A double-layer stator type radial magnetic bearing integrated in a doubly salient permanent magnet motor

Abstract

The application discloses a double-layer stator type radial magnetic bearing integrated in a doubly salient permanent magnet motor, and belongs to the technical field of power generation, power transformation or power distribution. The double-layer stator type radial magnetic bearing comprises a magnetic bearing stator-rotor, a control coil, a magnetic isolation ring and a magnetic conducting bridge. The magnetic bearing stator comprises upper-layer stator magnetic poles and lower-layer stator magnetic poles used for forming a direction control loop, and the two layers of magnetic bearing stator magnetic pole yoke parts are isolated by the magnetic isolation ring. A closed radial bias magnetic field main loop is formed by the permanent magnet extending out of the motor stator section, the circumferential magnetic conducting bridge, the double-layer stator magnetic poles, the radial working air gap and the magnetic bearing rotor, the bias loop and the control loop are decoupled, and the multipurpose reuse of the permanent magnet magnetic field of the doubly salient stator permanent magnet motor is realized. The motor yoke part space is fully utilized, the axial length of the magnetic suspension motor system is reduced, the dynamic performance of the motor rotor is improved, and the target of high compactness, high integration and component reuse of the "stator type permanent magnet motor + magnetic suspension bearing" is achieved.

Description

Technical Field

[0001] This invention discloses a double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, which relates to electrical and mechanical transmission equipment technology and belongs to the technical field of power generation, transformation or distribution. Background Technology

[0002] In recent years, high-speed and ultra-high-speed motors have been increasingly widely used in machine tool processing, turbine machinery, flywheel energy storage systems, and hybrid vehicles. In terms of motor structure, unlike rotor permanent magnet motors, stator permanent magnet motors have their permanent magnets located on one side of the stator, while the rotor has neither permanent magnets nor windings. Therefore, they do not face the risks of permanent magnet breakage due to centrifugal force or high-temperature demagnetization common in traditional rotor permanent magnet motors. This overcomes the disadvantages of traditional rotor permanent magnet motors, such as complex structure, high manufacturing cost, complex processing technology, large equivalent air gap, difficult rotor cooling, and the risk of irreversible demagnetization.

[0003] However, existing stator permanent magnet motor systems generally use mechanical bearings. During use, mechanical bearings are prone to failure due to prolonged mechanical friction, wear, fatigue, and lubricant corrosion, resulting in a significantly shortened service life and the risk of failure. This makes them unreliable at high speeds, which limits the reliability of stator permanent magnet motors. Therefore, high-speed bearing systems are necessary. To address the problems of traditional mechanical bearings, the industry has proposed using magnetic levitation bearings to replace traditional bearings such as ball bearings, oil-filled bearings, and air bearings, in order to achieve levitation support for the high-speed rotor.

[0004] Existing "permanent magnet biased magnetic levitation bearing + permanent magnet motor" systems treat the permanent magnet biased magnetic levitation bearing and the permanent magnet motor as independent components. This results in a more complex structure and larger size compared to the "mechanical bearing + permanent magnet motor" system. The excessively long shaft length of the former leads to complex rotor dynamics problems, which limits the system's speed increase and wider application.

[0005] In summary, the present invention aims to propose a double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor to overcome the above-mentioned defects, in order to achieve the design goal of "stator permanent magnet motor + magnetic levitation bearing" with high compactness, high integration and component reuse. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a double-layer stator radial magnetic bearing integrated into a double-salient pole permanent magnet motor. Through the design of its key components, the stator and permanent magnet, the magnetic field of the permanent magnet in the double-salient pole permanent magnet motor can be bypassed by a designed magnetic guide bridge to achieve other uses of the magnetic field energy, thereby improving the integration of the magnetic levitation motor system. At the same time, by adopting a double-layer stator structure, the radial two-degree-of-freedom magnetic flux path and the permanent magnet bias path and control magnetic flux path are decoupled, thereby improving the performance of the magnetic levitation motor system, shortening its overall axial length, and solving the technical problems of complex structure and large size of existing motor systems composed of permanent magnet bias magnetic levitation bearings and permanent magnet motors, as well as the existence of complex rotor dynamics issues.

[0007] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0008] A permanent magnet is circumferentially assembled within the stator yoke space of a doubly salient permanent magnet motor, with a permanent magnet segment extending beyond the motor stator at its end. A double-layer stator-type radial magnetic bearing integrated into a doubly salient permanent magnet motor includes: a magnetic bearing stator core, a magnetic bearing rotor core, a control coil, and magnetic bridges. Each magnetic bridge is assembled within the space between two adjacent permanent magnet segments extending beyond the motor stator. These magnetic bridges form a circumferential magnetic bridge structure. The magnetic bearing stator core is embedded in and in contact with the circumferential magnetic bridge structure. The magnetic bearing rotor core rotates relative to the magnetic bearing stator core. A control coil is wound around each stator pole of the magnetic bearing stator core.

[0009] As a further optimization of the double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, the magnetic bearing stator core includes: an upper stator magnetic pole and a lower stator magnetic pole. A magnetic isolation ring is assembled between the upper stator magnetic pole and the lower stator magnetic pole. A control coil is wound on each stator magnetic pole in the upper and lower stator magnetic poles, and the control coils wound on the same layer of stator magnetic poles are connected in series.

[0010] As a further optimization scheme for the double-layer stator radial magnetic bearing integrated into the double salient pole permanent magnet motor, the stack thickness of the two stator magnetic poles of the magnetic bearing stator core plus the thickness of the magnetic shielding ring is equal to the stack thickness of the magnetic bearing rotor core.

[0011] As a further optimization of the double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, the magnetic isolation ring is axially magnetized, and the inner diameter of the magnetic isolation ring is equal to the inner diameter of the stator core yoke of the magnetic bearing, and the outer diameter of the magnetic isolation ring is equal to the outer diameter of the stator core yoke of the magnetic bearing.

[0012] As a further optimization scheme for the double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, the inner diameter of the circumferential magnetic bridge is larger than the outer diameter of the magnetic bearing stator core, and the circumferential magnetic bridge has a protruding structure that contacts the radial outer side of the magnetic bearing stator core. The radial width of the magnetic bridge is less than or equal to the width of the motor stator yoke, and the axial thickness of the magnetic bridge is equal to the length of the permanent magnet section extending out of the motor stator. The number of magnetic bridges is equal to the number of magnetic poles of the magnetic bearing stator and is 4N, where N is a positive integer and 4N is less than or equal to the number of permanent magnets in the motor stator.

[0013] As a further optimization of the double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, the magnetization direction of the permanent magnet is tangential, and the magnetization directions of two adjacent permanent magnets are opposite.

[0014] As a further optimization scheme for the double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, the length of the permanent magnet section extending out of the motor stator is calculated based on the target magnetic field strength and the structural magnetic circuit.

[0015] As a further optimization scheme for the double-layer stator radial magnetic bearing integrated into the double salient pole permanent magnet motor, the radial permanent magnet bias magnetic circuit formed by the radial bias magnetic field generated by the permanent magnet is as follows: permanent magnet N pole → magnetic bridge → upper stator magnetic pole → air gap → magnetic bearing rotor core → air gap → lower stator magnetic pole → magnetic bridge → permanent magnet S pole.

[0016] As a further optimization scheme for the double-layer stator radial magnetic bearing integrated into a double salient pole permanent magnet motor, the horizontal direction parallel to the motor end face is defined as the x-direction, and the direction perpendicular to the x-direction is defined as the y-direction. The magnetic flux path generated by the control coil in the x-direction is: upper stator magnetic pole → air gap → magnetic bearing rotor core → air gap → upper stator magnetic pole → upper stator yoke; the magnetic flux path generated by the control coil in the y-direction is: lower stator magnetic pole → air gap → rotor core → air gap → lower stator magnetic pole → lower stator yoke.

[0017] A double salient pole permanent magnet motor integrates the above-mentioned double-layer stator radial magnetic bearing. The double salient pole permanent magnet motor includes: a motor stator core, a motor rotor core, and an armature winding. The motor stator cores are evenly distributed along the circumference of the motor to form the motor stator. An armature winding is wound on the stator teeth of each motor stator core. The motor rotor core rotates relative to the motor stator.

[0018] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0019] (1) This invention designs a double-layer stator magnetic bearing integrated into a double salient pole permanent magnet motor. It makes full use of the space of the motor yoke and, by reasonably designing the shape and size of the magnetic bridge and the stator core of the magnetic bearing, the stator core of the magnetic bearing is embedded in the circumferential magnetic bridge structure and makes good contact with the magnetic bridge. This allows the magnetic field of the permanent magnet in the stator permanent magnet motor to be introduced into the integrated magnetic levitation bearing, providing a bias magnetic field for the magnetic levitation bearing. This enables the reuse of the permanent magnet components in the stator permanent magnet motor, thereby realizing the multi-purpose reuse of the magnetic field energy of the permanent magnet in the permanent magnet motor, reducing the axial length of the magnetic levitation motor system, and improving the dynamic performance of the motor rotor.

[0020] (2) The stator structure of the magnetic bearing proposed in this invention is a double-layer design. The stator magnetic poles of the upper and lower magnetic bearings are separated by a magnetic isolation ring. The control magnetic flux in each direction flows only in the corresponding stator layer, thereby achieving decoupling of different control magnetic circuits and facilitating the design of the control system.

[0021] (3) By rationally designing the path of the control magnetic flux, the present invention enables the control magnetic flux to pass through the permanent magnet and does not require an additional air gap, thereby achieving the separation of the bias magnetic circuit and the control magnetic circuit. The required control current is small and will not cause demagnetization of the permanent magnet. The system has low loss and high reliability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the double-layer stator magnetic bearing integrated into a double salient pole permanent magnet motor according to the present invention.

[0023] Figure 2 This is a three-dimensional assembly diagram of the magnetic bearing in an embodiment of the present invention.

[0024] Figure 3 This is a front view of the overall structure of the 12 / 8 pole doubly salient permanent magnet motor after the magnetic bearing stator core, magnetic bridge, and permanent magnet are assembled in an embodiment of the present invention.

[0025] Figure 4(a) is a schematic diagram of the 1 / 4 permanent magnet biasing magnetic circuit of the double-layer stator magnetic bearing integrated in the 12 / 8 pole double salient pole permanent magnet motor of the present invention, and Figure 4(b) is a radial view of Figure 4(a).

[0026] Figure 5(a) is a schematic diagram of the x-direction control magnetic circuit of the double-layer stator magnetic bearing integrated in the 12 / 8-pole double salient permanent magnet motor in an embodiment of the present invention, and Figure 5(b) is a schematic diagram of the y-direction control magnetic circuit of the double-layer stator magnetic bearing integrated in the 12 / 8-pole double salient permanent magnet motor in an embodiment of the present invention.

[0027] Figure 6 This is a half-sectional view of a 12 / 8-pole doubly salient permanent magnet motor with integrated double-layer stator magnetic bearings in an embodiment of the present invention.

[0028] Figure 7(a) is a schematic diagram of the overall structure of the 12 / 8 pole doubly salient permanent magnet motor with integrated double-layer stator magnetic bearing in an embodiment of the present invention, and Figure 7(b) is a schematic diagram of the structure of the radial magnetic levitation bearing integrated on the 12 / 8 pole doubly salient permanent magnet motor.

[0029] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0030] 1. Motor stator core; 2. Motor rotor core; 3. Armature winding; 4. Permanent magnet; 401~404, first~fourth permanent magnet; 5. Magnetic bearing stator core; 501, upper stator pole; 502, lower stator pole; 6. Magnetic bearing rotor core; 7. Control coil; 8. Magnetic isolation ring; 9. Magnetic guide bridge; 901~904, first~fourth magnetic guide bridge. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] like Figure 1 As shown, this invention presents a double-layer stator magnetic bearing integrated into a double salient pole permanent magnet motor. Due to the asymmetry of the upper and lower parts of the overall structure, it is achieved through... Figure 2 The three-dimensional assembly diagram shown provides a better understanding of its structure.

[0033] like Figure 1 As shown, the double salient pole permanent magnet motor includes: a stator core 1, a rotor core 2, an armature winding 3, and permanent magnets 4. Both the stator core 1 and the rotor core 2 are made of non-oriented multilayer silicon steel sheets. The stator cores 1 are evenly distributed along the circumference of the motor to form the stator. An armature winding 3 is wound around the stator teeth of each stator core 1. The rotor core 2 is located in the middle of the stator and has an air gap with it, allowing the rotor core 2 to rotate relative to the stator. Permanent magnets 4 are embedded in the yoke gaps between adjacent stator cores 1. The permanent magnets 4 can be neodymium iron boron or samarium cobalt, or a combination thereof, and are tangentially magnetized with opposite magnetization directions for adjacent permanent magnets. The axial length of the permanent magnet is slightly longer than the axial length of the motor stator. It is used to cooperate with the magnetic bridge to introduce the magnetic field of the permanent magnet into the magnetic levitation bearing, so as to realize the purpose of reusing the permanent magnet of the double salient pole permanent magnet motor in the magnetic levitation bearing. The length of the permanent magnet section that extends out of the motor stator can be calculated according to the required magnetic field strength and the structural magnetic circuit.

[0034] like Figure 1, Figure 2 As shown, the double-layer stator magnetic bearing includes: a magnetic bearing stator core 5, a magnetic bearing rotor core 6, a control coil 7, a magnetic isolation ring 8, and a magnetic guide bridge 9. Both the magnetic bearing stator core 5 and the magnetic bearing rotor core 6 are made of multi-layered, non-oriented silicon steel sheets. The magnetic bearing rotor core 6 is located in the middle of the magnetic bearing stator core 5 and has an air gap with it. The magnetic bearing rotor core 6 has an axially hollow structure, allowing the motor shaft to pass through the inner ring of the magnetic bearing rotor core. The magnetic bearing rotor core and the shaft are secured and reliably contacted through interference fits, keyways, and other connection methods. The magnetic bearing rotor core 6 can rotate relative to the magnetic bearing stator core 5. The outer diameter of the magnetic bearing stator core 5 is smaller than the inner diameter of the circumferential magnetic bridge structure, meaning the magnetic bearing stator core 5 is surrounded by the circumferential magnetic bridge structure. The outer side of the magnetic bearing stator core 5 makes good contact with the protruding portion on the inner diameter of the circumferential magnetic bridge structure. A control coil 7 is wound around the stator teeth of the magnetic bearing stator core 5. The magnetic bearing stator core has a double-layer structure, including an upper stator magnetic pole 501 and a lower stator magnetic pole 502. A magnetic isolation ring 8 is located between the yokes of the two stator core layers and is axially magnetized to isolate magnetic flux, reduce leakage flux, and increase the bias magnetic field. The inner and outer diameters of the magnetic isolation ring can be chosen to be equal to the inner and outer diameters of the yoke of the magnetic bearing stator core. The combined thickness of the two magnetic bearing stator core layers plus the thickness of the magnetic isolation ring equals the combined thickness of the magnetic bearing rotor core. A magnetic bridge 9 is provided in the space of the motor stator yoke. Each magnetic bridge 9 is assembled in the space between the ends of two adjacent permanent magnets extending out of the motor stator core. The magnetic bridge is arc-shaped, and the magnetic bridges are distributed along the circumference of the motor to form a circumferential magnetic bridge structure. The radial width of each magnetic bridge is... w b Less than or equal to the width of the motor stator yoke w s axial thickness t b Equal to the length of the permanent magnet segment extending from the motor stator t m As shown in Figure 4, the magnetic bridge can be made of forged steel, or by stacking multiple layers of non-oriented silicon steel sheets or pressing soft magnetic composite materials. The number of magnetic poles contained in the two layers of stator core is equal to the number of magnetic bridges, is an integer multiple of 4, and is not greater than the number of permanent magnets in the motor stator.

[0035] In a preferred embodiment of the present invention, the motor has a 12 / 8 structure, the magnetic bearing stator core is four-pole, and the number of magnetic bridges and permanent magnets are both 4. Each stator core contains 4 magnetic poles, and a control coil is wound on each stator tooth or magnetic pole. The coils of the same phase on the motor stator core are connected to form a winding. Two control coils on the first layer of stator poles of the magnetic bearing are connected in series to control the position of the magnetic bearing rotor core in one direction, driven by a power amplifier. In this embodiment, the motor and the magnetic bearing stator and rotor are made of multiple layers of non-oriented silicon steel sheets, the thickness of which can be 0.2mm, 0.35mm, or 0.5mm. The permanent magnets are made of high-performance sintered NdFeB material, processed into cuboids, and embedded in the space between the stator yokes of the motor. They are tangentially magnetized, with each pair 90° out of phase and in opposite magnetization directions. The permanent magnet segment extending from the motor stator is embedded in the space between two adjacent magnetic bridges. These magnetic bridges can be made of laminated electrical pure iron or silicon steel sheets. The magnetic bearing stator core is located within the space surrounded by four magnetic bridges, with the outer edge of the core in good contact with the protruding inner portion of each bridge. The upper and lower stator cores are separated by a magnetic isolation ring. The ring has the same dimensions as the yoke of the two stator poles, and its thickness can be selected as 5mm, much larger than the air gap length. The material can be a ferrite material with low magnetic properties, and it is axially magnetized. Although both the permanent magnet bias circuit and the control circuit are radial circuits, they only intersect at the air gap. Control circuits in different control directions are located on different layers of the stator core, achieving separation of the bias magnetic circuit and the control magnetic circuit, as well as decoupling of different control magnetic circuits.

[0036] A front view of the overall structure of a 12 / 8-pole bisalient permanent magnet motor after assembly of the magnetic bearing stator core, magnetic bridge, and permanent magnet is shown below. Figure 3 As shown, the permanent magnet segment of the first permanent magnet 401 extending from the motor stator is embedded in the gap between the first magnetic bridge 901 and the second magnetic bridge 902. The permanent magnet segment of the second permanent magnet 402 extending from the motor stator is embedded in the gap between the second magnetic bridge 902 and the third magnetic bridge 903. The permanent magnet segment of the third permanent magnet 403 extending from the motor stator is embedded in the gap between the third magnetic bridge 903 and the fourth magnetic bridge 904. The permanent magnet segment of the fourth permanent magnet 404 extending from the motor stator is embedded in the gap between the fourth magnetic bridge 904 and the first magnetic bridge 901. The magnetic bearing stator core 5 is embedded in the circumferential magnetic bridge structure composed of the first to second magnetic bridges 901 to 904.

[0037] Figures 4 and 5 are schematic diagrams of the permanent magnet biasing magnetic circuit and control magnetic circuit of the magnetic bearing section, respectively. Figure 4(a) shows the 1 / 4 permanent magnet biasing magnetic circuit, and Figure 4(b) is a radial view of Figure 4(a). The horizontal direction parallel to the plane of the motor end face is defined as the x-direction, and the direction perpendicular to the x-direction is defined as the y-direction. Figure 5(a) shows the x-direction control magnetic circuit, and Figure 5(b) shows the y-direction control magnetic circuit. As shown in Figures 4 and 5, both the permanent magnet biasing magnetic circuit and the control magnetic circuit are radial magnetic circuits.

[0038] The operating principle of the magnetic bearing proposed in this invention is as follows:

[0039] The permanent magnet generates a radial bias magnetic field, and the control coil generates a radial control magnetic field to adjust the air gap composite magnetic field. As shown in Figure 4, the radial permanent magnet bias magnetic circuit formed by the bias magnetic flux generated by the permanent magnet is as follows: permanent magnet N pole → magnetic bridge → upper stator pole → air gap → magnetic bearing rotor core → air gap → lower stator pole → magnetic bridge → permanent magnet S pole.

[0040] As shown in Figure 5(a), the magnetic flux path generated by the control coil in the x direction is: upper stator magnetic pole → air gap → magnetic bearing rotor core → air gap → upper stator magnetic pole → upper stator yoke.

[0041] As shown in Figure 5(b), the magnetic flux path generated by the control coil in the y direction is: lower stator magnetic pole → air gap → rotor core → air gap → lower stator magnetic pole → lower stator yoke.

[0042] In one control direction, the magnetic field is enhanced in one air gap and weakened in the other air gap, thereby adjusting the magnitude of the magnetic force exerted by the magnetic bearing on the magnetic bearing rotor core.

[0043] In summary, the integrated magnetic bearing of this invention features an intuitive principle and compact structure, effectively utilizing the space of the motor stator yoke. The main difference from existing magnetic levitation motor systems lies in utilizing the motor's permanent magnets to provide a bias magnetic field for the permanent magnet biased magnetic levitation bearing, thus shortening the system's axial length. Two adjacent magnetic poles of the magnetic bearing stator form a closed magnetic field main loop through a double-layer stator structure. By designing independent magnetic circuits, the control magnetic circuits do not pass through the permanent magnets and do not interfere with each other, resulting in high reliability and low coupling. The magnetic bearing stator has 4N poles (4 in this example), reducing the frequency of air gap magnetic field alternation, which is beneficial for reducing rotor core losses under high-speed operating conditions.

[0044] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A double-layer stator type radial magnetic bearing integrated in a doubly salient permanent magnet motor, characterized in that, the doubly salient permanent magnet motor comprises motor stator cores which are uniformly distributed along the motor circumferential direction to form motor stators, permanent magnets are embedded in the yoke part gap between adjacent two motor stator cores, and the end part of the permanent magnet has a permanent magnet segment extending out of the motor stator; the double-layer stator type radial magnetic bearing comprises a magnetic bearing stator core, a magnetic bearing rotor core, control coils, and magnetic conductive bridges, each magnetic conductive bridge is assembled in the space between the end part of the adjacent two permanent magnets and the permanent magnet segment extending out of the motor stator, each magnetic conductive bridge forms a circumferential magnetic conductive bridge structure, the magnetic bearing stator core is embedded in the circumferential magnetic conductive bridge structure, the magnetic bearing stator core comprises upper layer stator magnetic poles and lower layer stator magnetic poles, a magnetic shield ring is assembled between the upper layer stator magnetic poles and the lower layer stator magnetic poles, one control coil is wound on each of the upper layer stator magnetic poles and the lower layer stator magnetic poles, the control coils wound on the stator magnetic poles in the same layer are connected in series, and each magnetic conductive bridge alternately contacts the upper layer stator magnetic poles and the lower layer stator magnetic poles, and the magnetic bearing rotor core rotates relative to the magnetic bearing stator core.

2. The dual-layer stator type radial magnetic bearing integrated with a doubly salient permanent magnet motor according to claim 1, characterized in that, The thickness of the two layers of stator magnetic poles of the magnetic bearing stator core plus the thickness of the magnetic shield ring is equal to the thickness of the magnetic bearing rotor core.

3. The dual-layer stator type radial magnetic bearing integrated with a doubly salient permanent magnet motor according to claim 1, wherein, The magnetic shield ring is axially magnetized, the inner diameter of the magnetic shield ring is equal to the inner diameter of the yoke part of the magnetic bearing stator core, and the outer diameter of the magnetic shield ring is equal to the outer diameter of the yoke part of the magnetic bearing stator core.

4. The double-layer stator type radial magnetic bearing integrated with a doubly salient permanent magnet motor according to any one of claims 1 to 3, characterized in that, The inner diameter of the circumferential magnetic conductive bridge is greater than the outer diameter of the magnetic bearing stator core, the circumferential magnetic conductive bridge has a protruding structure in contact with the radial outer side of the magnetic bearing stator core, the radial width of the magnetic conductive bridge is less than or equal to the width of the yoke part of the motor stator, the axial thickness of the magnetic conductive bridge is equal to the length of the permanent magnet segment extending out of the motor stator, the number of magnetic conductive bridges is equal to the number of magnetic bearing stator magnetic poles and is 4N (N is a positive integer), and 4N is less than or equal to the number of permanent magnets of the motor stator.

5. The dual-stage radial magnetic bearing integrated with the dual- salient permanent magnet motor of claim 4, wherein, The magnetization direction of the permanent magnet is tangential, and the magnetization directions of adjacent two permanent magnets are opposite.

6. The dual-stage radial magnetic bearing integrated with the dual- salient permanent magnet motor of claim 4, wherein, The length of the permanent magnet segment extending out of the motor stator is calculated according to the target magnetic field strength and the structure magnetic circuit.

7. The dual-stage radial magnetic bearing integrated with the dual- salient permanent magnet motor of claim 1, wherein, The radial permanent magnet bias magnetic circuit formed by the radial bias magnetic field generated by the permanent magnet is: permanent magnet N pole → magnetic conductive bridge → upper layer stator magnetic pole → air gap → magnetic bearing rotor core → air gap → lower layer stator magnetic pole → magnetic conductive bridge → permanent magnet S pole.

8. The dual-stage radial magnetic bearing integrated with the dual- salient permanent magnet motor of claim 1, wherein, The horizontal direction parallel to the motor end face is defined as the x direction, and the direction perpendicular to the x direction is the y direction, the magnetic flux path of the x direction control coil is: upper layer stator magnetic pole → air gap → magnetic bearing rotor core → air gap → upper layer stator magnetic pole → upper layer stator yoke, and the magnetic flux path of the y direction control coil is: lower layer stator magnetic pole → air gap → rotor core → air gap → lower layer stator magnetic pole → lower layer stator yoke.

9. A doubly salient permanent magnet motor, characterized by The doubly salient permanent magnet motor integrated with the double-layer stator type radial magnetic bearing according to claim 1 further comprises a motor rotor core and an armature winding, the armature winding is wound on the stator tooth of each motor stator core, and the motor rotor core rotates relative to the motor stator.

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