A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system

Abstract

The present invention discloses a magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system. Inside the inner rotor core, four sets of permanent magnet groups with the same structure are evenly embedded along the circumferential direction. Each permanent magnet group is distributed in n layers of permanent magnets along the diameter direction. Each layer of permanent magnets is composed of a first neodymium iron boron permanent magnet, an inner circular arc permanent magnet, and a second neodymium iron boron permanent magnet connected in sequence to form a V shape. On the outer surface of the rotor core, four surface-mounted circular arc neodymium iron boron permanent magnets are evenly surface-mounted along the circumferential direction. The magnetization directions of the first and second neodymium iron boron permanent magnets are both from their inner ends to their outer ends. The magnetization directions of all the inner circular arc permanent magnets are from the inside to the outside along their center line directions. The magnetization direction of each surface-mounted circular arc neodymium iron boron permanent magnet is the same as that of the inner circular arc permanent magnet facing it. When combined with a centrifugal pump, the present invention can not only reduce the rotor core and eddy current losses, but also effectively reduce the torque ripple and ensure the stable operation of the centrifugal pump in a levitated state.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor design, and specifically relates to a magnetic levitation permanent magnet thin-film motor with an internal and surface-mounted hybrid rotor structure, which is applied to a centrifugal pump system. Background Technique

[0002] As a general-purpose machine, centrifugal pumps have been widely used in many fields such as agricultural field irrigation, petrochemical industry, power industry, and urban drainage. In a centrifugal pump system, the motor often serves as the core component for energy transmission, and the performance of the motor directly affects the energy conversion efficiency and the reliability of the centrifugal pump system. The drive of a traditional centrifugal pump is to connect the impeller shaft of the pump to the electric shaft through a coupling, so that the impeller and the motor rotate together to work. Since there is a sealing ring between the motor shaft and the impeller of the centrifugal pump, leakage occurs in the centrifugal pump, inevitably reducing the efficiency of the centrifugal pump system.

[0003] The bearingless permanent magnet thin-film motor (BPMSM) can effectively solve the leakage problem of centrifugal pumps. The impeller of the centrifugal pump and the motor rotor are integrated into one body, and they are jointly sealed in the pump cavity, and the rotating magnetic field is provided by the stator winding of the motor to drive the impeller to rotate. This structure eliminates the rotating shaft sealing device of the traditional centrifugal pump and can achieve completely leak-free operation. The bearingless permanent magnet thin-film motor utilizes the similarity between the motor stator structure and the electromagnetic bearing structure. The bearing winding that generates the radial suspension force is embedded on the stator teeth of the motor. The pole numbers of the torque winding and the suspension winding satisfy the difference of ±1 between them. The active suspension of the rotor in two radial degrees of freedom is realized through the uneven air gap generated after the two sets of windings are conducted. In addition, the excited rotor is designed in a disc shape, and the passive suspension of the rotor in three axial degrees of freedom of the motor is ensured by the magnetic resistance effect. The bearingless permanent magnet thin-film motor uses a combined active and passive suspension method, simplifies the traditional motor structure, and greatly reduces the cost of the motor.

[0004] Due to using a permanent magnet of a single structure such as neodymium iron boron as the excitation, the permanent magnet motor has a constant air-gap magnetic field, but the speed regulation range of the motor is narrow. For example, the motor disclosed in the Chinese patent publication No. CN202021211305.4 forms a permanent magnet assisted reluctance motor by embedding a permanent magnet and a non-magnetic conductor in an arc-shaped slot. This type of motor utilizes the permanent magnet torque and the reluctance torque, and can effectively improve the torque density. However, when the permanent magnet is embedded in the magnetic isolation bridge, it can only generate a relatively low air-gap magnetic flux density, and this magnetic flux density contains large harmonics, resulting in large torque ripple and core loss, further restricting the improvement of the motor efficiency. To address the large torque ripple, it is improved by optimizing the structure of the motor body. For example, the motor disclosed in the Chinese patent publication No. 201711308185.2 reasonably optimizes the stator magnetic circuit of the motor by placing permanent magnets with different polarization directions, effectively reducing the torque ripple of the motor. However, the structure of this motor contains two rotating components, with a complex structure and large processing difficulty.

[0005] A centrifugal pump system with high energy conversion efficiency requires a motor with high torque density and low torque ripple. Therefore, under the condition of maintaining the high torque density of the motor, how to effectively reduce the torque ripple output by the motor, reduce the air-gap harmonic content, and improve the problem of high-temperature demagnetization of the permanent magnet has become an urgent problem to be solved in the design field of bearingless permanent magnet thin-film motors. Summary of the Invention

[0006] Aiming at the defects of the above-mentioned prior art, the present invention proposes a magnetic levitation permanent magnet thin-film motor that can reasonably adjust the air-gap magnetic field of the motor, improve the torque density, reduce the air-gap harmonics and torque ripple, and is applicable to a centrifugal pump system.

[0007] The technical solution adopted by the magnetic levitation permanent magnet thin-film motor applicable to a centrifugal pump system in the present invention is as follows:

[0008] It includes an outer stator and an inner rotor. The inner rotor includes a rotor core. Inside the rotor core, four sets of permanent magnet groups with the same structure are evenly embedded along the circumferential direction. Each set of permanent magnet groups is distributed in n layers of permanent magnets along the diameter direction, where n≥5. Each layer of permanent magnets is composed of a first neodymium iron boron permanent magnet, an inner circular arc permanent magnet, and a second neodymium iron boron permanent magnet connected in sequence to form a V shape. The V-shaped opening of each layer of permanent magnets and the arc opening of the inner circular arc permanent magnet both face outward. The center lines of the n inner circular arc permanent magnets 3 are collinear along the same diameter direction. The first neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet are symmetrically arranged with respect to the center line of the connected inner circular arc permanent magnet. The inner ends of the first neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet in each layer of permanent magnets are seamlessly fixedly connected to the corresponding inner circular arc permanent magnet, and the outer ends are flush with the outer surface of the rotor core. Four surface-mounted circular arc neodymium iron boron permanent magnets are evenly surface-mounted on the outer surface of the rotor core along the circumferential direction. Each one faces an inner circular arc permanent magnet and their center lines are collinear. The magnetization directions of the first neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet are both along the direction from their inner ends to their outer ends. The magnetization directions of all the inner circular arc permanent magnets are magnetized from the inside to the outside along the direction of their center lines. The magnetization direction of each surface-mounted circular arc neodymium iron boron permanent magnet is the same as that of the inner circular arc permanent magnet it faces. The rotor core is integrated with the centrifugal pump impeller.

[0009] Both the surface-mounted circular arc permanent magnets and the inner circular arc permanent magnets are made of NdFe30 neodymium iron boron material, and both the first neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet are made of NdFe35 neodymium iron boron material.

[0010] A rotor protective sleeve is commonly sleeved on the outer surfaces of the four surface-mounted circular arc neodymium iron boron permanent magnets. The rotor protective sleeve is made of a mesh-like fiber material into a cylindrical structure with a threaded shape.

[0011] The n layers of permanent magnets are arranged at intervals along the radial direction inside and outside, and the distance between adjacent layers of permanent magnets is equal.

[0012] The n first neodymium iron boron permanent magnets in the n layers of permanent magnets are parallel to each other, and the n second neodymium iron boron permanent magnets in the n layers of permanent magnets are parallel to each other.

[0013] The radian occupied by each inner circular arc permanent magnet is 120°, and the included angle between the first neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet in each layer of permanent magnets is 60°.

[0014] The beneficial effects highlighted by the present invention adopting the above technical solutions are:

[0015] 1. When combined with a centrifugal pump, the present invention can not only reduce the rotor core and eddy current losses, but also effectively reduce the torque ripple, ensuring the stable suspension operation of the centrifugal pump.

[0016] 2. The present invention uses permanent magnet materials with different models, resulting in relatively low magnetic properties on the outer surface of the rotor and relatively high magnetic properties inside the rotor, effectively increasing the field weakening range of the motor, achieving the effects of increasing the saliency ratio of the motor and reducing torque ripple.

[0017] 3. The present invention sets the magnetization directions of the surface-mounted and inner circular arc permanent magnets to be the same, generating a magnetic flux density close to a sine distribution in the air gap, with smaller harmonic components in the back electromotive force and enabling smooth torque output. Brief Description of the Drawings

[0018] The following further elaborates on the present invention in detail in conjunction with the drawings and specific embodiments:

[0019] Figure 1 It is a schematic diagram of the radial structure of a magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to the present invention;

[0020] Figure 2 For Figure 1 the enlarged structure and geometric dimension marking diagram of one group of permanent magnet groups in

[0021] Figure 3 It is a schematic diagram of the magnetic circuit when the present invention works;

[0022] Figure 4 It is a schematic diagram comparing the 3rd harmonic components of the air gap magnetic flux density of the structure of the present invention with that of a conventional surface-mounted motor and a conventional inner-mounted motor;

[0023] Figure 5 It is a schematic diagram comparing the 3rd harmonic components of the air gap magnetic flux density of the hybrid magnetization method adopted by the present invention with the parallel / radial magnetization method;

[0024] Figure 6 It is a comparison diagram of the core losses of the motor with the hybrid magnetization method adopted by the present invention and the single parallel magnetization / radial magnetization;

[0025] Figure 7 It is a comparison diagram of the eddy current losses of the motor with the hybrid magnetization method adopted by the present invention and the single parallel magnetization / radial magnetization;

[0026] Figure 8 It is a comparison diagram of the core losses and eddy current losses of the motor with different permanent magnet material combinations (NdFe30 + NdFe35) adopted by the present invention and the use of the same permanent magnet material (NdFe35 + NdFe35);

[0027] In the figure: 1 - stator core; 2 - surface-mounted circular arc permanent magnet; 3 - inner circular arc permanent magnet; 4 - rotor protective sleeve; 5 - stator coil; 6 - rotor core; 7 - first neodymium iron boron permanent magnet, 8 - second neodymium iron boron permanent magnet, 9 - surface-mounted permanent magnet filler. Specific Embodiments

[0028] See Figure 1 Figure 1 , the magnetic levitation permanent magnet thin - film motor applicable to a centrifugal pump system described in the present invention is a permanent magnet motor with an inner - surface - mounted hybrid rotor structure, which includes an outer stator and an inner rotor. The outer stator consists of a stator core 1 and a coil 5. The stator core 1 is provided with stator teeth and stator slots, and the stator coils 5 are wound around the stator teeth. The inner rotor includes a rotor core 6, which is coaxially placed inside the stator core 1. A rotor protective sleeve 4 is wrapped around the outside of the rotor core 6. Radially, there is a 2 - mm radial air gap between the inner wall of the stator core 1 and the outer wall of the rotor protective sleeve 4. Both the stator core 1 and the rotor core 6 are laminated from DW465 - 50 silicon steel sheets with a thickness of 0.35 mm, and the lamination factor is 0.95.

[0029] There is no rotating shaft in the exact middle of the rotor core 6. The centrifugal pump impeller is integrated with the rotor core 6, and then they are jointly sealed inside the centrifugal pump. The rotor core 6 rotates to drive the centrifugal pump impeller to rotate.

[0030] Combined with Figure 2 Figure 2 , inside the rotor core 6, four groups of permanent magnet groups are evenly embedded along the circumferential direction, and the structures of the four groups of permanent magnet groups are exactly the same. Each group of permanent magnet groups is distributed in n layers of permanent magnets along the diameter direction, where n≥5, and only 5 layers are shown in the figure. This structure can form a multi - layer magnetic circuit structure in the air gap, meeting the electromagnetic performance requirements of high - power motors.

[0031] Each layer of permanent magnets is sequentially connected into a V - shaped structure by a first neodymium - iron - boron permanent magnet 7, an inner - built arc - shaped permanent magnet 3, and a second neodymium - iron - boron permanent magnet 8. The radial cross - sections of the first neodymium - iron - boron permanent magnet 7 and the second neodymium - iron - boron permanent magnet 8 are square, and the radial cross - section of the inner - built arc - shaped permanent magnet 3 is arc - shaped. The n layers of permanent magnets are arranged at intervals along the radial inner and outer sides, and adjacent layers of permanent magnets do not touch, with equal spacing. The V - shaped openings of the V - shaped structures of each layer of permanent magnets all face outward, that is, towards the air - gap side. The arc - shaped openings of the inner - built arc - shaped permanent magnets 3 also all face the air - gap side. The structures of the five arc - shaped permanent magnets 3 in the n layers of permanent magnets are exactly the same, and the center lines of the n inner - built arc - shaped permanent magnets 3 are collinear along the same diameter direction. The inner - built arc - shaped permanent magnet 3 in each layer of permanent magnets is at the bottom of the V - shape, and the first neodymium - iron - boron permanent magnet 7 and the second neodymium - iron - boron permanent magnet 8 are symmetrically arranged with respect to the center line of the connected inner - built arc - shaped permanent magnet 3, forming the two sides of the V - shape. Therefore, the structures of the first neodymium - iron - boron permanent magnet 7 and the second neodymium - iron - boron permanent magnet 8 in the same layer of permanent magnets are exactly the same. The inner ends of the first neodymium - iron - boron permanent magnet 7 and the second neodymium - iron - boron permanent magnet 8 in each layer of permanent magnets are seamlessly and fixedly connected to the corresponding inner - built arc - shaped permanent magnet 3, and the outer ends are flush with the outer surface of the rotor core 6. The n first neodymium - iron - boron permanent magnets 7 in the n layers of permanent magnets are parallel to each other, and the n second neodymium - iron - boron permanent magnets 8 in the n layers of permanent magnets are parallel to each other.

[0032] The magnetization directions of all the first NdFeB permanent magnets 7 and the second NdFeB permanent magnets 8 are all along the direction from their inner ends to their outer ends, which is also the length direction inside the rotor core 6. The magnetization directions of all the built-in arc-shaped permanent magnets 3 are all magnetized from inside to outside along the direction of their center lines, which is also the direction from inside to outside along the radius direction of the rotor core 6 passing through the built-in arc-shaped permanent magnets 3.

[0033] The radian α occupied by each built-in arc-shaped permanent magnet 3 is 120°. The included angle between the first NdFeB permanent magnet 7 and the second NdFeB permanent magnet 8 in each layer of permanent magnets is 60°, and the included angle β between the first NdFeB permanent magnet 7, the second NdFeB permanent magnet 8 and the center line of the arc-shaped permanent magnet 3 is 30°.

[0034] The distance h between adjacent two layers of permanent magnets is 2 mm, that is, there is the same distance between adjacent two first NdFeB permanent magnets 7, adjacent two second NdFeB permanent magnets 8 and adjacent two built-in arc-shaped permanent magnets 3 in adjacent two layers of permanent magnets, and the distance h is 2 mm.

[0035] The widths of all the first NdFeB permanent magnets 7 and the second NdFeB permanent magnets 8 are the same, both being δ2 = 2 mm.

[0036] See Figure 2 , on the outer surface of the rotor core 6, a total of 4 surface-mounted arc-shaped NdFeB permanent magnets 2 with two pairs of poles are evenly surface-mounted along the circumferential direction. The radian occupied by each surface-mounted arc-shaped NdFeB permanent magnet 2 is 120°. The radial thickness of each surface-mounted arc-shaped NdFeB permanent magnet 2 is δ1 = 4 mm, and the opening faces inward. The center line of one surface-mounted arc-shaped NdFeB permanent magnet 2 is collinear with the center line of one of the built-in arc-shaped permanent magnets 3, and one surface-mounted arc-shaped NdFeB permanent magnet 2 faces one built-in arc-shaped permanent magnet 3.

[0037] The magnetization direction of each surface-mounted arc-shaped NdFeB permanent magnet 2 is the same as that of one of the built-in arc-shaped permanent magnets 3 it faces. Since both the surface-mounted arc-shaped NdFeB permanent magnets 2 and the built-in arc-shaped permanent magnets 3 are arc-shaped structures, it is easier to generate a magnetic density distribution close to sine in the air gap by using the parallel magnetization method with the same direction. The harmonic components of the back electromotive force are smaller, which is beneficial to the smooth output of torque.

[0038] The pole arc coefficients of each surface-mounted arc-shaped NdFeB permanent magnet 2 are the same, all being 0.7. The space between adjacent two surface-mounted arc-shaped permanent magnets 2 is filled with a resin filling medium, that is, the surface-mounted permanent magnet filler 9 is used for filling and fixing to prevent the permanent magnet from being thrown out due to the centrifugal force.

[0039] All the NdFeB permanent magnets of the present invention adopt permanent magnet materials with different models and different magnetic properties. The surface-mounted arc-shaped permanent magnet 2 and the built-in arc-shaped permanent magnet 3 both adopt NdFe30 NdFeB materials, and the first NdFeB permanent magnet 7 and the second NdFeB permanent magnet 8 both adopt NdFe35 NdFeB materials. This makes the magnetic properties on the outer surface of the rotor smaller, and the magnetic properties of the permanent magnets at the V-shaped structure inside the rotor larger. This arrangement can effectively increase the field weakening range of the motor, achieving the effects of increasing the saliency ratio of the motor and reducing torque ripple.

[0040] See Figure 1 , a rotor protective sleeve 4 is attached to the outer side of the surface-mounted arc-shaped permanent magnet 2. The rotor protective sleeve 4 is a cylindrical structure with a thickness of 1 mm made of mesh-shaped fiber material, and the outer shape of the rotor protective sleeve 4 is threaded. The dual design of the mesh-shaped material and the threaded structure can increase the contact area between the surface-mounted arc-shaped permanent magnet 2 and the air, effectively improving the demagnetization problem of the permanent magnet caused by overheating.

[0041] See Figure 3 , taking two adjacent groups of permanent magnets as an example to illustrate the magnetic circuit of the present invention. The permanent magnet group where the N pole is located is the first group, and the permanent magnet group where the S pole is located is the second group. There are two magnetic paths on the rotor core 6. As shown by the solid line in the figure, the path of the first magnetic path is as follows: starting from the N pole of the built-in arc-shaped permanent magnet 3 in the first group of permanent magnet groups, passing through the N pole of the second NdFeB permanent magnet 8 in the first group of permanent magnet groups, the surface-mounted arc-shaped NdFeB permanent magnet 2, the air gap, the stator core 1, the surface-mounted arc-shaped NdFeB permanent magnet 2, the S pole of the second NdFeB permanent magnet 8 in the second group of permanent magnet groups, the built-in arc-shaped permanent magnet 3 in the second group of permanent magnet groups, the rotor core 6, and finally returning to the N pole of the built-in arc-shaped permanent magnet 3 in the first group of permanent magnet groups, forming a circular path. As shown by the dotted line in the figure, the path of the second magnetic path is as follows: starting from the N pole of the built-in arc-shaped permanent magnet 3 in the first group of permanent magnet groups, passing through the N pole of the first NdFeB permanent magnet 7 in the first group of permanent magnet groups, the surface-mounted arc-shaped NdFeB permanent magnet 2, the air gap, the stator core 1, the surface-mounted arc-shaped NdFeB permanent magnet 2, the S pole of the first NdFeB permanent magnet 7 in the second group of permanent magnet groups, the built-in arc-shaped permanent magnet 3 in the second group of permanent magnet groups, the rotor core 6, and finally returning to the N pole of the built-in arc-shaped permanent magnet 3 in the first group of permanent magnet groups, forming a circular path.

[0042] After the motor of the present invention is powered on, two magnetic paths on the rotor core 6 interact with the magnetic field generated by the stator coil 5 of the motor simultaneously to generate electromagnetic torque to drive the load to operate. Since the present invention adopts the combination of surface-mounted and interior permanent magnet, the motor can effectively improve the torque density by using the permanent magnet torque and reluctance torque. Therefore, when the present invention is combined with a centrifugal pump, if the torque ripple output by the motor is too large, the suspension effect will fail and the system will stop. Therefore, the present invention can realize the suspension operation of the centrifugal pump, which can not only reduce the core and eddy current losses of the rotor, but also effectively reduce the torque ripple, ensuring the stable suspension operation of the centrifugal pump.

[0043] Figure 4 Figure for comparing the 3rd harmonic component of the air-gap magnetic density during the test of the present invention with that of a conventional surface-mounted and a conventional interior permanent magnet motor. From Figure 4 it can be seen that the present invention can reduce the harmonic component.

[0044] Figure 5 Figure for comparing the 3rd harmonic component of the air-gap magnetic density of the hybrid magnetization method adopted by the present invention with that of the single parallel magnetization or radial magnetization method. From Figure 5 it can be seen that the present invention can reduce the air-gap harmonic content.

[0045] Figure 6 Figure for comparing the core losses of the hybrid magnetization method adopted by the present invention with that of the single parallel magnetization or radial magnetization of the motor. From Figure 6 it can be seen that the present invention can reduce the core losses.

[0046] Figure 7 Figure for comparing the eddy current losses of the hybrid magnetization method adopted by the present invention with that of the single parallel magnetization or radial magnetization of the motor. From Figure 7 it can be seen that the present invention can reduce the eddy current losses.

[0047] Figure 8 Figure for comparing the core losses and eddy current losses of the motor when different permanent magnet materials are combined (NdFe30+NdFe35) with the same permanent magnet material (NdFe35+NdFe35) adopted by the present invention. From Figure 8 it can be seen that the present invention can reduce the core losses and eddy current losses.

[0048] The above are the embodiments of the present invention. It should be noted that any equivalent structure substitution based on the concept and principle of the present invention, or the direct or indirect application of the content of the specification and drawings in other related technical fields, shall fall within the protection scope of the present invention.

Claims

1. A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system, comprising an outer stator and an inner rotor, characterized in that: The inner rotor described above includes a rotor core (6). Inside the rotor core (6), four sets of identically structured permanent magnet groups are evenly embedded along the circumferential direction. Each set of permanent magnet groups is distributed in n layers of permanent magnets along the diameter direction, where n ≥ 5. Each layer of permanent magnets is composed of a first neodymium iron boron permanent magnet (7), an inner circular arc permanent magnet (3), and a second neodymium iron boron permanent magnet (8) connected in sequence to form a V shape. The V-shaped opening of each layer of permanent magnets and the arc opening of the inner circular arc permanent magnet (3) both face outward. The center lines of the n inner circular arc permanent magnets (3) are collinear along the same diameter direction. The first neodymium iron boron permanent magnet (7) and the second neodymium iron boron permanent magnet (8) are symmetrically arranged with respect to the center line of the connected inner circular arc permanent magnet (3). The inner ends of the first neodymium iron boron permanent magnet (7) and the second neodymium iron boron permanent magnet (8) in each layer of permanent magnets are seamlessly and fixedly connected to the corresponding inner circular arc permanent magnet (3), and the outer ends are flush with the outer surface of the rotor core (6). Four surface-mounted circular arc neodymium iron boron permanent magnets (2) are evenly surface-mounted on the outer surface of the rotor core (6) along the circumferential direction. Each one is opposite to an inner circular arc permanent magnet (3) and their center lines are collinear. The magnetization directions of the first neodymium iron boron permanent magnet (7) and the second neodymium iron boron permanent magnet (8) are both along the direction from their inner ends to their outer ends. The magnetization direction of all the inner circular arc permanent magnets (3) is magnetized from the inside to the outside along the direction of their center lines. The magnetization direction of each surface-mounted circular arc neodymium iron boron permanent magnet (2) is the same as that of the inner circular arc permanent magnet (3) it faces. The rotor core (6) is integrated with the centrifugal pump impeller.

2. The magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, wherein: Both the surface-mounted circular arc permanent magnet (2) and the inner circular arc permanent magnet (3) are made of NdFe30 neodymium iron boron material, and both the first neodymium iron boron permanent magnet (7) and the second neodymium iron boron permanent magnet (8) are made of NdFe35 neodymium iron boron material.

3. The magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: A rotor protective sleeve (4) is commonly sleeved on the outer surfaces of the four surface-mounted circular arc neodymium iron boron permanent magnets (2). The rotor protective sleeve (4) is a cylindrical structure made of mesh-like fiber material, and its outer shape is threaded.

4. A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: The n layers of permanent magnets are arranged at intervals along the radial direction, inside and outside, and the distance between adjacent layers of permanent magnets is equal.

5. A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: The n first neodymium iron boron permanent magnets (7) in the n layers of permanent magnets are parallel to each other, and the n second neodymium iron boron permanent magnets (8) in the n layers of permanent magnets are parallel to each other.

6. A magnetic levitation permanent magnet thin plate motor applicable to a centrifugal pump system according to claim 1, characterized in that: The radian occupied by each inner circular arc permanent magnet (3) is 120°, and the included angle between the first neodymium iron boron permanent magnet (7) and the second neodymium iron boron permanent magnet (8) in each layer of permanent magnets is 60°.

7. A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: The same spacing of 2 mm is provided between adjacent two first neodymium iron boron permanent magnets (7) and between adjacent two second neodymium iron boron permanent magnets (8) in adjacent layers of permanent magnets.

8. The magnetically levitated permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: The radial thickness of each surface-mounted circular arc neodymium iron boron permanent magnet (2) is 4 mm.

9. A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: The space between adjacent two surface-mounted circular arc permanent magnets (2) is filled with resin.

10. A magnetic levitation permanent magnet thin film motor applicable to a centrifugal pump system according to claim 1, characterized in that: The pole arc coefficient of each surface-mounted circular arc neodymium iron boron permanent magnet (2) is 0.7.

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