Axial flux permanent magnet motor magnetic circuit matching method

Abstract

This invention relates to the field of high-efficiency motor technology and discloses a magnetic circuit matching method for an axial flux permanent magnet motor. The method obtains the initial structural parameters and performance design indicators of the axial flux permanent magnet motor. Based on the principle of equal flux area, the effective air gap region is radially divided into multiple annular calculation layers with equal areas. For each annular calculation layer, the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density are determined, thereby generating magnetic circuit deviation information characterizing the radial non-uniformity of the air gap magnetic flux density and the saturation degree of the stator core magnetic flux density. Based on this magnetic circuit deviation information, stator and rotor magnetic circuit parameters such as the ratio of stator tooth width to tooth pitch, stator yoke thickness, permanent magnet pole arc coefficient, and axial thickness are adjusted and matched in a zoned manner. This ensures that the air gap magnetic flux density of each annular calculation layer tends to be consistent radially, and that the stator tooth magnetic flux density and yoke magnetic flux density do not exceed the knee magnetic flux density of the core material. This optimizes magnetic field coupling, suppresses leakage flux, and improves the motor's torque performance and operating efficiency.

Description

Technical Field

[0001] This invention relates to the field of high-efficiency motor technology, and in particular to a magnetic circuit matching method for an axial flux permanent magnet motor. Background Technology

[0002] Axial flux permanent magnet motors (APMs) possess advantages such as short axial dimensions, high power density, and high torque density, representing a significant development direction in the field of high-efficiency motors. They are widely used in electric vehicles, distributed power generation, and industrial drives. However, due to the axially opposite arrangement of the stator and rotor and the radial distribution of the air gap magnetic field, differences exist in circumferential velocity, tooth structure, and magnetic circuit saturation at different radii. This often results in uneven radial distribution of the air gap magnetic flux density, leading to localized magnetic flux saturation in the stator teeth and yoke. Furthermore, magnetic leakage exists between adjacent poles and at the radial edges of the permanent magnet, resulting in decreased magnetic field coupling and hindering the full realization of torque performance and operating efficiency. Existing designs often use a single-radius cross-section or uniform structural parameters for magnetic circuit calculations, failing to effectively match the stator and rotor magnetic circuit parameters based on the magnetic flux density distribution in different radial regions. This makes it difficult to balance the uniformity of the air gap magnetic flux density with the core magnetic flux density constraint, thus limiting further performance improvements in APMs. Therefore, a magnetic circuit matching method that can coordinate stator and rotor magnetic circuit parameters and improve magnetic flux density distribution is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a magnetic circuit matching method for axial flux permanent magnet motors to solve the problems of poor stator-rotor magnetic field coupling, torque performance, and operating efficiency caused by uneven radial distribution of air gap magnetic flux density, local magnetic flux saturation of stator core, and magnetic leakage between poles and ends in existing axial flux permanent magnet motors. By layering according to the principle of equal magnetic flux area and performing partitioned coordinated matching of stator and rotor magnetic circuit parameters, the air gap magnetic flux density of each annular calculation layer tends to be consistent radially, and the magnetic flux density of stator teeth and yoke does not exceed the knee magnetic flux density of the core material, thereby optimizing magnetic field coupling, suppressing magnetic leakage, and improving the torque performance and operating efficiency of the motor.

[0004] To achieve the above objectives, this invention provides a magnetic circuit matching method for an axial flux permanent magnet motor, applied to a magnetic circuit matching device. This device is communicatively connected to an electromagnetic simulation unit of the axial flux permanent magnet motor. The axial flux permanent magnet motor includes a stator and a rotor arranged coaxially opposite each other. The stator has stator teeth arranged circumferentially, and the rotor has permanent magnets arranged circumferentially. The method includes: obtaining the initial structural parameters and performance design indicators of the axial flux permanent magnet motor; dividing the effective air gap region of the motor radially into multiple annular calculation layers; and for each annular calculation layer, determining the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke of that annular calculation layer. The magnetic flux density is calculated to obtain magnetic flux density distribution information. Based on preset matching evaluation rules, magnetic circuit deviation information is generated according to the magnetic flux density distribution information. This magnetic circuit deviation information characterizes the radial non-uniformity of the air gap magnetic flux density of each annular calculation layer and the magnetic flux density saturation of the stator core. The stator magnetic circuit parameters and rotor magnetic circuit parameters of the stator are matched and adjusted according to the magnetic circuit deviation information so that the air gap magnetic flux density of each annular calculation layer tends to be consistent in the radial direction, and the magnetic flux density of the stator teeth and the stator yoke does not exceed the knee point magnetic flux density of the stator core material magnetization curve. This ensures that the torque performance and operating efficiency of the axial flux permanent magnet motor meet the performance design indicators, thus achieving magnetic circuit matching.

[0005] Optionally, when dividing the effective air gap region into multiple annular calculation layers radially, the division is carried out according to the principle of equal magnetic flux area, so that the annular area of ​​each annular calculation layer is equal to that of each other, and the number of annular calculation layers is not less than three. The radial width of each annular calculation layer decreases sequentially from the inner diameter side to the outer diameter side. When determining the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density of each annular calculation layer, the circumferential unfolded section at the average radius of the annular calculation layer is used as the calculation plane. Based on the preset layered magnetic circuit model, the air gap magnetic flux and stator core magnetic flux of the annular calculation layer are solved according to the initial structural parameters to obtain the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density of the annular calculation layer.

[0006] Optionally, when establishing a preset layered magnetic circuit model, the permanent magnet in the annular calculation layer is equivalent to a branch in series between the magnetomotive force source and the magnetic permeability in the permanent magnet. In the preset layered magnetic circuit model, an air gap magnetic permeability branch, an inter-pole leakage magnetic permeability branch located between adjacent magnetic poles, and an end leakage magnetic permeability branch located at the radial edge of the permanent magnet are set.

[0007] Optionally, the magnetic circuit deviation information includes air gap magnetic flux density uniformity deviation and magnetic flux density saturation deviation. When generating the magnetic circuit deviation information, the average value of the air gap magnetic flux density amplitude of all annular calculation layers is determined based on the air gap magnetic flux density of each annular calculation layer. The deviation between the air gap magnetic flux density amplitude of each annular calculation layer and the average value is determined as the air gap magnetic flux density uniformity deviation. The deviation between the stator tooth magnetic flux density, the stator yoke magnetic flux density and the stator core material magnetization curve knee point magnetic flux density is determined as the magnetic flux density saturation deviation.

[0008] Optionally, the magnetic circuit deviation information also includes a comprehensive matching deviation index; when generating the magnetic circuit deviation information, the weighting coefficients corresponding to the air gap magnetic flux uniformity deviation and the magnetic flux saturation deviation are obtained respectively, and the air gap magnetic flux uniformity deviation and the magnetic flux saturation deviation are weighted and summed according to each weighting coefficient to obtain the comprehensive matching deviation index.

[0009] Optionally, before performing matching adjustments, if the comprehensive matching deviation index is greater than or equal to the first deviation threshold, the magnetic circuit is determined to be in the first mismatch level; if the comprehensive matching deviation index is greater than or equal to the second deviation threshold and less than the first deviation threshold, the magnetic circuit is determined to be in the second mismatch level; wherein the first deviation threshold is greater than the second deviation threshold, and the adjustment step size corresponding to the first mismatch level is greater than the adjustment step size corresponding to the second mismatch level, and the adjustment step size is used to determine the single adjustment amplitude when performing matching adjustments.

[0010] Optionally, the stator magnetic circuit parameters include the ratio of the stator tooth width to the stator tooth pitch and the stator yoke thickness, and the rotor magnetic circuit parameters include the pole arc coefficient of the permanent magnet and the axial thickness of the permanent magnet. When performing matching adjustment, the magnetic circuit parameters to be adjusted and the adjustment direction of the magnetic circuit parameters to be adjusted corresponding to the magnetic circuit deviation information are determined according to the preset deviation-adjustment mapping relationship, and the matching adjustment of the magnetic circuit parameters to be adjusted is performed according to the magnetic circuit parameters to be adjusted and their adjustment direction.

[0011] Optionally, when determining the magnetic circuit parameters to be adjusted and their adjustment direction, for annular calculation layers where the stator tooth magnetic flux density reaches the knee magnetic flux density of the stator core material magnetization curve, the ratio of the stator tooth width to the stator tooth pitch of the annular calculation layer is determined as the magnetic circuit parameter to be adjusted, and the adjustment direction is to increase; for annular calculation layers where the air gap magnetic flux density amplitude is lower than the average of the air gap magnetic flux density amplitudes of all annular calculation layers, the permanent magnet pole arc coefficient of the corresponding radial segment of the annular calculation layer is determined as the magnetic circuit parameter to be adjusted, and the adjustment direction is to increase; for annular calculation layers where the air gap magnetic flux density amplitude is higher than the average value, the permanent magnet pole arc coefficient of the corresponding radial segment is determined as the magnetic circuit parameter to be adjusted, and the adjustment direction is to decrease; the single adjustment amplitude of the magnetic circuit parameter to be adjusted is determined according to the mismatch level of the magnetic circuit.

[0012] Optionally, after matching and adjusting, the updated magnetic flux density distribution information of each annular computing layer is determined based on the matched and adjusted magnetic circuit parameters, and updated magnetic circuit deviation information is generated. When the updated magnetic circuit deviation information indicates that the air gap magnetic flux density does not tend to be consistent radially or the magnetic flux density of the stator teeth and the stator yoke exceeds the knee magnetic flux density, the matching and adjusting is performed again based on the updated magnetic circuit deviation information until the magnetic circuit deviation information meets the preset convergence condition or the number of adjustments reaches the preset number threshold. When the number of adjustments reaches the preset number threshold and the magnetic circuit deviation information still does not meet the preset convergence condition, a magnetic circuit matching anomaly prompt is generated.

[0013] Optionally, the method further includes: obtaining electromagnetic performance verification information of the matched and adjusted axial flux permanent magnet motor through an electromagnetic simulation unit, the electromagnetic performance verification information including at least one of average torque, torque ripple and operating efficiency; and updating at least one of knee magnetic flux density and preset matching evaluation rules based on the electromagnetic performance verification information, so that the torque performance and operating efficiency of the axial flux permanent magnet motor meet the performance design indicators in the subsequent matching process.

[0014] This invention divides the effective air gap region radially into multiple annular calculation layers with equal areas according to the principle of equal magnetic flux area. For each annular calculation layer, the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density are calculated separately. This accurately characterizes the radial distribution differences of the axial flux permanent magnet motor's magnetic flux density, providing a basis for fine matching of magnetic circuit parameters. Furthermore, based on magnetic circuit deviation information characterizing the radial non-uniformity of the air gap magnetic flux density and the saturation degree of the stator core magnetic flux density, the invention optimizes the ratio of stator tooth width to tooth pitch, stator yoke thickness, permanent magnet pole arc coefficient, and axial flux density. By performing zoned and coordinated matching adjustments to the stator and rotor magnetic circuit parameters, such as thickness, the air gap magnetic flux density of each annular calculation layer tends to be consistent radially, effectively improving the uniformity of the air gap magnetic field distribution and enhancing the magnetic field coupling effect between the stator and rotor. At the same time, the magnetic flux density of the stator teeth and yoke does not exceed the knee magnetic flux density of the core material, avoiding local magnetic flux saturation, and reducing leakage flux loss by suppressing inter-pole and end leakage flux. In turn, the average torque of the motor is improved, torque pulsation is suppressed, and operating efficiency is improved, achieving reasonable matching and performance optimization of the magnetic circuit of the axial flux permanent magnet motor. Attached Figure Description

[0015] Figure 1 A schematic flowchart illustrating the magnetic circuit matching method for an axial flux permanent magnet motor provided by the present invention; Figure 2 A schematic diagram illustrating the ring-shaped computing layer partitioning provided by this invention; Figure 3 A schematic diagram of the layered magnetic circuit model provided by the present invention; Figure 4 A schematic diagram illustrating the magnetic circuit matching adjustment principle provided by this invention; Figure 5 This is a schematic diagram showing the comparison of magnetic flux density distribution matching before and after the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0018] To more clearly illustrate the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0019] Example 1: This embodiment provides a magnetic circuit matching method for an axial flux permanent magnet motor, the main process of which is described in [link to main flowchart]. Figure 1 By layering according to the principle of equal magnetic flux area and solving the magnetic flux density of each annular calculation layer, evaluating the deviation, and matching and adjusting, the air gap magnetic flux density tends to be consistent in the radial direction, and the magnetic flux density of the stator teeth and the stator yoke does not exceed the knee point magnetic flux density, thereby improving the coupling of the stator and rotor magnetic fields, suppressing leakage flux, and improving the torque performance and operating efficiency of the motor; the method includes steps S1 to S5.

[0020] The system structure shared by all embodiments of the present invention includes a magnetic circuit matching device 1, an electromagnetic simulation unit 2, and an axial flux permanent magnet motor 3. The magnetic circuit matching device 1 is communicatively connected to the electromagnetic simulation unit 2. The magnetic circuit matching device 1 is used to perform each step of magnetic circuit matching, and the electromagnetic simulation unit 2 is used to verify the electromagnetic performance of the matching results. The axial flux permanent magnet motor 3 includes a stator and a rotor arranged coaxially opposite to each other. The stator has stator teeth arranged circumferentially, and the rotor has permanent magnets arranged circumferentially. In subsequent embodiments, unless otherwise stated, the system structure is the same as this paragraph and will not be repeated here.

[0021] Step S1: Obtain the initial structural parameters and performance design indicators of the axial flux permanent magnet motor 3, and divide the effective air gap region of the motor into multiple annular calculation layers radially according to the principle of equal flux area.

[0022] Specifically, the initial structural parameters are used to describe the initial geometry and material properties of the stator and rotor, including the motor outer diameter, inner diameter, number of pole pairs, number of stator teeth, initial stator tooth width, initial stator yoke thickness, initial pole arc coefficient of permanent magnet, initial axial thickness of permanent magnet, and axial air gap length, etc.; the performance design index is used to define the target to be achieved by the matching, including the target value of average torque and the target value of operating efficiency.

[0023] Furthermore, the division in step S1 is performed according to the principle of equal magnetic flux area, ensuring that the annular areas of each annular calculation layer are equal. Since the annular areas of each annular calculation layer are equal but their radii are different, the radial width of the annular calculation layer on the inner diameter side is larger, and the radial width of the annular calculation layer on the outer diameter side is smaller. That is, the radial width of each annular calculation layer decreases sequentially from the inner diameter side to the outer diameter side. See [link to relevant documentation]. Figure 2 The number of annular calculation layers shall be no less than three to reflect sufficient distribution differences in the radial direction; in this embodiment, the number is five, but it can also be any integer from three to ten. For example, taking a motor with an outer diameter of 280 mm and an inner diameter of 180 mm as an example, after dividing it into five annular calculation layers according to the principle of equal magnetic flux area, the radial width of each annular calculation layer from the inner diameter side to the outer diameter side is approximately 24 mm, 21 mm, 19 mm, 18 mm, and 17 mm respectively, and its average radius increases sequentially from the inner diameter side to the outer diameter side. The above values ​​are all exemplary values ​​and can be adjusted accordingly based on the motor size.

[0024] Step S2: For each annular computing layer, determine the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density of that annular computing layer to obtain magnetic flux density distribution information.

[0025] Specifically, for each annular computational layer, the circumferentially expanded section at the average radius of the annular computational layer is used as the computational plane of that annular computational layer, and a layered magnetic circuit model is established on this computational plane. When establishing this layered magnetic circuit model, the permanent magnet within the annular computational layer is equivalent to a branch where a magnetomotive force source and the magnetic permeability within the permanent magnet are connected in series. An air gap magnetic permeability branch, an inter-pole leakage magnetic permeability branch located between adjacent magnetic poles, and an end leakage magnetic permeability branch located at the radial edge of the permanent magnet are set in the layered magnetic circuit model to obtain the layered magnetic circuit model of the annular computational layer. See [link to relevant documentation]. Figure 3 Among them, the magnetic permeability within the permanent magnet is used to characterize the permanent magnet's ability to conduct magnetic flux, the air gap magnetic permeability branch is used to characterize the transmission path of magnetic flux from the rotor to the stator through the air gap, and the inter-pole leakage magnetic permeability branch and the end leakage magnetic permeability branch are used to characterize the leakage magnetic paths between adjacent magnetic poles and at the radial edge of the permanent magnet that are not effectively coupled by the air gap, respectively.

[0026] Furthermore, on this computational plane, the layered magnetic circuit model is solved based on the initial structural parameters to obtain the air gap flux and stator core flux of the annular computational layer. The air gap flux is then divided by the corresponding effective air gap area to obtain the air gap magnetic flux density of the annular computational layer. The stator tooth flux is divided by the effective cross-sectional area of ​​the stator teeth to obtain the stator tooth magnetic flux density, and the stator yoke flux is divided by the effective cross-sectional area of ​​the stator yoke to obtain the stator yoke magnetic flux density. This process is repeated for all annular computational layers to obtain the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density for each annular computational layer. Understandably, other equivalent magnetic circuit calculation methods can also be used here, as long as the above three magnetic flux densities for each annular computational layer can be obtained.

[0027] Step S3: Based on the preset matching evaluation rules, generate magnetic circuit deviation information according to the magnetic flux density distribution information. This magnetic circuit deviation information characterizes the radial non-uniformity of the air gap magnetic flux density of each annular calculation layer and the magnetic flux density saturation of the stator core.

[0028] Specifically, the average value of the air gap magnetic flux density amplitude of all annular computational layers is first determined based on the air gap magnetic flux density of each annular computational layer. Then, the deviation between the air gap magnetic flux density amplitude of each annular computational layer and this average value is used as a characterization of the radial non-uniformity of the air gap magnetic flux density. Simultaneously, the stator tooth magnetic flux density, stator yoke magnetic flux density of each annular computational layer are compared with the knee magnetic flux density of the stator core material magnetization curve, and the deviation between the two is used as a characterization of the saturation degree of the stator core magnetic flux density. Among them, the knee magnetic flux density is the magnetic flux density corresponding to the inflection point on the stator core material magnetization curve where it transitions from the linear region to the saturation region, and is used to define whether the core is approaching saturation. For example, taking commonly used silicon steel sheets as an example, the knee magnetic flux density is taken as approximately 1.6 Tesla to 1.7 Tesla, and the specific value is determined according to the selected core material.

[0029] Step S4: Match and adjust the stator magnetic circuit parameters of the stator and the rotor magnetic circuit parameters of the rotor according to the magnetic circuit deviation information, so that the air gap magnetic flux density of each annular calculation layer tends to be consistent in the radial direction, and the magnetic flux density of the stator teeth and the magnetic flux density of the stator yoke do not exceed the knee point magnetic flux density.

[0030] Specifically, the stator magnetic circuit parameters include the ratio of stator tooth width to stator tooth pitch and the stator yoke thickness, and the rotor magnetic circuit parameters include the permanent magnet pole arc coefficient and the permanent magnet axial thickness. In this embodiment, step S4 is performed in the following general manner: for the annular calculation layer where the stator tooth magnetic flux density reaches the knee magnetic flux density, the ratio of stator tooth width to stator tooth pitch of the annular calculation layer is increased to reduce the stator tooth magnetic flux density at that location; for the annular calculation layer where the air gap magnetic flux density amplitude is lower than the aforementioned average value, the permanent magnet pole arc coefficient of the corresponding radial segment of the annular calculation layer is increased; for the annular calculation layer where the air gap magnetic flux density amplitude is higher than the average value, the permanent magnet pole arc coefficient of the corresponding radial segment is decreased, thereby making the air gap magnetic flux density amplitudes of each annular calculation layer closer to each other; in addition, the stator yoke thickness is determined based on the annular calculation layer with the largest stator yoke magnetic flux, so that the stator yoke magnetic flux density at that location does not exceed the knee magnetic flux density, and the matching relationship between the permanent magnet axial thickness and the axial air gap length is determined based on the target amplitude of the air gap magnetic flux density.

[0031] Step S5: Determine whether the average torque and operating efficiency meet the performance design specifications; when both meet the performance design specifications, output the matched stator magnetic circuit parameters and rotor magnetic circuit parameters to complete the magnetic circuit matching.

[0032] For example, taking an axial flux permanent magnet motor with an outer diameter of 280 mm, an inner diameter of 180 mm, ten pole pairs, and twelve stator teeth as an example, the initial pole arc coefficient is taken as 0.7, the ratio of the initial stator tooth width to the stator tooth pitch is taken as 0.42, and the knee point magnetic flux density is taken as 1.7 Tesla. After matching according to steps S1 to S5, the amplitude of the air gap magnetic flux density of each annular calculation layer tends to approach each other from the obvious radial fluctuations at the matching front edge. The magnetic flux density of the stator teeth and the stator yoke both drop below the knee point magnetic flux density. For a comparison of the radial distribution of the air gap magnetic flux density and the stator tooth magnetic flux density before and after matching, see [link to relevant documentation]. Figure 5 The structural parameters, pole arc coefficient, tooth width to tooth pitch ratio, knee magnetic flux density, and motor dimensions mentioned above are all exemplary values ​​and can be adjusted accordingly based on the actual motor.

[0033] Understandably, the specific implementation of steps S1 to S5 in this embodiment, including the number of annular calculation layers, the radial width and average radius of each annular calculation layer, the branch structure of the layered magnetic circuit model, the solution method for each magnetic flux density, and the specific values ​​of the matching adjustment, are all exemplary descriptions. Those skilled in the art can make corresponding adjustments based on the specific structure, material properties, and performance design indicators of the motor, without departing from the concept of this invention.

[0034] Example 2: This embodiment, based on Embodiment 1, further refines the method for generating magnetic circuit deviation information and classifies the degree of magnetic circuit mismatch according to the comprehensive matching deviation index. This allows the matching adjustment to determine the single adjustment amplitude according to the degree of mismatch, thereby improving the uniformity of air gap magnetic flux density, avoiding stator core magnetic flux density saturation, and increasing the efficiency of matching adjustment. The system structure of this embodiment is the same as that of Embodiment 1; see [link to Embodiment 1]. Figures 1 to 3 This will not be elaborated upon here.

[0035] In step S3, the magnetic circuit deviation information is set to include air gap magnetic flux uniformity deviation and magnetic flux saturation deviation.

[0036] Specifically, the average value of the air gap magnetic flux density amplitude of all annular calculation layers is first determined based on the air gap magnetic flux density of each annular calculation layer. Then, the deviation between the air gap magnetic flux density amplitude of each annular calculation layer and this average value is taken as the air gap magnetic flux density uniformity deviation. At the same time, the deviations between the stator tooth magnetic flux density, the stator yoke magnetic flux density, and the knee magnetic flux density of each annular calculation layer are taken as the magnetic flux density saturation deviation. Furthermore, the air gap magnetic flux density uniformity deviation is used to reflect the degree of radial fluctuation of the air gap magnetic flux density, and the magnetic flux density saturation deviation is used to reflect the degree to which the stator core approaches saturation.

[0037] In step S3, the magnetic circuit deviation information is also set to include the comprehensive matching deviation index.

[0038] For example, weighting coefficients are assigned to the air gap magnetic flux density uniformity deviation and the magnetic flux density saturation deviation, respectively, and the two are weighted and summed to obtain the comprehensive matching deviation index. In this embodiment, the weighting coefficient for the air gap magnetic flux density uniformity deviation is 0.6, and the weighting coefficient for the magnetic flux density saturation deviation is 0.4. These coefficients can also be adjusted between 0 and 1 depending on the emphasis placed on uniformity and saturation, with the sum of the two weighting coefficients being 1. The larger the comprehensive matching deviation index, the higher the degree of magnetic circuit mismatch.

[0039] Before step S4, the mismatch level of the magnetic circuit is determined based on the comprehensive matching deviation index.

[0040] Specifically, when the comprehensive matching deviation index is greater than or equal to the first deviation threshold, the magnetic circuit is determined to be in the first mismatch level; when the comprehensive matching deviation index is greater than or equal to the second deviation threshold and less than the first deviation threshold, the magnetic circuit is determined to be in the second mismatch level. The first deviation threshold is greater than the second deviation threshold. In this embodiment, the first deviation threshold is set to 0.15 and the second deviation threshold to 0.08, which can be adjusted accordingly based on the accuracy requirements of the motor. The adjustment step size corresponding to the first mismatch level is greater than the adjustment step size corresponding to the second mismatch level. This adjustment step size is used to determine the single adjustment amplitude when matching and adjusting the stator and rotor magnetic circuit parameters in step S4. For example, the adjustment step size corresponding to the first mismatch level is twice the adjustment step size corresponding to the second mismatch level, thereby allowing for a larger adjustment amplitude when the mismatch degree is high and a smaller adjustment amplitude when the mismatch degree is low.

[0041] It is understood that the weighting coefficient, the first deviation threshold, the second deviation threshold, and the adjustment step size corresponding to each mismatch level in this embodiment are all illustrative examples, and those skilled in the art can make corresponding adjustments according to the specific structure and accuracy requirements of the motor.

[0042] Example 3: This embodiment, based on Embodiment 1 or Embodiment 2, further refines the partitioned collaborative matching method of stator and rotor magnetic circuit parameters. By adjusting the ratio of stator tooth width to stator tooth pitch and the permanent magnet pole arc coefficient according to the annular calculation layer partition, the air gap magnetic flux density is made radially uniform and the stator core magnetic flux density saturation is suppressed. This is the key to improving the motor torque performance and operating efficiency. The adjustment principle is described in [reference needed]. Figure 4 The system structure in this embodiment is the same as that in Embodiment 1, and will not be described again here.

[0043] In step S4, the stator magnetic circuit parameters are set to include the ratio of stator tooth width to stator tooth pitch and the stator yoke thickness, and the rotor magnetic circuit parameters are set to include the pole arc coefficient of the permanent magnet and the axial thickness of the permanent magnet.

[0044] Specifically, the ratio of stator tooth width to stator tooth pitch is used to adjust the magnetic flux density of the stator teeth, the thickness of the stator yoke is used to adjust the magnetic flux density of the stator yoke, the permanent magnet pole arc coefficient is used to adjust the air gap magnetic flux density of the corresponding radial section, and the matching relationship between the axial thickness of the permanent magnet and the axial air gap length is used to adjust the overall amplitude of the air gap magnetic flux density.

[0045] In step S4, the magnetic circuit parameters to be adjusted and their adjustment directions are determined according to the preset deviation-adjustment mapping relationship, and the matching adjustment is performed in the following manner.

[0046] Furthermore, for the annular calculation layer where the stator tooth magnetic flux density reaches the knee point magnetic flux density, the ratio of the stator tooth width to the stator tooth pitch of this annular calculation layer is determined as the magnetic circuit parameter to be adjusted, and its adjustment direction is to increase it to reduce the magnetic flux density of the stator tooth at that location; for the annular calculation layer where the air gap magnetic flux density amplitude is lower than the aforementioned average value, the permanent magnet pole arc coefficient of the corresponding radial segment of this annular calculation layer is determined as the magnetic circuit parameter to be adjusted, and its adjustment direction is to increase it; for the annular calculation layer where the air gap magnetic flux density amplitude is higher than the average value, the permanent magnet pole arc coefficient of the corresponding radial segment is determined as the magnetic circuit parameter to be adjusted, and its adjustment direction is to decrease it, thereby making the air gap magnetic flux density amplitudes of each annular calculation layer closer to each other. See [link to relevant documentation]. Figure 4 Furthermore, the thickness of the stator yoke is determined based on the annular calculation layer with the largest magnetic flux in the stator yoke, ensuring that the magnetic flux density of the stator yoke at that location does not exceed the magnetic flux density at the knee point.

[0047] For example, for a certain annular calculation layer where the air gap magnetic flux density amplitude is lower than the average value, the permanent magnet pole arc coefficient of that radial section is increased from 0.70 to 0.78; for a certain annular calculation layer where the stator tooth magnetic flux density reaches 1.7 Tesla, the ratio of the stator tooth width to the stator tooth pitch of that annular calculation layer is increased from 0.42 to 0.60. After the above-mentioned zoned coordinated matching adjustment, the air gap magnetic flux density amplitude of each annular calculation layer tends to be close, and the stator tooth magnetic flux density drops below the knee magnetic flux density. The above values ​​are all exemplary values ​​and can be adjusted accordingly based on the actual motor.

[0048] Furthermore, in conjunction with the aforementioned mismatch levels, the single adjustment range of each magnetic circuit parameter to be adjusted is determined according to the mismatch level of the magnetic circuit, that is, a larger adjustment is made at the first mismatch level and a smaller adjustment is made at the second mismatch level.

[0049] It is understood that the specific values ​​and adjustment ranges of each magnetic circuit parameter in this embodiment are merely illustrative examples, and those skilled in the art can make corresponding adjustments based on the specific structure and performance design specifications of the motor.

[0050] Example 4: This embodiment, based on the aforementioned embodiments, further provides an iterative convergence and parameter sensitivity ranking method after step S4 to achieve magnetic circuit deviation convergence within a finite number of attempts, and provides an error message when convergence fails, ensuring the executability and robustness of the method. The system structure of this embodiment is the same as that of Embodiment 1, and will not be repeated here.

[0051] After step S4, the updated magnetic flux density distribution information of each annular calculation layer is determined based on the matched and adjusted magnetic circuit parameters, and the updated magnetic circuit deviation information is generated.

[0052] Specifically, the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density of each annular calculation layer are recalculated using the matched and adjusted stator and rotor magnetic circuit parameters to obtain updated magnetic flux density distribution information. Based on this, updated magnetic circuit deviation information is generated to characterize the radial non-uniformity of air gap magnetic flux density and the saturation degree of stator core magnetic flux density.

[0053] When the updated magnetic circuit deviation information indicates that the air gap magnetic flux density has not become consistent along the radial direction, or when the magnetic flux density of the stator teeth and the magnetic flux density of the stator yoke exceed the knee point magnetic flux density, the stator and rotor magnetic circuit parameters are re-matched and adjusted according to the updated magnetic circuit deviation information until the magnetic circuit deviation information meets the preset convergence condition or the number of adjustments reaches the preset number threshold.

[0054] Furthermore, a preset convergence condition is used to determine whether the air gap magnetic flux density is sufficiently uniform and the core magnetic flux density is not saturated. For example, this is taken as follows: the sum of the absolute values ​​of the deviations between the amplitude and the average value of the air gap magnetic flux density of each annular calculation layer no longer decreases, and the magnetic flux density of the stator teeth and the stator yoke does not exceed the knee magnetic flux density. A preset iteration threshold is used to limit the number of iterations; in this embodiment, it is set to twenty iterations, which can be adjusted according to accuracy requirements. When the number of adjustments reaches the preset threshold and the magnetic circuit deviation information still does not meet the preset convergence condition, a magnetic circuit matching anomaly prompt is generated to prompt a review of the initial structural parameters or performance design indicators.

[0055] When repeating steps S2 to S4, the adjustment sequence is determined based on the sensitivity of each magnetic circuit parameter.

[0056] For example, single-parameter perturbations are applied to the ratio of stator tooth width to stator tooth pitch and the permanent magnet pole arc coefficient, respectively. The sensitivity of each parameter is determined based on the change in average torque, and the magnetic circuit parameters are adjusted sequentially in order of sensitivity from high to low in order to accelerate convergence.

[0057] It is understood that the preset convergence conditions, preset number thresholds, and sensitivity determination methods in this embodiment are all exemplary descriptions, and those skilled in the art can make corresponding adjustments according to actual needs.

[0058] Example 5: This embodiment, based on the previous embodiment, further verifies the electromagnetic performance of the matching results through electromagnetic simulation unit 2, and updates the knee magnetic flux density and preset matching evaluation rules in reverse according to the verification results, so that the subsequent matching process is closer to the actual electromagnetic performance of the motor. The system structure of this embodiment is the same as that of Embodiment 1, and will not be described again here.

[0059] Electromagnetic performance verification information of the axial flux permanent magnet motor 3 after matching and adjustment is obtained through electromagnetic simulation unit 2. This electromagnetic performance verification information includes at least one of average torque, torque ripple and operating efficiency.

[0060] Specifically, the electromagnetic simulation unit 2 uses three-dimensional finite element simulation to verify the electromagnetic performance of the matched motor, obtains verification information such as average torque, torque pulsation and operating efficiency, and transmits the verification information to the magnetic circuit matching device 1.

[0061] Based on the electromagnetic performance verification information, at least one of the knee magnetic flux density and the preset matching evaluation rules is updated so that the torque performance and operating efficiency of the axial flux permanent magnet motor 3 meet the performance design indicators during the subsequent matching process.

[0062] Furthermore, the magnetic flux density of each of the aforementioned annular computational layers is obtained from the layered magnetic circuit model. This layered magnetic circuit model is a reduced-order model, which has a fast computation speed but lower accuracy than the three-dimensional finite element simulation. Accordingly, based on the verification results of the three-dimensional finite element simulation, the value of the knee magnetic flux density or the weight coefficients and deviation thresholds in the preset matching evaluation rules are modified to make the reduced-order layered magnetic circuit model more consistent with the results of the three-dimensional finite element simulation, thereby balancing computational efficiency and accuracy in subsequent matching. For example, when the torque pulsation obtained from the verification is too large, the value of the knee magnetic flux density is appropriately lowered or the weight coefficient of the air gap magnetic flux density uniformity deviation is increased to more strongly suppress the radial non-uniformity of the air gap magnetic flux density in subsequent matching.

[0063] It is understood that the electromagnetic performance verification method and the specific content of the reverse update in this embodiment are illustrative examples, and those skilled in the art can make corresponding adjustments according to actual needs.

[0064] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A magnetic circuit matching method for an axial flux permanent magnet motor, applied to a magnetic circuit matching device, characterized in that, The magnetic circuit matching device is communicatively connected to the electromagnetic simulation unit of the axial flux permanent magnet motor. The axial flux permanent magnet motor includes a stator and a rotor arranged coaxially opposite each other. The stator has stator teeth arranged circumferentially, and the rotor has permanent magnets arranged circumferentially. The magnetic circuit matching method of the axial flux permanent magnet motor includes: The initial structural parameters and performance design indicators of the axial flux permanent magnet motor are obtained, and the effective air gap region of the motor is divided into multiple annular calculation layers along the radial direction. For each of the annular computing layers, the air gap magnetic flux density, stator tooth magnetic flux density, and stator yoke magnetic flux density of the annular computing layer are determined to obtain magnetic flux density distribution information; Based on the preset matching evaluation rules, magnetic circuit deviation information is generated according to the magnetic flux density distribution information. The magnetic circuit deviation information characterizes the degree of non-uniformity of the air gap magnetic flux density of each of the annular calculation layers along the radial direction and the degree of magnetic flux density saturation of the stator core. Based on the magnetic circuit deviation information, the stator magnetic circuit parameters of the stator and the rotor magnetic circuit parameters of the rotor are matched and adjusted so that the air gap magnetic flux density of each of the annular calculation layers tends to be consistent radially, and the magnetic flux density of the stator teeth and the magnetic flux density of the stator yoke do not exceed the knee point magnetic flux density of the stator core material magnetization curve. This ensures that the torque performance and operating efficiency of the axial flux permanent magnet motor meet the performance design indicators, thus achieving magnetic circuit matching.

2. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 1, characterized in that, The step of dividing the effective air gap region of the motor into multiple annular calculation layers radially includes: dividing according to the principle of equal magnetic flux area, so that the annular area of ​​each annular calculation layer is equal to that of the others, the number of annular calculation layers is not less than three, and the radial width of each annular calculation layer decreases sequentially from the inner diameter side to the outer diameter side; the step of determining the air gap magnetic flux density, stator tooth magnetic flux density and stator yoke magnetic flux density of the annular calculation layer includes: using the circumferential unfolded section at the average radius of the annular calculation layer as the calculation plane of the annular calculation layer, and based on the preset layered magnetic circuit model, solving the air gap magnetic flux and stator core magnetic flux of the annular calculation layer according to the initial structural parameters to obtain the air gap magnetic flux density, the stator tooth magnetic flux density and the stator yoke magnetic flux density of the annular calculation layer.

3. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 2, characterized in that, Before solving based on the preset layered magnetic circuit model, the method further includes the step of establishing the preset layered magnetic circuit model: the permanent magnet in the annular computing layer is equivalent to a branch in series with the magnetomotive force source and the magnetic permeability in the permanent magnet; in the preset layered magnetic circuit model, an air gap magnetic permeability branch, an inter-pole leakage magnetic permeability branch located between adjacent magnetic poles, and an end leakage magnetic permeability branch located at the radial edge of the permanent magnet are set to obtain the preset layered magnetic circuit model of the annular computing layer.

4. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 1, characterized in that, The magnetic circuit deviation information includes air gap magnetic flux density uniformity deviation and magnetic flux density saturation deviation; the step of generating magnetic circuit deviation information based on the magnetic flux density distribution information according to the preset matching evaluation rules includes: determining the average value of the air gap magnetic flux density amplitude of all annular computing layers according to the air gap magnetic flux density of each annular computing layer, and determining the deviation between the air gap magnetic flux density amplitude of each annular computing layer and the average value as the air gap magnetic flux density uniformity deviation; and determining the deviation between the stator tooth magnetic flux density, the stator yoke magnetic flux density and the stator core material magnetization curve knee point magnetic flux density as the magnetic flux density saturation deviation.

5. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 4, characterized in that, The magnetic circuit deviation information also includes a comprehensive matching deviation index; the step of generating magnetic circuit deviation information based on the magnetic flux density distribution information according to the preset matching evaluation rules further includes: obtaining the weighting coefficients corresponding to the air gap magnetic flux density uniformity deviation and the magnetic flux density saturation deviation respectively; and performing a weighted summation of the air gap magnetic flux density uniformity deviation and the magnetic flux density saturation deviation according to each of the weighting coefficients to obtain the comprehensive matching deviation index.

6. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 5, characterized in that, Before the step of matching and adjusting the stator magnetic circuit parameters of the stator and the rotor magnetic circuit parameters of the rotor according to the magnetic circuit deviation information, the method further includes: when the comprehensive matching deviation index is greater than or equal to a first deviation threshold, determining that the magnetic circuit is in a first mismatch level; when the comprehensive matching deviation index is greater than or equal to a second deviation threshold and less than the first deviation threshold, determining that the magnetic circuit is in a second mismatch level; wherein, the first deviation threshold is greater than the second deviation threshold, the adjustment step size corresponding to the first mismatch level is greater than the adjustment step size corresponding to the second mismatch level, and the adjustment step size is used to determine the single adjustment amplitude when matching and adjusting the stator magnetic circuit parameters and the rotor magnetic circuit parameters.

7. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 1, characterized in that, The stator magnetic circuit parameters include the ratio of the stator tooth width to the stator tooth pitch and the stator yoke thickness; the rotor magnetic circuit parameters include the pole arc coefficient and the axial thickness of the permanent magnet; the step of matching and adjusting the stator magnetic circuit parameters and the rotor magnetic circuit parameters according to the magnetic circuit deviation information includes: determining the magnetic circuit parameters to be adjusted corresponding to the magnetic circuit deviation information and the adjustment direction of the magnetic circuit parameters to be adjusted according to a preset deviation-adjustment mapping relationship; and matching and adjusting the magnetic circuit parameters to be adjusted according to the magnetic circuit parameters to be adjusted and their adjustment direction.

8. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 7, characterized in that, The step of determining the magnetic circuit parameters to be adjusted corresponding to the magnetic circuit deviation information and the adjustment direction of the magnetic circuit parameters to be adjusted according to the preset deviation-adjustment mapping relationship includes: for the annular calculation layer where the stator tooth magnetic flux density reaches the knee magnetic flux density of the stator core material magnetization curve, the ratio of the stator tooth width to the stator tooth pitch of the annular calculation layer is determined as the magnetic circuit parameter to be adjusted, and its adjustment direction is to increase; for the annular calculation layer where the air gap magnetic flux density amplitude is lower than the average value of the air gap magnetic flux density amplitude of all annular calculation layers, the permanent magnet pole arc coefficient of the corresponding radial segment of the annular calculation layer is determined as the magnetic circuit parameter to be adjusted, and its adjustment direction is to increase; for the annular calculation layer where the air gap magnetic flux density amplitude is higher than the average value, the permanent magnet pole arc coefficient of the corresponding radial segment is determined as the magnetic circuit parameter to be adjusted, and its adjustment direction is to decrease; the single adjustment amplitude of the magnetic circuit parameter to be adjusted is determined according to the mismatch level of the magnetic circuit.

9. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 1, characterized in that, After the step of matching and adjusting the stator magnetic circuit parameters of the stator and the rotor magnetic circuit parameters of the rotor according to the magnetic circuit deviation information, the method further includes: determining the updated magnetic flux density distribution information of each of the annular computing layers according to the matched and adjusted magnetic circuit parameters, and generating updated magnetic circuit deviation information according to the updated magnetic flux density distribution information; when the updated magnetic circuit deviation information indicates that the air gap magnetic flux density does not tend to be consistent radially or the magnetic flux density of the stator teeth and the magnetic flux density of the stator yoke exceeds the knee magnetic flux density, the stator magnetic circuit parameters and the rotor magnetic circuit parameters are rematched and adjusted according to the updated magnetic circuit deviation information until the magnetic circuit deviation information meets the preset convergence condition or the number of adjustments reaches the preset number threshold; when the number of adjustments reaches the preset number threshold and the magnetic circuit deviation information still does not meet the preset convergence condition, a magnetic circuit matching abnormality prompt message is generated.

10. The magnetic circuit matching method for an axial flux permanent magnet motor according to claim 1, characterized in that, The magnetic circuit matching method for the axial flux permanent magnet motor further includes: obtaining electromagnetic performance verification information of the axial flux permanent magnet motor after matching and adjustment through the electromagnetic simulation unit, wherein the electromagnetic performance verification information includes at least one of average torque, torque ripple, and operating efficiency; and updating at least one of the knee point magnetic flux density and the preset matching evaluation rules according to the electromagnetic performance verification information, so that the torque performance and operating efficiency of the axial flux permanent magnet motor meet the performance design indicators in the subsequent matching process.

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