Motor rotor structure with magnetism gathering effect, assembling method and motor

Abstract

The invention discloses a motor rotor structure with a magnetism gathering effect, an assembling method and a motor, and belongs to the field of permanent magnet synchronous motors. The rotor structure comprises a rotor iron core and a Halbach magnetic steel array; the Halbach magnetic steel array comprises circumferential magnetizing magnetic steel and radial magnetizing magnetic steel which are alternately distributed in the circumferential direction. The radial thickness of the radial magnetizing magnetic steel is greater than that of the circumferential magnetizing magnetic steel, so that the rotor iron core forms a rotor iron core boss at each circumferential magnetizing magnetic steel; the radial magnetizing magnetic steel is divided into N magnetic steel blocks in the circumferential direction, and the radial thickness of each side block is gradually increased from the outer side edge to the inner side edge. Preferably, the two side edges of the radial magnetizing magnetic steel are recessed towards the center block to form a V shape, and the vertex of the V shape is the intersection of the outer side edge of the edge block, the circumferential magnetizing magnetic steel and the rotor core boss. According to the Halbach permanent magnet array, the problems that the Halbach permanent magnet array is large in assembly difficulty, serious in demagnetization phenomenon and low in overload performance can be solved while the magnetism gathering effect of the Halbach permanent magnet array is utilized.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet synchronous motors, and more specifically, relates to a motor rotor structure with a magnetic field concentration effect, an assembly method and a motor. Background Art

[0002] Distributed electric propulsion is used to replace traditional fuel engines. It has the advantages of lightweight structure, high integration, high efficiency, low noise, etc. It also greatly improves the system safety redundancy capability, improves the aircraft starting efficiency and carrying capacity, and is an important technical means for aviation electrification. The electric drive system is the core power equipment for all-electric aircraft to perform take-off, landing and cruise flight. The quality of the aircraft and the driving experience are directly determined by its performance. Considering that the aerospace field is highly sensitive to weight and volume, and that the aircraft has different requirements for the electric drive system under multiple working conditions such as take-off, cruising, and landing, the electric drive system also has high power density, high torque density, high efficiency, high reliability and high overload performance requirements. How to seek greater torque density and stronger overload performance based on the traditional permanent magnet motor topology is the key and difficulty in the design of such aviation electric drive systems.

[0003] Permanent magnet synchronous motors are the preferred motor type for propulsion motors in such aviation electric drive systems due to their high power density and high efficiency. Halbach permanent magnet arrays have a magnetic concentration effect, which can increase the air gap magnetic density, increase the magnetic load of the motor, and thus improve the output torque of the motor. Therefore, the use of Halbach permanent magnet arrays is one of the feasible solutions to effectively improve the torque density of the motor; however, due to its unique magnetization direction, traditional Halbach magnets are difficult to install and fix. If they are reinforced by rotor sleeves, the thickness of the air gap will be occupied, which will seriously affect the electromagnetic properties of the motor, and the performance advantages brought by the Halbach permanent magnet array will be lost by the rotor sleeves used for its installation and fixation, and even negative improvement may occur. In addition, due to its unique magnetization direction, serious magnetic steel demagnetization will occur at the contact point between the circumferential block and the radial block. When the motor is overloaded or fails, the armature reaction is too strong and may even cause large-scale demagnetization of the magnetic steel, which seriously endangers the safety and reliability of the motor system. When used in the aviation field, it will cause serious flight accidents and endanger the safety of life and property. Therefore, how to correctly sort out the magnetic circuit distribution so that the magnetic density at the junction of the circumferential block and the radial block of the magnetic steel remains within a safe range is one of the important technical requirements for the application of Halbach magnetic steel in the field of high safety.

[0004] In addition to the above-mentioned high torque density and high reliability requirements, the electric drive system should also have high overload performance to cope with complex aircraft operating conditions. Although the traditional Halbach permanent magnet rotor structure optimizes the magnetic circuit guidance and can greatly reduce the saturation of the rotor core, it still fails to show more advantages in overload performance. Therefore, how to innovatively propose a new rotor structure that takes into account both high torque density and high overload performance based on the traditional motor topology and combined with the Halbach permanent magnet array is one of the important directions for the development of motor technology in future aviation electric drive systems.

[0005] In the patent document with application number CN202110253188.0, an outer rotor motor with a polygonal dovetail spliced ​​magnetic steel structure is disclosed, in which the rotor magnetic steel is designed by the first permanent magnet, the second permanent magnet and the third permanent magnet, and multiple permanent magnets with isosceles triangle or quadrilateral cross-sections are spliced ​​in a circle to form a closed-loop rotor magnetic steel, and the Halbach magnetization method is adopted so that the electromagnetic force exerted on the stator coil in each stator tooth slot forms a closed loop along the circumferential tangent, so that the outer rotor is subjected to a stable torque and achieves stable rotation. However, the rotor structure is too complicated, which may lead to insufficient mechanical strength; and the patent only sets up "reinforcement ribs" on the motor casing for fixation. If the magnetic steel is axially segmented, the stability of the installation will be seriously damaged.

[0006] In the patent document with application number CN202011388249.6, a high-torque density axial magnetic field permanent magnet motor rotor structure and its motor are disclosed. By combining surface-mounted and built-in permanent magnet rotor structures, a segmented modular rotor core is adopted to apply the Halbach permanent magnet array structure to the axial flux motor. This segmented rotor core structure has the advantages of easy processing and installation, and by adopting a non-magnetic rotor support disk, the permanent magnet leakage is reduced, the main magnetic flux is increased, and the motor torque density is further improved. However, this scheme only uses glue to bond the permanent magnets, and does not consider the possibility of thermal instability of the glue. At the same time, when the axial flux motor rotates too fast, it will have an impact on the mechanical strength after installation, and the application occasions will be significantly limited.

[0007] In general, while utilizing the magnetic field concentration effect of the Halbach permanent magnet array, there are still problems such as the difficulty in assembling the Halbach permanent magnet array, severe demagnetization and low overload performance. Summary of the invention

[0008] In view of the defects of the prior art and the need for improvement, the present invention provides a motor rotor structure, an assembly method and a motor with a magnetic focusing effect. Its purpose is to effectively solve the problems of the Halbach permanent magnet array being difficult to assemble, severe demagnetization and low overload performance while utilizing the magnetic focusing effect of the Halbach permanent magnet array.

[0009] To achieve the above object, according to one aspect of the present invention, a motor rotor structure with a magnetic concentration effect is provided, comprising a rotor core and a Halbach magnetic steel array embedded in the rotor core; the Halbach magnetic steel array comprises circumferential magnetized magnetic steels and radial magnetized magnetic steels alternately distributed along the circumferential direction; the radial thickness of the radial magnetized magnetic steels is greater than the radial thickness of the circumferential magnetized magnetic steels, so that the rotor core forms a rotor core boss at each circumferential magnetized magnetic steel;

[0010] The radially magnetized magnetic steel is divided into N magnetic steel blocks along the circumferential direction. The magnetic steel block located in the center is the center block, and the magnetic steel blocks located on both sides are the side blocks. The radial thickness of the side blocks gradually increases from the outer side to the inner side, and the radial thickness of the center block is not less than the maximum radial thickness of the side blocks.

[0011] Among them, N≥3; the outer side of the edge block is the side adjacent to the circumferentially magnetized magnetic steel, and the inner side is the side close to the center block.

[0012] Furthermore, the sides of the radially magnetized magnetic steel are recessed toward the center block to form a "V" shape, and the vertex of the "V" shape is the intersection of the outer edge of the side block, the circumferentially magnetized magnetic steel and the rotor core boss.

[0013] Furthermore, in the same radially magnetized magnetic steel, there is an angle between the magnetization direction of the side block and the magnetization direction of the center block.

[0014] Furthermore, the angle between the magnetization direction of the side block and the magnetization direction of the center block in the same radial magnetized magnetic steel is set as follows:

[0015] Taking the angle between the magnetizing direction of the side block and the magnetizing direction of the center block in the same radial magnetized magnetic steel as the optimization variable, and taking the maximum motor torque and the minimum demagnetization degree at the intersection of the outer edge of the side block, the circumferential magnetized magnetic steel and the rotor core boss as the goal, a multi-objective optimization model is established;

[0016] The multi-objective optimization model is solved, and the solution result is set as the angle between the magnetizing direction of the side block and the magnetizing direction of the center block in the same radial magnetized magnetic steel.

[0017] In some optional embodiments, the radially magnetized magnetic steel is in a "crown shape" with radial thickness gradually decreasing from the center to both sides.

[0018] In some optional embodiments, in the radially magnetized magnetic steel, the top end of the center block is flattened.

[0019] According to another aspect of the present invention, there is provided a method for assembling the above-mentioned motor rotor structure with magnetic field concentration effect, comprising:

[0020] After magnetizing each radial magnet, the magnet is embedded into the corresponding magnet slot in the rotor core;

[0021] After each circumferential magnet is magnetized, it is embedded into the corresponding magnet slot in the rotor core.

[0022] According to another aspect of the present invention, a permanent magnet synchronous motor is provided, comprising the motor rotor structure with magnetic field concentration effect provided by the present invention.

[0023] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0024] (1) In the motor rotor structure with magnetic concentration effect provided by the present invention, the radial thickness of the radial magnetized magnetic steel in the Halbach magnetic steel array is greater than the radial thickness of the circumferential magnetized magnetic steel, so that the rotor core forms a rotor core boss at the circumferential magnetized magnetic steel, and the rotor core boss can play a role in installation, fixing and positioning of the radial magnetized magnetic steel, effectively solving the problem of difficulty in assembling the magnetic steel; at the same time, the existence of the rotor core boss makes the magnetic resistance of the d-axis and q-axis of the rotor core no longer consistent, thereby introducing a magnetic resistance torque component for the motor. When the motor operates under high load conditions, a weak magnetic method can be adopted to further increase the motor torque, improve the torque density and overload performance of the motor; in the present invention, the radial magnetized magnetic steel is divided into multiple sections along the circumferential direction, and the radial thickness of the edge block gradually increases from the outer edge to the inner edge, so that the effective core area between adjacent radial magnetized magnetic steels is increased, the saturation phenomenon of the rotor core is alleviated, the torque density of the motor is further improved, and the demagnetization is alleviated. In general, the present invention can effectively solve the problems of difficult assembly, serious demagnetization and low overload performance of the Halbach permanent magnet array while utilizing the magnetic field concentration effect of the Halbach permanent magnet array.

[0025] (2) In the preferred embodiment of the present invention, the side edges of the radial magnetized magnetic steel are recessed toward the center block to form a "V" shape, and the end of the "V" shape is the intersection of the outer edge of the edge block, the circumferential magnetized magnetic steel and the rotor core boss. Based on this structural design, the edge block can be mutually engaged with the rotor core boss. When the motor rotor rotates, the rotor core will exert a tight pressure on the magnetic steel through this edge to ensure the assembly and fixation of the radial magnetized magnetic steel. At the same time, it plays a role of fixing and pressing the circumferential magnetized magnetic steel. Therefore, when the motor rotor rotates, a continuous self-fixing effect of the rotor core on the radial magnetized magnetic steel and the radial magnetized magnetic steel on the circumferential magnetized magnetic steel can be formed, thereby reducing the dependence on adhesive force.

[0026] (3) In the preferred embodiment of the present invention, in the radial magnetized magnetic steel, the magnetization directions of the side blocks and the center blocks are different, but there is a certain angle, which can further alleviate the saturation of the rotor core, improve the torque density of the motor, and achieve the effect of preventing the demagnetization of the permanent magnet. In a further preferred embodiment, the angle between the magnetization direction of the side blocks and the magnetization direction of the center blocks is optimized by comprehensively considering the motor torque and demagnetization conditions, thereby optimizing the comprehensive performance of the motor.

[0027] (4) In some optional embodiments of the present invention, the radially magnetized magnetic steel is generally in a "crown shape" with a radial thickness gradually decreasing from the center to both sides, thereby maximizing the effective core area between adjacent radially magnetized magnetic steels, thereby maximizing the saturation of the rotor core, improving the torque density of the motor, and preventing the demagnetization of the permanent magnet; in other optional embodiments, the top of the center block of the radially magnetized magnetic steel is flattened, thereby saving the amount of magnetic steel and reducing the cost of the motor while utilizing the structural design of the side blocks to alleviate the demagnetization of the rotor core. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a rotor structure with a magnetic field concentration effect provided in Example 1 of the present invention;

[0029] Figure 2 A schematic diagram of d-axis and q-axis currents in the rotor structure and a motor space vector diagram in Embodiment 1 of the present invention;

[0030] Figure 3 A schematic diagram of the main magnetic circuit magnetic lines of force and the effective core area in the rotor structure provided in Embodiment 1 of the present invention;

[0031] Figure 4 A schematic diagram of a rotor structure with a magnetic field focusing effect provided in Example 2 of the present invention;

[0032] Figure 5 A schematic diagram of a rotor structure with a magnetic field focusing effect provided in Example 3 of the present invention;

[0033] Figure 6 A schematic diagram of d-axis and q-axis currents in the rotor structure and a motor space vector diagram in Embodiment 1 of the present invention;

[0034] Figure 7 A schematic diagram of a rotor structure with a magnetic field focusing effect provided in Example 4 of the present invention;

[0035] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0036] 1- rotor core, 2- rotor core boss, 3- circumferentially magnetized magnetic steel, 4- radially magnetized magnetic steel, 5- center block, 6- side block. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects but not necessarily to describe a specific order or sequence.

[0039] In order to ensure that the electromagnetic performance of the motor is taken into account while enabling the magnets to be assembled and tightened with the rotor core, without the need for a rotor sleeve, and to improve the overload performance of the motor, the present invention provides a motor rotor structure, an assembly method and a motor with a magnetic concentration effect. The overall concept is to improve the structure of the radially magnetized magnets in the Halbach magnet array so that the rotor core forms a rotor core boss for installing, fixing and positioning the radially magnetized magnets, and a magnetic resistance torque component is introduced through the rotor core boss to improve the torque density and overload performance of the motor. In addition, the rotor core area between adjacent radially magnetized magnets is increased, the saturation level of the rotor core is reduced, the torque density of the motor is improved, and the effect of preventing the demagnetization of the permanent magnet is achieved.

[0040] The rotor structure provided by the present invention can be applied to both radial flux outer rotor motor topology and radial flux inner rotor motor topology. It is easy to understand that in the radial flux outer rotor motor topology, the Halbach magnet array is embedded in the inner circumference of the rotor core; in the radial flux inner rotor motor topology, the Halbach magnet array is embedded in the outer circumference of the rotor core.

[0041] The following are examples.

[0042] Embodiment 1:

[0043] A motor rotor structure with a magnetic field concentration effect, this embodiment is suitable for radial flux outer rotor permanent magnet motor topology, such as Figure 1 , Figure 2 and Figure 3 As shown, it includes a rotor core 1, and a Halbach magnetic steel array embedded in the inner circumference of the rotor core 1; the Halbach magnetic steel array includes circumferential magnetized magnetic steels 3 and radial magnetized magnetic steels 4 that are alternately distributed along the circumferential direction; the radial thickness of the radial magnetized magnetic steels 4 is greater than the radial thickness of the circumferential magnetized magnetic steels 3, so that the rotor core 2 forms a rotor core boss 2 at each circumferential magnetized magnetic steel 3;

[0044] The radially magnetized magnetic steel 4 is divided into three magnetic steel blocks along the circumferential direction. The magnetic steel block located in the center is the center block 5, and the magnetic steel blocks located on both sides are the side blocks 6. The radial thickness of the side block 6 gradually increases from the outer side to the inner side, and the radial thickness of the center block 5 is not less than the maximum radial thickness of the side block 6.

[0045] Among them, the outer side of the edge block is the side adjacent to the circumferentially magnetized magnetic steel, and the inner side is the side close to the center block.

[0046] In this embodiment, the radial thickness of the radial magnetized magnetic steel is greater than the radial thickness of the circumferential magnetized magnetic steel, so that a rotor core boss is formed on the rotor core. On the one hand, the rotor core plays a role in installing, fixing and positioning the radial magnetized magnetic steel, effectively solving the problem of the difficulty in installing the Halbach magnetic steel array; on the other hand, due to the existence of the rotor core boss 2, the magnetic resistance of the d-axis and q-axis of the rotor core 1 are no longer consistent, such as Figure 2 As shown, due to the different magnetic resistances of the d and q axes, a magnetic resistance torque component can be introduced into the motor. When the motor operates under high load conditions, a weak magnetic method can be used to further obtain torque, thereby improving the torque density and overload performance of the motor.

[0047] In addition, the radial magnetized magnetic steel is designed to be segmented in the circumferential direction in this embodiment, and the radial thickness of the side block gradually increases from the outer side to the inner side, that is, the side block is close to the uppermost part of the rotor core side and forms a certain angle with the center block, presenting a slope design, so that the effective core area between adjacent radial magnetized magnetic steels is increased, the saturation phenomenon of the rotor core is alleviated, and the torque density of the motor can be improved. Figure 3 shown.

[0048] In practical applications, the number of segments of the radial magnetized magnetic steel can be flexibly set to other numbers greater than or equal to 3 according to actual needs. It is easy to understand that in the radial magnetized magnetic steel, the side block refers to the magnetic steel block that is in contact with the circumferential magnetized magnetic steel on both sides, and the center block is the magnetic steel block located in the middle of the radial magnetized magnetic steel, and when the number of circumferential segments of the radial magnetized magnetic steel is an odd number, there is only one center block in one radial magnetized magnetic steel, and when the number of circumferential segments of the radial magnetized magnetic steel is an even number, there are two center blocks in one radial magnetized magnetic steel.

[0049] In practical applications, the magnetizing directions of multiple magnetic steel blocks in the same radial magnetized magnetic steel can be the same. In this case, the magnetizing directions of the side blocks and the center block are consistent, and the angle is 0°; the magnetizing directions of multiple magnetic steel blocks in the same radial magnetized magnetic steel can also be different. In this case, there is an angle greater than 0° between the magnetizing directions of the side blocks and the center block. In order to further reduce the risk of demagnetization of the motor, as a preferred implementation, in this embodiment, in the same radial magnetized magnetic steel, there is an angle between the magnetizing direction of the side blocks and the magnetizing direction of the center block, thereby further alleviating the saturation degree of the rotor core, improving the torque density of the motor, and achieving the effect of preventing the demagnetization of the permanent magnet. This embodiment further optimizes the design of the difference in magnetization angles. Specifically, the angle between the magnetizing direction of the side blocks and the magnetizing direction of the center block in the same radial magnetized magnetic steel is set in the following manner:

[0050] Taking the angle between the magnetizing direction of the side block and the magnetizing direction of the center block in the same radial magnetized magnetic steel as the optimization variable, and taking the maximum motor torque and the minimum demagnetization degree at the intersection of the outer edge of the side block, the circumferential magnetized magnetic steel and the rotor core boss as the goal, a multi-objective optimization model is established;

[0051] The multi-objective optimization model is solved, and the solution result is set as the angle between the magnetizing direction of the side block and the magnetizing direction of the center block in the same radial magnetized magnetic steel.

[0052] In the Halbach magnet array designed in this embodiment, the intersection of the outer edge of the radially magnetized magnet edge block, the circumferentially magnetized magnet and the rotor core boss is the point with the highest demagnetization degree in the entire motor. This embodiment takes the demagnetization degree at this point as one of the optimization targets, which can effectively prevent the effect of permanent magnet demagnetization and effectively improve the overall performance of the motor.

[0053] In practical applications, in radial magnetized magnetic steel, except for the edge blocks, the shapes of the remaining magnetic steel blocks can be set based on the comprehensive cost and performance, such as Figure 1 As shown, in this embodiment, the radial magnetized magnetic steel is in a "crown shape" with a radial thickness gradually decreasing from the center to both sides, thereby maximizing the effective core area between adjacent radial magnetized magnetic steels, thereby maximizing the saturation of the rotor core, improving the torque density of the motor, and preventing the demagnetization of the permanent magnet. It should be noted that this is only an optional implementation method and should not be understood as the only limitation of the present invention. In some other embodiments of the present invention, the top of the center block of the radial magnetized magnetic steel can also be flattened, thereby saving the amount of magnetic steel and reducing the cost of the motor while utilizing the structural design of the side block to alleviate the demagnetization of the rotor core.

[0054] In this embodiment, the material of the magnetic steel can be selected from rare earth permanent magnets, such as neodymium iron boron, samarium cobalt, etc.; the material of the rotor core can be selected from magnetically conductive soft magnetic materials such as silicon steel sheets or magnetic steel.

[0055] In general, the trapezoidal circumferential magnetized magnets, circumferentially segmented radial magnetized magnets and rotor core bosses proposed in this embodiment cooperate with each other to ensure that when the motor rotor rotates, the Halbach magnets are fastened to the rotor core, and no extra rotor sleeve is required to damage the electromagnetic performance of the motor. Therefore, the torque density and efficiency of the motor can be significantly improved. In addition, based on the self-fixing rotor structure, different magnetizing directions are set for the circumferentially segmented radial magnetized magnets to better optimize the magnetic circuit guidance, reduce the risk of rotor core saturation and permanent magnet demagnetization, and ensure high torque density and high reliability of the motor. The rotor core boss design introduces a magnetic resistance torque component into the motor, so that the motor can further improve the torque density through weak magnetic field under high load conditions, thereby improving the overload capacity of the motor. The technology proposed in this patent can be applied to both radial flux outer rotor motor topology and radial flux inner rotor motor topology. It has strong portability and versatility, focuses on further improving the torque density and overload capacity of the motor, while taking into account high reliability and simple assembly. It will effectively promote the application and promotion of such motors in the industrial sector, especially in electric vehicles and aviation fields that have high requirements for motor efficiency and power density.

[0056] Embodiment 2:

[0057] A motor rotor structure with magnetic field concentration effect. This embodiment is similar to the above-mentioned embodiment 1, except that this embodiment is applicable to radial flux inner rotor permanent magnet motor topology, such as Figure 4 As shown, it includes a rotor core 1 and a Halbach magnetic steel array embedded in the outer circumference of the rotor core 1.

[0058] Similar to the above-mentioned embodiment 1, in this embodiment, the Halbach magnetic steel array includes circumferentially magnetized magnetic steels 3 and radially magnetized magnetic steels 4 that are alternately distributed along the circumferential direction; the radial thickness of the radially magnetized magnetic steels 4 is greater than the radial thickness of the circumferentially magnetized magnetic steels 3, so that the rotor core 2 forms a rotor core boss 2 at each circumferentially magnetized magnetic steel 3; the radially magnetized magnetic steel 4 is divided into three magnetic steel blocks along the circumferential direction, the central magnetic steel block is the central block 5, and the magnetic steel blocks on both sides are the side blocks 6; the radial thickness of the side block 6 gradually increases from the outer side to the inner side, and the radial thickness of the center block 5 is not less than the maximum radial thickness of the side block 6.

[0059] In this embodiment, the specific implementation of the Halbach magnetic steel array can refer to the description in the above-mentioned embodiment 1 and will not be repeated here.

[0060] Embodiment 3:

[0061] A motor rotor structure with a magnetic field concentration effect, this embodiment is applicable to radial flux outer rotor permanent magnet motor topology. This embodiment is similar to the above-mentioned embodiment 1, except that this embodiment takes into account that in the above-mentioned embodiment 1, the fixation of the rotor magnetic steel still largely depends on the bonding force of high-temperature glue, etc. In view of this problem, the present invention further optimizes the design of radial magnetized magnetic steel and circumferential magnetized magnetic steel in the Halbach magnetic steel array, and proposes a Halbach structure with continuous sub-fixation capability.

[0062] As in the above-mentioned embodiment 1, Figure 5 and Figure 6 As shown, this embodiment includes a rotor core 1, and a Halbach magnetic steel array embedded in the inner circumference of the rotor core 1; the Halbach magnetic steel array includes circumferentially magnetized magnetic steels 3 and radially magnetized magnetic steels 4 that are alternately distributed along the circumferential direction; the radial thickness of the radially magnetized magnetic steels 4 is greater than the radial thickness of the circumferentially magnetized magnetic steels 3, so that the rotor core 2 forms a rotor core boss 2 at each circumferentially magnetized magnetic steel 3; the radially magnetized magnetic steel 4 is divided into three magnetic steel blocks along the circumferential direction, the central magnetic steel block is the central block 5, and the magnetic steel blocks on both sides are the side blocks 6; the radial thickness of the side block 6 gradually increases from the outer side to the inner side, and the radial thickness of the center block 5 is not less than the maximum radial thickness of the side block 6.

[0063] The difference from the above-mentioned embodiment 1 is that Figure 5 As shown, in this embodiment, the side edges of the radial magnetized magnetic steel are recessed toward the center block, forming a "V" shape, and the vertex of the "V" shape is the intersection of the outer edge of the edge block, the circumferential magnetized magnetic steel, and the rotor core boss; accordingly, the overall shape of the circumferential magnetized magnetic steel presents a trapezoidal structure, the side close to the rotor core is the long side of the trapezoid, and the air gap side is the short side of the trapezoid. At the same time, the rotor core boss also presents a trapezoidal structure, and the side in contact with the circumferential magnetized magnetic steel is the long side of the trapezoid. Based on this structural design, in the radial magnetized magnetic steel, the part of the outer edge of the edge block close to the core is mutually engaged with the rotor core boss. When the motor rotor rotates, the rotor core will exert a tight pressure on the magnetic steel through this edge to ensure the assembly and fixation of the radial magnetized magnetic steel; the outer edge of the edge block is the part in contact with the circumferential magnetized magnetic steel, which will play a role in fixing and pressing the circumferential magnetized magnetic steel when the motor rotates. Therefore, when the motor rotor rotates, a continuous self-fixing effect is formed, in which the rotor core has a radially magnetized magnetic steel, and the radially magnetized magnetic steel has a circumferentially magnetized magnetic steel.

[0064] In addition, as an optional implementation, Figure 5 As shown, in this embodiment, in the radially magnetized magnetic steel, the top end of the center block can also be flattened, thereby saving the amount of magnetic steel and reducing the cost of the motor while utilizing the structural design of the side blocks to alleviate the demagnetization of the rotor core.

[0065] like Figure 6As shown, in this embodiment, due to the different magnetic resistances of the d and q axes, a magnetic resistance torque component can be introduced into the motor. When the motor operates under high load conditions, a weak magnetic method can be used to further obtain torque, thereby improving the torque density and overload performance of the motor.

[0066] In this embodiment, the specific implementation of the remaining structures can refer to the description of the above-mentioned embodiment 1 and will not be repeated here.

[0067] Embodiment 4:

[0068] A motor rotor structure with a magnetic field concentration effect. This embodiment is similar to the above-mentioned embodiment 3, except that this embodiment is applicable to radial flux inner rotor permanent magnet motor topology, such as Figure 7 As shown, it includes a rotor core 1, and a Halbach magnetic steel array embedded in the inner circumference of the rotor core 1; the Halbach magnetic steel array includes circumferential magnetized magnetic steels 3 and radial magnetized magnetic steels 4 that are alternately distributed along the circumferential direction; the radial thickness of the radial magnetized magnetic steels 4 is greater than the radial thickness of the circumferential magnetized magnetic steels 3, so that the rotor core 2 forms a rotor core boss 2 at each circumferential magnetized magnetic steel 3;

[0069] The radially magnetized magnetic steel 4 is divided into three magnetic steel blocks along the circumferential direction. The magnetic steel block located in the center is the center block 5, and the magnetic steel blocks located on both sides are the side blocks 6; the radial thickness of the side block 6 gradually increases from the outer edge to the inner edge, and the radial thickness of the center block 5 is not less than the maximum radial thickness of the side block 6.

[0070] In this embodiment, the specific implementation of the Halbach magnetic steel array can refer to the description of the above-mentioned embodiment 3 and will not be repeated here.

[0071] Embodiment 5:

[0072] A method for assembling a motor rotor structure, wherein the motor rotor structure is the motor rotor structure with magnetic field concentration effect provided by any one of the above-mentioned embodiments 1 to 4. This embodiment includes:

[0073] After magnetizing each radial magnet, the magnet is embedded into the corresponding magnet slot in the rotor core;

[0074] After each circumferential magnet is magnetized, it is embedded into the corresponding magnet slot in the rotor core.

[0075] In the motor rotor structure with the Halbach magnet array, it is necessary to first magnetize a certain type of magnet and then assemble it into the rotor core, and then magnetize another type of magnet and then assemble it into the rotor core, so as to realize the assembly of the entire rotor structure. Since the magnetization directions of two adjacent magnets of the same type are opposite, they will attract each other after being assembled into the rotor core, resulting in great difficulty in fixing during installation. In this embodiment, since there is a rotor core boss in the rotor core, after the radially magnetized magnet is assembled into the rotor core, the presence of the rotor core boss can fix and position the radially magnetized magnet, effectively reducing the difficulty of assembly.

[0076] Embodiment 6:

[0077] A permanent magnet synchronous motor comprises a motor rotor structure with magnetic field concentration effect provided by any one of the above embodiments 1 to 4.

[0078] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A motor rotor structure with a magnetic concentration effect, comprising a rotor core and a Halbach magnetic steel array embedded in the rotor core; the Halbach magnetic steel array comprises circumferentially magnetized magnetic steels and radially magnetized magnetic steels alternately distributed along the circumferential direction; characterized in that: The radial thickness of the radial magnetized magnetic steel is greater than the radial thickness of the circumferential magnetized magnetic steel, so that the rotor core forms a rotor core boss at each circumferential magnetized magnetic steel; The radially magnetized magnetic steel is divided into N magnetic steel blocks along the circumferential direction, the magnetic steel block located at the center is the center block, and the magnetic steel blocks located at the two sides are the side blocks; the radial thickness of the side blocks gradually increases from the outer side to the inner side, and the radial thickness of the central block is not less than the maximum radial thickness of the side blocks; Among them, N≥3; the outer side of the edge block is the side adjacent to the circumferentially magnetized magnetic steel, and the inner side is the side close to the center block.

2. The motor rotor structure with magnetic field concentration effect according to claim 1, characterized in that: The side edges of the radially magnetized magnetic steel are recessed toward the center block to form a "V" shape, and the vertex of the "V" shape is the intersection of the outer edge of the side block, the circumferentially magnetized magnetic steel and the rotor core boss.

3. The motor rotor structure with magnetic field concentration effect according to claim 1 or 2, characterized in that: In the same radially magnetized magnetic steel, there is an angle between the magnetization direction of the side block and the magnetization direction of the center block.

4. The motor rotor structure with magnetic field concentration effect as claimed in claim 3, characterized in that: The angle between the magnetization direction of the side block and the magnetization direction of the center block in the same radial magnetized magnetic steel is set as follows: Taking the angle between the magnetizing direction of the side block and the magnetizing direction of the center block in the same radial magnetized magnetic steel as the optimization variable, and taking the maximum motor torque and the minimum demagnetization degree at the intersection of the outer edge of the side block, the circumferential magnetized magnetic steel and the rotor core boss as the goal, a multi-objective optimization model is established; The multi-objective optimization model is solved, and the solution result is set as the angle between the magnetization direction of the edge block and the magnetization direction of the center block in the same radial magnetized magnetic steel.

5. The motor rotor structure with magnetic field concentration effect according to claim 1 or 2, characterized in that: The radially magnetized magnetic steel is in a "crown shape" with radial thickness gradually decreasing from the center to both sides.

6. The motor rotor structure with magnetic field concentration effect according to claim 1 or 2, characterized in that: In the radially magnetized magnetic steel, the top end of the center block is flattened.

7. The method for assembling a motor rotor structure with a magnetic field concentration effect according to any one of claims 1 to 6, characterized in that: include: After magnetizing each radial magnet, the magnet is embedded into the corresponding magnet slot in the rotor core; After each circumferential magnet is magnetized, it is embedded into the corresponding magnet slot in the rotor core.

8. A permanent magnet synchronous motor, characterized in that: The invention comprises a motor rotor structure with magnetic field concentration effect as described in any one of claims 1 to 6.

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