A rotor with sinusoidal magnetic poles and asymmetric salient poles, a motor, and an optimization method

Abstract

The present invention proposes a rotor, motor, and optimization method with sinusoidal magnetic poles and asymmetric salient poles, and relates to the technical field. The rotor with sinusoidal magnetic poles and asymmetric salient poles includes an end disk, on which multiple groups of combined sinusoidal magnetic poles are evenly arranged, and adjacent combined sinusoidal magnetic poles are magnetized in opposite directions. Each of the combined sinusoidal magnetic poles includes multiple sector-shaped permanent magnets with different opening angles, and adjacent sector-shaped permanent magnets are separated by air gaps of a set angle. The angle design of the multiple sector-shaped permanent magnets follows the projection law of sinusoidal pulse width modulation. The combined sinusoidal magnetic poles proposed in the present invention include multiple sector-shaped permanent magnets, and the angle design of the multiple sector-shaped permanent magnets follows the projection law of sinusoidal pulse width modulation. The permanent magnet block of the combined sinusoidal magnetic poles helps to reduce the eddy current loss of the permanent magnets. The sinusoidal design of the permanent magnets modulated by the sinusoidal wave can effectively reduce the air gap flux density and back electromotive force harmonics.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet motors, and in particular relates to a rotor with sinusoidal magnetic poles and asymmetric salient poles, a motor, and an optimization method. Background Art

[0002] The third energy revolution is dedicated to achieving widespread adoption of clean, renewable energy. High-performance motors, as a key technology driving the transformation of energy production and usage patterns, are attracting significant attention. Current research on high-performance motors, from the perspective of torque components, primarily focuses on the following categories: non-salient-pole permanent magnet motors, salient-pole permanent magnet motors, and reluctance motors. Salient-pole permanent magnet motors generate reluctance torque due to the saliency effect. Compared to non-salient-pole permanent magnet motors, salient-pole permanent magnet motors can produce higher output torque using fewer permanent magnets, resulting in greater power density and improved field-weakening speed regulation capabilities. Salient-pole permanent magnet motors, with their inherent permanent magnet structure, offer higher power density and efficiency compared to reluctance motors.

[0003] Salient-pole motors have attracted interest in many applications, including electric vehicles, electric aircraft and helicopters, marine propulsion, and aerospace, due to their excellent torque density, high efficiency, wide constant-power operating speed range, and high rotor robustness. Furthermore, salient-pole motors utilize the reluctance torque generated by the rotor's salient poles to increase torque density without the need for additional permanent magnets.

[0004] Currently, salient-pole motors encompass many traditional rotor topologies, including bar, V-shaped, delta, double-V, and spoke rotor structures. Multi-layer rotor topologies have also been extensively researched. In salient-pole permanent magnet motors, electromagnetic torque comes from two sources: permanent magnet torque generated by the permanent magnets, and reluctance torque generated by the motor's saliency. Traditional salient-pole permanent magnet motor designs feature a symmetrical rotor structure, resulting in a 45-degree difference in the current phase angles at which the permanent magnet torque and reluctance torque reach their maximum values. This underutilizes both torque components. For example, with a per-unit value of 1 for permanent magnet torque and reluctance torque, in traditional designs, the sum of the permanent magnet and reluctance torques (1 + 1) is approximately equal to 1.76. This underutilization of both torques leaves much room for optimization of torque characteristics. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a rotor, a motor and an optimization method with sinusoidal magnetic poles and asymmetric salient poles. The proposed combined sinusoidal magnetic poles include multiple sector-shaped permanent magnets. The angle design of the multiple sector-shaped permanent magnets follows the projection law of sinusoidal pulse width modulation. The permanent magnet block structure of the combined sinusoidal magnetic poles helps to reduce the eddy current loss of the permanent magnets. The sinusoidal design of the permanent magnets modulated by sinusoidal waves can effectively reduce the air gap magnetic density and back electromotive force harmonics.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0007] A first aspect of the present invention provides a rotor with sinusoidal magnetic poles and asymmetric salient poles.

[0008] A rotor with sinusoidal magnetic poles and asymmetric salient poles includes an end disk, on which multiple groups of combined sinusoidal magnetic poles are evenly arranged. Adjacent combined sinusoidal magnetic poles are magnetized in opposite directions. Each of the combined sinusoidal magnetic poles includes multiple sector-shaped permanent magnets with different opening angles. Adjacent sector-shaped permanent magnets are separated by air gaps of a set angle. The angle design of the multiple sector-shaped permanent magnets follows the projection law of sinusoidal wave pulse width modulation.

[0009] Optionally, the plurality of sector-shaped permanent magnets of each combined sinusoidal magnetic pole are distributed as a whole along the circumference of the end disk, and each sector-shaped permanent magnet is arranged along the radial direction of the end disk.

[0010] Optionally, a salient pole is closely provided on one side of each combined sinusoidal magnetic pole, and the salient pole is formed by stacking oriented silicon steel sheets, and the oriented silicon steel sheets are rolled along the axial direction of the end disc, and the shape of the salient pole is fan-shaped.

[0011] Optionally, the multiple sector-shaped permanent magnets of each combined sinusoidal magnetic pole are arranged in a regular order from small to large opening angles and then from large to small.

[0012] A second aspect of the present invention provides a motor.

[0013] A motor comprises a stator and a rotor with sinusoidal magnetic poles and asymmetric salient poles as described in the first aspect, wherein the rotor with sinusoidal magnetic poles and asymmetric salient poles is arranged on both sides of the stator, and the stator comprises a modular iron core and a fractional slot distributed winding wound on the modular iron core.

[0014] Optionally, the modular core adopts an I-shaped structure and is formed by stacking oriented silicon steel sheets.

[0015] Optionally, the fractional-slot distributed winding adopts a double-layer winding design.

[0016] A third aspect of the present invention provides a method for optimizing a motor.

[0017] A method for optimizing a motor comprises the following steps:

[0018] The sector angle and thickness of each permanent magnet in the combined sinusoidal magnetic pole, as well as the salient pole angle and thickness are used as optimization variables, and the average torque, torque ripple and back electromotive force harmonic rate are used as optimization targets.

[0019] Use analytical methods to obtain the mathematical relationship between optimization variables and optimization objectives;

[0020] A hybrid particle swarm optimization algorithm based on hybridization is used to globally optimize the motor performance and obtain the optimal sector angle and thickness of each permanent magnet and the optimal salient pole angle and thickness parameters.

[0021] Optionally, a weight coefficient λ is introduced to establish the optimization objective function, specifically:

[0022]

[0023] Where x i is the optimization variable, f(x i ) is the optimization variable x i The corresponding optimization objective function value when changing, i = 1, 2, 3...; T av0 、T r0 、E THD0 are the initial values ​​of average torque, torque ripple and back electromotive force harmonic rate, T av (x i ), T r (x i ), E THD (x i ) are the optimization variables x i The corresponding average torque, torque ripple and back electromotive force harmonic rate, λ1, λ2, λ3 are weight coefficients of the average torque, torque ripple and back electromotive force harmonic rate respectively, and satisfy λ1+λ2+λ3=1.

[0024] Optionally, also include:

[0025] The optimal sector angle and thickness of each permanent magnet, as well as the optimal salient pole angle and thickness parameters, were substituted into the finite element model for simulation analysis, and the finite element simulation results were compared and verified with the analytical calculation results.

[0026] The frozen permeability method is used to separate the reluctance torque and permanent magnet torque of the asymmetric salient pole axial flux motor, and verify whether the two torques achieve maximum superposition at the same current phase angle to complete the performance verification.

[0027] One or more of the above technical solutions have the following beneficial effects:

[0028] (1) The present invention provides a rotor, a motor and an optimization method with sinusoidal magnetic poles and asymmetric salient poles. A combined sinusoidal magnetic pole is designed, each of which includes a plurality of sector-shaped permanent magnets with different opening angles, and an air gap of a set angle is spaced between adjacent sector-shaped permanent magnets. The permanent magnet block of the combined sinusoidal magnetic pole helps to reduce the eddy current loss of the permanent magnet. The sinusoidal design of the permanent magnet modulated by the sinusoidal wave can effectively reduce the air gap magnetic density and back electromotive force harmonics. At the same time, since the proposed combined sinusoidal magnetic pole will generate a back electromotive force close to a sinusoidal one, the torque pulsation in the motor is reduced, and the vibration noise of the motor is reduced; and while eliminating harmonics, the iron loss of the motor is reduced, which helps the motor to maintain high efficiency operation.

[0029] (2) The present invention is a motor based on a rotor with sinusoidal magnetic poles and asymmetric salient poles. By designing salient poles that are close to the combined sinusoidal magnetic poles, a reluctance torque is generated while forming asymmetric salient poles to offset the rotor magnetic flux, thereby affecting the phase of the torque component, achieving the design goal of achieving the maximum value of the permanent magnet and reluctance torque components at the same current phase angle, realizing full utilization of the reluctance torque and permanent magnet torque, and improving the torque density of the motor.

[0030] (3) The motor of the present invention uses high-performance oriented silicon steel sheets for the stator core and rotor salient poles, which have lower costs and smaller losses than traditional non-oriented silicon steel sheets under the same conditions.

[0031] (4) In the motor of the present invention, the fractional slot distribution winding forms a magnetomotive force with a high sinusoidality through the reasonable arrangement of the windings, which can weaken the high-order harmonic potential generated by the non-sinusoidal distribution of the magnetic pole magnetic field; and can effectively weaken the amplitude of the tooth harmonic potential and improve the electromotive force waveform; and alleviate the pulse amplitude of the magnetic flux of each pole caused by the change of the air gap magnetic permeability, which is conducive to the high-quality operation of the motor.

[0032] (5) The optimization scheme for the asymmetric salient pole axial flux motor proposed in this invention uses a global multi-objective optimization method that combines analytical methods with a hybrid particle swarm optimization algorithm. Compared with traditional three-dimensional finite element calculations, it can effectively reduce the calculation time and host computer memory requirements. The proposed optimization scheme can not only make the air gap flux waveform and the motor back electromotive force tend to be sinusoidal, while ensuring high electromagnetic torque while reducing torque ripple, but also ensure that the reluctance torque and permanent magnet torque achieve the maximum superposition at the same current phase angle, thereby giving full play to the stable performance of the asymmetric salient pole axial flux motor.

[0033] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 Schematic diagram of the exploded structure of a motor based on a rotor with sinusoidal magnetic poles and asymmetric salient poles.

[0036] Figure 2(a) is a schematic diagram of the motor stator winding structure.

[0037] Figure 2(b) is a schematic diagram of the stator winding connection.

[0038] Figure 3(a) is a schematic diagram of the rotor structure of a motor.

[0039] Figure 3(b) is another schematic diagram of the rotor structure of the motor.

[0040] Figure 3(c) is a schematic diagram of the magnetic pole principle of a traditional axial flux motor.

[0041] FIG3( d ) is a schematic diagram of the design principle of the combined sinusoidal magnetic poles of the present invention.

[0042] Figure 3(e) is a schematic diagram of the principle of maximizing the superposition of permanent magnet torque and reluctance torque by combining sinusoidal magnetic poles and asymmetric salient pole designs.

[0043] Figure 4 Schematic diagram of the parameter optimization method of Example 3.

[0044] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0045] 1. Stator; 1-1. Modular core; 1-2. Fractional-slot distributed winding; 2. Asymmetric salient-pole rotor I; 2-1. End disc; 2-2. Salient pole; 2-3. N-pole sinusoidally distributed permanent magnet; 2-4. S-pole sinusoidally distributed permanent magnet; 3. Asymmetric salient-pole rotor II; 4. Sector-shaped permanent magnet No. 1; 5. Sector-shaped permanent magnet No. 2; 6. Sector-shaped permanent magnet No. 3; 7. Sector-shaped permanent magnet No. 4; 8. Sector-shaped permanent magnet No. 5; 9. Sector-shaped permanent magnet No. 6; 10. Sector-shaped permanent magnet No. 7. DETAILED DESCRIPTION

[0046] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0047] It should be noted that the terms used herein are for describing particular embodiments only and are not intended to limit the exemplary embodiments according to the present invention.

[0048] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0049] Example 1

[0050] This embodiment discloses a rotor structure with sinusoidal magnetic poles and asymmetric salient poles.

[0051] As shown in Figure 3(a) and Figure 3(b), the rotor with sinusoidal magnetic poles and asymmetric salient poles includes an end disk 2-1, combined sinusoidal magnetic poles and salient poles 2-2. The end disk 2-1 is made of high-performance non-oriented silicon steel sheets. Multiple groups of combined sinusoidal magnetic poles are evenly arranged on the end disk 2-1. Adjacent combined sinusoidal magnetic poles are magnetized in opposite directions. Each combined sinusoidal magnetic pole includes multiple sector-shaped permanent magnets with different angles. Adjacent sector-shaped permanent magnets are separated by an air gap of a set angle. The angle design of the multiple sector-shaped permanent magnets follows the projection law of sinusoidal pulse width modulation.

[0052] As shown in Figures 3(a) and 3(b), a plurality of combined sinusoidal magnetic poles are evenly arranged on the rotor end disk 2-1 of the motor, and the magnetization directions of adjacent combined sinusoidal magnetic poles are opposite, that is, each combined sinusoidal magnetic pole is alternately arranged with an N pole and an S pole, such as the N-pole sinusoidally distributed permanent magnet 2-3 and the S-pole sinusoidally distributed permanent magnet 2-4 in Figure 3(a); each combined sinusoidal magnetic pole is composed of a plurality of sector-shaped permanent magnets with different angles and the same magnetic properties, and the permanent magnets are arranged in a regular order from small to large and then from large to small according to the opening angle. The permanent magnet angle design follows the projection law of sinusoidal pulse width modulation to form a sinusoidal magnetic pole.

[0053] The combined sinusoidal magnetic poles are composed of multiple sector-shaped permanent magnets with different opening angles, and each permanent magnet is separated by an air gap of a certain angle.

[0054] In this embodiment, each combined sinusoidal magnetic pole includes a total of 7 sector-shaped permanent magnets with different opening angles. As shown in FIG3(b), the 7 sector-shaped permanent magnets are numbered as sector-shaped permanent magnet No. 1 4, sector-shaped permanent magnet No. 2 5, sector-shaped permanent magnet No. 3 6, sector-shaped permanent magnet No. 4 7, sector-shaped permanent magnet No. 5 8, sector-shaped permanent magnet No. 6 9 and sector-shaped permanent magnet No. 7 10, respectively. Among them, the sector-shaped permanent magnet No. 1 4 to the sector-shaped permanent magnet No. 4 7 are arranged in an increasing order of opening angle, and the sector-shaped permanent magnet No. 4 7 to the sector-shaped permanent magnet No. 7 are arranged in an increasing order of opening angle. Permanent magnet No. 7 10 is arranged from large to small in angle; the gap between sector-shaped permanent magnet No. 1 4 and sector-shaped permanent magnet No. 2 5, the gap between sector-shaped permanent magnet No. 2 5 and sector-shaped permanent magnet No. 3 6, and the gap between permanent magnet No. 3 6 and permanent magnet No. 4 7 are arranged from large to small; the gap between permanent magnet No. 4 7 and permanent magnet No. 5 8, the gap between permanent magnet No. 5 8 and permanent magnet No. 6 9, and the gap between permanent magnet No. 6 9 and permanent magnet No. 7 10 are arranged from small to large.

[0055] In order to effectively utilize the space of the end disc 2-1, as shown in Figure 2, a salient pole 2-2 made of oriented silicon steel sheet material is also provided on the rotor end disc 2-1, close to the outermost side of the combined sinusoidal magnetic pole. The oriented silicon steel sheet is rolled in the axial direction and stacked in the radial direction.

[0056] Compared to a single combined sinusoidal pole, the salient pole is designed to be close to the combined permanent magnet. The salient pole 2-2 is asymmetrically arranged relative to the entire combined sinusoidal pole. This allows for the complete superposition of permanent magnet torque and reluctance torque. The core of the asymmetric salient pole 2-2 structure adopts a fan-shaped structure.

[0057] Sine wave pulse width modulation:

[0058] When performing pulse width modulation, the duty cycle of the pulse series is arranged according to the sinusoidal law. When the sine value is the largest, the pulse width is also the largest, and the interval between pulses is the smallest; conversely, when the sine value is smaller, the pulse width is also smaller, and the interval between pulses is larger. Such a voltage pulse series can greatly reduce the high-order harmonic components in the load current, which is called sinusoidal pulse width modulation.

[0059] Therefore, in this embodiment, the multiple sector-shaped permanent magnets of each combined sinusoidal magnetic pole are arranged in a pattern of opening angle from small to large and then from large to small; correspondingly, the gap sizes between adjacent sector-shaped permanent magnets are arranged in a pattern of gaps from large to small and then from small to large.

[0060] Example 2

[0061] This embodiment discloses a motor.

[0062] A motor comprises a stator 1 and a rotor with sinusoidal magnetic poles and asymmetric salient poles as described in Example 1, wherein the rotor with sinusoidal magnetic poles and asymmetric salient poles is arranged on both sides of the stator 1, and the stator 1 comprises a modular iron core 1-1 and a fractional-slot distributed winding 1-2 wound on the modular iron core 1-1.

[0063] In this embodiment, the rotors provided on both sides of the stator 1 are rotor I2 and rotor II3, and both have the same structure.

[0064] The motor stator 1 consists of a modular iron core 1-1 and a fractional slot distributed winding 1-2, wherein the modular iron core 1-1 is made of stacked oriented silicon steel sheets, which are rolled in the axial direction, and the fractional slot distributed winding 1-2 adopts a double-layer winding design, and the winding is wound on the modular core.

[0065] The motor of this embodiment is an asymmetric salient pole 2-2 axial flux motor. Figure 1Specifically, it includes: a motor stator 1, and a rotor I2 and a rotor II3 symmetrically arranged on both sides of the motor stator 1. The rotor I2 and the rotor II3 have the same structure, both adopting the rotor structure with sinusoidal magnetic poles and asymmetric salient poles of the first embodiment.

[0066] Among them, the iron core adopts an I-shaped structure, which is convenient for winding. The material is selected from high-performance oriented silicon steel sheets. The silicon steel sheets are rolled in the axial direction and stacked in the radial direction.

[0067] In combination with the motor stator 1 winding structure disclosed in Figures 2(a)-(b), taking the 27-slot winding as an example, Figure 2(a) is a wiring diagram of the upper winding in the double-layer winding, and Figure 2(b) is a wiring diagram of the entire winding structure.

[0068] Figure 3(c) is the schematic diagram of a traditional axial flux motor. This traditional solution generates square wave magnetomotive force, which results in high harmonic rates of back electromotive force and air gap magnetic field, causing high operating torque pulsation, which does not meet the requirements of high-performance motors.

[0069] Figure 3(d) shows the proposed axial flux motor with combined sinusoidal magnetic poles. The angle design of the permanent magnets follows the projection law of sinusoidal pulse width modulation, so that they form sinusoidal magnetic poles, which can effectively reduce the air gap magnetic density and back electromotive force harmonics and greatly improve the sinusoidality.

[0070] Figure 3(e) is the principle diagram of the asymmetric salient pole 2-2 design. The asymmetric salient pole 2-2 design generates reluctance torque and makes the permanent magnet and reluctance torque components reach their maximum values ​​at the same current phase angle, thereby fully utilizing the reluctance torque and permanent magnet torque.

[0071] The asymmetric salient pole 2-2 axial flux motor proposed in this embodiment integrates a sinusoidal pole design, a salient pole 2-2 design, and a fractional slot distributed winding 1-2 design:

[0072] The combined sinusoidal magnetic poles can effectively reduce the air gap magnetic density and back electromotive force harmonics, greatly improving the sinusoidality; the salient pole 2-2 design can generate reluctance torque, realize the full utilization of reluctance torque and permanent magnet torque, and improve the torque density of the motor; the fractional slot distributed winding 1-2 forms a magnetomotive force with higher sinusoidality through the reasonable arrangement of the windings, which is conducive to the high-quality operation of the motor.

[0073] Example 3

[0074] This embodiment discloses a method for optimizing a motor.

[0075] like Figure 4As shown, in this embodiment, the sector angle and thickness of each permanent magnet in the combined sinusoidal magnetic pole and the angle and thickness of the salient pole 2-2 of the oriented silicon steel sheet are used as optimization variables, and a reasonable optimization variable range is determined, with the average torque, torque pulsation and back electromotive force harmonic rate as optimization targets; an optimization scheme is designed to optimize the sector angle and thickness of each permanent magnet and salient pole 2-2.

[0076] In order to improve optimization efficiency and save optimization costs, combined Figure 4 , the optimization scheme of this embodiment is as follows:

[0077] (1) The sector angle and thickness of each permanent magnet in the combined sinusoidal magnetic pole and the 2-2 angle and thickness of the silicon steel salient pole are used as optimization variables, and a reasonable optimization variable range is determined, with average torque, torque ripple, and back electromotive force harmonic rate as optimization targets;

[0078] Since there are constraints between multiple optimization objectives that cannot be optimized at the same time, and the importance of the three optimization objectives is also different, the weight coefficient λ is introduced to establish the optimization objective function. The objective function covers the average torque and the torque ripple back electromotive force harmonic rate, as shown below:

[0079]

[0080] Where x i is the optimization variable, f(x i ) is the optimization variable x i The corresponding optimization objective function value when changing, i = 1, 2, 3... T av0 、T r0 、E THD0 are the initial values ​​of average torque, torque ripple and back electromotive force harmonic rate, T av (x i ), T r (x i ), E THD (x i ) are the optimization variables x i The corresponding average torque, torque pulsation and back electromotive force harmonic rate, λ1, λ2, λ3 are the weight coefficients of average torque, torque pulsation and back electromotive force harmonic rate respectively, and satisfy λ1+λ2+λ3=1. Since the asymmetric salient pole 2-2 axial flux motor pays more attention to the output torque performance, the weight coefficient λ1 of the average torque is set to 0.4, the weight coefficient λ2 of the torque pulsation is set to 0.3, and the weight coefficient λ3 of the back electromotive force harmonic rate is set to 0.3.

[0081] (2) An analytical model of the magnetic field of an asymmetric salient pole 2-2 axial flux motor is established using an analytical method. The motor back electromotive force and harmonic rate are obtained by calculating the no-load magnetic field of the motor. The torque waveform is solved using the Maxwell tensor method to obtain the effective average torque and torque ripple.

[0082] The motor analysis method establishes partial differential equations or integral equations representing the electromagnetic field characteristics of different regions of the motor based on the structure and size of the motor itself, and then solves the Laplace equation and Poisson equation in each region through boundary conditions to finally obtain the relationship expression between the motor performance and design parameters. It is a fast and effective motor analysis method.

[0083] This embodiment uses an analytical method to obtain the mathematical relationship between the optimization variables and the optimization target, namely, the relationship between the sector angle and thickness of each permanent magnet and the 2-2 angle and thickness of the silicon steel salient pole and the average torque, torque ripple, and back electromotive force harmonic rate;

[0084] The specific implementation of the analytical method is based on existing technology and can be achieved by rewriting the results of the asymmetric salient-pole 2-2 axial flux motor of the present invention. This embodiment will not be described in detail. Compared with the finite element method, the electromagnetic field analytical method based on classical mathematical analysis methods has the greatest advantages of clear physical concepts, easy to understand, and low solution workload and time consumption.

[0085] (3) A hybrid particle swarm algorithm based on hybridization is used to globally optimize the motor performance to obtain the optimal permanent magnet sector angle and thickness, and the optimal salient pole 2-2 angle and thickness parameters.

[0086] The range of each input optimization variable is divided into intervals, and a random sampling observation is performed on the input variable within each interval; the sampled permanent magnet sector angle and thickness, salient pole 2-2 angle and thickness values ​​are substituted into the analytical method function for solution to obtain the average torque, torque pulsation, and back electromotive force harmonic rate output results.

[0087] The particle swarm algorithm was used to optimize the objective function established by the analytical method, and the optimal dimensional parameters were obtained. To verify the accuracy of the analytical model optimization, the dimensional parameters of the optimal analytical model were substituted into the finite element model for simulation analysis. The average torque, torque ripple, and back-EMF harmonic ratio obtained from the finite element simulation were compared with the average torque, torque ripple, and back-EMF harmonic ratio calculated using the analytical method to verify performance matching.

[0088] (4) The frozen permeability method is used to separate the reluctance torque and permanent magnet torque of the proposed asymmetric salient pole 2-2 axial flux motor, and verify whether the two torques achieve maximum superposition at the same current phase angle to complete the performance verification.

[0089] To facilitate the study of the motor's output torque characteristics, the frozen permeability method is used to separate the permanent magnet torque and reluctance torque components. The specific approach is to first freeze the permeability of the rotor and stator silicon steel sheets using finite element simulation. Then, the permanent magnets are removed and the reluctance torque is simulated under the action of only the armature current. Finally, the reluctance torque is subtracted from the total electromagnetic torque to obtain the permanent magnet torque corresponding to the rated operating state.

[0090] The frozen permeability method is used to obtain the reluctance torque and permanent magnet torque of the optimal model, and it is verified whether the two torque waveforms achieve maximum superposition at the same current phase angle.

[0091] The parameter optimization method of this embodiment has the advantages of high optimization accuracy, strong algorithm adaptability, and short calculation time. The rotor magnetomotive force, air gap magnetic flux density, and back electromotive force of the obtained optimization results are highly sinusoidal, which significantly reduces torque pulsation and improves torque performance.

[0092] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A method for optimizing a motor, characterized in that: The following steps are involved: The fan angle and thickness of each permanent magnet in the combined sinusoidal magnetic pole, as well as the salient pole angle and thickness are used as optimization variables, and the average torque, torque ripple and back electromotive force harmonic rate are used as optimization targets. The mathematical relationship between the optimization variables and the optimization targets is obtained by analytical method, and the weight coefficient is introduced. Establish the optimization objective function, specifically: ； Where, To optimize the variables, To optimize variables The corresponding optimization objective function value when changes, ; 、 、 are the initial values ​​of average torque, torque ripple and back EMF harmonic rate, respectively. 、 、 Optimization variables The corresponding average torque, torque ripple and back EMF harmonic rate, 、 、 are the weight coefficients of average torque, torque ripple and back electromotive force harmonic rate, and satisfy ; A hybrid particle swarm optimization algorithm based on hybridization is used to globally optimize the motor performance and obtain the optimal sector angle and thickness of each permanent magnet, as well as the optimal salient pole angle and thickness parameters. The motor includes: a rotor with sinusoidal magnetic poles and asymmetric salient poles, multiple groups of combined sinusoidal magnetic poles evenly arranged on the end disk, adjacent combined sinusoidal magnetic poles have opposite magnetization directions, each of the combined sinusoidal magnetic poles includes multiple sector-shaped permanent magnets with different opening angles, and adjacent sector-shaped permanent magnets are separated by air gaps of a set angle. The angle design of the multiple sector-shaped permanent magnets follows the projection law of sinusoidal wave pulse width modulation.

2. The motor optimization method according to claim 1, characterized in that: Also includes: The optimal sector angle and thickness of each permanent magnet, as well as the optimal salient pole angle and thickness parameters, were substituted into the finite element model for simulation analysis, and the finite element simulation results were compared and verified with the analytical calculation results. The frozen permeability method is used to separate the reluctance torque and permanent magnet torque of the asymmetric salient pole axial flux motor, and verify whether the two torques achieve maximum superposition at the same current phase angle to complete the performance verification.

3. The motor optimization method according to claim 1, characterized in that: The plurality of sector-shaped permanent magnets of each combined sinusoidal magnetic pole are distributed as a whole along the circumference of the end disk, and each sector-shaped permanent magnet is arranged along the radial direction of the end disk.

4. The motor optimization method according to claim 1, wherein: A salient pole is closely arranged on one side of each combined sinusoidal magnetic pole. The salient pole is formed by stacking oriented silicon steel sheets, which are rolled along the axial direction of the end disc. The salient pole is fan-shaped.

5. The motor optimization method according to claim 1, wherein: The plurality of sector-shaped permanent magnets of each combined sinusoidal magnetic pole are arranged in a regular order from small to large opening angles and then from large to small opening angles.

6. A motor, characterized in that: The motor is obtained by using the motor optimization method described in any one of claims 1 to 5. The motor includes a stator and a rotor with sinusoidal poles and asymmetric salient poles. The rotor with sinusoidal magnetic poles and asymmetric salient poles is arranged on both sides of the stator. The stator includes a modular iron core and a fractional slot distributed winding wound on the modular iron core.

7. The motor according to claim 6, characterized in that The modular core adopts an I-shaped structure and is formed by stacking oriented silicon steel sheets.

8. The motor according to claim 6, wherein The fractional slot distributed winding adopts a double-layer winding design.

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