Generation method of motor rotor slot profile

Abstract

The invention discloses a generation method of a motor rotor slot profile, and belongs to the technical field of motor rotors. The method comprises the following specific steps: firstly, dividing a weight reduction area of a rotor core into a plurality of block weight reduction areas, then selecting a plurality of points from each block weight reduction area to form an initial weight reduction area, formulating a linear rule between adjacent points, defining a plurality of variables, and then calculating to obtain coordinate parameters of each point of the initial weight reduction area containing the variables; and finally, parameterization is carried out, comprehensive analysis is carried out in combination with the performance and the structural strength of the motor, and an optimal weight reduction scheme is selected on the premise that the basic performance and the strength of the motor are not reduced, so that the manufacturing cost and the motor weight are effectively reduced, and the motor power density is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor rotors, and more specifically to a method for generating a slot profile of a motor rotor. Background Art

[0002] Currently, permanent magnet synchronous motors have been widely used in electric vehicles. However, due to the high price of silicon steel sheets, it is of great significance to design a lightweight motor rotor while ensuring the electromagnetic performance and mechanical strength of the motor.

[0003] A Chinese patent with publication number CN 106451858A discloses a lightweight motor rotor core and a method for designing a weight-reducing hole thereof. The motor rotor core comprises a core body, a plurality of V-shaped magnetic steel holes are provided on the core body, positioning holes are provided between adjacent V-shaped magnetic steel holes, an axial hole is provided at the center of the core body, and a weight-reducing hole is provided on the core body between two adjacent positioning holes.

[0004] The Chinese patent with publication number CN111884378A discloses a composite rotor for electric vehicle permanent magnet motor, which is composed of a reluctance section rotor and a permanent magnet section rotor, specifically including a hollow rotor core and a central shaft, a central shaft hole for passing the central shaft is provided at the center of the rotor core, which is tightly sleeved on the central shaft of the motor, and N groups of magnetic steel slots for inserting permanent magnet monomers are provided on the end face of the rotor core, where N is an even number. The rotor core structure is also provided with a plurality of rotor weight reduction slots; the rotor weight reduction slots are provided between the central shaft and the magnetic steel slots, and are symmetrically distributed around the center of the rotor core.

[0005] However, since the magnetic lines of force of the V-shaped magnetic steel hole radiate outward along its axis, the weight-reducing hole is opened between the central shaft and the magnetic steel slot. In order not to affect the performance of the motor, the weight-reducing hole needs to be opened as far as possible away from the radiation area of ​​the magnetic lines of force. This limits the size of the weight-reducing hole, resulting in an insignificant weight-reducing effect. In addition, in pursuit of its weight-reducing effect, some have affected the electromagnetic performance and structural strength of the motor. To this end, we provide a method for generating a motor rotor slot. Summary of the invention

[0006] The present invention provides a method for generating a slot profile of a motor rotor, so as to solve the shortcomings of existing motor rotor weight reduction holes, such as insignificant weight reduction effect, and influence on electromagnetic performance and structural strength.

[0007] The present invention adopts the following technical solution:

[0008] A method for generating a slot profile of a motor rotor, the motor rotor comprising an iron core body, a center hole being provided at the center of the rotor iron core, and a plurality of magnetic steel slots being provided at equal intervals on the iron core body; the method for producing the rotor slot profile comprises the following steps:

[0009] (1) Select the weight reduction area according to the distribution of the motor rotor magnetic lines of force;

[0010] (2) Selecting the number of supporting ribs in the weight reduction area and dividing the weight reduction area into a number of sub-weight reduction areas by the supporting ribs;

[0011] (3) Regularly select a number of points in each block weight reduction area, connect adjacent points, and form a preliminary weight reduction area;

[0012] (4) Formulate linear rules between adjacent points and define multiple variables, and obtain the coordinate parameters of each point in the preliminary weight loss area containing the variables by calculation;

[0013] (5) Parameterize the variables in step (4) and define the parameterization range;

[0014] (6) Obtain a corresponding number of point coordinate schemes based on the variables, calculate the torque and iron loss for each scheme, and preliminarily screen the point coordinate parameter schemes with a torque higher than or close to the initial scheme;

[0015] (7) Perform strength simulation based on the point coordinate parameter schemes preliminarily screened out in step (6), and perform secondary screening to eliminate schemes with stress lower than the material strength.

[0016] (8) Perform a weight comparison based on the solutions screened twice in step (7) to select the solution with the lightest weight, that is, obtain the point coordinate parameters of the rotor slot type.

[0017] In the above step (2), the number of supporting ribs is the same as the number of rotor poles, and they are arranged at the centers of the two magnetic poles corresponding to the V-shaped magnetic steel slots.

[0018] The number and positions of the points in the above step (3) are consistent with the polygons presented by their corresponding block weight reduction areas.

[0019] In a preferred embodiment, the number of the above-mentioned support ribs is eight, and the number of points is 5, forming a pentagonal or pentagonal initial weight reduction area.

[0020] Preferably, the above-mentioned preliminary weight reduction area includes five points A, B, C, D, and E in sequence, and the line segment formed between two adjacent points is a straight line, 0 is set as the center of the circle, P is the inner hole of the rotor, L is the center line, M is the center line of the two magnetic poles, and N is the center line of the magnetic poles. ∠LOM=45° and L and N are symmetrical about M, HJ and FG are both magnetic steel slot line segments of the two poles; line segment AB and line segment AE are respectively the offset lines of line segment FG and line segment HJ and are symmetrical relative to the center line of M, and arc CD is the offset line of P.

[0021] Further, the coordinates of the known magnetic steel slot line segment FG are defined as F(Fx, Fy), G(Gx, Gy), and the coordinates of the known magnetic steel slot line segment HJ are defined as H(Hx, Hy), J(Jx, Jy); the radius of the inner circle of the rotor is known to be r, and the radius of the outer circle of the rotor is known to be R; the offset distances of the line segments FG and HJ are both variable m, the offset distances of the line segments BC and DE are both variable n, the offset distance of the magnetic pole center line N is variable n, and the offset distance of the rotor inner hole P is variable k; from the coordinates of the two points F and G, it can be seen that the function of the line segment FG is: Since line segment AB is obtained by offsetting line segment FG by a distance m, the function of AB is: Since line segment BC is offset from center line L by distance n, we know that the function of line segment BC is: F BC (x) = n-formula (3); Since M is the center line of the two magnetic poles, the linear function of OM is: F OM (x) = tan67.5°·x · -Formula (4); From the fact that line segment CD is the offset distance k of the rotor inner hole P, it can be seen that the function of CD is: The coordinates of point B can be obtained from formulas (2) and (3); the coordinates of point A can be obtained from formulas (2) and (4); the coordinates of point C can be obtained from formulas (3) and (5); and the coordinates of points D and E can be obtained by repeating the above calculations.

[0022] Furthermore, the rounded corners of point A are defined as Ra, and the rounded corners of points B, C, D, and E are defined as Rb, and the variables m, n, k, Ra, and Rb are parameterized.

[0023] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages:

[0024] The motor rotor slot generation method of the present invention first divides the weight reduction area of ​​the rotor into a plurality of block weight reduction areas, then selects a plurality of points in each block weight reduction area to form a preliminary weight reduction area, formulates a linear rule between adjacent points, and defines a plurality of variables, and then obtains the coordinate parameters of each point in the preliminary weight reduction area containing the variables by calculation; finally, parameterization is performed, and a comprehensive analysis is performed in combination with the performance and structural strength of the motor, and the optimal weight reduction scheme is selected without reducing its basic performance and strength, thereby effectively reducing the manufacturing cost and the weight of the motor and improving the power density of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the motor rotor of the present invention.

[0026] Figure 2 It is a flow chart of the steps of the present invention.

[0027] Figure 3 It is a distribution diagram of the weight loss area of ​​the present invention.

[0028] Figure 4 It is a schematic diagram of the design of the support ribs of the present invention.

[0029] Figure 5 It is a schematic diagram of the initial weight loss zone of the present invention.

[0030] Figure 6 It is a schematic diagram of the definition between the magnetic steel slot line segment and the initial weight reduction area of ​​the present invention.

[0031] Figure 7 For the present invention Figure 6 Schematic diagram of the coordinates of each point in the diagram.

[0032] Figure 8 Schematic diagram of the fillet of each point in the initial weight reduction area of ​​the present invention.

[0033] Fig. 9 This is a schematic diagram of an existing motor rotor that has not been designed to reduce weight.

[0034] Fig.10 Schematic diagram of equipping an existing electric motor rotor with a rotor bracket. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is described below with reference to the accompanying drawings. In order to fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details. For well-known components, methods and processes, they are not described in detail below.

[0036] The motor rotor involved in this embodiment refers to Figure 1 , including an iron core body 10, a center hole 100 is provided at the center of the rotor iron core, and a plurality of V-shaped magnetic steel slots 11 are provided at equal intervals on the iron core body 10. The method for generating the slot profile of the motor rotor is referred to Figure 2 , including the following steps:

[0037] 1. Select the weight reduction area according to the distribution of the rotor magnetic lines of force, where the selection criteria are areas where the magnetic lines of force are sparse or do not pass through. Figure 3 As shown in the dotted line portion, the weight reduction area of ​​this embodiment is a polygonal structure centered on the center hole, and each side of the polygon is an arc shape bent toward one side of the V-shaped magnetic steel groove.

[0038] 2. Reference Figure 4 , select the number of support ribs in the weight reduction area, and divide the weight reduction area into several block weight reduction areas according to the number of support ribs. The number of support ribs is usually the number of rotor poles. The motor rotor in this embodiment has eight poles, so eight reinforcement ribs are selected and evenly distributed at the centers of the two corresponding magnetic poles.

[0039] 3. Regularly select a number of points in the block weight reduction area, adhering to the principle of controlling the largest area with the least number of points. Usually, the number and position of the points are consistent with the polygon presented by the block weight reduction area. In this embodiment, after the number of reinforcing ribs is determined, the corresponding block weight reduction area presents a pentagon. Therefore, this embodiment selects five control points to connect them to form a preliminary weight reduction area similar to a pentagon, such as Figure 5 As shown in ABCDE.

[0040] The line segment formed by the adjacent points ABCDE can be a straight line, an arc or a curve. This embodiment is described with the most intuitive straight line. Figure 6 , 0 is the center of the circle, P is the inner hole of the rotor (shaft radius), L is the center line, M is the center line of the two poles, N is the center line of the poles, ∠LOM=45° and L and N are symmetrical about M. HJ and FG are both magnetic steel slot line segments of the two poles, ABCDE is the block weight reduction area. Definition: Line segment AB and line segment AE are the offset lines of line segment FG and line segment HJ respectively and are symmetrical relative to the center line of M; arc CD is the offset line of P.

[0041] 4. Reference Figure 7 , define the coordinates of the known magnetic steel slot line segment FG as F(Fx, Fy), G(Gx, Gy), the coordinates of the known magnetic steel slot line segment HJ as H(Hx, Hy), J(Jx, Jy); the radius of the inner circle of the rotor is known to be r, and the radius of the outer circle of the rotor is known to be R. Suppose that line segment AB is obtained by offsetting line segment FG, and its offset distance is variable m; line segment AE is obtained by offsetting line segment HJ by the same distance m; line segment BC is obtained by offsetting center line L, and its offset distance is variable n; line segment DE is obtained by offsetting magnetic pole center line N, and its offset distance is variable n; line segment CD is obtained by offsetting rotor inner hole P, and its offset distance is variable k.

[0042] From the coordinates of points F and G, we can know that the function of line segment FG is:

[0043]

[0044] Since line segment AB is obtained by offsetting line segment FG by a distance m, the function of AB is:

[0045]

[0046] Since line segment BC is offset from center line L by distance n, we know that the function of line segment BC is: F BC (x) = n - formula (3);

[0047] Since M is the center line of the two magnetic poles, the linear function of 0M is: F OM (x) = tan67.5°·x · -Formula (4);

[0048] Since line segment CD is the offset distance k of the rotor inner hole P, the function of CD is:

[0049] The coordinates of point B can be obtained from formulas (2) and (3); the coordinates of point A can be obtained from formulas (2) and (4); the coordinates of point C can be obtained from formulas (3) and (5); and the coordinates of points D and E can be obtained by repeating the above calculations.

[0050] 5. Reference Figure 8 , define the fillet of point A as Ra, and the fillets of points B, C, D, and E as Rb. Parameterize according to variables m, n, k, Ra, and Rb, and define the parameterization range and calculation step.

[0051] 6. Obtain a corresponding number of schemes based on the above five variables and calculation steps, calculate the torque and iron loss for each scheme, and conduct preliminary screening of the torque that is higher than or close to the initial scheme.

[0052] 7. Perform strength simulation based on the solutions initially screened out in step 6, and conduct secondary screening to eliminate solutions with stress lower than the material strength.

[0053] 8. Perform a weight comparison based on the solutions screened twice in step 7 and select the solution with the lightest weight, that is, obtain the point coordinate parameters of the rotor slot type.

[0054] The following is a diagram of the motor rotor slots of the present invention and the existing two motor rotor structures ( Fig. 9 , Fig.10 ) performance comparison table.

[0055]

[0056] By comparing the above table, it can be seen that the weight of the optimized design of the present invention is reduced by 27.9% compared with the simple optimization, the rotor strength is increased by 8.7%, and the cost is reduced by one rotor bracket (processing after casting). Under the same working conditions, the iron loss and torque of the motor remain basically unchanged.

[0057] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for generating a slot profile of a motor rotor, wherein the motor rotor comprises an iron core body, a center hole is provided at the center of the rotor iron core, and a plurality of magnetic steel slots are provided on the iron core body at equal intervals; characterized in that: The method for generating the rotor slot profile comprises the following steps: (1) Select the weight reduction area according to the distribution of the motor rotor magnetic lines of force; (2) Select the number of support ribs in the weight reduction area, and divide the weight reduction area into several sub-weight reduction areas through the support ribs; (3) Regularly select a number of points in each block weight reduction area, connect adjacent points, and form a preliminary weight reduction area; (4) Formulate linear rules between adjacent points and define multiple variables, and obtain the coordinate parameters of each point in the preliminary weight loss area containing the variables by calculation; (5) Parameterize the variables in step (4) and define the parameterization range; (6) Obtain a corresponding number of point coordinate schemes based on the variables, calculate the torque and iron loss for each scheme, and preliminarily screen the point coordinate parameter schemes with a torque higher than or close to the initial scheme; (7) Perform strength simulation based on the point coordinate parameter schemes preliminarily screened out in step (6), and perform secondary screening to eliminate schemes with stress lower than the material strength. (8) Perform a weight comparison based on the solutions screened twice in step (7) to select the solution with the lightest weight, that is, obtain the point coordinate parameters of the rotor slot type.

2. The method for generating a slot profile of a motor rotor according to claim 1, characterized in that: In the step (2), the number of the supporting ribs is the same as the number of rotor poles, and the supporting ribs are arranged at the centers of the two magnetic poles corresponding to the V-shaped magnetic steel slots.

3. The method for generating a slot profile of a motor rotor according to claim 1, characterized in that: The number and positions of the points in step (3) are consistent with the polygons presented by their corresponding block weight reduction areas.

4. The method for generating a slot profile of a motor rotor according to claim 3, characterized in that: The number of the supporting ribs is eight and the number of the points is five, forming a pentagonal or approximately pentagonal initial weight reduction area.

5. The method for generating a slot profile of a motor rotor according to claim 4, characterized in that: The preliminary weight reduction area includes five points A, B, C, D, and E in sequence. The line segment formed between two adjacent points is a straight line. 0 is set as the center of the circle, P is the inner hole of the rotor, L is the center line, M is the center line of the two magnetic poles, and N is the center line of the magnetic poles. ∠LOM=45° and L and N are symmetrical about M. HJ and FG are both magnetic steel slot line segments of the two poles; line segment AB and line segment AE are offset lines of line segment FG and line segment HJ respectively and are symmetrical relative to the center line of M, and arc CD is the offset line of P.

6. A method for generating a slot profile of a motor rotor according to claim 5, characterized in that: Define the coordinates of the known magnetic steel slot line segment FG as F(Fx, Fy), G(Gx, Gy), and the coordinates of the known magnetic steel slot line segment HJ as H(Hx, Hy), J(Jx, Jy); the radius of the inner circle of the rotor is r, and the radius of the outer circle of the rotor is R; assume that the offset distances of the line segments FG and HJ are both variables m, the offset distances of the line segments BC and DE are both variables n, the offset distance of the magnetic pole centerline N is variable n, and the offset distance of the rotor inner hole P is variable k; from the coordinates of points F and G, it can be seen that the function of the line segment FG is: Since line segment AB is obtained by offsetting line segment FG by a distance m, the function of AB is: Since line segment BC is offset from center line L by distance n, we know that the function of line segment BC is: F BC (x) = n-formula (3); Since M is the center line of the two magnetic poles, the linear function of 0M is: Since line segment CD is the offset distance k of the rotor inner hole P, the function of CD is: The coordinates of point B can be obtained from formulas (2) and (3); the coordinates of point A can be obtained from formulas (2) and (4); the coordinates of point C can be obtained from formulas (3) and (5); and the coordinates of points D and E can be obtained by repeating the above calculations.

7. The method for generating a slot profile of a motor rotor according to claim 6, characterized in that: Define the fillet of point A as Ra, and the fillets of points B, C, D, and E as Rb, and parameterize the variables m, n, k, Ra, and Rb.

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