustable back-EMF sinusoidal permanent magnet motor, and the device comprises a stator 1 and a motor rotor 2. Figures 1-2

[0045] ​The stator 1 comprises a stator core 11 and a motor winding 12 embedded in the stator core 11, the stator core 11 is provided with a groove body matching the arrangement of the motor winding 12, the shape and size of the groove body are designed according to the winding distribution requirement, so as to ensure the stable embedding of the winding and meet the electromagnetic performance requirement.

[0046] The motor rotor 2 comprises a rotating shaft, a rotor core 21 and combined magnetic poles arranged on the rotor core 21, the combined magnetic poles are divided into N poles and S poles, and the magnetization directions of adjacent combined magnetic poles are both radial and opposite.

[0047] Each combined magnetic pole is composed of a plurality of unequal-thickness sector-shaped Al-Ni-Co permanent magnets and sector-shaped Nd-Fe-B permanent magnet units, wherein the sector-shaped Al-Ni-Co permanent magnets with lower residual magnetism are arranged on the outer layer of the sector-shaped Nd-Fe-B permanent magnets with higher residual magnetism, and specifically include Al-Ni-Co S-pole permanent magnets 22 with lower residual magnetism, Al-Ni-Co N-pole permanent magnets 23 with lower residual magnetism, Nd-Fe-B S-pole permanent magnets 24 with higher residual magnetism, and Nd-Fe-B N-pole permanent magnets 25 with higher residual magnetism.

[0048] Under each pole, the thickness of the sector-shaped Al-Ni-Co permanent magnets is distributed in a "high-low-high" manner along the center of the magnetic pole, the thickness of the sector-shaped Nd-Fe-B permanent magnets is distributed in a "low-high-low" manner along the center of the magnetic pole, and the Nd-Fe-B permanent magnets and the Al-Ni-Co permanent magnets of each pole are processed in blocks, the overall thickness of each magnetic pole on the rotor core 21 is the same, and the sine degree of the motor no-load back electromotive force can be improved by adjusting the thickness of the two kinds of permanent magnets and the pole arc coefficient.

[0049] Embodiment two

[0050] As shown in the formula (1), the formula (1) is a parameter optimization method for a thickness-adjustable back electromotive force sine permanent magnet motor. Figure 3 -As shown in the formula (1), the formula (1) is a parameter optimization method for a thickness-adjustable back electromotive force sine permanent magnet motor. Figure 6 The method specifically comprises the following steps:

[0051] S1, determining optimization variables and a target function:

[0052] The optimization variables are the thickness of the sector-shaped Al-Ni-Co permanent magnet of each unit, the angle of the sector-shaped Al-Ni-Co permanent magnet, the thickness of the sector-shaped Nd-Fe-B permanent magnet, and the angle of the sector-shaped Nd-Fe-B permanent magnet;

[0053] The target function is the no-load back electromotive force amplitude and the no-load back electromotive force harmonic rate of the motor, and the expression is:

[0054] ;

[0055] In the formula (1), x is the optimization variable, y is the optimization variable, and f(x, y) is the optimization target function value corresponding to the change of the optimization variable x and the optimization variable y. The optimization variable x is the thickness of the sector-shaped Al-Ni-Co permanent magnet of each unit. The optimization variable y is the angle of the sector-shaped Al-Ni-Co permanent magnet. The optimization target function value f(x, y) is the no-load back electromotive force amplitude and the no-load back electromotive force harmonic rate of the motor. i =1, 2, 3… E 0,THD - E 0are the initial back EMF amplitude, the initial back EMF harmonic ratio, respectively, 、 are the optimization variables corresponding back EMF amplitude, back EMF harmonic ratio, respectively, 、 are the weight coefficients of the back EMF amplitude, the back EMF harmonic ratio, respectively, and satisfy .

[0056] S2, global optimization based on lion swarm optimization algorithm:

[0057] S21, divide the value range of each optimization variable into multiple intervals, and sample the optimization variable in each interval to obtain the sampled thickness and angle of the sector-shaped Al-Ni-Co permanent magnet and the thickness and angle of the sector-shaped Nd-Fe-B permanent magnet;

[0058] S22, substitute the sampled parameters into the motor air gap magnetic field modeling method to obtain the corresponding back EMF amplitude and back EMF harmonic ratio;

[0059] In S22, a modeling method of a thickness-adjustable back EMF sinusoidal permanent magnet motor is used to model the two types of permanent magnets respectively, and the motor air gap magnetic field modeling method specifically includes:

[0060] S221, according to the residual magnetism distribution and boundary conditions of the motor permanent magnet, the slotless no-load air gap magnetic density of the sector-shaped Al-Ni-Co permanent magnet and the sector-shaped Nd-Fe-B permanent magnet acting alone is calculated respectively;

[0061] S222, according to the stator slotting and slot opening shape, the relative permeability is calculated, and the slotless no-load air gap magnetic density is combined to calculate the slotting no-load air gap magnetic density of the two types of permanent magnets acting alone, and the motor slotting no-load air gap magnetic density is obtained after superposition;

[0062] S223, according to the armature winding distribution, the winding function and the winding factor are calculated, and the slotting no-load air gap magnetic density is combined to obtain the motor no-load back EMF and back EMF harmonic ratio through formula calculation; the calculation formula is:

[0063] ;

[0064] In the formula, is the motor A-phase no-load back EMF, is the inner diameter of the motor stator; is the motor shaft length; ω r is the angular velocity; k d and k pShort-pitch factor and pitch factor of winding, respectively; m For each order (n m =1,3,5...) after Fourier decomposition.

[0065] Wherein, the modeling method of air gap flux density in the case of no slot is:

[0066] For Alnico permanent magnet, according to the residual magnetism distribution of permanent magnet, it is assumed that within a pole range, the radial magnetization vector M r and the tangential magnetization vector M θ are obtained.

[0067] ;

[0068] ;

[0069] The thickness distribution of permanent magnet is:

[0070] ;

[0071] The Fourier series of

[0072] ;

[0073] Wherein,

[0074] ;

[0075] The air gap flux density of the proposed thickness-adjustable combined magnetic pole rotor of Alnico magnetic pole without slot is obtained:

[0076] ;

[0077] In the formula, B r ( r , θ ) and B θ ( r , θ ) are the radial component and the tangential component of the air gap flux density of the motor without slot, respectively; r is the sampling radius of air gap flux density; θ is the rotor position angle; n is the order (n n =1,3,5...) after Fourier decomposition;

[0078] , and are transition parameters, as shown below:

[0079] ;

[0080] ;

[0081] ;

[0082] wherein, is the relative permeability of the permanent magnet; p is the number of pole pairs; r is the air-gap flux sampling radius; R s , R m , R r are the inner diameter of the stator, the outer diameter of the permanent magnet and the outer diameter of the rotor core of the motor respectively.

[0083] For NdFeB permanent magnet, according to the residual magnetism distribution of the permanent magnet, it is assumed that within a pole range, the radial magnetization vector M r and the tangential magnetization vector M θ are:

[0084] ;

[0085] ;

[0086] The thickness distribution of the permanent magnet is:

[0087] ;

[0088] h nd The Fourier series of θ is:

[0089] ;

[0090] wherein,

[0091] ;

[0092] The slotless air-gap flux density of the NdFeB magnetic pole of the proposed thickness-adjustable combined magnetic pole rotor is obtained:

[0093] ;

[0094] wherein, B r r , θ and B θ r ,​​θ are the radial and tangential components of the slotless air-gap flux density of the motor, respectively; r is the air-gap flux sampling radius; θ is the rotor position angle; n is the order of Fourier decomposition (n = 1, 3, 5…); n

[0095] , and are transition parameters, as follows:

[0096] ;

[0097] ;

[0098] ;

[0099] wherein, is the relative permeability of the permanent magnet; p is the number of pole pairs; r is the air-gap flux sampling radius; R in , R m , R r are the inner diameter of the stator, the outer diameter of the permanent magnet, and the outer diameter of the rotor core of the motor, respectively.

[0100] The total air-gap flux density is:

[0101] ;

[0102] In some embodiments, the air-gap flux density calculation method for a low-torque ripple permanent magnet motor for high-precision operation scenarios under the condition of relative permeability and slotting is:

[0103] According to the conformal transformation method, the relative permeability of the motor is:

[0104] ;

[0105] wherein, is the radial relative permeability, is the radial relative permeability base component, is the radial relative permeability Fourier component, is the tangential relative permeability, is the tangential relative permeability Fourier component, Z is the number of slots of the motor.

[0106] ;

[0107] ​ ;

[0108] In the formula, k a , k b This is the air gap adjustment coefficient for the motor. t equal .

[0109] In some embodiments, the air gap slotted magnetic flux density is obtained by the following formula:

[0110] ;

[0111] In the formula, B r and B θ These are the radial and tangential components of the magnetic flux density in the slotted air gap of the motor, respectively.

[0112] In some embodiments, the method for calculating the no-load back electromotive force of a hybrid pole sinusoidal permanent magnet motor is as follows:

[0113] ;

[0114] in, E a The no-load back electromotive force of phase A of the motor. R in This is the inner diameter of the motor stator; This is the length of the motor shaft; ω r Angular velocity; k d and k p These are the short-pitch factor and pitch factor of the winding, respectively; m The orders after Fourier decomposition ( m =1, 3, 5...).

[0115] S23. Based on the lion pack optimization algorithm, a global search mechanism is used to iteratively update the optimization variables until the objective function value is optimal, and the optimal thickness, angle, and values ​​of the sector-shaped AlNiCo permanent magnet, NdFeB permanent magnet, and NdFeB permanent magnet are output.

[0116] S3, Performance Matching Verification:

[0117] Substitute the optimal parameters obtained from S2 into the finite element model to solve for the amplitude and harmonic rate of the no-load back EMF under the finite element model.

[0118] The solving result is compared with the back electromotive force parameters corresponding to the air gap magnetic flux density amplitude and air gap magnetic flux density harmonic rate obtained by the motor air gap magnetic field modeling method in S22, if the performances match (such as the sine degree of the optimized back electromotive force is higher, the harmonic content is less, such as Figure 6 (a) comparison chart of no-load back electromotive force before and after optimization, Figure 6 (b) comparison chart of no-load back electromotive force Fourier decomposition result), it is determined that the optimal parameters are the final design parameters; if they do not match, return to S2 to adjust the optimization variable interval or algorithm parameter again, and iterate optimization again until the performances match.

[0119] Therefore, the application provides a thickness-adjustable back electromotive force sinusoidal permanent magnet motor and a parameter optimization method thereof, which effectively reduces the back electromotive force harmonic, and the torque ripple can be minimized. In combination with the design of permanent magnets made of different materials, the motor cost and loss are effectively reduced, and the design does not require special permanent magnet forming process, simplifies the production process, and reduces the manufacturing cost. The parameter optimization method has the advantages of high optimization precision, strong algorithm adaptability, short calculation time, etc., the sine degree of the no-load back electromotive force of the obtained optimization result is higher, the torque ripple is significantly reduced, the system reliability is improved, and it is especially suitable for high-precision operation scenes.

[0120] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application and not to limit them, although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the application, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the application.

Claims

1. A thickness-regulated brushless permanent magnet motor with sinusoidal back EMF, characterized by, Comprise: Stator and rotor; the rotor comprises a rotating shaft, a rotor core and a combined magnetic pole arranged on the rotor core, the rotor is provided with two kinds of residual magnetism permanent magnets, which are aluminum-nickel-cobalt permanent magnet and neodymium-iron-boron permanent magnet respectively; the combined magnetic pole is divided into N pole and S pole, the magnetization direction of adjacent combined magnetic poles is opposite; each combined magnetic pole is composed of a plurality of unequal-thickness sector-shaped aluminum-nickel-cobalt permanent magnet units and sector-shaped neodymium-iron-boron permanent magnet units, and the sector-shaped aluminum-nickel-cobalt permanent magnet is arranged on the outer layer of the sector-shaped neodymium-iron-boron permanent magnet; under each pole, the thickness of the sector-shaped aluminum-nickel-cobalt permanent magnet is distributed as "high-low-high" along the center of the magnetic pole, and the thickness of the sector-shaped neodymium-iron-boron permanent magnet is distributed as "low-high-low" along the center of the magnetic pole; The permanent magnet with the highest residual magnetism is made of neodymium-iron-boron permanent magnet, and the permanent magnet with lower residual magnetism is made of aluminum-nickel-cobalt permanent magnet, and the residual magnetism of the sector-shaped aluminum-nickel-cobalt permanent magnet is lower than that of the sector-shaped neodymium-iron-boron permanent magnet; The overall thickness of each magnetic pole on the rotor core is the same, and the thickness and pole arc coefficient of the sector-shaped aluminum-nickel-cobalt permanent magnet and the sector-shaped neodymium-iron-boron permanent magnet are adjusted to improve the sine degree of the motor no-load back electromotive force; In the combined magnetic pole, the sector-shaped neodymium-iron-boron permanent magnet is arranged above each pole, the sector-shaped aluminum-nickel-cobalt permanent magnet is arranged below each pole, the sector-shaped aluminum-nickel-cobalt permanent magnet unit corresponds to the sector-shaped neodymium-iron-boron permanent magnet unit one by one, the neodymium-iron-boron permanent magnet and the aluminum-nickel-cobalt permanent magnet of each pole are processed in a block manner, and the angle and thickness of the two are determined by the back electromotive force sinusoidal optimization method.

2. The thickness adjustable back EMF sinusoidalization permanent magnet motor of claim 1, wherein, The magnetization direction of the sector-shaped aluminum-nickel-cobalt permanent magnet and the sector-shaped neodymium-iron-boron permanent magnet is radial magnetization.

3. The thickness adjustable back EMF sinusoidalization permanent magnet motor of claim 1, wherein, The stator comprises a stator core and an armature winding embedded in the stator core; the stator core is provided with a slot body, and the shape and size of the slot body are matched with the arrangement of the armature winding.

4. A method for parameter optimization of a thickness-adjustable back-EMF sinusoidalization permanent magnet motor according to any one of claims 1-3, characterized in that, The method comprises the following steps: S1, determine the optimization variables and the objective function, the optimization variables are the thickness of the sector-shaped aluminum-nickel-cobolt permanent magnet, the angle of the sector-shaped aluminum-nickel-cobolt permanent magnet, the thickness of the sector-shaped neodymium-iron-boron permanent magnet and the angle of the sector-shaped neodymium-iron-boron permanent magnet; the objective function is the amplitude and harmonic rate of the motor no-load back electromotive force; S2, based on the objective function, the lion swarm optimization algorithm is used to globally optimize the motor performance to obtain the optimal thickness of the sector-shaped aluminum-nickel-cobolt permanent magnet, the angle of the sector-shaped aluminum-nickel-cobolt permanent magnet, the thickness of the sector-shaped neodymium-iron-boron permanent magnet and the angle of the sector-shaped neodymium-iron-boron permanent magnet; S3, substitute the optimal parameters obtained in S2 into the finite element model to solve the amplitude and harmonic rate of the no-load back electromotive force under the finite element model; compare the solving results with the back electromotive force parameters corresponding to the air gap magnetic flux density amplitude and air gap magnetic flux density harmonic rate obtained by the motor air gap magnetic field modeling method to verify the performance matching.

5. The parameter optimization method of claim 4, wherein, In S1, the objective function is expressed by the following formula: ； In the formula, is an optimization variable, is an optimization variable corresponding to the optimization objective function value when the change, respectively, initial back-EMF amplitude, initial back-EMF harmonic rate, respectively, optimization variable corresponding to the back-EMF amplitude, back-EMF harmonic rate, respectively, weight coefficients of the back-EMF amplitude, back-EMF harmonic rate, and satisfy .

6. The parameter optimization method of claim 4, wherein, In S2, the specific process of global optimization by using the lion swarm optimization algorithm is as follows: S21, divide the value range of each optimization variable into multiple intervals, and randomly sample the optimization variable in each interval to obtain the sampled thickness and angle of the sector-shaped aluminum-nickel-cobolt permanent magnet and the sector-shaped neodymium-iron-boron permanent magnet; S22, the parameters obtained by sampling are substituted into the motor air gap magnetic field modeling method to solve, and the corresponding back electromotive force amplitude and back electromotive force harmonic ratio are obtained; S23, based on the global search mechanism of lion swarm optimization algorithm, the optimization variables are iteratively updated until the target function value is optimal, and the optimal parameters are output.

7. The parameter optimization method of claim 4, wherein, In S3, the motor air gap magnetic field modeling method comprises: S31, according to the residual magnetism distribution and boundary conditions of the motor permanent magnet, the slotless no-load air gap magnetic density of the fan-shaped al-ni-co permanent magnet and the fan-shaped Nd-Fe-B permanent magnet respectively is calculated when they act alone; S32, according to the relative magnetic permeability calculated by the stator slotting and slot opening shape, combined with the slotless no-load air gap magnetic density, the slotting no-load air gap magnetic density of the two kinds of permanent magnets respectively is calculated when they act alone, and the motor slotting no-load air gap magnetic density is obtained after superposition; S33, according to the winding function and winding factor calculated by the armature winding distribution, combined with the slotting no-load air gap magnetic density, the motor no-load back electromotive force and back electromotive force harmonic ratio are calculated.

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