An asymmetric permanent magnet motor with a combined magnetic pole Halbach structure

Abstract

The application discloses a kind of asymmetric permanent magnet motor of combined magnetic pole Halbach structure, including outer stator and inner rotor, rotor surface is provided with non-uniform Halbach array, each magnetic pole of Halbach array is composed of segmented unequal-width three-part unit block combined arrangement, including the mixed permanent magnet main magnetic pole unit block of radial magnetization and its left and right adjacent ferrite permanent magnet auxiliary magnetic pole unit block, and the tangential magnetization ferrite permanent magnet unit block.Rotor inside alternately distributes two different sizes V type and inverted V type symmetrical air magnetic barrier, wherein one side of V type air magnetic barrier is built-in neodymium iron boron permanent magnet, inverted V type air magnetic barrier is built-in two pieces of neodymium iron boron permanent magnet, which is not symmetrical with magnetic barrier axis and unequal length.The present application, under the premise of certain permanent magnet consumption, makes the maximum current angle of permanent magnet torque and reluctance torque component more approximate by the magnetic pole offset design of permanent magnet, enhances the asymmetric magnetic field offset effect, improves torque component utilization, effectively improves the torque output capacity.

Description

Technical Field

[0001] This invention relates to an asymmetric permanent magnet motor with a combined magnetic pole Halbach structure, belonging to the field of permanent magnet motor technology. Background Technology

[0002] Rare-earth permanent magnet motors have become the primary choice for electric vehicle drive motors due to their advantages such as high power density, high efficiency, and high reliability. However, traditional built-in rare-earth permanent magnet motors typically employ a symmetrical structure, resulting in a low torque superposition rate between the permanent magnet torque and reluctance torque components. This leads to issues such as low power and torque density in the motor. Furthermore, the rising price of rare-earth permanent magnet materials has objectively increased the design cost of the motor. Therefore, under the premise of controlling the cost of permanent magnet usage, how to further improve the motor torque utilization and torque density by using asymmetric optimization design to approximate the maximum torque current angle of the permanent magnet torque and reluctance torque has become a research challenge in the field of permanent magnet motors.

[0003] Currently, the optimization of asymmetric structures in permanent magnet motors mainly relies on changing the angle difference between the permanent magnet direct axis and the magnetic shaft direct axis. The main optimization design methods are divided into single magnetic shaft offset and double magnetic shaft offset methods. The principle of single magnetic shaft offset is to offset or offset the permanent magnet in a local space to change the position of the permanent magnet direct axis without changing the original rotor core symmetric structure. The principle of double magnetic shaft offset is to change the rotor core symmetric structure while asymmetrically arranging the permanent magnets to achieve the joint deflection of the permanent magnet direct axis and the magnetic shaft direct axis, so that the maximum torque current angle of the permanent magnet torque and the reluctance torque is close. The different torque component ratios under the two optimization methods also result in the advantages and disadvantages of motor performance.

[0004] The asymmetric rotor-type permanent magnet motor structure proposed in Chinese patent application 201810203005.2 solves the problem of low torque utilization in traditional built-in permanent magnet motors by using permanent magnet biasing to achieve an asymmetric distribution of permanent magnets inside the rotor. However, the use of rare earth permanent magnet materials for all permanent magnets inside the rotor leads to high costs for permanent magnet materials. In addition, the parallel arrangement of the traditional V-shaped air magnetic barrier structure does not fully consider the utilization of internal space of the rotor. Therefore, there is a need for further rational optimization design of the magnetic barrier structure arrangement.

[0005] The asymmetric segmented embedded permanent magnet motor structure proposed in Chinese patent application 202310400139.4 places radially magnetized permanent magnets between adjacent V-shaped air magnetic barriers, which makes full use of the internal structure of the motor to improve torque density. However, the leakage of magnetic flux is relatively serious, so there is a need for further reasonable optimization design of the embedded permanent magnet structure.

[0006] Therefore, in the existing technology, for the design of asymmetric permanent magnet motors, there are still problems to be solved in order to achieve a reasonable configuration of the amount of permanent magnet material to reduce the cost of permanent magnets, and to reasonably optimize the permanent magnet structure to make full use of the internal space of the rotor, so as to ensure that the permanent magnet torque and reluctance torque components can reach their maximum values ​​at similar current angles and improve the torque output capability.

[0007] The applicant discovered through a search that Chinese Patent Publication No. CN114640201A proposes a novel permanent magnet motor rotor based on a Halbach array. This rotor structure utilizes the reluctance torque of V-shaped permanent magnets to increase the torque density of the motor. Combined with the Halbach array, it reduces torque pulsation, improves the sinusoidal nature of the air gap magnetic flux density, and reduces core losses, thereby achieving the goal of improving the efficiency of the permanent magnet synchronous motor.

[0008] The technical comparison between this application and patent CN114640201A, "A Novel Permanent Magnet Motor Rotor Based on Halbach Array," is as follows:

[0009] 1. Patent CN114640201A addresses the improvement of torque performance under traditional symmetrical structures. It employs a symmetrical permanent magnet structure within the V-shaped air magnetic barrier inside the rotor, combined with a Halbach array, primarily aiming to reduce torque ripple and improve motor efficiency. This patent, however, focuses on enhancing torque output capability by increasing the torque superposition rate in asymmetrical motors. This asymmetrical structure requires careful consideration of the approximation of the maximum torque-current angle between the permanent magnet torque and reluctance torque components. To address this issue, this patent uses a parallel design approach of permanent magnet deflection and permanent magnet offset, thereby offsetting the permanent magnet torque axis twice to ensure that it reaches its peak value at a similar current angle to the magnetic axis torque axis, thus improving the power density of the total torque. This differs from the application objective of patent CN114640201A.

[0010] 2. Patent CN114640201A adopts a symmetrical V-shaped air magnetic barrier structure, while this patent proposes to use two different sizes of V-shaped and inverted V-shaped air magnetic barriers arranged alternately, which makes fuller use of the internal space of the rotor. The permanent magnets inside the magnetic barriers in patent CN114640201A are symmetrical about the magnetic barrier axis, while the V-shaped air magnetic barrier in this patent has a neodymium iron boron permanent magnet built into one side, and the inverted V-shaped air magnetic barrier has two neodymium iron boron permanent magnets that are not symmetrical about the magnetic barrier axis and have different lengths. The three are designed with different lengths, which can effectively control the flow of magnetic lines of force, which is different from the structural properties of patent CN114640201A.

[0011] 3. Patent CN114640201A employs a surface-mounted Halbach uniform symmetrical array with two magnetic blocks per pole, enhancing the unilateral magnetic field through the alternating arrangement of radially and tangentially magnetized permanent magnets. This patent, however, uses an embedded Halbach asymmetrical array with five magnetic blocks per pole, resulting in a more complex structure. Its magnetic poles are primarily composed of three groups of permanent magnet unit blocks: segmented radially magnetized permanent magnets of unequal width, tangentially magnetized permanent magnets, and auxiliary permanent magnets. Furthermore, its main magnetic poles, compared to those in patent CN114640201A, employ a combined magnetic pole stacking design and are deflected counterclockwise by a certain mechanical angle. In terms of the purpose of Halbach structural design, this patent differs fundamentally from patent CN114640201A.

[0012] The applicant found through a search that Chinese Patent Publication No. CN108808910A proposed an invention patent for a built-in hybrid permanent magnet motor. This invention improves the utilization rate of permanent magnets, output torque and efficiency, and reduces torque pulsation by asymmetrically setting permanent magnet structures of different materials.

[0013] The technical comparison between this application and patent CN108808910A, "A Built-in Hybrid Permanent Magnet Motor," is as follows:

[0014] 1. Patent CN108808910A mainly focuses on improving torque performance through asymmetrical placement of permanent magnets. However, this patent, based on asymmetrical placement, can more effectively improve motor torque utilization through permanent magnet deflection and unilateral bias design. The structural nature of this patent is different from that of patent CN108808910A, and the design requirements are more complex.

[0015] 2. In patent CN108808910A, the internal V-groove structure of the rotor is formed by two rectangular permanent magnets that form a parallel magnetic circuit and are placed end to end to form an asymmetrical structure. The overall magnetic flux circuit is not significantly changed. However, the internal V-shaped air magnetic barrier of this patent has a permanent magnet built into one side. The magnetic lines of force are effectively isolated by the left magnetic barrier, which changes the overall magnetic circuit structure. The asymmetrical magnetic axis offset effect is stronger, which is different from the magnetic barrier design purpose of patent CN108808910A.

[0016] 3. In patent CN108808910A, the outer layer of the slot and the internal radial magnetized permanent magnet present a symmetrical structure. However, the outer layer of this patent has an embedded Halbach asymmetrical array structure. By asymmetrically deflecting the main magnetic poles, the permanent magnet axis is effectively offset. The magnetic pole structure is more special and the magnetic focusing ability is stronger. It is significantly different from patent CN108808910A. Summary of the Invention

[0017] To address the aforementioned technical problems, the present invention aims to provide an asymmetric permanent magnet motor with a combined magnetic pole Halbach structure. Without altering the symmetrical structure of the rotor core, the permanent magnet axis offset is achieved by changing the symmetry of the permanent magnet structure through permanent magnet deflection and offset design. This allows the permanent magnet torque and reluctance torque components to reach their maximum values ​​at similar current angles, thereby effectively overcoming the defect of low motor torque utilization.

[0018] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0019] A combined-pole Halbach structure asymmetric permanent magnet motor is characterized by comprising an outer stator with an even number of stator slots and an inner hybrid surface-embedded-embedded permanent magnet rotor. An air gap separates the stator and rotor. The rotor is placed around the central axis of the stator and located at the center of the stator. The stator includes a stator core and a three-phase armature winding wound around the stator core. The stator core includes stator teeth, a stator yoke, and stator slots. One end of each stator tooth is close to the rotor, and the end of the stator tooth away from the rotor is connected to the stator yoke. The stator slots are located between adjacent stator teeth. The rotor comprises inner and outer layers. A fan-shaped first opening slot is provided on the outer wall of the rotor. A tangentially magnetized fourth ferrite permanent magnet of a Halbach array is placed and fixed within the first opening slot. A second opening slot formed between the first opening slots is completely filled with a main magnetic pole of a Halbach array, consisting of a first neodymium iron boron permanent magnet in the upper layer and a second ferrite permanent magnet in the lower layer, radially magnetized. The two adjacent ferrite permanent magnet auxiliary poles are the first and third ferrite permanent magnets, respectively. The central axis of the second slot on the outer wall of the rotor coincides with the rotor axis. The number of the first slots is the same as the number of poles of the motor. Two different sizes of V-shaped and inverted V-shaped air barriers are alternately distributed on the inner rotor yoke. The axes of both the V-shaped and inverted V-shaped air barriers pass through the rotor axis and coincide with the axis of the tangentially magnetized fourth ferrite permanent magnet. The inverted V-shaped air magnetic barrier is placed to the left of the first NdFeB permanent magnet magnetized in the N direction, and the inner and outer inclined sides of the inverted V-shaped air magnetic barrier are close to the inner diameter of the first ferrite permanent magnet. The V-shaped air magnetic barrier is placed to the right of the first NdFeB permanent magnet magnetized in the N direction. The inverted V-shaped air magnetic barrier contains two built-in NdFeB permanent magnets of different lengths that are not symmetrical about the axis of the inverted V-shaped air magnetic barrier, namely the second NdFeB permanent magnet and the third NdFeB permanent magnet. A fourth NdFeB permanent magnet is built into one side of the V-shaped air magnetic barrier.

[0020] As a preferred technical solution of the present invention: the three-phase armature winding is a double-layer fractional slot concentrated winding.

[0021] As a preferred technical solution of the present invention: the optimal position of the inner and outer inclined sides of the V-shaped air magnetic barrier is set close to the inner diameter of the second opening groove.

[0022] As a preferred technical solution of the present invention: a fourth neodymium iron boron permanent magnet is built into the right side of the V-shaped air magnetic barrier, a second neodymium iron boron permanent magnet is built into the left side of the inverted V-shaped air magnetic barrier, and a third neodymium iron boron permanent magnet is built into the right side. The third neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet have different lengths and exhibit an asymmetrical structure compared to the axis of the inverted V-shaped air magnetic barrier.

[0023] As a preferred embodiment of the present invention: the first NdFeB permanent magnet is fan-shaped, and the second, third, and fourth NdFeB permanent magnets are all rectangular.

[0024] As a preferred embodiment of the present invention: the outer diameter of the fourth ferrite permanent magnet is the same as the outer diameter of the rotor; the central angles of the second ferrite permanent magnet and the first neodymium iron boron permanent magnet are the same; the outer diameter of the first neodymium iron boron permanent magnet is the same as that of the rotor; and the thickness ratio of the first neodymium iron boron permanent magnet to the second ferrite permanent magnet is 3:1; the outer diameters of the adjacent left third ferrite permanent magnet and right first ferrite permanent magnet are the same as the radius of the first neodymium iron boron permanent magnet.

[0025] As a preferred embodiment of the present invention, the central angle ratio of the third ferrite permanent magnet, the first neodymium iron boron permanent magnet, and the first ferrite permanent magnet is 1:4:8.

[0026] As a preferred technical solution of the present invention: the inner included angle of the inverted V-shaped air magnetic barrier is β1, the inner included angle of the V-shaped air magnetic barrier is β2, and β2-β1=10°.

[0027] As a preferred embodiment of the present invention: the length ratio of the third NdFeB permanent magnet on the left side of the inverted V-shaped air magnetic barrier, the second NdFeB permanent magnet on the right side, and the fourth NdFeB permanent magnet on the right side of the V-shaped air magnetic barrier is 9:8:12, the thickness ratio of the three is 1:1:1.25, and the distance ratio of the three to the intersection point with the inner side of the magnetic barrier is 1:6:10.

[0028] In the above structure: the asymmetric permanent magnet motor with a combined magnetic pole Halbach structure proposed in this invention includes an outer stator with an even number of stator slots and an inner hybrid surface-embedded-built permanent magnet rotor. There is an air gap between the stator and the rotor. The fourth ferrite permanent magnets are all tangentially magnetized, and the magnetization directions of two adjacent fourth ferrite permanent magnets are completely opposite. The first neodymium iron boron permanent magnet on the upper layer of the main magnetic pole and the second ferrite permanent magnet on the lower layer are both radially magnetized, and the magnetization directions of two adjacent main magnetic pole permanent magnets are also completely opposite. The magnetization direction of the auxiliary magnetic pole of the third ferrite permanent magnet on the left and the first ferrite permanent magnet on the right adjacent to the main magnetic pole is inclined towards the outer diameter of the upper first neodymium iron boron permanent magnet.

[0029] Fixing the fourth ferrite permanent magnet in the first slot helps to utilize the difference between the rotor's quadrature and direct-axis magnetic circuits to generate a larger difference in quadrature and direct-axis inductance, thereby increasing the reluctance torque. The main magnetic poles, through the stacking of mixed permanent magnet materials, can effectively reduce the cost of rare-earth permanent magnet materials. In addition, the unequal width design of the main and auxiliary magnetic poles in the second slot can fully utilize the high magnetic energy product of neodymium iron boron materials to improve the magnetic field line orientation of the ferrite permanent magnet circuits on both sides. The overall outer Halbach array structure can generate a stronger unilateral magnetic field, effectively reducing leakage magnetism and improving the utilization rate of permanent magnets.

[0030] The magnetic flux lines of the permanent magnet start from the N-direction main magnetic pole formed by the radial magnetization combination of the upper layer first NdFeB permanent magnet and the lower layer second ferrite permanent magnet in the second open slot, and sequentially reach the stator teeth, stator yoke, stator teeth and S-direction main magnetic pole permanent magnet. Then, they return to the N-direction main magnetic pole permanent magnet through the rotor yoke, the fourth NdFeB permanent magnet, the third NdFeB permanent magnet and the second NdFeB permanent magnet, forming a complete closed path. The inner and outer inclined sides of the V-shaped air magnetic barrier are as close as possible to the inner diameter of the Halbach array, which can effectively reduce magnetic leakage.

[0031] l c Let l1 represent the original permanent magnet d-axis, l2 represent the permanent magnet d-axis after the main magnetic pole is offset, and l3 represent the permanent magnet d-axis after the permanent magnet is biased based on l2. Since the rotor core maintains a symmetrical structure and the same axis, the position of the reluctance d-axis l1 remains unchanged. With the second slot fully filled, the main magnetic pole is deflected counterclockwise by a mechanical angle α°. At this point, the outer Halbach array exhibits an asymmetrical structure, and its unequal width design more effectively highlights the permanent magnet direct axis, causing the permanent magnet d-axis l1 to align with the reluctance d-axis l2. c When deflected to position l2, the maximum current angle of the permanent magnet torque also approaches the maximum current angle of the reluctance torque from 0° under the original symmetrical structure to 45°. The magnitude of the approaching current angle depends on α*p. r p rThis refers to the number of rotor pole pairs. Due to the limited space in the second slot of the rotor, the deflection angle of the main magnetic poles is limited. By using a permanent magnet offset design, the symmetrical permanent magnet structure of the V-shaped air magnetic barrier is changed to a single-sided right-side permanent magnet structure. This allows the left-side magnetic barrier of the V-shaped barrier to isolate magnetic field lines, improve the direction of the magnetic field lines, and further align the permanent magnet d-axis l2 with the reluctance d-axis l. c By deflecting to position l3, the asymmetric magnetic field offset effect is enhanced, ultimately enabling the permanent magnet torque and reluctance torque components to reach their maximum values ​​at similar current angles. This solves the problem of low torque component utilization and effectively improves torque output capability.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. Under the premise of a certain amount of permanent magnets, the motor of this invention enhances the asymmetric magnetic field offset effect through asymmetric design such as rectangular permanent magnet offset and Halbach array main magnetic pole offset, which significantly changes the original position of the permanent magnet axis, so that the permanent magnet torque and reluctance torque components can reach their maximum values ​​at similar current angles, improve the proportion of reluctance torque, enhance the motor's field weakening speed extension capability, solve the problem of low torque component utilization, and effectively improve torque output capability. In addition, the design of Halbach array composite main magnetic poles can effectively control the cost of permanent magnet materials, and the staggered design of V-shaped and inverted V-shaped air magnetic barriers also makes full use of the rotor's internal space.

[0034] 2. The motor of this invention adopts a pole-slot ratio design of 10 poles and 12 slots. Considering the influence of unbalanced radial magnetic pull and the number of cycles of cogging torque, a higher winding factor can be obtained. The winding adopts a fractional slot concentrated winding design suitable for low speed and high torque. The winding process is simple, which helps to reduce the manufacturing cost of the motor and can also greatly reduce the amount of copper wire used in the winding. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of the motor of the present invention;

[0036] Figure 2 This is a simplified partial schematic diagram of the Halbach array on the outer layer of the motor rotor according to the present invention;

[0037] Figure 3 This is a diagram showing the distribution of magnetic field lines in the motor of the present invention;

[0038] Figure 4 This is a schematic diagram of the permanent magnet shaft offset of the motor according to the present invention;

[0039] Figure 5 This is a diagram showing the separation of motor output torque according to the present invention.

[0040] List of reference numerals in the attached diagram:

[0041] 1. Neodymium iron boron permanent magnet; 1.1 First neodymium iron boron permanent magnet; 1.2 Second neodymium iron boron permanent magnet; 1.3 Third neodymium iron boron permanent magnet; 1.4 Fourth neodymium iron boron permanent magnet; 2. Ferrite permanent magnet; 2.1 First ferrite permanent magnet; 2.2 Second ferrite permanent magnet; 2.3 Third ferrite permanent magnet; 2.4 Fourth ferrite permanent magnet; 3. Stator; 3.1 Stator teeth; 3.2 Stator yoke; 3.3 Stator slot; 4. Rotor; 4.1 First open slot; 4.2 Inverted V-shaped air barrier; 4.3 V-shaped air barrier; 4.4 Second open slot; 4.5 Rotor yoke; 5. Three-phase armature winding; 6. Shaft. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0043] This invention proposes an asymmetric permanent magnet motor with a combined pole Halbach structure, such as... Figure 1 As shown, the motor includes an outer stator 3 with an even number of stator slots 3.3 and an inner permanent magnet rotor 4 with mixed surface mounting. There is an air gap between the stator 3 and the rotor 4. A three-phase armature winding 5 is wound on the stator core. The rotor 4 is placed around the central axis shaft 6 and is located inside the center of the stator 3.

[0044] The stator 3 includes a stator core and a three-phase armature winding 5. The stator core includes stator teeth 3.1, stator yoke 3.2 and stator slots 3.3. One end of the stator teeth 3.1 is close to the rotor 4, and the end of the stator teeth 3.1 away from the rotor 4 is connected to the stator yoke 3.2. The stator slots 3.3 are located between two adjacent stator teeth 3.1. The three-phase armature winding 5 is a double-layer fractional-slot concentrated winding.

[0045] The rotor 4 is divided into inner and outer layers. The outer wall of the rotor 4 is provided with a fan-shaped first opening slot 4.1. The first opening slot 4.1 is placed and fixed with a fourth ferrite permanent magnet 2.4 tangentially magnetized by a Halbach array. The second opening slot 4.4 formed between the first opening slots 4.1 is completely filled with the main magnetic pole of the Halbach array, which is composed of a first neodymium iron boron permanent magnet 1.1 in the upper layer and a second ferrite permanent magnet 2.2 in the lower layer, and the auxiliary magnetic pole of the third ferrite permanent magnet 2.3 on the left and the first ferrite permanent magnet 2.1 on the right. The central axis of the second opening slot 4.4 on the outer layer of the rotor 4 coincides with the axis of the rotor 4. The number of first opening slots 4.1 is the same as the number of poles of the motor.

[0046] Among them, the first NdFeB permanent magnet 1.1 is fan-shaped, and the second NdFeB permanent magnet 1.2, the third NdFeB permanent magnet 1.3 and the fourth NdFeB permanent magnet 1.4 are all rectangular.

[0047] The optimal position of the inner and outer inclined sides of the V-shaped air magnetic barrier 4.3 is close to the inner diameter of the second opening slot 4.4. Therefore, the inner and outer inclined sides of the V-shaped air magnetic barrier 4.3 need to be as close as possible to the inner diameter of the second opening slot 4.4.

[0048] The outer diameter of the fourth ferrite permanent magnet 2.4 in the first opening slot 4.1 of the outer layer of rotor 4 is the same as that of rotor 4. The central angles of the second ferrite permanent magnet 2.2 and the first neodymium iron boron permanent magnet 1.1 with the fan-shaped structure are the same, and the outer diameter of the first neodymium iron boron permanent magnet 1.1 with the fan-shaped structure is the same as that of rotor 4.

[0049] The thickness ratio of the first NdFeB permanent magnet 1.1 to the second ferrite permanent magnet 2.2 is 3:1; the outer diameters of the adjacent left-side third ferrite permanent magnet 2.3 and right-side first ferrite permanent magnet 2.1 are the same as the radius of the first NdFeB permanent magnet 1.1. Furthermore, the ratio of the central angles of the left-side third ferrite permanent magnet 2.3, the first NdFeB permanent magnet 1.1, and the right-side first ferrite permanent magnet 2.1 is 1:4:8.

[0050] Two different sizes of V-shaped air magnetic barriers 4.3 and inverted V-shaped air magnetic barriers 4.2 are alternately distributed on the rotor yoke 4.5 of the inner layer of rotor 4. The axes of both pass through the axis of rotor 4 and coincide with the axis of the tangentially magnetized fourth ferrite permanent magnet 2.4. The inverted V-shaped air magnetic barrier 4.2 is placed to the left of the N-axis magnetized first NdFeB permanent magnet 1.1, and the inner and outer inclined sides of the inverted V-shaped air magnetic barrier 4.2 are as close as possible to the inner diameter of the first ferrite permanent magnet 2.1. The air magnetic barrier 4.3 is placed to the right of the first NdFeB permanent magnet 1.1 magnetized in the N direction. The right side of the V-shaped air magnetic barrier 4.3 houses the fourth NdFeB permanent magnet 1.4. The left side of the inverted V-shaped air magnetic barrier 4.2 houses the third NdFeB permanent magnet 1.3, and the right side houses the second NdFeB permanent magnet 1.2. The second NdFeB permanent magnet 1.2 and the third NdFeB permanent magnet 1.3 have different lengths and exhibit an asymmetrical structure relative to the axis of the inverted V-shaped air magnetic barrier 4.4.

[0051] The inner angle of the inverted V-shaped air magnetic barrier 4.4 is β1, and the inner angle of the V-shaped air magnetic barrier 4.3 is β2, where β2-β1=10°.

[0052] The length ratio of the third NdFeB permanent magnet 1.3 on the left side of the inverted V-shaped air magnetic barrier 4.2, the second NdFeB permanent magnet 1.2 on the right side, and the fourth NdFeB permanent magnet 1.4 on the right side of the V-shaped air magnetic barrier 4.3 is 9:8:12, the thickness ratio of the three is 1:1:1.25, and the distance ratio of the three to the intersection point with the inner side of the magnetic barrier is 1:6:10.

[0053] The Halbach array structure of the outer layer of the motor rotor of the present invention is as follows: Figure 2As shown, the fourth ferrite permanent magnet 2.4 is tangentially magnetized, and the magnetization directions of two adjacent fourth ferrite permanent magnets 2.4 are completely opposite. The upper first neodymium iron boron permanent magnet 1.1 and the lower second ferrite permanent magnet 2.2 in the main magnetic pole are radially magnetized, and the magnetization directions of two adjacent main magnetic pole permanent magnets are also completely opposite. The magnetization direction of the auxiliary magnetic poles of the third ferrite permanent magnet 2.3 on the left and the first ferrite permanent magnet 2.1 on the right of the main magnetic pole is inclined towards the outer diameter of the upper first neodymium iron boron permanent magnet 1.1.

[0054] Fixing the ferrite permanent magnet through the first opening slot 4.1 helps to generate a larger difference in quadrature and direct axis inductance by utilizing the different quadrature and direct axis magnetic circuits of rotor 4, thereby increasing the magnetic reluctance torque. The main magnetic poles can effectively reduce the cost of rare earth permanent magnet materials by stacking mixed permanent magnet materials. In addition, the main magnetic poles and auxiliary magnetic poles in the second opening slot 4.4 adopt an unequal width design, which can make full use of the high magnetic energy product of neodymium iron boron materials to improve the magnetic field line orientation of the ferrite permanent magnet circuits on both sides. The overall outer Halbach array structure can generate a stronger unilateral magnetic field, effectively reducing leakage magnetism and improving the utilization rate of permanent magnets.

[0055] The magnetic field lines of the motor of this invention are as follows Figure 3 As shown, corresponding to the permanent magnet magnetic field section, the magnetic field lines of the permanent magnet flux originate from the N-direction main magnetic pole formed by the radial magnetization combination of the upper layer of the first NdFeB permanent magnet 1.1 and the lower layer of the second ferrite permanent magnet 2.2 in the second open slot 4.4, and sequentially reach the stator tooth 3.1, stator yoke 3.2, stator tooth 3.1 and the S-direction main magnetic pole permanent magnet. Then, through the rotor yoke 4.5, the fourth NdFeB permanent magnet 1.4, the third NdFeB permanent magnet 1.3, and the second NdFeB permanent magnet 1.2, they return to the N-direction main magnetic pole permanent magnet, forming a complete closed path. The inner and outer inclined sides of the V-shaped air magnetic barrier 4.3 are as close as possible to the inner diameter of the Halbach array to effectively reduce magnetic leakage.

[0056] The permanent magnet shaft offset of the motor in this invention is as follows: Figure 4 As shown, l c Let l1 represent the original permanent magnet d-axis, l2 represent the permanent magnet d-axis after the main magnetic poles are offset, and l3 represent the permanent magnet d-axis after the permanent magnets are biased based on l2. Since the rotor core maintains a symmetrical structure and the same axis overall, the reluctance d-axis l1... c The position remains unchanged; with the second slot 4.4 fully filled, the main magnetic pole is deflected counterclockwise by a mechanical angle of α°. At this time, the outer Halbach array exhibits an asymmetrical structure, and its unequal width design more effectively highlights the permanent magnet direct axis, causing the permanent magnet d-axis l1 to align with the reluctance d-axis l. c When deflected to position l2, the maximum current angle of the permanent magnet torque also approaches the maximum current angle of the reluctance torque from 0° under the original symmetrical structure to 45°. The magnitude of the approaching current angle depends on α*p.r p r This refers to the number of rotor pole pairs. Due to space constraints in the second slot 4.4 within rotor 4, the deflection angle of the main magnetic poles is limited. By using a permanent magnet offset design, the symmetrical permanent magnet structure of the V-shaped air magnetic barrier 4.3 is changed to a single-sided right-side permanent magnet structure. This utilizes the left-side V-shaped magnetic barrier to isolate magnetic field lines, improving the direction of the magnetic field lines. Furthermore, it deflects the permanent magnet d-axis towards the reluctance d-axis, enhancing the asymmetric magnetic field offset effect, such as... Figure 5 As shown in the motor output torque separation diagram, the permanent magnet torque and reluctance torque components ultimately reached their maximum values ​​at similar current angles, solving the problem of low torque component utilization and effectively improving torque output capability.

[0057] Therefore, under the premise of a certain amount of permanent magnets, the motor of this invention enhances the asymmetric magnetic field offset effect through asymmetric design such as rectangular permanent magnet offset and Halbach array main magnetic pole offset, which significantly changes the original position of the permanent magnet axis, so that the permanent magnet torque and reluctance torque components can reach their maximum values ​​at similar current angles, improve the proportion of reluctance torque, enhance the motor's field weakening speed extension capability, solve the problem of low torque component utilization, and effectively improve torque output capability. In addition, the design of Halbach array composite main magnetic poles can effectively control the cost of permanent magnet materials, and the staggered design of V-shaped and inverted V-shaped air magnetic barriers 4.4 also makes full use of the internal space of rotor 4.

[0058] The motor of this invention adopts a 10-pole, 12-slot pole-slot ratio design. Considering the influence of unbalanced radial magnetic pull and the number of cogging torque cycles, a higher winding factor can be obtained. The winding adopts a fractional-slot concentrated winding design suitable for low speed and high torque. The winding process is simple, which helps to reduce the manufacturing cost of the motor and can also greatly reduce the amount of copper wire used in the winding.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A composite magnet Halbach structure asymmetric permanent magnet motor Its features are: The device includes an outer stator (3) with an even number of stator slots (3.3) and an inner hybrid surface-embedded-built permanent magnet rotor (4). An air gap separates the stator (3) and rotor (4). The rotor (4) is positioned around a centrally located shaft (6) and is located at the center of the stator (3). The stator (3) includes a stator core and a three-phase armature winding (5) wound around the stator core. The stator core includes stator teeth (3.1), a stator yoke (3.2), and stator slots (3.3). One end of each stator tooth (3.1) is close to the rotor (4), and the end of each stator tooth (3.1) away from the rotor (4) is connected to the stator yoke (3.2). The stator slot (3.3) is located between adjacent stator teeth (3.1). The rotor (4) includes inner and outer layers. A fan-shaped first opening slot (4.1) is provided on the outer wall of the rotor (4). A fourth ferrite permanent magnet (2.4) of the Halbach array is placed and fixed in the first opening slot (4.1). The second opening slot (4.4) formed between each first opening slot (4.1) is completely filled with the main magnetic pole formed by the radial magnetization combination of the upper layer of the Halbach array, which is the first neodymium iron boron permanent magnet (1.1) and the lower layer of the second ferrite permanent magnet (2.2), and two ferrite permanent magnets on the adjacent sides. The auxiliary magnetic poles are a first ferrite permanent magnet (2.1) and a third ferrite permanent magnet (2.3), respectively. The central axis of the second opening slot (4.4) on the outer wall of the rotor (4) coincides with the axis of the rotor (4). The number of the first opening slots (4.1) is the same as the number of poles of the motor. Two different sizes of V-shaped air magnetic barriers (4.3) and inverted V-shaped air magnetic barriers (4.2) are alternately distributed on the rotor yoke (4.5). The axes of the V-shaped air magnetic barriers (4.3) and the inverted V-shaped air magnetic barriers (4.2) both pass through the axis of the rotor (4) and coincide with the axis of the tangentially magnetized fourth ferrite permanent magnet (2.4). The inverted V-shaped air magnetic barrier (4.3) .2) The first NdFeB permanent magnet (1.1) is placed to the left of the N-axis magnetized first NdFeB permanent magnet (1.1), and the inner and outer inclined sides of the inverted V-shaped air magnetic barrier (4.2) are close to the inner diameter of the first ferrite permanent magnet (2.1); the V-shaped air magnetic barrier (4.3) is placed to the right of the first NdFeB permanent magnet (1.1) magnetized in the N-axis, and two built-in NdFeB permanent magnets of different lengths that are not symmetrical about the axis of the inverted V-shaped air magnetic barrier (4.2) are placed in the inverted V-shaped air magnetic barrier (4.2), namely the second NdFeB permanent magnet (1.2) and the third NdFeB permanent magnet (1.3), respectively. A fourth NdFeB permanent magnet (1.4) is built-in on one side of the V-shaped air magnetic barrier (4.3).

2. A combined magnet according to claim 1 Halbach structure asymmetric permanent magnet motor Its features are: The three-phase armature winding (5) is a double-layer fractional slot concentrated winding.

3. A combined magnet according to claim 1 Halbach structure asymmetric permanent magnet motor Its features are: The optimal position of the inner and outer inclined sides of the V-shaped air magnetic barrier (4.3) is set close to the inner diameter of the second opening slot (4.4).

4. A combined magnet according to claim 3 Halbach structure asymmetric permanent magnet motor Its features are: The V-shaped air magnetic barrier (4.3) has a fourth neodymium iron boron permanent magnet (1.4) built into one side on the right side. The inverted V-shaped air magnetic barrier (4.2) has a second neodymium iron boron permanent magnet (1.2) built into the left side and a third neodymium iron boron permanent magnet (1.3) built into the right side. The third neodymium iron boron permanent magnet (1.3) and the second neodymium iron boron permanent magnet (1.2) have different lengths and exhibit an asymmetrical structure compared to the axis of the inverted V-shaped air magnetic barrier (4.2).

5. A combined magnet according to claim 1 Halbach structure asymmetric permanent magnet motor Its features are: The first NdFeB permanent magnet (1.1) is fan-shaped, and the second NdFeB permanent magnet (1.2), the third NdFeB permanent magnet (1.3) and the fourth NdFeB permanent magnet (1.4) are all rectangular.

6. A combined magnet according to claim 1 Halbach structure asymmetric permanent magnet motor Its features are: The outer diameter of the fourth ferrite permanent magnet (2.4) is the same as that of the rotor (4). The central angles of the second ferrite permanent magnet (2.2) and the first neodymium iron boron permanent magnet (1.1) are the same, and the outer diameter of the first neodymium iron boron permanent magnet (1.1) is the same as that of the rotor (4). The thickness ratio of the first neodymium iron boron permanent magnet (1.1) to the second ferrite permanent magnet (2.2) is 3:

1. The outer diameters of the adjacent left third ferrite permanent magnet (2.3) and right first ferrite permanent magnet (2.1) are the same as the radius of the first neodymium iron boron permanent magnet (1.1).

7. A combined magnet according to claim 6 Halbach structure asymmetric permanent magnet motor Its features are: The central angle ratio of the third ferrite permanent magnet (2.3), the first neodymium iron boron permanent magnet (1.1), and the first ferrite permanent magnet (2.1) is 1:4:

8.

8. A combined magnet according to claim 1 Halbach structure asymmetric permanent magnet motor Its features are: The inner angle of the inverted V-shaped air magnetic barrier (4.2) is β1, and the inner angle of the V-shaped air magnetic barrier (4.3) is β2, where β2-β1=10°.

9. A combined magnet according to claim 1 Halbach structure asymmetric permanent magnet motor Its features are: The length ratio of the third NdFeB permanent magnet (1.3) on the left side of the inverted V-shaped air magnetic barrier (4.2), the second NdFeB permanent magnet (1.2) on the right side, and the fourth NdFeB permanent magnet (1.4) on the right side of the V-shaped air magnetic barrier (4.3) is 9:8:12, the thickness ratio of the three is 1:1:1.25, and the distance ratio of the three to the intersection point with the inner side of the magnetic barrier is 1:6:10.

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