Method for calculating magnetic network of trapezoidal air gap unit of axial synchronous motor

Abstract

The application provides a kind of axial synchronous motor trapezoidal air gap unit magnetic network calculation method.The method comprises the following steps: S1, under given constraint condition, complete the grid discretization of stator domain, determine the stator side node coordinates;S2, based on the number of stator side grid and its topological structure, carry out matching grid division to rotor domain, to realize one-to-one mapping of stator and rotor grid;S3, carry out layered grid division to the air gap between stator and rotor.The axial synchronous motor trapezoidal air gap unit magnetic network calculation method provided by the application can quickly and accurately solve the air gap magnetic field of axial flux motor with adaptive geometric boundary and dynamic relative displacement characteristics.

Description

Technical Field

[0001] This invention relates to a method for calculating the magnetic network of an axial synchronous motor, specifically a method for calculating the magnetic network of a trapezoidal air gap unit in an axial synchronous motor. Background Technology

[0002] Axial flux permanent magnet motors (ACMs) offer significant advantages in new energy vehicle hub motors and distributed drive systems due to their compact axial dimensions and high power density. In the initial design phase of the motor, the magnetic network method is typically used for electromagnetic analysis to balance computational accuracy and cost. However, since the air gap magnetic field of an ACM is distributed axially, and the stator and rotor tooth geometry exhibits a fan-shaped characteristic as the radius changes, constructing an air gap magnetic network model that accurately reflects the axial flux and circumferential leakage flux is a key research challenge in this field.

[0003] Existing magnetic network calculation methods typically simplify the air gap into simple rectangular branches, which has limitations when dealing with the disc structure of axial flux motors: on the one hand, traditional rectangular elements are difficult to adapt to the geometric distortion of the tooth slot edges of axial flux motors, resulting in large errors in the calculation of edge leakage flux near the slot opening; on the other hand, when the rotor rotates, the overlapping area of ​​the stator and rotor meshes changes in real time, and traditional single rectangular meshes are difficult to smoothly handle the changes in the interfacial magnetic permeability, which can easily cause numerical oscillations in the calculation results.

[0004] While some scholars have proposed increasing the number of air gap layers or introducing empirical correction coefficients to improve accuracy, these methods either increase the dimensionality of the computational equations or reduce the model's generality. Especially for scenarios requiring simultaneous consideration of axial main magnetic flux and circumferential trans-slot magnetic flux, existing meshing strategies lack a unit structure that can accommodate multi-directional magnetic flux coupling and possess strong geometric adaptability. Therefore, designing a model for a magnetic network calculation method using trapezoidal air gap elements in axial synchronous motors is of great significance for improving the design efficiency and computational accuracy of axial flux motors. Summary of the Invention

[0005] The purpose of this invention is to propose a magnetic network calculation method for the trapezoidal air gap unit of an axial synchronous motor, which can quickly and accurately solve the air gap magnetic field of an axial flux motor with adaptive geometric boundaries and dynamic relative displacement characteristics.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a magnetic network calculation method for a trapezoidal air gap unit of an axial synchronous motor, comprising the following steps: S1, under given constraints, complete the mesh discretization of the stator domain and determine the coordinates of the stator side nodes; S2, based on the number and topology of the stator side mesh, performs matching mesh division of the rotor domain to achieve a one-to-one mapping between the stator and rotor meshes; S3. Perform layered meshing on the air gap between the stator and rotor: establish trapezoidal mesh units on the stator side and the rotor side respectively, with their top edges corresponding to the discrete meshes on the stator side and the rotor side respectively; define a rectangular transition mesh between the bottom edges of two opposite trapezoidal mesh units, and keep the width of the rectangular transition mesh consistent with the length of its bottom edge, forming a complete trapezoidal-rectangular air gap magnetic network model.

[0007] Furthermore, the given constraints for step S1 are as follows: a) Constant air gap permeability: The permeability within the air gap region is considered constant and uniformly taken as the vacuum permeability; b) Uniform magnetic flux distribution within the cell: It is assumed that the magnetic flux density distribution within each trapezoidal grid cell or rectangular transition grid cell is uniform, and the magnetic flux flows along the center line of the grid. c) Ignore external edge magnetic leakage: In the mesh generation model, only the effective magnetic flux inside the air gap and the specified trapezoidal branch magnetic flux are considered, and the diffused magnetic leakage outside the motor end is ignored; d) Quasi-static assumption: Neglect displacement current and ensure that the magnetic field distribution in the air gap satisfies the quasi-static field distribution law, and that the magnetic flux at the grid nodes satisfies Kirchhoff's first law.

[0008] Furthermore, the magnetic reluctance of the trapezoidal mesh element in step S3 is calculated as follows: Upper side of the vertical axis magnetic reluctance : ; Lower side magnetic reluctance of the vertical axis : ; transverse axis magnetic reluctance : ; In the formula, and Here, represents the width of the upper base and the width of the lower base of the trapezoid, respectively; h is the height of the trapezoid; and d is the axial length of the motor. The average width at the center line. 1 represents the permeability of the material in the region containing the trapezoidal magnetic permeability.

[0009] Furthermore, the magnetic reluctance of the rectangular transition grid cell in step S3 is calculated as follows: ; In the formula, For rectangular transition grid cells, the magnetoresistance value is... The width of the rectangle. The length of the rectangle. 2 represents the magnetic permeability of the material in the region containing the rectangular magnetic permeability, used to characterize the material's magnetic permeability, and is related to the material's magnetic field strength and magnetic field density. This refers to the axial length of the axial synchronous motor.

[0010] Furthermore, the transverse axis magnetoresistive middle; ; In the formula, The calculation formula is: .

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1. Based on the fan-shaped characteristic of the air gap magnetic field of the axial flux motor changing with the radius, a trapezoidal air gap mesh model based on the central node and four-branch reluctance was designed. By co-discretizing the stator and rotor meshes, trapezoidal element parameters reflecting the change of geometric boundaries were extracted, and the air gap magnetic permeability variation characteristics that can adapt to the relative displacement of the stator and rotor were obtained.

[0013] 2. A magnetoresistive equivalent logic that can accurately characterize the axial main magnetic flux and circumferential leakage flux is proposed. The complex three-dimensional air gap field distribution is simplified into a nodal magnetic network composed of four branch magnetoresistives, which can be quickly obtained through the nodal magnetopotential equation. The complex geometric topological correlation is transformed into a branch magnetoresistive function calculated by trapezoidal mesh geometric parameters, which can be directly solved using algebraic equations. The calculation speed is fast and the accuracy is high, without the need to establish a complex three-dimensional finite element model.

[0014] 3. Based on the established trapezoidal-rectangular composite air gap magnetic network model, the air gap magnetic field distribution under no-load and armature reaction conditions is considered respectively. By decoupling and superimposing calculations of permanent magnet excitation and winding current excitation, the accurate calculation of air gap magnetic flux density, leakage flux and electromagnetic torque of the motor under no-load and full load conditions is realized. This solves the problem of insufficient calculation accuracy or poor mesh adaptability of existing technologies when dealing with axial flux motor load conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the air gap grid and trapezoidal magnetoresistance of the present invention;

[0016] Figure 2 This is a magnetic permeability structure diagram of the trapezoidal transition grid unit of the present invention;

[0017] Figure 3 This is a magnetic permeability structure diagram of the rectangular transition grid unit of the present invention;

[0018] Figure 4 This is a diagram of the transverse magnetic flux density network and finite element experiment of the present invention;

[0019] Figure 5 This is a diagram of the longitudinal magnetic flux density network and finite element experiment of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0021] This invention provides a method for calculating the magnetic network of a trapezoidal air gap unit in an axial synchronous motor, comprising the following steps:

[0022] Step S1, given the constraints, as follows:

[0023] a) Constant air gap permeability: The permeability within the air gap region is considered constant and uniformly taken as the vacuum permeability;

[0024] b) Uniform magnetic flux distribution within the cell: It is assumed that the magnetic flux density distribution within each trapezoidal grid cell or rectangular transition grid cell is uniform, and the magnetic flux flows along the center line of the grid.

[0025] c) Ignore external edge magnetic leakage: In the mesh generation model, only the effective magnetic flux inside the air gap and the specified trapezoidal branch magnetic flux are considered, and the diffused magnetic leakage outside the motor end is ignored;

[0026] d) Quasi-static assumption: Ignore displacement current, assume that the magnetic field distribution in the air gap satisfies the quasi-static field distribution law, and that the magnetic flux at the grid nodes satisfies Kirchhoff's first law, complete the grid discretization of the stator domain, and determine the coordinates of the stator side nodes;

[0027] Step S2: Based on the number and topology of the stator side mesh, perform matching mesh division on the rotor domain to achieve a one-to-one mapping between the stator and rotor meshes;

[0028] Step S3: Perform layered meshing of the air gap between the stator and rotor: Establish trapezoidal mesh elements on both the stator and rotor sides, with their top edges corresponding to the discrete meshes on the stator and rotor sides, respectively; define a rectangular transition mesh between the bottom edges of two opposing trapezoidal mesh elements, ensuring the width and bottom length of the rectangular transition mesh are consistent, forming a complete trapezoidal-rectangular air gap magnetic network model. Based on the motor magnetic network structure design, such as... Figure 1 As shown, magnetic reluctance calculations were performed, and the magnetic permeability structure of the trapezoidal transition mesh element is illustrated below. Figure 2 As shown, the magnetic permeability structure of the rectangular transition grid cell is as follows. Figure 3 As shown:

[0029] First, based on the trapezoidal magnetic network structure, the magnetic reluctance of the trapezoidal grid element is obtained, and calculated as follows:

[0030] The longitudinal magnetic reluctance of the trapezoidal grid cell is calculated as follows: Upper side of the vertical axis magnetic reluctance : ; Lower side magnetic reluctance of the vertical axis : ;

[0031] The transverse magnetic reluctance of the trapezoidal grid cell is calculated as follows:

[0032] ;

[0033] In the formula, and Here, represents the width of the upper base and the width of the lower base of the trapezoid, respectively; h is the height of the trapezoid; and d is the axial length of the motor. The average width at the center line. 1 represents the material's magnetic permeability.

[0034] The magnetic reluctance of the rectangular transition mesh element in step S3 is calculated as follows:

[0035] ;

[0036] The magnetic reluctance value is for a rectangle. The width of the rectangle. The length of the rectangle. 2 represents the magnetic permeability of the material in the region containing the rectangular magnetic permeability, characterizing the quality of the material's magnetic permeability, and is related to the material's magnetic field strength and magnetic field density. This refers to the axial length of the axial synchronous motor.

[0037] Magnetic network and finite element simulation experiments were conducted on an axial flux motor to obtain the transverse magnetic flux density Bx and the longitudinal magnetic flux density By components, such as... Figure 4 and Figure 5 :

[0038] according to Figure 4 and Figure 5 The magnetic network and finite element simulation experiments show that the simulated magnetic flux density structure obtained by this invention is similar to the structure obtained in the finite element experiment.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A method for calculating the magnetic network of a trapezoidal air gap unit in an axial synchronous motor, characterized in that, Includes the following steps: S1, under given constraints, complete the mesh discretization of the stator domain and determine the coordinates of the stator side nodes; S2, based on the number and topology of the stator side mesh, performs matching mesh division of the rotor domain to achieve a one-to-one mapping between the stator and rotor meshes; S3, perform layered meshing of the air gap between the stator and rotor: establish trapezoidal mesh units on the stator side and the rotor side respectively, with their top edges corresponding to the discrete meshes on the stator side and the rotor side respectively; define a rectangular transition mesh between the bottom edges of two opposite trapezoidal mesh units, and keep the width of the rectangular transition mesh consistent with the length of its bottom edge, forming a complete trapezoidal-rectangular air gap magnetic network model. The magnetic reluctance of the trapezoidal mesh element in step S3 is calculated as follows: Upper side of the vertical axis magnetic reluctance : ； Lower side magnetic reluctance of the vertical axis : ； transverse axis magnetic reluctance : ； In the formula, and Here, represents the width of the upper base and the width of the lower base of the trapezoid, respectively; h is the height of the trapezoid; and d is the axial length of the motor. The average width at the center line. 1 represents the permeability of the material in the region containing the trapezoidal magnetic permeability; The magnetic reluctance of the rectangular transition grid cell in step S3 is calculated as follows: ； In the formula, The value represents the magnetoresistance of the rectangular transition grid cell. The width of the rectangle. The length of the rectangle. 2 represents the magnetic permeability of the material in the region containing the rectangular magnetic permeability, used to characterize the material's magnetic permeability, and is related to the material's magnetic field strength and magnetic field density. This refers to the axial length of the axial synchronous motor.

2. The magnetic network calculation method for a trapezoidal air gap unit of an axial synchronous motor according to claim 1, characterized in that, The given constraints for step S1 are as follows: a) Constant air gap permeability: The permeability within the air gap region is considered constant and uniformly taken as the vacuum permeability; b) Uniform magnetic flux distribution within the cell: It is assumed that the magnetic flux density distribution within each trapezoidal grid cell or rectangular transition grid cell is uniform, and the magnetic flux flows along the center line of the grid. c) Ignore external edge magnetic leakage: In the mesh generation model, only the effective magnetic flux inside the air gap and the specified trapezoidal branch magnetic flux are considered, and the diffused magnetic leakage outside the motor end is ignored; d) Quasi-static assumption: Neglect displacement current and ensure that the magnetic field distribution in the air gap satisfies the quasi-static field distribution law, and that the magnetic flux at the grid nodes satisfies Kirchhoff's first law.

3. The magnetic network calculation method for a trapezoidal air gap unit of an axial synchronous motor according to claim 2, characterized in that, The transverse axis magnetic reluctance middle; ； In the formula, The calculation formula is: .

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