Magnetic pole head with optimized shape for wound rotor of rotating electrical machine
By optimizing the shape of the magnetic pole head of the salient-pole wound rotor, harmonic voltage and electromagnetic torque components are reduced, the problems of motor vibration and poor coupling are solved, and a high-quality torque and compact motor design is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-26
- Publication Date
- 2026-03-27
AI Technical Summary
Existing salient-pole wound rotor synchronous motors in electric and hybrid vehicles exhibit large harmonic voltage and electromagnetic torque components, leading to vibration and poor electromagnetic coupling, which affects operating quality and compactness.
Design a salient-pole wound rotor with a pole head having a curved central region with a constant radius of curvature and a narrowing lateral region. The lateral region is elliptical in shape. By optimizing the shape of the pole head to reduce harmonic components, torque is maximized and vibration is minimized.
It achieves the generation of high-quality torque while limiting torque ripple and harmonics, thus improving the compactness and operational stability of the motor.
Smart Images
Figure CN121753224A_ABST
Abstract
Description
[0001] The present invention relates to a rotor for a synchronous rotating electric motor of the type having a salient-pole wound rotor, and more particularly to a rotor for such a motor used as an electric drive motor in electric and hybrid motor vehicles.
[0002] A conventional salient-pole wound-rotor synchronous motor includes a rotor having a body made of magnetic material and consisting of a stack of pre-cut laminations stacked parallel to the rotor's axis of rotation. The stack of laminations thus defines alternating arms and slots arranged radially between the central and outer peripheral portions of the rotor.
[0003] These arms and slots extend axially along the rotor body to define multiple alternating north and south magnetic poles, which are formed by multiple excitation coils wound on corresponding radial arms between two consecutive slots. Each radial arm is then substantially aligned on the central radial axis of the corresponding magnetic pole. The stator surrounds the rotor, with an air gap between the stator and the rotor.
[0004] In the field of motors used for the aforementioned applications, wound-rotor synchronous motors have many magnetic poles and a considerable amount of harmonic voltage and electromagnetic torque components. The harmonics of the electromagnetic torque can cause considerable vibration.
[0005] In order to overcome these adverse effects on the operating quality of these motors, it is necessary to reduce the harmonic components in order to reduce the electromagnetic coupling between the rotor and stator windings caused by these harmonic components.
[0006] The object of this invention is to provide a wound-rotor motor in which the shape of the rotor's magnetic poles enables the generation of high-quality torque while minimizing torque harmonics to limit vibrations that may be caused by said harmonics. Therefore, the object of this invention is to achieve a good trade-off between the performance in terms of torque generated by such a motor and the limitation of torque ripple caused by the rotation of the rotor within the motor.
[0007] Another object of the present invention is to provide a motor that is more compact than motors known in the prior art. Summary of the Invention
[0008] Therefore, the present invention relates to a salient-pole wound rotor comprising a body made of a magnetic material and having a plurality of magnetic poles radially arranged between a central portion and an outer peripheral portion of the rotor to define alternating arms and slots, wherein the arms project radially, the magnetic poles being formed by a plurality of excitation coils wound on corresponding arms between two adjacent slots, the arms being covered by magnetic pole heads that project orthogonally radially on both sides of the arms, the magnetic pole heads having a base connected to the arms and an outer periphery with a convex surface, the rotor being characterized in that the convex surface of the magnetic pole heads has a curved central region with a constant radius of curvature and two narrowing lateral regions located on either side of the central region.
[0009] According to a specific embodiment, the lateral regions of the convex surface of the magnetic pole head each have a shape that is part of an ellipse and have Cartesian coordinates in a Cartesian coordinate system that satisfy the following equation:
[0010]
[0011]
[0012] in,
[0013]
[0014] And among them:
[0015] X_scale is the multiplication coefficient;
[0016] y_scale is the multiplication coefficient;
[0017] Dc represents the distance between the origin of the Cartesian coordinate system and the center of the ellipse that shapes the lateral region of the convex surface of the magnetic pole head;
[0018] It is a parameter representing the polar angle;
[0019] It is a parameter representing the distance between the center of the ellipse and the point in question on the ellipse;
[0020] 'a' is the first variable, allowing the parameter to be changed. ;
[0021] b is the second variable, allowing the parameter to be changed. .
[0022] According to one embodiment, the first variable a is between 10 and 20, or even between 14.42 and 14.62, or even equal to 14.5, and the second variable b is between 20 and 30, or even between 25.44 and 25.74, or even equal to 25.56.
[0023] According to one embodiment, the distance between the origin of the Cartesian coordinate system and the center of the ellipse, which is a portion of the ellipse defining the lateral region of the convex surface of the magnetic pole head, is between 40 mm and 75 mm or equal to 57.1 mm.
[0024] According to one embodiment, the constant radius of curvature for determining the curvature of the central region of the bend is between 50 mm and 90 mm or equal to 77.15 mm.
[0025] According to one embodiment, each of these lateral areas is connected to the central area via a first rounded corner.
[0026] According to one embodiment, the radius of curvature of the first fillet is between 1 mm and 60 mm, or even between 2.76 mm and 7.76 mm, or equal to 4.76 mm.
[0027] According to one embodiment, the end of the outer periphery of the magnetic pole head is connected to a lateral edge located at the base of the magnetic pole head by a second fillet, and the second fillet has a radius of curvature between 2.5 mm and 0.5 mm or equal to 1 mm.
[0028] According to one embodiment, these multiplication coefficients x_scale and y_scale are each between 0.8 and 1.2, or even between 1 and 1.012, or even equal to 1.
[0029] The present invention also relates to a salient pole wound rotor synchronous motor, the motor including such a rotor and a stator surrounding the rotor to define a variable-sized air gap between the stator and the rotor. Attached Figure Description
[0030] These subjects, features, and advantages of the invention will be set forth in detail in the following description of various specific embodiments provided by way of non-limiting example with reference to the accompanying drawings, in which:
[0031] Figure 1 This is a schematic diagram showing details of a motor including a salient pole rotor according to a preferred embodiment of the present invention.
[0032] Figure 2 yes Figure 1 Another schematic diagram showing the details of the motor.
[0033] Figure 3 This is a schematic diagram showing details of the magnetic pole head of a salient pole rotor according to a preferred embodiment of the present invention.
[0034] Figure 4It is a graph showing the Cartesian coordinates of a set of points on the lateral region of the convex surface of the magnetic pole head.
[0035] Figure 5 It is a graph showing the torque of various types of rotors as a function of the rotor's position. Detailed Implementation
[0036] Figure 1 A portion of an electric motor including a salient-pole 2 rotor 1 according to a preferred embodiment of the present invention is shown. Thus, the motor includes a salient-pole 2 rotor 1 and a stator 3 surrounding the rotor 1 to define an air gap 4 between the stator 3 and the rotor 2.
[0037] The salient pole 2 wound rotor 1 includes a body made of magnetic material. Multiple magnetic poles 2 are radially arranged between the central portion of the body and the outer peripheral portion of the rotor 1 to define alternating arms 8 and slots 10, as shown below. Figure 1 What is shown.
[0038] Arm 8 protrudes radially relative to the body of rotor 1. Magnetic pole 2 is thus formed by a plurality of excitation coils 12 wound on corresponding arms 8 between two adjacent slots 10. Each arm 8 is covered by a magnetic pole head 14 that protrudes orthogonally radially on both sides of the arm 8.
[0039] Each pole head 14 has a base 16 connected to the arm 8 on one side, and an outer periphery with a convex surface 17 on the other side. The convex surface 17 of the pole head 14 has a curved central region 18 with a constant radius of curvature R, and two narrowing lateral regions 20a and 20b located on each side of the central region 18. In the curved central region 18, the constant radius of curvature R provides a constant-sized air gap 4 between the stator 3 and the rotor 1.
[0040] To maximize the torque generated by the motor, it is preferable to minimize the air gap 4 between the magnetic pole head 14 of the rotor 1 and the stator 3, particularly in the bending center region 18 of the convex surface 17. For example, the air gap 4 is between 0.5 mm and 1.5 mm.
[0041] According to a preferred embodiment, the constant radius of curvature R of both the curvature of the bending center region 18 and the size of the air gap 4 between the bending center region 18 of the convex surface 17 of the pole head 14 of the stator 3 and the rotor 1 is between 50 mm and 90 mm. According to a preferred embodiment, the constant radius of curvature R is equal to 77.15 mm.
[0042] For the magnetic pole head 14, each of the lateral regions 20a and 20b is connected to the central region 18 via a first fillet r1, as shown below. Figure 2 and Figure 3As shown. According to one embodiment, the first fillet r1 has a radius of curvature between 1 mm and 60 mm.
[0043] In a preferred embodiment, the first fillet radius r1 is between 2.76 mm and 7.76 mm. According to a particular example, the first fillet radius r1 connecting each of the lateral regions 20a, 20b to the central region 18 is equal to 4.76 mm. This first fillet radius r1 ensures a smooth transition from each of the lateral regions 20a, 20b to the central region 18, while also making it easier to manufacture the magnetic pole head 14.
[0044] The two lateral regions 20a and 20b, located on either side of the central region 18, narrow, meaning that the air gap 4 is constant within the curved central region 18 of the pole head 14 between the rotor 1 and the stator 3, but no longer constant in the two lateral regions 20a and 20b. The air gap 4 has an expanding shape in the two lateral regions 20a and 20b; therefore, the size of the air gap 4 gradually increases between the convex surface 17 of the pole head 14 and the stator 3. In other words, the air gap 4 between the convex surface 17 of the pole head 14 and the stator 3 is not constant, but has a variable size.
[0045] According to a preferred embodiment, the lateral regions 20a and 20b of the convex surface 17 of the magnetic pole head 14 each have a shape that is part of an ellipse. This ellipse is based on a specific geometry, which is defined based on a geometry commonly referred to as the "Cassinioval".
[0046] Points located on these lateral regions 20a and 20b have Cartesian coordinates that satisfy the following equation:
[0047] [Formula 1]
[0048]
[0049] [Formula 2]
[0050]
[0051] [Formula 3]
[0052]
[0053] In these equations, the parameter Dc represents the distance between the origin of the Cartesian coordinate system used and the center of the ellipse into which the lateral regions 20a, 20b of the convex surface 17 of the magnetic pole head 14 are shaped. Indicates the polar angle, and It is a parameter representing the distance between the center of the ellipse and the point on the ellipse in question, where the coordinates x and y are calculated.
[0054] The origin of the Cartesian coordinate system is located at the base of arm 8. According to one embodiment, the distance Dc between the origin of this Cartesian coordinate system and the center of the ellipse that defines a portion of the elliptical shape of the lateral regions 20a, 20b of the convex surface 17 of the magnetic pole head 14 is between 40 mm and 75 mm. According to a preferred example, this distance Dc is equal to 57.1 mm.
[0055] The first axis X of the Cartesian coordinate system extends orthogonally radially on both sides of the radial arm 8. The second axis Y of the Cartesian coordinate system extends perpendicular to the X-axis. Figure 3 and Figure 4 The image shows the first axis X and the second axis Y.
[0056] In this coordinate system, the Y-axis forms the axis of symmetry for the curved central region 18 and the two lateral regions 20a and 20b located on either side of the curved central region 18. In other words, the Y-axis passes through the middle of the curved central region 18 and forms the axis of symmetry for the two symmetrically arranged lateral regions 20a and 20b on either side of the Y-axis.
[0057] In the same coordinate system, for the first lateral region 20a, the angle The angle varies between 45.585° and 62.5°. The x-coordinate varies between 22.38 and 14.00, while the y-coordinate varies between 71.38 and 75.87. For example... Figure 4 As shown, the x and y coordinates of the points on the convex surface 17 in the first lateral region 20a are located above the Y-axis.
[0058] Still within the same coordinate system, for the second lateral region 20b, the angle The x-coordinate varies between 117.5° and 134.415°. The x-coordinate varies between -14.00 and -22.38, while the y-coordinate varies between 75.87 and 71.38. For example... Figure 4 As shown, the x and y coordinates of the points on the convex surface 17 in the second lateral region 20b are located below the Y-axis.
[0059] Define parameters In equation 3, variables a and b affect the shape of the ellipse; in particular, they allow modification of the ellipse's curvature, thereby changing the parameters. .
[0060] According to one embodiment, the first variable a is between 10 and 20, or even between 14.42 and 14.62. According to a preferred example, the first variable a is equal to 14.5.
[0061] Similarly, the second variable b is between 20 and 30, or even between 25.44 and 25.74. According to a preferred example, the second variable b is equal to 25.56.
[0062] In equations 2 and 3, x_scale is a multiplication coefficient, and y_scale is also a multiplication coefficient. In one embodiment, the multiplication coefficients x_scale and y_scale are each between 0.8 and 1.2, or even between 1 and 1.012. In a preferred example, both the multiplication coefficients x_scale and y_scale are equal to 1. These multiplication coefficients affect the size of the ellipse that determines the shape of the lateral regions 20a and 20b of the convex surface 17 of the magnetic pole head 14.
[0063] Furthermore, the outer periphery of the magnetic pole head 14 is connected to the lateral edge located at the base 16 of the magnetic pole head 14 via a second fillet r2, such as... Figure 2 and Figure 3 As shown. According to one embodiment, the second fillet r2 has a radius of curvature between 2.5 mm and 0.5 mm. In a preferred embodiment, the second fillet r2 has a radius of curvature equal to 1 mm. This second fillet r2 ensures a smooth transition between the end of the outer periphery of the magnetic pole head 14 and the lateral edge located at the base of the magnetic pole head 14, while also making the manufacture of the magnetic pole head 14 easier.
[0064] The wound rotor 1 motor equipped with a rotor 1 having magnetic poles 2 with specific magnetic pole heads 14 according to the invention enables the average torque obtained during operation to be maximized, while enabling the torque ripple and induced harmonics in the air gap to be limited.
[0065] The wound rotor motor 1 equipped with a rotor 1 according to the invention, having magnetic poles 2 with specific magnetic pole heads 14, allows for maximizing the generated torque while minimizing vibrations caused by the rotation of the rotor 1. In other words, equipping the wound rotor motor 1 with the rotor 1 according to the invention allows for limiting the torque ripple of the motor, thereby keeping the torque ripple at a reasonable level. This is in Figure 5 The curve is shown here. Figure 5 In comparison with the torque obtained with a rotor having magnetic poles with a specific shape according to the invention, the torque obtained with a rotor having magnetic poles with smooth magnetic poles (i.e., magnetic poles with a convex surface defined by a constant radius of curvature, thereby maintaining a constant air gap between the stator and rotor of the motor) exhibits a more pronounced peak.
[0066] In other words, the specific shapes of the lateral regions 20a and 20b at the ends of the pole head 14 allow for the reduction of harmonic components, thereby reducing the impact of these harmonic components on the electromagnetic coupling between the windings of the rotor 1 and the stator 3. This allows for a good trade-off between the average torque generated by this motor and the limitation of torque ripple.
Claims
1. A salient pole (2) wound rotor (1), the rotor comprising a body made of a magnetic material and having a plurality of magnetic poles (2) radially arranged between a central portion and an outer peripheral portion of the rotor (1) to define alternating arms (8) and slots (10), wherein, These arms (8) protrude in the radial direction, and these magnetic poles (2) are formed by a plurality of excitation coils (12) wound on the respective arms (8) between two adjacent slots (10). Each of these arms (8) is covered by a magnetic pole head (14) that protrudes radially orthogonally on both sides of the arm (8). The magnetic pole head (14) has a base (16) connected to the arm (8) and an outer periphery with a convex surface (17). The rotor (1) is characterized in that the convex surface (17) of the magnetic pole head (14) has a curved central region (18) with a constant radius of curvature (R) and two narrowing lateral regions (20a, 20b) located on each side of the central region (18).
2. The rotor as described in the preceding claim, characterized in that, The lateral regions (20a, 20b) of the convex surface (17) of the magnetic pole head (14) each have a shape in the form of a partial ellipse, and have Cartesian coordinates (x, y) in a Cartesian coordinate system that satisfy the following equation: in, And among them: X_scale is the multiplication coefficient; y_scale is the multiplication coefficient; Dc represents the distance between the origin of the Cartesian coordinate system and the center of the ellipse that gives shape to the lateral regions (20a, 20b) of the convex surface (17) of the magnetic pole head (14); It is a parameter representing the polar angle; It is a parameter representing the distance between the center of the ellipse and the point in question on the ellipse; 'a' is the first variable, allowing the parameter to be changed. ; b is the second variable, allowing the parameter to be changed. .
3. The rotor as described in the preceding claim, characterized in that, The first variable a is between 10 and 20, or even between 14.42 and 14.62, or even equal to 14.5, and the second variable b is between 20 and 30, or even between 25.44 and 25.74, or even equal to 25.
56.
4. The rotor as described in any one of claims 2 to 3, characterized in that, The distance (Dc) between the origin of the Cartesian coordinate system and the center of the ellipse that defines the lateral regions (20a, 20b) of the convex surface (17) of the magnetic pole head (14), which is part of an ellipse, is between 40 mm and 75 mm or equal to 57.1 mm.
5. The rotor as described in any one of claims 2 to 4, characterized in that, The constant radius of curvature (R) that determines the curvature of the central region (18) is between 50 mm and 90 mm or equal to 77.15 mm.
6. The rotor as described in any one of the preceding claims, characterized in that, Each of these lateral zones is connected to the central zone (18) via a first rounded corner (r1).
7. The rotor as described in the preceding claim, characterized in that, The radius of curvature of the first fillet (r1) is between 1 mm and 60 mm, or even between 2.76 mm and 7.76 mm, or equal to 4.76 mm.
8. The rotor as described in any one of the preceding claims, characterized in that, The end of the outer periphery of the magnetic pole head (14) is connected to the lateral edge located at the base (16) of the magnetic pole head (14) by a second fillet (r2), and the second fillet (r2) has a radius of curvature between 2.5 mm and 0.5 mm or equal to 1 mm.
9. The rotor as claimed in any one of the preceding claims, characterized in that, These multiplication coefficients, x_scale and y_scale, are each between 0.8 and 1.2, or even between 1 and 1.012, or even equal to 1.
10. A synchronous motor with a salient pole (2) wound rotor (1), characterized in that, The motor includes a rotor (1) as described in any of the preceding claims and a stator (3) surrounding the rotor (1) to define a variable-sized air gap (4) between the stator (3) and the rotor (1).