Design method of magnetic isolation hole, magnetic steel rotor and permanent magnet motor

Abstract

The invention provides a design method of magnetic isolation holes, a magnetic steel rotor and a permanent magnet motor. The design method comprises the following steps: determining the position of a target straight line parallel to a first magnetic steel groove edge according to the position of the first magnetic steel groove edge of a magnetic steel groove (13) and a magnetic isolation bridge strength condition; according to the position of the first magnetic steel groove edge and the skewed pole angle of the magnetic steel rotor, the positions of two target points on the target straight line are determined, and the line segment, between the two target points, of the target straight line is determined as the symmetrical straight edge of the magnetic isolation hole (15), so that the corresponding magnetic steel groove (13) and the corresponding magnetic isolation hole (15) have the maximum overlapping area; therefore, the torsional rigidity of the rotor is improved, the torsional modal frequency of the rotor is improved, motor noise is reduced, and motor performance is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of permanent magnet motors, and particularly relates to a design method of a magnetic isolation hole, a magnetic steel rotor and a permanent magnet motor. BACKGROUND

[0002] New energy vehicles generally adopt permanent magnet motors as driving motors, and the permanent magnet motors mostly adopt an embedded magnetic steel structure, a plurality of pairs of magnetic steel grooves are arranged on a rotor core, and magnetic steels are inserted into the magnetic steel grooves to realize excitation. For new energy vehicles, motor noise is the main source of vehicle noise. Under the action of tangential force, the rotor of the permanent magnet motor will vibrate and resonate, which is one of the sources of noise of the permanent magnet motor. Therefore, improving the stiffness of the rotor and reducing the vibration of the rotor are of great significance to improve the noise level of the permanent magnet motor. SUMMARY

[0003] In view of the above problems, the purpose of the application is to provide a design method of a magnetic isolation hole, a magnetic steel rotor and a permanent magnet motor, which aims to improve the stiffness of the rotor and improve the modal frequency.

[0004] To achieve the above purpose, the application provides a design method of a magnetic isolation hole, the magnetic isolation hole is arranged on a magnetic steel section of a magnetic steel rotor and located between end portions of two magnetic steel grooves arranged in a V shape and close to the center of the magnetic steel rotor, a plurality of magnetic steel sections can be installed around the axis of the magnetic steel rotor at a predetermined angle to form a skew pole, and the design method comprises the following steps:

[0005] According to the position of the first magnetic steel groove edge of the magnetic steel groove and the strength condition of the magnetic isolation bridge, the position of a target straight line parallel to the first magnetic steel groove edge is determined;

[0006] According to the position of the first magnetic steel groove edge and the skew pole angle of the magnetic steel rotor, the positions of two target points on the target straight line are determined, and a line segment between the two target points on the target straight line is determined as a symmetrical straight side of the magnetic isolation hole, so that the corresponding magnetic steel groove and the corresponding magnetic isolation hole have a maximum overlapping area.

[0007] Optionally, the method for determining the positions of the two target points on the target straight line comprises:

[0008] The position of the first target point on the target straight line is determined, and the position of the first target point satisfies a first constraint condition, the first constraint condition is determined according to the position of a first groove point on the first magnetic steel groove edge, and the skew pole angle of a top angle formed by the first magnetic steel groove edge and a second magnetic steel groove edge intersecting at the first groove point;

[0009] And, determine the position of the second target point on the target straight line so that the position of the second target point satisfies the second constraint condition, and the second constraint condition is determined based on the position of the second slot point on the edge of the first magnetic steel slot and the oblique pole angle.

[0010] Optionally, the first constraint condition is a first constraint equation, and a first limit position is obtained based on the first constraint equation, so that the position of the first target point coincides with the first limit position, or the position of the first target point is farther away from the center of the magnetic steel rotor than the first limit position.

[0011] Optionally, the second magnetic steel slot edge after deflection has an intersection with the target straight line, and the position of the intersection is used as the first limit position.

[0012] Optionally, the first magnetic steel slot edge is parallel to the d-axis, and based on the first constraint equation, the distance from the intersection to the first axis centerline perpendicular to the d-axis is obtained and defined as the minimum distance. The minimum distance is used as the first limit position, and the distance from the first target point to the first axis centerline is greater than or equal to the minimum distance.

[0013] Optionally, the second constraint condition is a second constraint equation, and a second limit position is obtained based on the second constraint equation, so that the position of the second target point coincides with the second limit position, or the position of the second target point is farther away from the center of the magnetic steel rotor than the second limit position.

[0014] Optionally, the second limit position is the position of the second slot point of the first magnetic steel slot edge after deflection.

[0015] Optionally, the first magnetic steel slot edge is parallel to the d-axis, and based on the second constraint equation, the distance from the second slot point of the deflected first magnetic steel slot edge to the first axis centerline perpendicular to the d-axis is obtained and defined as the maximum distance. The maximum distance is used as the second limit position, and the distance from the second target point to the first axis centerline is less than or equal to the maximum distance.

[0016] Optionally, the magnetic isolation bridge strength condition is the minimum width of the magnetic isolation bridge, so that the distance between the symmetrical straight side of the magnetic isolation hole and the edge of the first magnetic steel slot is greater than or equal to the minimum width of the magnetic isolation bridge.

[0017] Optionally, the magnetic isolation hole is rectangular or trapezoidal and symmetrical about the d axis.

[0018] To achieve the above-mentioned purpose, the present invention also provides a magnetic steel rotor, which is divided into several magnetic steel segments, and several of the magnetic steel segments are installed around the axial center line of the magnetic steel rotor with a predetermined angle to form oblique poles. A plurality of magnetic steel slots are provided on the magnetic steel segments, and a magnet is inserted into each of the magnetic steel slots; wherein, the corresponding two magnetic steel slots are arranged in a V-shape, and a magnetic isolation hole is provided between the ends close to the center of the magnetic steel rotor, and the magnetic isolation hole is made by adopting the design method of the magnetic isolation hole described in any of the above items.

[0019] Optionally, the magnetic steel rotor adopts any one of a single V-type topology structure, a double V-type topology structure, a V-type topology structure and a 3V-type topology structure.

[0020] To achieve the above-mentioned object, the present invention further provides a permanent magnet motor, which is provided with the magnetic steel rotor described in any one of the above items.

[0021] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0022] The aforementioned design method of the magnetic isolation hole includes: first, determining the position of the target straight line parallel to the first magnetic steel slot edge according to the position of the first magnetic steel slot edge of the magnetic steel slot and the magnetic isolation bridge strength condition, thereby indirectly constraining the distance between the symmetrical straight edge of the magnetic isolation hole and the first magnetic steel slot edge, and the distance meets the magnetic isolation bridge strength requirement; secondly, determining the positions of the two target points on the target straight line according to the position of the first magnetic steel slot edge and the oblique pole angle of the magnetic steel rotor, and determining the line segment of the target straight line between the two target points as the symmetrical straight edge of the magnetic isolation hole, so that the corresponding magnetic steel slot and the magnetic isolation hole at the corresponding position have a maximized overlapping area.

[0023] With such a configuration, on the one hand, the magnetic isolation holes can meet the strength requirements of the magnetic isolation bridge and reduce the stress concentration and deformation of the magnetic isolation bridge, thereby ensuring the reliability and stability of the motor. On the other hand, by optimizing the position, shape and size of the magnetic isolation holes, the overlapping area of ​​the magnetic isolation holes and the magnetic steel slots can be maximized after the rotor is tilted. Then, the cross-overlapping area of ​​the circumferentially staggered magnetic isolation holes and magnetic steel slots on the axially adjacent magnetic steel segments can be used to fill the injection molding compound, thereby significantly improving the torsional stiffness of the rotor, improving the torsional modal frequency of the rotor, thereby reducing motor noise and improving the overall performance of the permanent magnet motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are provided for a better understanding of the present invention and are not intended to limit the present invention.

[0025] Figure 1 FIG1 is a schematic diagram of a one-eighth cross-section of a magnetic steel segment according to an embodiment of the present invention, wherein the hatching in the figure represents the filled injection molding compound;

[0026] Figure 2 is a complete cross-sectional schematic diagram of a magnetic steel segment provided according to one embodiment of the present invention;

[0027] Figure 3 2. It is a cross-sectional schematic diagram of a comparative embodiment in which two axially adjacent magnetic steel segments are staggered at a certain angle, and the corresponding magnetic steel slots and corresponding magnetic isolation holes overlap, but no optimization is performed;

[0028] Figure 4 This is a schematic cross-sectional view of an optimized state in which two axially adjacent magnetic steel segments are staggered at a certain angle, and the corresponding magnetic steel slots and corresponding magnetic isolation holes overlap, according to an embodiment of the present invention;

[0029] Figure 5 is a complete cross-sectional schematic diagram of a magnetic steel segment provided in a comparative embodiment, in which the magnetic steel segment is not provided with magnetic isolation holes;

[0030] Figure 6 1 is a schematic cross-sectional view of two axially adjacent magnetic steel segments staggered at a certain angle according to an embodiment of the present invention;

[0031] Figure 7 is a schematic diagram of a one-eighth cross-section of a single V-shaped magnetic steel segment provided according to one embodiment of the present invention;

[0032] Figure 8 is a schematic diagram of a one-eighth cross-section of a double-V-shaped magnetic steel segment provided according to one embodiment of the present invention;

[0033] Figure 9 FIG. 1 is a schematic diagram of a one-eighth cross-section of a V-shaped magnetic steel segment provided according to one embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components during actual implementation. During actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0035] In addition, each embodiment described below has one or more technical features. However, this does not mean that users of the present invention must implement all technical features in any embodiment at the same time, or that they can only implement some or all technical features in different embodiments separately. In other words, as long as implementation is possible, those skilled in the art can, based on the disclosure of the present invention and depending on design specifications or implementation requirements, selectively implement some or all technical features in any embodiment, or selectively implement a combination of some or all technical features in multiple embodiments, thereby increasing the flexibility of the implementation of the present invention.

[0036] As used in this specification, the singular forms "a," "an," and "the" include plural referents, and the plural form "a plurality" includes more than two referents, unless the context clearly indicates otherwise. As used in this specification, the term "or" is generally used in a sense that includes "and / or," unless the context clearly indicates otherwise, and the terms "installed," "connected," and "connected" should be understood broadly, for example, to mean fixedly connected, removably connected, or integrally connected. It can be mechanically connected or electrically connected. It can be directly connected or indirectly connected through an intermediary, and it can be internal communication between two elements or an interactive relationship between two elements. Relational terms such as "first," "second," and the like are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations, nor do they indicate or imply relative importance or implicitly specify the number of technical features indicated. For those skilled in the art, the specific meanings of the above terms in this invention can be understood based on the specific circumstances.

[0037] One of the objects of the present invention is to provide a design method for magnetic isolation holes, by which the position, shape and size of the magnetic isolation holes are optimized so that the magnetic isolation holes can meet the strength requirements of the magnetic isolation bridge while maximizing the overlapping area of ​​the magnetic isolation holes and magnetic steel slots of adjacent magnetic steel segments, thereby improving the torsional stiffness of the rotor and the torsional modal frequency of the rotor.

[0038] A second objective of the present invention is to provide a magnetic rotor that is divided into a plurality of magnetic segments. These segments are installed at a predetermined angle around the rotor's axis to form skewed (or staggered) poles. Specifically, the magnetic rotor utilizes a segmented core structure, dividing the entire rotor core into a plurality of equal segments. For example, "N-segment skewed" means the entire rotor core is divided into N segments for skewed polarity.

[0039] It should be noted that the skewed poles used in the present invention may be V-shaped skewed poles, cross-skewed poles or linear skewed poles. The magnetic steel rotor of the present invention is a built-in rotor, and the permanent magnets are arranged inside the rotor core.

[0040] A third objective of the present invention is to provide a permanent magnet motor incorporating the magnetic steel rotor of the present invention. Compared to the prior art, the magnetic steel rotor of the present invention has higher rigidity, can reduce vibration of the magnetic steel rotor, thereby improving the noise level of the permanent magnet motor and enhancing the performance of the permanent magnet motor.

[0041] To make the objects, advantages, and features of the present invention more apparent, the present invention is further described below in detail with reference to the accompanying drawings. It should be noted that the drawings are greatly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention. The same or similar reference numerals in the drawings represent the same or similar components.

[0042] Figure 1 FIG2 shows a schematic diagram of a one-eighth cross section of a magnetic steel segment provided in one embodiment of the present invention. Figure 2 A complete cross-sectional schematic diagram of a magnetic steel segment provided according to an embodiment of the present invention is shown.

[0043] refer to Figure 1 and Figure 2 The magnetic steel rotor of the present invention is divided into a plurality of magnetic steel segments 10. Each magnetic steel segment 10 includes an iron core 11 and multiple magnetic pole groups 12. The multiple magnetic pole groups 12 are arranged at intervals along the circumference of the iron core 11. Each magnetic pole group 12 includes a plurality of magnetic steel slots 13 provided on the iron core 11 and extending axially therethrough, and magnets 14 inserted one by one into the magnetic steel slots 13. Since the magnets 14 in the drawings are already inserted into the magnetic steel slots 13, for the sake of distinction, the lead lines in the drawings point to the magnetic steel slots 13 when they point to the lines, and to the magnets 14 when they point to the non-line areas.

[0044] Each magnetic pole group 12 is provided with at least one pair of V-shaped magnetic steel slots 13. More specifically, the pair of magnetic steel slots 13 extend away from each other, with a gap 100 formed between the ends of the pair of magnetic steel slots 13 near the center of the core 11. This reduces the air gap harmonic content and improves the utilization rate of the permanent magnets. Each magnetic pole group 12 is arranged symmetrically about the d-axis (also known as the direct axis), while adjacent magnetic pole groups 12 are arranged symmetrically about the q-axis (also known as the quadrature axis).

[0045] As can be understood by those skilled in the art, the plurality of magnetic pole groups 12 are arranged in the circumferential direction of the core 11 in the form of N poles and S poles, for example, the magnetic pole group 12 in the 12 o'clock direction is an N pole, and the circumferentially adjacent magnetic pole group 12 is an S pole, and the N pole-S pole-N pole is alternately arranged. However, the present application does not limit the number of magnetic pole groups 12 and the interval 100 distance between the magnetic steel grooves 13, and the number and interval 100 distance are selected according to the requirements that can be achieved by the application of the permanent magnet motor, for example, in the present embodiment, eight magnetic pole groups 12 are provided, and one magnetic pole group 12 is arranged at an interval of 45°. The present application also does not limit the shape of the magnetic steel 14, and in the present embodiment, a rectangular cross-section magnetic steel 14 is used, of course, which is not limited in practice.

[0046] The magnetic steel 14 needs to be fixed, generally using injection molding filling fixation, by placing the magnetic steel 14 in the magnetic steel groove 13, and using thermoplastic or thermosetting plastic material to fill the area corresponding to the two ends of the magnetic steel 14 in the magnetic steel groove 13, thereby achieving fixation. Such integrated fixation can effectively prevent the magnetic steel 14 from being displaced or falling off due to centrifugal force, and can also achieve complex shape filling, one-time forming to improve production efficiency. Therefore, each magnetic steel segment 10 can be integrated by injection molding filling fixation, and the injection molding material penetrates through each magnetic steel segment 10 in the axial direction, ensuring the structural strength of the entire magnetic steel rotor.

[0047] The present application also does not limit the radial topology form of the magnetic pole group 12. The following is described exemplarily.

[0048] As Figure 7 described in an exemplary embodiment, the magnetic pole group 12 is provided with only one pair of magnetic steel grooves 13, and the magnetic steel 14 is inserted into the pair of magnetic steel grooves 13 one by one, forming a single V-type topology structure.

[0049] As Figure 8 described in another exemplary embodiment, the magnetic pole group 12 is provided with two pairs of magnetic steel grooves 13, and the magnetic steel 14 is inserted into the two pairs of magnetic steel grooves 13 one by one, forming a double V-type topology structure.

[0050] As Figure 9 described in another exemplary embodiment, the magnetic pole group 12 is provided with a pair of V-type magnetic steel grooves 13, and a magnetic steel groove 13 located in the V-type structure, and the magnetic steel 14 is inserted into the pair of magnetic steel grooves 13 and the transverse magnetic steel groove 13 one by one, forming a V-one type topology structure.

[0051] Referring Figure 1 and Figure 2 , in the present embodiment, the magnetic pole group 12 is provided with three pairs of magnetic steel grooves 13, and the magnetic steel 14 is inserted into the three pairs of magnetic steel grooves 13 one by one, forming a 3V-type topology structure.

[0052] The above 3V topology is the main development direction of the current permanent magnet motor. In the 3V topology, each pair of magnetic steel grooves 13 is arranged in a V shape, and three pairs of magnetic steel grooves 13 are arranged in a spaced manner from the outside to the inside.

[0053] Further, each magnetic pole group 12 further comprises a magnetic isolation hole 15 arranged on the iron core 11 and penetrating in the axial direction. The number of magnetic isolation holes 15 corresponds to the number of magnetic pole groups 12 one by one, and the plurality of magnetic isolation holes 15 are arranged in a spaced manner along the circumferential direction of the iron core 11. Each magnetic pole group 12 is provided with a magnetic isolation hole 15 between the end portions of the corresponding two magnetic steel grooves 13 close to the center of the iron core 11, that is, the magnetic isolation hole 15 is arranged at the interval 100 between the end portions of the corresponding two magnetic steel grooves 13 close to the center of the magnetic steel rotor. Any magnetic isolation hole 15 is arranged symmetrically about the d-axis of the corresponding position. The magnetic isolation hole 15 can effectively reduce the leakage of the magnetic field, prevent the magnetic field from leaking out of the two ends of the rotor, thereby ensuring the concentration of the magnetic field inside the motor, improving the efficiency of the motor, and improving the overall performance of the motor.

[0054] Next, the magnetic isolation hole 15 will be further described in relation to the topology of various magnetic steel rotors.

[0055] Reference Figure 1-2 In the 3V topology, a magnetic isolation hole 15 is arranged at the interval 100 between the end portions of the innermost pair of magnetic steel grooves 13 close to the center of the iron core 11.

[0056] Reference Figure 7 and Figure 9 In the single V and V-I topologies, only a magnetic isolation hole 15 is arranged at the interval 100 between the end portions of the corresponding two magnetic steel grooves 13 close to the center of the iron core 11.

[0057] Reference Figure 8 Similar to the 3V type, in the double V topology, a magnetic isolation hole 15 is arranged at the interval 100 between the end portions of the innermost pair of magnetic steel grooves 13 close to the center of the iron core 11.

[0058] The shape of the magnetic isolation hole 15 is not particularly limited in the present application, for example, the magnetic isolation hole 15 can be a rectangular hole, or a trapezoidal hole or other shapes, as long as the magnetic isolation hole 15 is symmetric about the d-axis, and the two symmetric straight edges of the magnetic isolation hole 15 are parallel to the magnetic steel groove edge on the same side. The magnetic steel groove edge close to the center of the iron core 11. Therefore, the shape of the magnetic isolation hole 15 can be appropriately changed, including but not limited to the rectangular hole described in the figure.

[0059] For example, in the embodiment, the magnetic isolation hole 15 is composed of AB, BC, CD and DA ring, the adjacent straight lines are perpendicular to each other, and the whole is rectangular. If the magnetic isolation hole 15 is a rectangular hole, the four corners of the magnetic isolation hole 15 can be right angles or rounded corners, which is not limited by the present application. The two symmetrical straight sides AB and CD of the magnetic isolation hole 15 can be parallel or not parallel to the d-axis. At this time, the two symmetrical straight sides of the magnetic isolation hole 15 are AB and CD, and the same side adjacent magnetic steel slot 13 has a first magnetic steel slot side FG close to the d-axis, and the symmetrical straight sides AB and CD are parallel to the same side adjacent first magnetic steel slot side FG.

[0060] When each magnetic steel segment 10 is installed, the area corresponding to the two end portions of the magnetic steel 14 of each magnetic steel slot 13 is filled with injection plastic, and the magnetic isolation hole 15 is also filled with injection plastic, and the connection of each magnetic steel segment 100 is realized by injection filling, which ensures the strength of the whole magnetic steel rotor.

[0061] As described above, the magnetic steel rotor provided by the present application adopts a rotor skew pole structure (or a rotor misaligned pole structure).

[0062] Reference Figure 6 , the case that the two magnetic steel segments 10 axially adjacent are placed at a certain angle around the axis of the magnetic steel rotor is schematically described. In the drawing, the red part represents the magnetic steel segment 10 that has been deflected by an angle α skew relative to the black part of the magnetic steel segment 10. It can be seen that after the magnetic steel rotor is skewed by an angle α skew , the two magnetic steel segments 10 axially adjacent will have a part of the magnetic steel slot 13 and the magnetic isolation hole 15 overlapping at the position corresponding to each magnetic pole group 12. Specifically, the magnetic steel slot 13 of the red line part of the magnetic steel segment 10 after rotation will have a part overlapping with the magnetic isolation hole 15 of the black line part. More clearly, reference can be made to Figure 3 and Figure 4 , the area defined by the section line in the drawing is the overlapping area of the deflected magnetic steel slot 13 and the corresponding magnetic isolation hole 15.

[0063] It is found that the larger the overlapping area of the magnetic steel slot 13 and the magnetic isolation hole 15, the larger the area of the magnetic isolation hole 15 and the magnetic steel slot 13 intersected when filling with injection plastic, and the torsional stiffness of the whole magnetic steel rotor will be improved. Therefore, based on the rotor skew pole, the intersection area between the magnetic isolation hole 15 and the magnetic steel slot 13 can be maximally utilized to fill with injection plastic to improve the torsional stiffness of the rotor.

[0064] Specifically, the larger the overlapping area between the magnetic isolation holes 15 and the magnetic steel slots 13 of axially adjacent magnetic steel segments 10, the more injection plastic can penetrate axially. The injection plastic is usually a damping material similar to rubber. The magnetic steel segments 10 are penetrated and combined into one in the axial direction through the injection plastic. The injection plastic limits the torsion of the rotor and increases the overall torsional stiffness of the rotor. This is different from the traditional method of improving the rotor stiffness by modifying the rotor material or process.

[0065] To this end, an embodiment of the present invention provides a design method for a magnetic isolation hole, and uses a symmetrical straight edge AB example to illustrate the design method. The design method includes:

[0066] (1) Based on the position of the first magnetic steel slot edge FG of any magnetic steel slot 13 and the strength requirement of the magnetic isolation bridge, the position of the target straight line parallel to the first magnetic steel slot edge FG is determined, and the symmetrical straight side AB of the magnetic isolation hole 15 is located on the target straight line. In this way, the distance between the symmetrical straight side AB and the first magnetic steel slot edge FG is indirectly constrained, and this distance meets the strength requirement of the magnetic isolation bridge. However, at this time, only the position of the target straight line where the symmetrical straight side AB is located is obtained, and the specific positions of the endpoints A and B on the two symmetrical straight sides AB cannot be determined.

[0067] In more detail, taking the symmetrical straight side AB parallel to the d-axis as an example, and establishing the x-axis and y-axis, the x-axis corresponds to the direction of the first axis of the magnetic steel rotor, which passes through the center O of the magnetic steel rotor and is perpendicular to the d-axis, and the y-axis corresponds to the direction of the second axis of the magnetic steel rotor and coincides with the d-axis. Then, based on the position of the first magnetic steel slot edge FG and the strength requirements of the magnetic isolation bridge, the distance from the target straight line where the symmetrical straight side AB is located to the y-axis can be determined. That is, the x-coordinate value of the target straight line where the symmetrical straight side AB is located is determined, and the range of the y-value is the entire coordinate system. Then, it is only necessary to determine the y-coordinate values ​​of the two endpoints A and B of the symmetrical straight side AB to determine the length of the symmetrical straight side AB;

[0068] (2) According to the position of the first magnetic steel slot edge FG and the deflection angle of the magnetic steel rotor (i.e., the skew angle), the positions of the two target points on the target straight line are determined, and the line segment of the target straight line between the two target points is determined as the symmetrical straight side AB of the magnetic isolation hole 15, so that the corresponding magnetic steel slot 13 and the corresponding magnetic isolation hole 15 have a maximized overlapping area.

[0069] As can be understood from the above, after the axially adjacent magnetic steel segments 10 are installed with a predetermined angle of deflection, any magnetic steel slot 13 and the magnetic isolation hole 15 at the corresponding position will have an overlapping area ( Figure 3 、 Figure 4The position of the filled cross-hatching (which indicates the overlap region) is defined by the deflected first magnet slot edge F'G', the undeflected symmetrical straight edge AB, the deflected second magnet slot edge F'E', and the deflected third magnet slot edge G'H'. In order to maximize the area of the overlap region, the positions of the two end points of the symmetrical straight edge AB are important. In practice, the symmetrical straight edge AB is positioned as close as possible to the first magnet slot edge FG to maximize the circumferential dimension of the magnetic gap 15, and as close as possible to the center of the magnet rotor to maximize the radial dimension of the magnetic gap 15.

[0070] It should be noted that the position of the first magnet slot edge FG and the skew angle of the deflection of the magnet rotor are known conditions when designing the magnetic gap 15. When the position of the first magnet slot edge FG and the skew angle are fixed, optimizing the position, shape, and size of the magnetic gap 15 can maximize the overlap area between the deflected magnet slot 13 of the magnet segment 10 and the corresponding magnetic gap 15 on the adjacent magnet segment 10. Similarly, the other symmetrical straight edge CD of the magnetic gap 15 can also be designed using the same method, which will not be repeated here. It should be understood that any magnetic gap 15 on all magnet segments 10 can be designed according to the above method.

[0071] Therefore, the present application can optimize the position, shape, and size of the magnetic gap 15 based on the above design method, on the one hand, to meet the strength requirements of the magnetic bridge, reduce stress concentration and deformation of the magnetic bridge, and ensure the reliability and stability of the motor, on the other hand, to maximize the overlap area between the corresponding magnetic gap 15 and the corresponding magnet slot 13 by further adjusting the positions of the two end points of the symmetrical straight edge AB, and to significantly improve the rotor torsional stiffness and the rotor torsional modal frequency when filling the injection molding material, thereby reducing the motor noise and improving the overall performance of the permanent magnet motor. In the embodiment of the present application, the magnetic gap 15 also functions as a weight-reducing hole.

[0072] In the embodiment, the first target point corresponds to the first end point A of the symmetrical straight edge AB of the magnetic gap 15, which is also the first magnetic bridge point, the second target point corresponds to the second end point B of the symmetrical straight edge AB of the magnetic gap 15, which is also the second magnetic bridge point, and the first magnet slot edge FG has a first slot point F and a second slot point G, the first end point A is farther from the center of the magnet rotor than the second end point B, and the first slot point F is farther from the center of the magnet rotor than the second slot point G.

[0073] To maximize the overlap area, the first endpoint A should fall on the line where the second magnetic steel slot edge F'E' lies after deflection, or the first endpoint A should be above the line where the second magnetic steel slot edge F'E' lies after deflection, and the distance between the second endpoint B and the first axis should either be equal to the distance between the second slot point G' after deflection and the first axis, or be less than the distance between the second slot point G' after deflection and the first axis. In other words, the polar coordinate radius of the second endpoint B should be less than or equal to the polar radius of the second slot point G. In this way, the overlap area between the injection molding area (e.g., F'-G'-H'-E') of the magnetic steel slot 13 corresponding to the inner end of the magnetic steel 14 near the center of the iron core 11 and the magnetic isolation hole 15 can be maximized.

[0074] In one embodiment, the aforementioned magnetic isolation bridge strength condition is a minimum magnetic isolation bridge width, such that the distance between the symmetrical straight side AB of the magnetic isolation hole 15 and the first magnetic steel slot side FG is greater than or equal to the minimum magnetic isolation bridge width. For example, in this embodiment, the first magnetic steel slot side FG and the symmetrical straight side AB are parallel to the d-axis. In this case, the distance between the symmetrical straight side AB and the first magnetic steel slot FG should meet the following requirements:

[0075] F x -A x ≥δ (1)

[0076] In formula (1): F x is the x coordinate of the first slot point F, A x is the x-coordinate of the first endpoint A, and δ is the minimum magnetic isolation bridge width that meets the strength requirements.

[0077] refer to Figure 2 In one embodiment, a rectangular coordinate system is established with the origin at the center O of the magnetic rotor. The x-axis corresponds to the direction of the first axis of the magnetic rotor, and the y-axis corresponds to the direction of the second axis of the magnetic rotor. The y-axis and the d-axis coincide. However, the x-axis and y-axis are not absolute and should be adjusted according to the position of the magnetic pole group 12.

[0078] When the symmetrical straight side AB of the magnetic isolation hole 15 is parallel to the y-axis, the distance between the symmetrical straight side AB and the first magnetic steel slot side FG is the x-coordinate difference between the first slot point F and the first endpoint A. When the symmetrical straight side AB of the magnetic isolation hole 15 is not parallel to the y-axis, those skilled in the art can also calculate the distance between the symmetrical straight side AB and the first magnetic steel slot side FG through conversion and meet the minimum magnetic isolation bridge width requirement.

[0079] In one embodiment, the method for determining the positions of two target points on the target straight line includes:

[0080] Step 1: Determine the position of the first target point (i.e., the first endpoint A) on the target straight line so that the position of the first target point satisfies a first constraint condition, wherein the first constraint condition is determined based on the position of the first slot point F on the first magnetic steel slot edge FG, and the vertex angle and oblique polar angle formed by the intersection of the first magnetic steel slot edge FG and the second magnetic steel slot edge FE at the first slot point F;

[0081] Step 2: Determine the position of the second target point (i.e., B at the second end) on the target straight line so that the position of the second target point satisfies the second constraint condition, which is determined based on the position and oblique pole angle of the second slot point G on the first magnetic steel slot edge FG.

[0082] The position of the first slot point F, the vertex angle at the first slot point F, and the skew angle are all known conditions. Therefore, on the basis of meeting the strength requirements of the magnetic isolation bridge, by further optimizing the positions of the two endpoints on the symmetrical straight edge AB, the overlapping area of ​​the magnetic isolation hole 15 and the magnetic steel slot 13 can be maximized.

[0083] Preferably, the first slot point F and the second slot point G are converted into a polar coordinate system for calculation, which is simpler and more convenient.

[0084] refer to Figure 6 In this embodiment, a polar coordinate system is established with the x-axis as the polar axis and ρ as the polar radius. The position of the first slot point F is expressed as F(ρ,θ) in the polar coordinate system, and the position of the second slot point G is expressed as G(ρ,θ) in the polar coordinate system. The vertex angle formed by the intersection of the first magnetic steel slot edge FG and the second magnetic steel slot edge FE at the first slot point F is expressed as ∠EFG, that is, the angle between EF and FG.

[0085] Furthermore, the first constraint condition is set as a first constraint equation. Specifically, the first constraint equation is established based on the position (e.g., polar coordinates) of the first slot point F, the vertex angle, and the skew polar angle at the first slot point F. Preferably, a first limit position is obtained based on the first constraint equation, and then the position of the first target point is made to coincide with the first limit position, or the position of the first target point is made to be further away from the center of the magnetic steel rotor than the first limit position.

[0086] Specifically in this embodiment, the second magnetic steel slot edge F'E' after deflection intersects the target straight line where the symmetrical straight edge AB is located (see Figure 4 , with the intersection being A). This intersection is not a physical point of intersection; rather, it refers to the point where the projection of the deflected second magnetic steel slot edge F'E' intersects the target straight line on which the symmetrical straight edge AB lies. The location of this intersection is then used as the first limit position. In other words, the first endpoint A should be located on or above the intersection.

[0087] For example, when the first magnetic steel slot edge FG is parallel to the d-axis, the distance from the intersection point to the first axis centerline is obtained based on the first constraint equation and defined as the minimum distance (i.e., the y-coordinate value). This minimum distance is used as the first limit position, and the distance from the first target point to the first axis centerline is greater than or equal to the minimum distance. In other words, the y-coordinate value of the first endpoint A is greater than or equal to the y-coordinate value defined by the minimum distance. Therefore, in the limit case, the first endpoint A falls on the line containing the deflected second magnetic steel slot edge F'E', which is the minimum distance for the first endpoint A. Preferably, the first slot point F and the second slot point G are converted to a polar coordinate system to calculate the minimum distance.

[0088] For ease of understanding, Figure 3 Reference Figure 3 If the first end point A is located below the second magnetic steel slot edge F'E' after deflection, the overlapping area is not the largest. Therefore, Figure 4 In the embodiment, the first endpoint A should fall on the second magnetic steel slot edge F'E' after deflection, or be above the second magnetic steel slot edge F'E' after deflection.

[0089] Furthermore, in the polar coordinate system, the position of the first endpoint A is calculated and satisfies the following first constraint condition, and the first constraint equation is established as follows:

[0090] A y ≥F ρ sin(F θ +α skew )+(A x -F ρ cos(F θ +α skew ))tan(α ∠EFG -90°+α skew ) (2)

[0091] That is, A y ≥F′ y +△AF′ y ;

[0092] In formula (2): A y represents the y coordinate of the first endpoint A, F′y is the y coordinate of the first slot point F′ after deflection, △AF′y is the y coordinate difference between the first endpoint A and the first slot point F′ after deflection, F ρ represents the polar radius of the first endpoint A, F θ represents the polar coordinate angle of the first endpoint A, α ∠EFG represents the included angle (i.e., vertex angle) between the second magnetic steel slot edge EF and the first magnetic steel slot edge FG, α skew Indicates the oblique polar angle.

[0093] Similarly, the second constraint condition is set as a second constraint equation, which is determined based on the position of the second slot point G and the skew angle. Preferably, a second limit position is obtained based on the second constraint equation, thereby causing the position of the second target point to coincide with the second limit position, or causing the position of the second target point to be further away from the center of the magnetic steel rotor than the second limit position. Specifically, in this embodiment, the second limit position is the position of the second slot point G' after deflection.

[0094] For example, when the first magnetic steel slot edge FG is parallel to the d-axis, the second constraint equation is used to determine the distance from the deflected second slot point G' to the first axis centerline and define it as the maximum distance (y-coordinate). This maximum distance serves as the second limit position, and the distance from the second target point to the first axis centerline is set to be less than or equal to the maximum distance. Therefore, in the extreme case, the second endpoint B is at the same height as the deflected second slot point G', which serves as the maximum distance for the second endpoint B.

[0095] refer to Figure 3 and Figure 4 , the second endpoint B may fall below the second slot point G' after deflection, for example, the distance from the second endpoint B to the first axis is less than the distance from the second slot point G' to the first axis after deflection. However, in the extreme case, the distance from the second endpoint B to the first axis may be equal to the distance from the second slot point G' to the first axis after deflection. In other words, the second slot point G' after deflection falls on the straight side BC of the magnetic isolation slot 15 or above the straight side BC. Therefore, the maximum distance is the distance from the second slot point G' after deflection to the first axis. Preferably, the maximum distance is calculated in a polar coordinate system.

[0096] Furthermore, in the polar coordinate system, the position of the second endpoint B is calculated and satisfies the following second constraint condition, and the second constraint equation is established as follows:

[0097] B y ≤G ρ (sin(G θ +α skew )) (3)

[0098] That is, B y ≤G′ y ;

[0099] In formula (3): B y represents the y coordinate of the second endpoint B, G′ y is the y coordinate of the second slot point G' after deflection, G ρ Indicates the polar radius of the second slot point G, G θ Indicates the polar coordinate angle of the second slot point G.

[0100] After the above constraints are met, the overlap between the magnetic steel slot 13 and the magnetic isolation hole 15 after the magnetic steel segment 10 is deflected is as follows: Figure 4 shown.

[0101] Next, the advantages of the technical solution of the present invention are further illustrated by experimental data.

[0102] Figure 5 The three-layer magnetic steel rotor in the comparative embodiment lacks magnetic isolation holes, while the present invention utilizes a three-layer magnetic steel rotor with magnetic isolation holes. The magnetic steel rotors in both the present invention and comparative embodiments are equally divided axially into three magnetic steel segments, with the magnetic steel segments 10 skewed at a 2.5° angle. Modal simulations were then performed on both magnetic steel rotors after filling them with injection molding compound. The simulation results are shown in Table 1.

[0103] Table 1 is a comparison of rotor modal indicators with and without magnetic isolation holes.

[0104] Indicator No flux barrier hole With flux barrier hole Optimization effect First order torsional frequency / Hz 2555 2713 +6.2％ Second order torsional frequency / Hz 4236 4485 +5.9％

[0105] As shown in Table 1, the first-order torsional frequency of the three-layer magnetic steel rotor with magnetic isolation holes is increased by 6.2% compared to the first-order torsional frequency of the three-layer magnetic steel rotor without magnetic isolation holes, and the second-order torsional frequency is increased by 5.9%. Therefore, the magnetic steel rotor provided by the embodiment of the present invention has better torsional stiffness and can effectively improve the torsional modal frequency.

[0106] It can be seen that according to the technical solution provided by the present invention, the position, shape and size of the magnetic isolation hole 15 can be optimized while the magnetic isolation hole 15 meets the strength requirements of the magnetic isolation bridge, so that the overlapping area of ​​the magnetic isolation hole 15 and the magnetic steel slot 13 can be maximized after the rotor is tilted, and then the cross-overlapping area of ​​the magnetic isolation hole 15 and the magnetic steel slot 14 of the axially adjacent magnetic steel segments 10 can be used to fill the injection molding compound, which significantly improves the torsional stiffness of the rotor, improves the torsional modal frequency of the rotor, thereby improving the noise level of the motor and improving the overall performance of the permanent magnet motor.

[0107] While the present invention is disclosed above, it is not limited thereto. Those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, the present invention is intended to encompass such modifications and variations as fall within the scope of the present invention and its equivalents.

Claims

1. A method for designing a magnetic isolation hole, wherein the magnetic isolation hole (15) is arranged on a magnetic steel segment (10) of a magnetic steel rotor and is located between the ends of a pair of two V-shaped magnetic steel slots (13) close to the center of the magnetic steel rotor, and a plurality of the magnetic steel segments (10) can be installed to deflect a predetermined angle around the axis of the magnetic steel rotor to form a skew pole, characterized in that: The design method includes: Determining the position of a target straight line parallel to the first magnetic steel slot edge of the magnetic steel slot (13) based on the position of the first magnetic steel slot edge and the strength condition of the magnetic isolation bridge; According to the position of the first magnetic steel slot edge and the oblique pole angle of the magnetic steel rotor, the positions of the two target points on the target straight line are determined, and the line segment of the target straight line between the two target points is determined as the symmetrical straight edge of the magnetic isolation hole (15), so that the corresponding magnetic steel slot (13) and the corresponding magnetic isolation hole (15) have a maximized overlapping area.

2. The design method of the magnetic isolation hole according to claim 1, characterized in that: The method for determining the positions of two target points on the target straight line includes: Determine a position of a first target point on the target straight line so that the position of the first target point satisfies a first constraint condition, where the first constraint condition is determined based on a position of a first slot point on the first magnetic steel slot edge, a vertex angle formed by the intersection of the first magnetic steel slot edge and the second magnetic steel slot edge at the first slot point, and the oblique polar angle; And, determine the position of the second target point on the target straight line so that the position of the second target point satisfies the second constraint condition, and the second constraint condition is determined based on the position of the second slot point on the edge of the first magnetic steel slot and the oblique pole angle.

3. The design method of the magnetic isolation hole according to claim 2, characterized in that: The first constraint condition is a first constraint equation, and a first limit position is obtained based on the first constraint equation, so that the position of the first target point coincides with the first limit position, or the position of the first target point is farther away from the center of the magnetic steel rotor than the first limit position.

4. The design method of the magnetic isolation hole according to claim 3, characterized in that: After deflection, the second magnetic steel slot edge and the target straight line have an intersection, and the position of the intersection is used as the first limit position.

5. The design method of the magnetic isolation hole according to claim 4, characterized in that: The first magnetic steel slot edge is parallel to the d-axis, and based on the first constraint equation, the distance from the intersection to the first axis centerline perpendicular to the d-axis is obtained and defined as the minimum distance. The minimum distance is used as the first limit position, and the distance from the first target point to the first axis centerline is greater than or equal to the minimum distance.

6. The method for designing a magnetic isolation hole according to claim 2, wherein: The second constraint condition is a second constraint equation, and a second limit position is obtained based on the second constraint equation, so that the position of the second target point coincides with the second limit position, or the position of the second target point is farther away from the center of the magnetic steel rotor than the second limit position.

7. The method for designing a magnetic isolation hole according to claim 6, characterized in that: The second limit position is the position of the second slot point of the first magnetic steel slot edge after deflection.

8. The method for designing a magnetic isolation hole according to claim 7, characterized in that: The first magnetic steel slot edge is parallel to the d-axis, and based on the second constraint equation, the distance from the second slot point of the deflected first magnetic steel slot edge to the first axis centerline perpendicular to the d-axis is obtained and defined as the maximum distance. The maximum distance is used as the second limit position, and the distance from the second target point to the first axis centerline perpendicular to the first axis is less than or equal to the maximum distance.

9. The method for designing a magnetic isolation hole according to claim 1, wherein: The strength condition of the magnetic isolation bridge is the minimum width of the magnetic isolation bridge, so that the distance between the symmetrical straight side of the magnetic isolation hole (15) and the edge of the first magnetic steel slot is greater than or equal to the minimum width of the magnetic isolation bridge.

10. A magnetic steel rotor, divided into a plurality of magnetic steel segments (10), wherein the plurality of magnetic steel segments (10) are installed around the axis of the magnetic steel rotor at a predetermined angle to form skew poles, characterized in that: A plurality of magnetic steel slots (13) are provided on the magnetic steel segment (10), and a magnetic steel (14) is inserted into each of the magnetic steel slots (13); wherein, the corresponding two magnetic steel slots (13) are arranged in a V-shape, and a magnetic isolation hole (15) is provided between the ends close to the center of the magnetic steel rotor, and the magnetic isolation hole (15) is made by adopting the design method of the magnetic isolation hole as described in any one of claims 1 to 9.

11. The magnetic steel rotor according to claim 10, characterized in that: The magnetic steel rotor adopts any one of a single V-type topology structure, a double V-type topology structure, a V-type topology structure and a 3V-type topology structure.

12. A permanent magnet motor, characterized in that: A magnetic steel rotor as claimed in claim 10 or 11 is provided.

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