Disc type motor rotor performance calculation method

Abstract

The invention relates to the technical field of motor rotor design, in particular to a disc type motor rotor performance calculation method. The permanent magnet skewed pole technology is adopted to reduce the eddy current loss and improve the torque of the rotor, the skewed poles of the permanent magnets introduce the deviation of a mechanical angle on the magnetic poles of the rotor, so that the waveform of the magnetic flux density is smoother, the fluctuation of the magnetic flux density is reduced, the eddy current loss is reduced, and the torque of the motor is improved. The performance calculation model of the rotor is established based on the data obtained by the disc type motor model, and the performance of the rotor is accurately predicted according to the performance calculation model, that is, the improvement degree of the motor performance is represented through specific data.

Description

Technical Field

[0001] The invention relates to the technical field of motor rotor design, in particular to a method for calculating the performance of a disc motor rotor. Background Art

[0002] Disc motors have the advantages of high power density, small size, high operating efficiency, high energy utilization, short response time, and good dynamic performance. Therefore, they are widely used in new energy electric vehicles, automation equipment, robots, engineering machinery, military industry, aerospace and other fields.

[0003] Due to its own characteristics, the disc motor is only suitable for small loads and precision control occasions, not for large loads. In the process of using the disc motor, permanent magnet skewed pole technology is usually used to reduce eddy current losses to increase the rotor torque. Patent CN208955759U discloses a magnetic pole skewed pole structure that effectively weakens the motor cogging torque. The magnetic pole skewed pole structure includes magnetic poles, a yoke and an iron core. The magnetic poles are parallel processed at a certain angle, and the magnetic poles are bonded to the cylindrical surface of the yoke in a certain order. The iron core is a straight slot structure. The magnetic pole skewed pole structure adopts a relatively simple parallel processing method to achieve magnetic pole tilting, which can increase the rotor torque while reducing the motor cogging torque. Although the above-mentioned prior art can increase the rotor torque while reducing eddy current losses. However, how much eddy current loss is reduced, how much eddy current loss is reduced, how much torque is increased, and how much torque is increased, there is no quantitative analysis in the above-mentioned prior art, which makes it impossible to clearly and accurately express the degree of improvement in motor performance. Summary of the invention

[0004] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a method for calculating the performance of a disc motor rotor. The present invention can relatively accurately calculate the torque and eddy current loss corresponding to the rotor, and then use accurate data to indicate the degree of improvement in motor performance.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for calculating the performance of a disc motor rotor comprises the following steps:

[0007] S1, constructing a rotor in which each permanent magnet on the rotor yoke is distributed in a spiral shape;

[0008] S2, constructing a disc motor model, and assembling the rotor into the disc motor model, and obtaining the torque and eddy current loss of the disc motor model using the current rotor during operation;

[0009] S3, constructing a plurality of rotors with different wrap angles according to the contents of step S1 and step S2, and assembling each rotor into the same disc motor model, so as to obtain the torque and eddy current loss corresponding to each rotor in the current disc motor model under the premise of controlling variables;

[0010] S4. Construct a performance calculation model of the rotor according to the wrap angle, torque, and eddy current loss of each rotor, and predict the performance of the rotor according to the performance calculation model.

[0011] As a further solution of the present invention: the rotor constructed in step S1 includes a circular rotor yoke, and a plurality of permanent magnets are installed on the upper ring surface of the rotor yoke, and each permanent magnet is evenly arranged around the circumference of the rotor yoke, and each permanent magnet is arranged on the rotor yoke at an angle along the same clockwise direction to form a spiral distribution state.

[0012] As a further solution of the present invention: each permanent magnet is in the shape of a sector plate that gradually decreases from the outside to the inside along the radial direction of the rotor yoke, the plate surface of the permanent magnet is parallel to the annular surface of the rotor yoke, and both side surfaces of the permanent magnet are perpendicular to the annular surface of the rotor yoke; the outer arc surface of the permanent magnet is coplanar with the outer circumferential surface of the rotor yoke, and the inner arc surface of the permanent magnet is coplanar with the inner circumferential surface of the rotor yoke;

[0013] Along the axial direction of the rotor yoke, the vertical projection of the permanent magnet on the annular surface of the rotor yoke forms a quadrilateral ABCD, and the vertical projection of the axis of the rotor yoke on the annular surface of the rotor yoke forms a point O; the angle between the straight line AB and the straight line AO ​​is θ1, the angle between the straight line DC and the straight line DO is θ2, and θ=θ1=θ2, θ1 and θ2 are the spiral angle θ.

[0014] As a further solution of the present invention: the performance calculation model of the rotor is expressed as follows:

[0015]

[0016]

[0017] In the formula, F represents the torque generated by the rotor; F1 represents the first-stage torque of the rotor; F2 represents the second-stage torque of the rotor; F3 represents the third-stage torque of the rotor; F4 represents the fourth-stage torque of the rotor; Q represents the eddy current loss generated by the rotor; Q1 represents the first-stage eddy current loss of the rotor; Q2 represents the second-stage eddy current loss of the rotor; Q3 represents the third-stage eddy current loss of the rotor.

[0018] As a further solution of the present invention: a disc motor model is constructed using finite element analysis software, and then rotors with different scroll angles are assembled into the same disc motor model, and the torque and eddy current loss corresponding to each rotor are obtained during the operation of the disc motor; and then mathematical and statistical analysis is performed on the obtained data to construct a performance calculation model of the rotor corresponding to the current disc motor model;

[0019] By changing the motor parameters to construct multiple different disc motor models, rotors with different wrap angles are then assembled into each disc motor model for operation to obtain the torque and eddy current loss corresponding to each rotor, and a performance calculation model of the rotor corresponding to each disc motor model is constructed based on the obtained torque and eddy current loss.

[0020] As a further solution of the present invention: a mounting groove for fixing and installing the permanent magnet is opened on the upper annular surface of the rotor yoke, and the mounting grooves are evenly arranged on the rotor yoke around the circumference of the rotor yoke, and each mounting groove is a through groove that gradually shrinks from the outside to the inside along the radial direction of the rotor yoke; the notch direction of the mounting groove is parallel to the axial direction of the rotor yoke, and the notch of the mounting groove is a closing structure that can prevent the permanent magnet from sliding out of the mounting groove along the axial direction of the rotor yoke.

[0021] As a further solution of the present invention: the top edges of both sides of the permanent magnet are rounded, the notch of the mounting groove is an arc surface that fits the rounded corner, and the radius of the arc surface is R1; the radius R1 and the outer circle radius R of the rotor yoke satisfy the relationship: 0.016<R1 / R<0.047.

[0022] As a further solution of the present invention: positioning grooves are provided on both side surfaces of the permanent magnet, and positioning strips that fit into the positioning grooves are installed on both inner wall surfaces at the groove openings of the installation grooves, and the length direction of the positioning strips is parallel to the length direction of the installation grooves; the cross-section of the positioning strip is a rectangle, the length of the rectangle is l, the width is w, and the length l and the width w satisfy the relationship: 0.5<l / w<1.5.

[0023] As a further solution of the present invention: the angle between the straight line OD and the straight line OA is θ3, the angle θ3 is the central angle of the permanent magnet, and satisfies: 0.056<θ3 / 360<0.083.

[0024] As a further solution of the present invention: the inner radius of the rotor yoke is r, and the radius r satisfies: 0.5<r / R<0.7.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention adopts permanent magnet slanted pole technology to reduce eddy current loss and improve rotor torque. The slanted pole of the permanent magnet introduces a mechanical angle offset on the rotor magnetic pole, making the magnetic flux density waveform smoother, reducing the fluctuation of magnetic flux density, thereby reducing eddy current loss, thereby improving the torque of the motor. Based on the data obtained from the disc motor model, a performance calculation model of the rotor is established, and the performance of the rotor is accurately predicted based on the performance calculation model, that is, the degree of improvement of the motor performance is characterized by specific data.

[0027] 2. The present invention increases the contact area between the stator and the air by opening guide holes on the stator packaging disk of the disk motor, thereby increasing the air flow inside the motor when the rotor rotates, thereby achieving the purpose of rapid heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a calculation flow chart of the present invention.

[0029] Figure 2 It is a schematic diagram of the size structure of the rotor in the present invention.

[0030] Figure 3 It is a schematic diagram of the split structure of the rotor in the present invention.

[0031] Figure 4 It is a schematic diagram of the size structure of the radius R1 in the present invention.

[0032] Figure 5 It is a schematic diagram of the split structure of the rotor provided with guide grooves and guide bars in the present invention.

[0033] Figure 6 It is a schematic diagram of the size structure of the guide strip in the present invention.

[0034] Figure 7 It is a schematic diagram of the split structure of the rotor with the mounting groove provided with an inclination angle in the present invention.

[0035] Figure 8 It is a schematic diagram of the size structure of the installation groove in the present invention.

[0036] Fig. 9 It is a curve diagram of the torque and eddy current loss changing with the scroll angle (offset angle) in the present invention.

[0037] Fig.10 It is a schematic diagram of the structure of the stator in the present invention.

[0038] Fig.11 It is the cooling curve of the motor without guide holes in the present invention.

[0039] Fig.12 This is the cooling curve of the motor with guide holes in the present invention.

[0040] In the figure: 1, rotor yoke; 11, mounting groove; 111, positioning bar; 2, permanent magnet; 21, positioning groove; 3, stator packaging disk; 31, guide hole. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See also Figures 1 to 9 In a disc motor, the rotor is mainly composed of a rotor yoke 1, a permanent magnet 2 mounted on the rotor yoke 1, and a rotor bracket fixed at the axis of the rotor yoke 1 and used to connect with the motor shaft. The present invention mainly improves the rotor yoke 1 and the permanent magnet 2, because the present invention mainly studies the rotor yoke 1 and the permanent magnet 2.

[0043] like Figure 2 and Figure 3 As shown, the outer radius of the annular rotor yoke 1 is R, the inner radius is r, and the radius r satisfies: 0.5<r / R<0.7. A plurality of permanent magnets 2 are mounted on the upper annular surface of the rotor yoke 1, and each permanent magnet 2 is evenly arranged around the circumference of the rotor yoke 1, and each permanent magnet 2 is tilted and arranged on the rotor yoke 1 along the same clockwise direction to form a spiral distribution state. The permanent magnets 2 are all fan-shaped plates that gradually shrink from the outside to the inside along the radial direction of the rotor yoke 1. The plate surface of the permanent magnet 2 is parallel to the annular surface of the rotor yoke 1, and the two side surfaces of the permanent magnet 2 are perpendicular to the annular surface of the rotor yoke 1. The outer arc surface of the permanent magnet 2 is coplanar with the outer circumferential surface of the rotor yoke 1, and the inner arc surface of the permanent magnet 2 is coplanar with the inner circumferential surface of the rotor yoke 1. The permanent magnet 2 is fixedly mounted in the mounting groove 11 by gluing.

[0044] Along the axial direction of the rotor yoke 1, the vertical projection of the permanent magnet 2 on the annular surface of the rotor yoke 1 forms a quadrilateral ABCD, and the vertical projection of the axis of the rotor yoke 1 on the annular surface of the rotor yoke 1 forms a point O; the angle between the straight line AB and the straight line AO ​​is θ1, the angle between the straight line DC and the straight line DO is θ2, and θ=θ1=θ2, θ1 and θ2 are the scroll angle θ, and the scroll angle θ is also called the oblique pole angle. 0<θ1=θ2<38°, and 0<θ1 / 360<0.11, 0<θ2 / 360<0.11. 20°<θ<30°, and 0.056<θ3 / 360<0.083.

[0045] like Figure 4As shown, the top edges of both sides of the permanent magnet 2 are rounded, the notch of the mounting groove 11 is an arc surface that fits the rounded corner, and the radius of the arc surface is R1; the radius R1 and the outer radius R of the rotor yoke 1 satisfy the relationship: 0.016<R1 / R<0.047.

[0046] like Figure 5 and Figure 6 As shown, positioning grooves 21 are provided on both sides of the permanent magnet 2, and positioning strips 111 are installed on both inner wall surfaces at the notch of the mounting groove 11, and the length direction of the positioning strips 111 is parallel to the length direction of the mounting groove 11. The cross section of the positioning strip 111 is a rectangle, the length of the rectangle is l, the width is w, and the length l and the width w satisfy the relationship: 0.5<l / w<1.5.

[0047] like Figure 7 and Figure 8 As shown, the two groove walls of the installation groove 11 gradually tilt inward from bottom to top, and the tilt angles of the two groove walls are α1 and α2 respectively, and 1°<α1=α2<10°, 0.1<α1 / 10<0.8, 0.1<α2 / 10<0.8. The two side surfaces of the permanent magnet 2 are also tilted accordingly, and the vertical projection of the bottom surface of the permanent magnet 2 on the upper annular surface of the rotor yoke 1 forms a quadrilateral ABCD.

[0048] A disk motor model is constructed using finite element analysis software, and then rotors with different wrap angles are assembled into the same disk motor model to obtain the torque and eddy current loss corresponding to each rotor during the operation of the disk motor; the obtained data is then subjected to mathematical and statistical analysis to construct a performance calculation model of the rotor corresponding to the current disk motor model; multiple different disk motor models are constructed by changing the motor parameters, and then rotors with different wrap angles are assembled into each disk motor model for operation to obtain the torque and eddy current loss corresponding to each rotor, and a performance calculation model of the rotor corresponding to each disk motor model is constructed based on the obtained torque and eddy current loss.

[0049] like Fig. 9 As shown, the performance calculation model of the rotor obtained through simulation data.

[0050] The performance calculation model of the rotor is expressed as follows:

[0051]

[0052] It can be seen from the rotor performance calculation model that the calculation accuracy can be effectively improved by using a segmented form according to the actual conditions of torque and eddy current loss.

[0053] exist Fig. 9The figure shows the variation trend of the rotor torque and eddy current loss with the scroll angle. When the scroll angle θ is around 27°, the eddy current loss decreases significantly and the torque amplitude is also improved. Fig. 9 It can be seen that the torque increases first and then decreases with the increase of the scroll angle, and the scroll loss gradually decreases with the increase of the scroll angle. It can be seen that based on the performance calculation model, the torque and eddy current loss of the rotor can be calculated more accurately, and compared with the torque and eddy current loss of the conventional rotor, and then the degree of improvement of the motor performance can be characterized by specific data.

[0054] The present invention increases the contact area between the stator and the air by opening a guide hole 31 on the stator packaging disk 3 of the disc motor, thereby increasing the air flow inside the motor when the rotor rotates, thereby achieving the purpose of rapid heat dissipation. A guide hole 31 with a rectangular cross section is opened in the area where the magnetic field distribution of the stator packaging disk 3 is the least, and the length direction of the guide hole 31 is parallel to the axial direction of the rotor to minimize its impact on the motor. Fig.10 As shown, the opening width b of the guide hole 31 is 2 mm, the opening length L is 6 mm, and the radius R from the opening center to the center of the stator packaging disk 3 is a =25mm, hole depth H=10mm.

[0055] The outer diameter D of the stator packaging disk 3 is 65 mm.

[0056] 1 The width b of the orifice satisfies the relationship: 0.02<b / D<0.1.

[0057] 2 The length L of the orifice satisfies the relationship: 0.02<L / D<0.67.

[0058] 3. Radius R of the orifice center a Satisfying the relationship: 0.35<R a / D<0.45.

[0059] After determining the stator structure, the heat transfer coefficients of the surfaces with and without guide holes 31 are calculated by simulation software. The heat load and heat transfer coefficient are imported into the simulation software. The initial temperature of the motor is taken as 80°C as the steady-state boundary condition, and the natural convection time is set to 300s. After simulating and calculating the natural convection for 300s, the cooling curves of the motor with and without guide holes 31 are obtained as follows: Fig.11 and Fig.12 By comparison, it can be concluded that the motor with the guide hole 31 has a better heat dissipation effect than the motor without the guide hole 31.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for calculating the performance of a disc motor rotor, characterized in that: The following steps are involved: S1, constructing a rotor in which the permanent magnets (2) on the rotor yoke (1) are distributed in a spiral shape; S2. Build a disc motor model and assemble the rotor into the disc motor model to obtain the torque and eddy current loss of the disc motor model using the current rotor during operation; S3. Construct multiple rotors with different wrap angles according to the contents of step S1 and step S2, and assemble each rotor into the same disc motor model, thereby obtaining the corresponding torque and eddy current loss of each rotor in the current disc motor model under the premise of controlling variables; S4. Construct a performance calculation model of the rotor based on the wrap angle, torque, and eddy current loss of each rotor, and predict the performance of the rotor based on the performance calculation model.

2. The method for calculating the performance of a disc motor rotor according to claim 1, characterized in that: The rotor constructed in step S1 includes a circular rotor yoke (1), and a plurality of permanent magnets (2) are mounted on the upper annular surface of the rotor yoke (1). The permanent magnets (2) are evenly arranged around the circumference of the rotor yoke (1), and the permanent magnets (2) are all arranged on the rotor yoke (1) in an inclined manner along the same clockwise direction to form a spiral distribution state.

3. The method for calculating the performance of a disc motor rotor according to claim 2, characterized in that: Each permanent magnet (2) is in the form of a sector plate that gradually shrinks from the outside to the inside along the radial direction of the rotor yoke (1); the plate surface of the permanent magnet (2) is parallel to the annular surface of the rotor yoke (1); both side surfaces of the permanent magnet (2) are perpendicular to the annular surface of the rotor yoke (1); the outer arc surface of the permanent magnet (2) is coplanar with the outer circumferential surface of the rotor yoke (1); and the inner arc surface of the permanent magnet (2) is coplanar with the inner circumferential surface of the rotor yoke (1); Along the axial direction of the rotor yoke (1), the vertical projection of the permanent magnet (2) on the annular surface of the rotor yoke (1) forms a quadrilateral ABCD, and the vertical projection of the axis of the rotor yoke (1) on the annular surface of the rotor yoke (1) forms a point O; the angle between the straight line AB and the straight line AO ​​is θ1, the angle between the straight line DC and the straight line DO is θ2, and θ=θ1=θ2, and θ1 and θ2 are the spiral angle θ.

4. The method for calculating the performance of a disc motor rotor according to claim 3, characterized in that: The performance calculation model of the rotor is expressed as follows: In the formula, F represents the torque generated by the rotor; F1 represents the first-stage torque of the rotor; F2 represents the second-stage torque of the rotor; F3 represents the third-stage torque of the rotor; F4 represents the fourth-stage torque of the rotor; Q represents the eddy current loss generated by the rotor; Q1 represents the first-stage eddy current loss of the rotor; Q2 represents the second-stage eddy current loss of the rotor; Q3 represents the third-stage eddy current loss of the rotor.

5. The method for calculating the performance of a disc motor rotor according to claim 4, characterized in that: A disc motor model was constructed using finite element analysis software. Rotors with different wrap angles were then assembled into the same disc motor model. The torque and eddy current losses corresponding to each rotor were obtained during the operation of the disc motor. The obtained data was then subjected to mathematical and statistical analysis to construct a performance calculation model for the rotor corresponding to the current disc motor model. By changing the motor parameters to construct multiple different disc motor models, rotors with different scroll angles are then assembled into each disc motor model for operation to obtain the torque and eddy current loss corresponding to each rotor, and based on the obtained torque and eddy current loss, a performance calculation model of the rotor corresponding to each disc motor model is constructed.

6. A disc motor rotor performance calculation method according to any one of claims 2 to 5, characterized in that: The upper annular surface of the rotor yoke (1) is provided with mounting grooves (11) for fixing and mounting the permanent magnets (2), each mounting groove (11) being evenly arranged on the rotor yoke (1) in a circumferential direction around the rotor yoke (1), and each mounting groove (11) is a through groove that gradually shrinks from the outside to the inside along the radial direction of the rotor yoke (1); the slot opening direction of the mounting groove (11) is parallel to the axial direction of the rotor yoke (1), and the slot opening of the mounting groove (11) is a closing structure that can prevent the permanent magnets (2) from sliding out of the mounting groove (11) along the axial direction of the rotor yoke (1).

7. The method for calculating the performance of a disc motor rotor according to claim 6, characterized in that: The top edges of both sides of the permanent magnet (2) are rounded, and the slot opening of the mounting slot (11) is an arc surface that fits the rounded corner, and the radius of the arc surface is R1; the radius R1 and the outer circle radius R of the rotor yoke (1) satisfy the relationship: 0.016<R1 / R<0.

047.

8. The method for calculating the performance of a disc motor rotor according to claim 6, characterized in that: Positioning grooves (21) are provided on both side surfaces of the permanent magnet (2); positioning strips (111) are installed on both inner wall surfaces at the slot opening of the mounting slot (11) and are engaged with the positioning grooves (21); the length direction of the positioning strips (111) is parallel to the length direction of the mounting slot (11); the cross section of the positioning strips (111) is rectangular, the length of the rectangle is l, the width is w, and the length l and the width w satisfy the relationship: 0.5<l / w<1.

5.

9. The method for calculating the performance of a disc motor rotor according to claim 3, characterized in that: The angle between the straight line OD and the straight line OA is θ3, which is the central angle of the permanent magnet (2) and satisfies the following relationship: 0.056<θ3 / 360<0.

083.

10. The method for calculating the performance of a disc motor rotor according to claim 9, characterized in that: The inner radius of the rotor yoke (1) is r, and the radius r satisfies: 0.5<r / R<0.7.

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