Composite magnetism gathering type permanent magnet synchronous linear motor

Abstract

The invention belongs to the field of linear motors, and particularly relates to a composite magnetism gathering type permanent magnet synchronous linear motor, which comprises a primary, a secondary and an air gap, and is characterized in that the secondary comprises a secondary yoke and a plurality of composite magnetism gathering type permanent magnet units; the composite magnetism gathering type permanent magnet units are installed in the secondary yoke according to a certain polar distance to form a composite magnetism gathering type permanent magnet array. The composite magnetism gathering type permanent magnet unit is composed of a U-shaped permanent magnet and a magnetism assisting structure installed in an opening of the U-shaped permanent magnet. The magnetism assisting structure comprises a sixth permanent magnet which is installed in the direction parallel to the air gap, and the magnetization direction of the sixth permanent magnet is parallel to the depth direction of the opening of the U-shaped permanent magnet. The thrust performance of the permanent magnet synchronous linear motor is improved, the utilization rate of the permanent magnet and the thrust density of the motor are improved, and the permanent magnet synchronous linear motor is particularly suitable for engineering application of high-thrust and high-power linear motors.

Description

Technical Field

[0001] The present invention belongs to the technical field of linear motors, and particularly relates to a composite magnetic concentrating permanent magnet synchronous linear motor. Background Art

[0002] Permanent magnet synchronous linear motors have the advantages of large thrust density, high acceleration, high positioning accuracy, etc., and have broad application prospects in the fields of rail transit with large thrust and long stroke and vertical lifting. However, restricted by the arrangement method, installation space, etc., higher requirements are put forward for permanent magnet synchronous linear motors. Especially for linear motors with a driving arrangement of short primary, long secondary, and moving primary, how to improve the utilization rate of permanent magnet materials is crucial for developing linear motors with large thrust density.

[0003] Regarding the problem of improving the performance of the motor, many new permanent magnet structures such as Halbach, magnetic concentrating type, and V-type permanent magnet structures have been used to improve magnetic leakage, increase the magnetic load of the motor, and enhance its thrust density; there are also papers developing different winding methods such as fractional-slot concentrated windings, toroidal windings, etc. to reduce the copper consumption at the ends and effectively improve the motor efficiency; reducing the thrust fluctuation of permanent magnet synchronous linear motors by means of tilting magnetic poles, adjusting the primary length, modular combination, etc. For example, in the invention CN108462358B, the Halbach array is used in a tubular doubly salient permanent magnet linear motor, and the secondary is set as a salient pole Halbach array, which solves the problems of small thrust density and power density existing in the existing tubular permanent magnet linear motor; the invention CN110165852B proposes a two-phase group concentrated winding magnetic concentrating permanent magnet linear motor, which has high power density and high output thrust, and effectively suppresses magnetic resistance and thrust fluctuation.

[0004] However, the magnetic leakage phenomenon of traditional Halbach, magnetic concentrating type, and V-type permanent magnet arrays is still relatively large, resulting in large electromagnetic losses during the operation of the motor. At the same time, while reducing the thrust fluctuation of the motor by means of tilting magnetic poles, adjusting the primary length, modular combination, etc., it will also bring a reduction in the average thrust. Therefore, it is urgent to design a secondary permanent magnet array structure with small magnetic leakage and high permanent magnet utilization rate to solve the problems of obvious magnetic leakage phenomenon and low thrust density of permanent magnet linear motors. Summary of the Invention

[0005] Aiming at the problems of obvious magnetic leakage phenomenon in the secondary permanent magnet array of the existing permanent magnet synchronous linear motor and the magnetic concentrating effect to be improved, the present invention provides a composite magnetic concentrating permanent magnet synchronous linear motor. By adopting a composite magnetic concentrating permanent magnet unit, the magnetic field distribution is optimized, the magnetic leakage effect is significantly reduced, the magnetic load and thrust density of the permanent magnet synchronous linear motor are improved, so as to comprehensively improve the dynamic performance of the motor.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] A composite magnet - concentrating permanent - magnet synchronous linear motor, comprising a primary and a secondary. There is an air gap between the primary and the secondary. The primary includes a primary iron core and a three - phase winding coil; the secondary includes a secondary yoke and a plurality of composite magnet - concentrating permanent - magnet units; the composite magnet - concentrating permanent - magnet units are installed in the secondary yoke according to a certain pole pitch to form a composite magnet - concentrating permanent - magnet array;

[0008] The composite magnet - concentrating permanent - magnet unit is composed of a U - shaped permanent magnet and a magnetic - assisting structure installed in the opening of the U - shaped permanent magnet; the magnetic - assisting structure includes a sixth permanent magnet arranged along the direction parallel to the air gap, and the magnetization direction of the sixth permanent magnet is parallel to the depth direction of the opening of the U - shaped permanent magnet.

[0009] Further, both ends of the sixth permanent magnet are directly fixed or respectively fixed in the opening of the U - shaped permanent magnet through a magnetic isolation bridge; the magnetic isolation bridge is made of non - magnetic material; the magnetization direction of the magnetic - assisting structure faces or backs the U - shaped opening direction; the cross - sectional shape of the magnetic - assisting structure is a straight - line shape, an arc shape, a trapezoid shape or an irregular shape; the magnetic - assisting structure includes one or more sixth permanent magnets.

[0010] Further, the magnetization directions of the U - shaped permanent magnets all point to the opening of the U - shaped permanent magnet, or the magnetization directions of the U - shaped permanent magnets all back the opening of the U - shaped permanent magnet.

[0011] Further, magnetic conduction sheets are arranged on the upper side and / or the lower side of the sixth permanent magnet.

[0012] Further, the U - shaped permanent magnet is formed by a whole permanent magnet or spliced by multiple sub - permanent magnets; the widths of the U - shaped permanent magnets in the composite magnet - concentrating permanent - magnet array are unified.

[0013] Further, the outer shape of the U - shaped permanent magnet is one or more of a conventional U - shape, a flat - bottom U - shape, a narrow - mouth U - shape, and a narrow - mouth flat - bottom U - shape; the shape of the opening of the U - shaped permanent magnet is one or more of a rectangle, a dovetail shape, a conventional U - shape, and a narrow - mouth U - shape; the cross - sectional shape of the sub - permanent magnet is a rectangle, a sector, a parallelogram, a semi - circular ring, or a U - shape.

[0014] Further, the magnetization direction of the sixth permanent magnet points to the air gap, or the magnetization directions of the sixth permanent magnet are alternately arranged in the direction pointing to the air gap and the direction backing the air gap.

[0015] Further, the arrangement requirement of the pole pitch is that the permanent - magnet pole pitch τ pm has a relationship with the length of the motor primary as L = 2×p×τ pm , where p is the number of pairs of permanent - magnet poles.

[0016] Furthermore, the composite permanent magnet type permanent magnet synchronous linear motor adopts a driving arrangement of short primary, long secondary, moving primary type or short secondary, long primary, moving secondary type; the number of pole pairs of the three-phase winding coil is the same as that of the magnetic poles of the composite permanent magnet type permanent magnet array.

[0017] Optionally, the composite permanent magnet type permanent magnet synchronous linear motor is of the alternating pole type permanent magnet synchronous linear motor; the magnetization directions of the U-shaped permanent magnets all point to the opening, and at the same time, the magnetization direction of the sixth permanent magnet points to the air gap, or, the magnetization directions of the U-shaped permanent magnets all face away from the opening, and at the same time, the magnetization direction of the sixth permanent magnet faces away from the air gap.

[0018] Optionally, the composite permanent magnet type permanent magnet synchronous linear motor is of the salient pole type permanent magnet synchronous linear motor; denote the adjacent composite permanent magnet type permanent magnet units as permanent magnet unit A and permanent magnet unit B respectively, then the magnetization directions of the U-shaped permanent magnets in the permanent magnet unit A all point to the opening, and the magnetization direction of the sixth permanent magnet points to the air gap; in the permanent magnet unit B, the magnetization directions of the U-shaped permanent magnets all face away from the opening, and at the same time, the magnetization direction of the sixth permanent magnet faces away from the air gap.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention provides a composite permanent magnet type permanent magnet synchronous linear motor, which realizes the optimization of the leakage magnetic flux of the permanent magnet structure of the permanent magnet synchronous linear motor and the construction of a strong air gap magnetic field, improves the thrust performance of the permanent magnet synchronous linear motor, improves the utilization rate of the permanent magnet and the motor thrust density, and enhances the field weakening speed regulation ability of the motor;

[0021] The permanent magnet structure of the secondary adopts a novel composite permanent magnet type permanent magnet unit array. The composite permanent magnet type permanent magnet unit is composed of a U-shaped permanent magnet and a magnetic field assisting structure installed in the opening of the U-shaped permanent magnet; the U-shaped structure not only has the ability to concentrate magnetic flux but also can reduce leakage magnetic flux, and the sixth permanent magnet in the magnetic field assisting structure plays a role in assisting the magnetic field; the composite permanent magnet type permanent magnet unit can greatly enhance the magnetic flux density amplitude on the air gap side, reduce leakage magnetic flux and reduce the magnetic flux density on the secondary yoke side;

[0022] The present invention is particularly suitable for the engineering applications of large-thrust and high-power linear motors, can overcome a series of engineering limitations such as the arrangement method and installation space, and provides certain reference for the design and development of the linear permanent magnet motor body. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. Among them:

[0024] Figure 1 It is a schematic two-dimensional cross-sectional structure diagram of an embodiment of the present invention.

[0025] Figure 2 This is the 3D assembly drawing of the embodiment of the present invention.

[0026] Figure 3 This is the 3D exploded view of the secondary of the embodiment of the present invention.

[0027] Figure 4 This is the schematic diagram of the two-dimensional structure of four composite magnetic concentrating permanent magnet units of the embodiment of the present invention.

[0028] Figure 5 This is the 3D exploded view of the primary of the embodiment of the present invention.

[0029] Figure 6 This is the schematic diagram of the two-dimensional cross-sectional structure of another embodiment of the present invention.

[0030] Figure 7 This is the layout diagram of the sixth permanent magnet in Embodiment 1 of the present invention; wherein,

[0031] (a), (d), and (c) are respectively the positions of the sixth permanent magnet in the high-level group, middle-level group, and low-level group.

[0032] Figure 8 This is the no-load back electromotive force simulation result of Embodiment 1 of the present invention.

[0033] Figure 9 This is the definition diagram of the height-width ratio of the sixth permanent magnet in Embodiment 2 of the present invention.

[0034] Figure 10 This is the no-load back electromotive force simulation result of Embodiment 2 of the present invention.

[0035] Figure 11 This is the motor performance of two groups of magnetic concentrating permanent magnet units in Embodiment 3 of the present invention, wherein, (a) is the result comparison diagram of the no-load air-gap magnetic flux density amplitude; (b) is the result comparison diagram of the back electromotive force; (c) is the result comparison diagram of the thrust.

[0036] Figure 12 This is the schematic diagram of the structure of the surface-mounted permanent magnet synchronous linear motor of Comparative Example 1.

[0037] Figure 13 This is the schematic diagram of the structure of the Halbach permanent magnet synchronous linear motor of Comparative Example 2.

[0038] Figure 14 This is the finite element simulation magnetic field line distribution diagram of three permanent magnet synchronous linear motors; wherein, (a), (b), and (c) are respectively the finite element simulation magnetic field line distribution diagrams of the permanent magnet synchronous linear motors of Embodiment 4, Comparative Example 1, and Comparative Example 2.

[0039] Figure 15Normal air-gap magnetic density distribution diagrams at the center line of the air gap of the three permanent magnet synchronous linear motors in Embodiment 4, Comparative Example 1, and Comparative Example 2.

[0040] Figure 16 Back electromotive force characteristics at the center line of the air gap of the three permanent magnet synchronous linear motors in Embodiment 4, Comparative Example 1, and Comparative Example 2.

[0041] Figure 17 Thrust characteristics at the center line of the air gap of the three permanent magnet synchronous linear motors in Embodiment 4, Comparative Example 1, and Comparative Example 2.

[0042] In the figure: 1. Secondary yoke; 2. Primary iron core; 3. Composite magnetic concentrating permanent magnet unit; 4. Three-phase winding coil; 5. U-shaped groove; 6. First permanent magnet; 7. Second permanent magnet; 8. Third permanent magnet; 9. Fourth permanent magnet; 10. Fifth permanent magnet; 11. First magnetic isolation bridge; 12. Second magnetic isolation bridge; 13. Sixth permanent magnet; 14. Lower magnetic conduction sheet; 15. Upper magnetic conduction sheet; 16. Air gap; 17. Primary tooth part; 18. Primary yoke part; 19. Seventh permanent magnet; 20. Eighth permanent magnet; 21. Ninth permanent magnet; 22. Tenth permanent magnet; 23. Primary fixing device. Detailed implementation manners

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0044] In the description of the present invention, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate component. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] The present invention will be described in detail below with reference to the drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0046] As Figures 1-6As shown in the figure, a composite permanent magnet type permanent magnet synchronous linear motor includes a primary and a secondary. There is an air gap 16 between the primary and the secondary. The primary includes a primary iron core 2 and a three-phase winding coil 4. The primary iron core 2 includes a primary yoke 18 and a plurality of primary teeth 17. These primary teeth 17 are fixed on the primary yoke along the moving direction at a certain tooth pitch. Each primary tooth 17 is sleeved with a coil, and the three-phase winding coil 4 is formed by series and parallel connection. Among them, the tooth pitch = 2 × pole pitch × number of permanent magnet pole pairs / number of teeth, which is related to the pole-slot combination of the permanent magnet synchronous linear motor. In this embodiment, the common 15-slot 16-pole is selected as the unit motor, and the permanent magnet pole pitch τ pm = 22.5 mm. According to the formula, the tooth pitch is calculated as 2 × 22.5 mm × 8 / 15 = 24 mm. Other common unit linear motors also include 3-slot 2-pole, 3-slot 4-pole, 9-slot 8-pole, and 9-slot 10-pole.

[0047] The secondary includes a secondary yoke iron 1. Several U-shaped grooves 5 are opened along the moving direction on the side of the secondary yoke iron 1 close to the air gap 16. The composite permanent magnet type permanent magnet unit 3 is closely attached to the inside of the U-shaped groove 5. The composite permanent magnet type permanent magnet units 3 are installed in the secondary yoke iron 1 at a certain pole pitch to form a composite permanent magnet array. The composite permanent magnet type permanent magnet unit 3 is composed of a U-shaped permanent magnet and a magnetic assisting structure installed in the opening of the U-shaped permanent magnet. The magnetic assisting structure includes a sixth permanent magnet 13 arranged along the direction parallel to the air gap 16, and the magnetization direction of the sixth permanent magnet 13 is parallel to the depth direction of the opening of the U-shaped permanent magnet. The U-shaped permanent magnet plays a role in concentrating the magnetic field, and the sixth permanent magnet 13 is inserted into the U-shaped permanent magnet to play a role in assisting the magnetic field.

[0048] Further, there are two setting methods for the magnetization direction of the U-shaped permanent magnet, which are respectively pointing to the opening of the U-shaped permanent magnet and facing away from the opening of the U-shaped permanent magnet. There are also two setting methods for the magnetization direction of the sixth permanent magnet 13, which are respectively pointing to the air gap 16 and facing away from the air gap 16.

[0049] Further, the shape of the magnetic assisting structure is adapted to the opening shape of the U-shaped permanent magnet, and the cross-sectional shape of the magnetic assisting structure is a straight shape, a rectangular shape, an arc shape, a trapezoidal shape or an irregular shape.

[0050] Further, both ends of the sixth permanent magnet 13 are directly bonded inside the opening of the U-shaped permanent magnet, or are respectively fixed inside the opening of the U-shaped permanent magnet through magnetic isolation bridges. If magnetic isolation bridges are used, the magnetic isolation bridges occupy positions to center the sixth permanent magnet 13, as Figure 4 shown. Figure 4 In the figure, the magnetic isolation bridges at both ends of the sixth permanent magnet 13 are respectively the first magnetic isolation bridge 11 and the second magnetic isolation bridge 12. The magnetic isolation bridge is made of non-magnetic material. The sixth permanent magnet 13 of the present invention spans across the opening of the U-shaped permanent magnet. The simulation results show that if the sixth permanent magnet 13 is erected inside the opening of the U-shaped permanent magnet, the effect is relatively poor.

[0051] Further, the magnetic assisting structure further includes magnetic conductive sheets disposed on the upper and lower sides of the sixth permanent magnet 13. The magnetic conductive sheets are necessary structures constituting the magnetic assisting structure. The sixth permanent magnet 13 in the magnetic assisting structure plays a role in magnetic assistance to further enhance the magnetic field.

[0052] Further, one or more sixth permanent magnets 13 are included in the magnetic assisting structure. For the sake of distinction, the second and subsequent sixth permanent magnets 13 are denoted as tenth permanent magnets 22. Then, the tenth permanent magnets 22 are spaced apart and disposed above or below the sixth permanent magnet 13. A magnetic conductive sheet is disposed between the sixth permanent magnet 13 and the tenth permanent magnet 22. If there are multiple tenth permanent magnets 22 on the same side of the sixth permanent magnet 13, a magnetic conductive sheet is also required to be disposed between two adjacent tenth permanent magnets 22. The sixth permanent magnet 13 and the tenth permanent magnet 22 are bonded through a magnetic isolation bridge and a magnetic conductive sheet to form a multi-layer magnetic assisting structure, which further enhances the magnetic field and improves the magnetic assisting effect.

[0053] As Figure 3 shown, the cross-sectional shape of the composite magnetic concentrating permanent magnet unit 3 can be a conventional U shape, a flat-bottom U shape, a narrow-mouth U shape, or a narrow-mouth flat-bottom U shape. The shape of the opening of the U-shaped permanent magnet can be a rectangle, a dovetail shape, a conventional U shape, a narrow-mouth U shape, etc. The width of the sixth permanent magnet 13 is 2 / 3 or more of the opening width of the U-shaped permanent magnet, and it is best to occupy the full opening width. Simulation tests show that the closer the sixth permanent magnet 13 is to the opening of the U-shaped permanent magnet, the worse the performance. Therefore, the sixth permanent magnet 13 is disposed in the middle and lower part of the U-shaped permanent magnet, and the preferred position is at the bottom of the opening of the U-shaped permanent magnet.

[0054] Further, the U-shaped permanent magnet, the sixth permanent magnet 13, and the tenth permanent magnet 22 are made of common neodymium iron boron permanent magnet materials, such as N48SH. The magnetic conductive sheets are made of soft magnetic materials. The magnetic isolation bridge is made of non-magnetic materials, such as filled with resin materials or using plastic blocks or rubber blocks. Multiple permanent magnets and magnetic conductive sheets are connected by a bonding method.

[0055] The U-shaped permanent magnet is formed by a single piece of permanent magnet or assembled by multiple sub-permanent magnets; the widths of the U-shaped permanent magnets in the composite magnetic focusing permanent magnet array are unified; the cross-sectional shape of the sub-permanent magnet is rectangular, fan-shaped, parallelogram-shaped, semi-annular, or U-shaped. Specifically, in one example, the U-shaped permanent magnet is sequentially composed of a fourth permanent magnet 9, a first permanent magnet 6, a second permanent magnet 7, a third permanent magnet 8, and a fifth permanent magnet 10 closely fitted and spliced; among them, the cross-sections of the second permanent magnet 7, the fourth permanent magnet 9, and the fifth permanent magnet 10 are rectangular or parallelogram-shaped; the cross-sections of the first permanent magnet 6 and the third permanent magnet 8 are fan-shaped, and the magnetization direction forms a 45° angle with the extension direction of the air gap 16, which can focus the magnetic field and play a role in reducing magnetic leakage; the magnetization direction of the second permanent magnet 7 points to the air gap 16, and the magnetization directions of the fourth permanent magnet 9 and the fifth permanent magnet 10 are opposite. As Figure 4 (a) and 4(b), the composite magnetic focusing permanent magnet unit 3 both includes six sub-magnets; Figure 4 In the composite magnetic focusing permanent magnet unit 3 in (b), the fourth permanent magnet 9 and the fifth permanent magnet 10 magnetized in parallel are inclined at a certain angle to form a parallelogram cross-section, which can increase the cooperation between the tenth permanent magnet 22 and the sixth permanent magnet, and further enhance the magnetic field. In another example, as Figure 4 (c) and 4(d) show, the U-shaped permanent magnet is sequentially composed of a seventh permanent magnet 19, an eighth permanent magnet 20, and a ninth permanent magnet 21 closely fitted and spliced; among them, the cross-sections of the seventh permanent magnet 19 and the eighth permanent magnet 20 are rectangular or parallelogram-shaped, and the cross-section of the ninth permanent magnet 21 is semi-annular; the magnetization directions of the seventh permanent magnet 19 and the eighth permanent magnet 20 are opposite; the magnetization direction of the ninth permanent magnet 21 is axial.

[0056] Furthermore, considering the installation space and the reliability requirements of the permanent magnet synchronous linear motor, a certain air gap 16 length is set between the primary and the secondary. The thickness of the air gap 16 is 3.5 mm - 4.5 mm. For example, the thickness of the air gap 16 can be 3.8 mm, 3.9 mm, 4 mm, 4.1 mm, 4.2 mm, etc.; the arrangement requirement of the pole pitch is that the permanent magnet pole pitch τ pm has the relationship with the length of the motor primary as L = 2 × p × τ pm , where p is the number of pairs of permanent magnet poles. The larger the air gap 16 length is, the more convenient the installation is, the unilateral magnetic pull (the attraction of the permanent magnet to the primary iron core) is reduced, and the cogging force also decreases. The disadvantage is that the magnetic reluctance of the motor air gap increases, reducing the performance of the motor thrust. When the amount of permanent magnet used, the air gap 16 length, and the permanent magnet pole pitch are the same, the size of the composite unit will affect the magnetic density in the air gap 16, and at the same time will affect the magnitude of the thrust and the no-load back electromotive force.

[0057] Further, the number of pole pairs of the three-phase winding coil is the same as that of the composite magnetic concentrating permanent magnet array; the composite magnetic concentrating permanent magnet array includes composite magnetic concentrating permanent magnet units 3 with the same or different cross-sectional shapes. The composite magnetic concentrating permanent magnet synchronous linear motor adopts a driving arrangement of short primary, long secondary, and moving primary, or can also adopt a driving arrangement of short secondary, long primary, and moving secondary. During assembly, the secondary of the composite magnetic concentrating permanent magnet unit 3 is placed below the primary, and the secondary and the primary are combined according to a certain air gap 16 by using a slide rail, a slider, and a primary fixing device 23 to form a composite magnetic concentrating permanent magnet synchronous linear motor.

[0058] Optionally, as Figure 1 shown, the type of the composite magnetic concentrating permanent magnet synchronous linear motor is an alternating pole type permanent magnet synchronous linear motor; the magnetization directions of the U-shaped permanent magnets all point to the opening, and at the same time, the magnetization direction of the sixth permanent magnet 13 points to the air gap 16, or the magnetization directions of the U-shaped permanent magnets all face away from the opening, and at the same time, the magnetization direction of the sixth permanent magnet 13 faces away from the air gap 16.

[0059] Optionally, as Figure 6 shown, the type of the composite magnetic concentrating permanent magnet synchronous linear motor is an explicit pole type permanent magnet synchronous linear motor; denote the adjacent composite magnetic concentrating permanent magnet units 3 as permanent magnet unit A and permanent magnet unit B respectively, then the magnetization directions of the U-shaped permanent magnets in the permanent magnet unit A all point to the opening, and the magnetization direction of the sixth permanent magnet 13 points to the air gap 16; in the permanent magnet unit B, the magnetization directions of the U-shaped permanent magnets all face away from the opening, and at the same time, the magnetization direction of the sixth permanent magnet 13 faces away from the air gap 16.

[0060] The thrust performance of the linear motor has a certain correlation with the change laws of the motor magnetic flux linkage and the no-load back electromotive force magnitude. In the motor field, the magnetic flux linkage constant, the back electromotive force constant, and the thrust constant are in a ratio relationship. When the motor speed is consistent with the applied current, the thrust corresponds to the no-load back electromotive force, and the greater the no-load back electromotive force, the greater the thrust. Therefore, in the following Examples 1-4 and Comparative Examples 1-2, the motor performance changes are mainly illustrated through the index of the no-load back electromotive force.

[0061] Example 1

[0062] In Example 1, the influence of the sixth permanent magnet at different position heights on the motor performance was explored.

[0063] As Figure 7As shown in (a), (b), and (c), the sixth permanent magnet 13 is respectively arranged at the top, the middle one-half, and the bottom of the U-shaped permanent magnet, and is respectively denoted as the high-position group, the middle-position group, and the low-position group. The magnetic isolation bridge is not used, and both ends of the sixth permanent magnet 13 are directly in contact with the inner wall of the opening of the U-shaped permanent magnet. The vertical cross-section of the opening of the U-shaped permanent magnet is rectangular, and the thickness of the sixth permanent magnet 13 is one-third of the opening of the U-shaped permanent magnet.

[0064] The no-load back electromotive force simulation results of different groups are shown in Figure 8 , and it can be seen from the results that the closer the setting position of the sixth permanent magnet 13 is to the opening, the continuous decrease of the no-load back electromotive force of the linear motor and the decline of the motor performance. Therefore, in the present invention, the sixth permanent magnet 13 is arranged in the middle and lower part, and preferably, the sixth permanent magnet 13 is arranged at the bottom of the opening of the U-shaped permanent magnet.

[0065] Embodiment 2

[0066] In this Embodiment 2, the influence of different height-width ratios of the sixth permanent magnet on the motor performance is explored.

[0067] As Figure 9 shown, denote the opening width of the U-shaped permanent magnet as k 1 , the width of the sixth permanent magnet as L 1 , and the height as h 1 , and define the height-width ratio of the six permanent magnets as: m 1 = h 1 / L 1 , and the ratio to the opening of the U-shaped permanent magnet as: m 2 = L 1 / k 1 .

[0068] In this embodiment, a magnetic isolation bridge is adopted, and three groups of sixth permanent magnets with different height-width ratios are set for comparison, which are respectively: Group 1, m 1 = 2.5 / 13 mm, m 2 = 1; Group 2, m 1 = 3.25 / 10 mm, m 2 = 0.77; Group 3, m 1 = 5 / 6.5 mm, m 2 = 0.5.

[0069] The no-load back electromotive force simulation results in three cases are as Figure 10 shown, and the results show that: the larger the height-width ratio of the sixth permanent magnet 13, the smaller the proportion of the U-shaped opening width, and the continuous decrease of the no-load back electromotive force of the motor; compared with the height of the sixth permanent magnet 13, the width has a greater influence on the magnetic assisting effect. Therefore, the present invention limits the width of the sixth permanent magnet 13 to 2 / 3 or more of the opening width of the U-shaped permanent magnet, and preferably, the width of the sixth permanent magnet 13 accounts for the entire U-shaped opening width.

[0070] Embodiment 3

[0071] This embodiment explores the influence of different widths w of the U-shaped permanent magnet pm1 / opening width k 1 on the performance of the motor.

[0072] When the amount of permanent magnet used, the length of air gap 16, and the permanent magnet pole pitch are the same, the size of the composite unit will affect the magnetic flux density in the air gap 16, and at the same time will affect the magnitude of the thrust and no-load back electromotive force, and then will affect the magnitude of the thrust. In this embodiment, with the same amount of permanent magnet used, the width of the sixth permanent magnet 13 accounts for 100% of the opening width of the U-shaped permanent magnet, the length of the air gap 16 is 4 mm, and the permanent magnet pole pitch τ pm is 22.5 mm, w pm1 + k 1 = τ pm ; The composite magnetic focusing type permanent magnet unit of the present invention (denoted as U+-type group) and the magnetic focusing type permanent magnet unit with only U-shaped permanent magnet and soft magnetic body (denoted as U-type group) are respectively set. Compare the motor performance changes of the two when the width w of the U-shaped permanent magnet pm1 is 6.5 mm, 7.5 mm, 8.5 mm, 9.5 mm respectively, and the corresponding k 1 is 16 mm, 15 mm, 14 mm, 13 mm. The no-load air gap magnetic flux density amplitude B y , no-load back electromotive force, and thrust results of the two groups of magnetic focusing type permanent magnet units are respectively as Figure 11 (a), 10(b), 10(c) shown.

[0073] From Figure 11 the results, it can be seen that, first, comparing the changes in the air gap magnetic flux density, the air gap magnetic flux density amplitude B y at the midline of the air gap is selected for comparison. It is found that as the width w of the permanent magnet pm1 gradually increases, that is, when the opening width k 1 gradually decreases, the air gap magnetic flux density amplitude B y gradually increases, and the no-load back electromotive force and thrust show the same change law. Second, when the width w of the permanent magnet in the U+-type group pm1 is small, the no-load air gap magnetic flux density amplitude B y , no-load back electromotive force, and thrust are much larger than those of the U-type group. Third, as the width w of the permanent magnet pm1 increases, the differences in the no-load air gap magnetic flux density amplitude B y , no-load back electromotive force, and thrust between the two groups also gradually decay. However, the performance of the U+-type group at different widths w of the permanent magnet pm1 is better than that of the U-type group. It shows that although the use of the sixth permanent magnet does not change the change law of the differences in the no-load air gap magnetic flux density amplitude B y , no-load back electromotive force, and thrust, it can play a role in enhancing the magnetic field and improve the no-load air gap magnetic flux density amplitude B y to a certain extent., no-load back electromotive force and thrust.

[0074] Next, Example 4, Comparative Example 1, and Comparative Example 2 will be described. The linear motor types of Example 4, Comparative Example 1, and Comparative Example 2 are the composite magnetic-concentrating permanent magnet synchronous linear motor, surface-mounted permanent magnet synchronous linear motor, and Halbach permanent magnet synchronous linear motor of the present invention, respectively.

[0075] In Example 4, as Figure 1 shown, the composite magnetic-concentrating permanent magnet unit 3 uses a U-shaped permanent magnet with a conventional U-shaped cross-section. Its structure includes a second permanent magnet 7, a fourth permanent magnet 9, and a fifth permanent magnet 10 with a rectangular cross-section, as well as a first permanent magnet 6 and a third permanent magnet 8 with a fan-shaped cross-section; the opening shape of the U-shaped permanent magnet is rectangular, the opening width of the U-shaped permanent magnet is 13 mm, and the depth is 7.5 mm; the cross-section of the sixth permanent magnet 13 is flat rectangular, the width is 13 mm, and the thickness is 2.5 mm; it is directly bonded at 1 / 2 of the opening of the U-shaped permanent magnet. An upper magnetic conductive sheet 15 is installed on the upper side of the sixth permanent magnet 13, and a lower magnetic conductive sheet 14 is filled in the lower side.

[0076] Comparative Example 1 is a surface-mounted permanent magnet synchronous linear motor with an equal amount of permanent magnet material. The two-dimensional cross-section schematic diagram of this surface-mounted permanent magnet synchronous linear motor is as Figure 12 shown.

[0077] Comparative Example 2 is a Halbach permanent magnet synchronous linear motor with an equal amount of permanent magnet material. The two-dimensional cross-section schematic diagram of this Halbach permanent magnet synchronous linear motor is as Figure 13 shown.

[0078] Figure 14 (a), (b), and (c) are the two-dimensional cross-section magnetic force line distribution diagrams of the composite magnetic-concentrating permanent magnet synchronous linear motor (Example 4), surface-mounted (Comparative Example 1), and Halbach alternating poles (Comparative Example 2) composed of different combined forms of magnetic pole units under an equal amount of permanent magnet material. From Figure 14 it can be seen that the inter-pole leakage magnetic flux between the N pole and the S pole of the surface-mounted permanent magnet structure in Comparative Example 1 is relatively large and there is no protruding iron pole, and the magnetic-concentrating ability is weak; the leakage magnetic flux on the back yoke side of the Halbach permanent magnet structure in Comparative Example 2 is relatively large; on the one hand, the leakage magnetic flux on the back yoke side (i.e., the bottom end) of the composite magnetic-concentrating permanent magnet unit in Example 1 of the present invention is greatly suppressed, realizing leakage magnetic flux optimization, and on the other hand, there are protruding iron poles and assisting permanent magnets, increasing the design freedom of the magnetic-concentrating unit and realizing the construction of a strong air-gap magnetic field.

[0079] Figure 15 It is the normal air-gap magnetic flux density distribution diagram at the air-gap center line of the three permanent magnet synchronous linear motors in Example 4, Comparative Example 1, and Comparative Example 2. From Figure 15It can be known that under the condition of equal amount of permanent magnetic materials, the normal air-gap magnetic density at the midline of the air gap of surface-mounted, Halbach, and composite magnetic-concentrating permanent magnet synchronous linear motors composed of pole units with different combination forms. It can be found that the normal air-gap magnetic density of the permanent magnet synchronous linear motor in Embodiment 4 of the present invention is the strongest, realizing the construction of a strong air-gap magnetic field.

[0080] From Figure 16 it can be known that under the condition of equal amount of permanent magnetic materials, the no-load back electromotive force characteristics of surface-mounted, Halbach, and composite magnetic-concentrating permanent magnet synchronous linear motors composed of pole units with different combination forms; the results show that the no-load back electromotive force of the composite magnetic-concentrating permanent magnet synchronous linear motor of the present invention is higher than that of the surface-mounted and Halbach permanent magnet synchronous linear motors.

[0081] As Figure 17 shown, under the condition of equal amount of permanent magnetic materials, the thrust characteristics of surface-mounted, Halbach, and composite magnetic-concentrating permanent magnet synchronous linear motors composed of pole units with different combination forms. It can be seen that the average thrust of the composite magnetic-concentrating permanent magnet synchronous linear motor is 16.8% and 4.24% higher than that of the surface-mounted and Halbach permanent magnet synchronous linear motors respectively, indicating that the use of composite magnetic-concentrating permanent magnet units can improve the utilization rate of permanent magnets and improve the thrust characteristics of permanent magnet synchronous linear motors.

[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A composite magnetic concentrating permanent magnet synchronous linear motor, comprising a primary and a secondary, wherein an air gap (16) is provided between the primary and the secondary, wherein the primary comprises a primary iron core (2) and a three-phase winding coil (4); characterized in that: The secondary comprises a secondary yoke (1) and a plurality of composite magnetic concentrating permanent magnetic units (3); the composite magnetic concentrating permanent magnetic units (3) are installed in the secondary yoke (1) according to a certain pole pitch to form a composite magnetic concentrating permanent magnetic array; The composite magnetic concentrating permanent magnet unit (3) is composed of a U-shaped permanent magnet and a magnetic assisting structure installed in the opening of the U-shaped permanent magnet; the magnetic assisting structure includes a sixth permanent magnet (13) arranged in a direction parallel to the air gap (16), and the magnetization direction of the sixth permanent magnet (13) is parallel to the depth direction of the opening of the U-shaped permanent magnet.

2. The composite magnetic concentrating permanent magnet synchronous linear motor according to claim 1 is characterized in that: The two ends of the sixth permanent magnet (13) are fixed directly or respectively via a magnetic isolation bridge in the opening of the U-shaped permanent magnet; the magnetic isolation bridge is made of non-magnetic material; The magnetization direction of the magnetic assist structure is toward or away from the U-shaped opening direction; The cross-sectional shape of the magnetic assist structure is a straight line, an arc, a trapezoid or an irregular shape; The magnetic assisting structure includes one or more sixth permanent magnets (13).

3. The composite magnetic concentrating permanent magnet synchronous linear motor according to claim 1 is characterized in that: The magnetization direction of the U-shaped permanent magnet points to the opening of the U-shaped permanent magnet, or the magnetization direction of the U-shaped permanent magnet faces away from the opening of the U-shaped permanent magnet.

4. The composite magnetic concentrating permanent magnet linear synchronous motor according to claim 1 or 2, characterized in that: A magnetic conductive sheet is provided on the upper side and / or the lower side of the sixth permanent magnet (13).

5. The composite magnetic concentrating permanent magnet synchronous linear motor according to claim 1, characterized in that: The U-shaped permanent magnet is formed by a whole permanent magnet or by splicing a plurality of sub-permanent magnets; the width of each U-shaped permanent magnet in the composite magnetic concentrating permanent magnet array is uniform.

6. The composite magnetic concentrating permanent magnet linear synchronous motor according to claim 5, characterized in that: The shape of the U-shaped permanent magnet is one or more of a conventional U-shape, a flat-bottomed U-shape, a narrow-mouthed U-shape, and a narrow-mouthed flat-bottomed U-shape; the shape of the opening of the U-shaped permanent magnet is one or more of a rectangle, a dovetail shape, a conventional U-shape, and a narrow-mouthed U-shape; the cross-sectional shape of the sub-permanent magnet is a rectangle, a fan-shaped, a parallelogram, a semi-circular shape, or a U-shape.

7. The composite magnetic concentration type permanent magnet synchronous linear motor according to claim 1, characterized in that: The magnetization direction of the sixth permanent magnet (13) points to the air gap (16), or the magnetization direction of the sixth permanent magnet (13) is arranged alternately in a direction pointing to the air gap (16) and a direction facing away from the air gap (16).

8. The composite magnetic concentration type permanent magnet synchronous linear motor according to claim 1, characterized in that: The type of the composite magnetic concentrated permanent magnet synchronous linear motor is an alternating pole permanent magnet synchronous linear motor; the magnetization directions of the U-shaped permanent magnets all point to the opening, and the magnetization direction of the sixth permanent magnet (13) points to the air gap (16); or, the magnetization directions of the U-shaped permanent magnets all face away from the opening, and the magnetization direction of the sixth permanent magnet (13) faces away from the air gap (16).

9. The composite magnetic concentration type permanent magnet synchronous linear motor according to claim 1, characterized in that: The type of the composite magnetic concentrator permanent magnet synchronous linear motor is a salient pole permanent magnet synchronous linear motor; the adjacent composite magnetic concentrator permanent magnet units (3) are respectively permanent magnet units A and permanent magnet units B, then the magnetization directions of the U-shaped permanent magnets in the permanent magnet unit A all point to the opening, and the magnetization direction of the sixth permanent magnet (13) points to the air gap (16); in the permanent magnet unit B, the magnetization directions of the U-shaped permanent magnets all face away from the opening, and the magnetization direction of the sixth permanent magnet (13) faces away from the air gap (16).

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