A built-in permanent magnet synchronous motor with permanent magnets embedded on the rotor surface

Abstract

A built-in permanent magnet synchronous motor with permanent magnets embedded on the surface of the rotor belongs to the field of permanent magnet motors. The present invention is to solve the problem of mutual restriction between electromagnetic performance and mechanical strength of the built-in permanent magnet synchronous motor. The present invention includes a stator core, a stator winding, a rotor core and a rotating shaft; n layers of permanent magnet slots are arranged under each pole of the rotor core, each slot runs through the entire motor along the axial direction, a main flux permanent magnet is placed in each slot, the main flux permanent magnet under each pole constitutes a main flux permanent magnet group providing the main permanent magnetic flux, and functional permanent magnets are embedded on the surface of the rotor core at both sides of the ends of each permanent magnet slot, and the functional permanent magnet under each pole constitutes a functional permanent magnet group that changes the magnetic flux path, and a magnetic bridge is arranged between the functional permanent magnet embedded on the surface and the permanent magnet slot, and the magnetic field generated by the main flux permanent magnet group directly enters the stator from the rotor through the air gap via the magnetic bridge, the functional permanent magnet group and the magnetic field generated by the functional permanent magnet group.

Description

Technical Field

[0001] The invention relates to a high-performance design technology for a permanent magnet motor, and belongs to the field of permanent magnet motors. Background Art

[0002] Permanent magnet synchronous motors have become the main driving motors for new energy transportation devices due to their high power density, high power factor and high efficiency. In order to increase power density by increasing motor speed and increase torque density by using reluctance torque, the topology of built-in permanent magnet synchronous motors has become the choice of more new energy transportation equipment. Compared with surface-mounted permanent magnet synchronous motors, built-in permanent magnet synchronous motors have reluctance torque through the arrangement of permanent magnet slots, so that they can produce greater output torque under the same motor volume. In addition, the permanent magnets are placed inside the motor rotor core, which improves the mechanical strength of the rotor structure and increases the maximum speed that the motor can withstand, so that the motor can have a higher power density. However, the existing built-in permanent magnet synchronous motor topology solutions all have the problem of conflict between the mechanical strength of the motor structure and the electromagnetic performance. In order to ensure the mechanical strength and operation safety of the motor under high-speed or high-torque conditions, the width of the supporting magnetic bridge and other structures in the motor rotor is usually increased as much as possible, but this will lead to an increase in motor leakage and a significant decrease in electromagnetic performance. At the same time, it will also cause local saturation of the rotor core, which will further affect the electromagnetic performance. A common improvement method is to obtain a rotor topology solution that compromises mechanical strength and electromagnetic performance through multi-physics field coupling analysis such as stress field and electromagnetic field, but the effect is limited, the R&D cost and time are high, and it cannot fundamentally solve this problem. Therefore, through the topological structure research of the built-in permanent magnet synchronous motor, discovering the improvement method that can solve the conflict between its mechanical strength and electromagnetic performance is the research focus of improving the performance of the built-in permanent magnet synchronous motor. Summary of the invention

[0003] In order to solve the problem of the mutual restriction between the electromagnetic performance and mechanical strength of the built-in permanent magnet synchronous motor and reduce the magnetic leakage and local saturation of the rotor permanent magnet, the present invention provides a built-in permanent magnet synchronous motor with permanent magnets embedded on the rotor surface. According to the structural characteristics and positional relationship of the permanent magnet slots with permanent magnets under each pole of the conventional built-in permanent magnet synchronous motor and the increased salient pole ratio, the structure embeds permanent magnets on the rotor surface and changes the position of the original magnetic bridge accordingly; it avoids the decrease in electromagnetic performance when increasing the width of the magnetic bridge to improve the mechanical strength of the motor, and at the same time, by changing the rotor magnetic circuit, the permanent magnet magnetic field amplitude is larger and the sinusoidal degree is higher; thereby ensuring that the motor can output a larger and smoother torque and withstand a higher speed.

[0004] The present invention discloses a built-in permanent magnet synchronous motor with a permanent magnet embedded in the rotor surface, comprising a stator core 1, a stator winding 2, a rotor core 3 and a rotating shaft 8; inside the stator core 1, the rotor core 3 is fixed on the rotating shaft 8, and the stator winding 2 is arranged on the stator core 1;

[0005] N layers of permanent magnet slots 4 are arranged under each pole of the rotor core 3, and each slot runs through the entire motor axially. A main flux permanent magnet 5 is placed in each slot. The main flux permanent magnet 5 under each pole constitutes a main flux permanent magnet group 9 that provides the main permanent magnetic flux. Functional permanent magnets 6 are embedded on the surface of the rotor core 3 at both sides of the ends of each permanent magnet slot 4. The functional permanent magnets 6 under each pole constitute a functional permanent magnet group 10 that changes the magnetic flux path. A magnetic bridge 7 is arranged between the functional permanent magnets 6 embedded on the surface and the permanent magnet slots 4. The magnetic field generated by the main flux permanent magnet group 9 directly enters the stator from the rotor through the air gap via the magnetic bridge 7, the functional permanent magnet group 10 and the magnetic field generated by the functional permanent magnet group 10. n is between 2 and 5.

[0006] Preferably, each permanent magnet in the two permanent magnet groups, the main flux permanent magnet group 9 and the functional permanent magnet group 10, adopts a straight-line, arc-shaped, V-shaped or U-shaped structure, and the magnetic field directions of the two permanent magnet groups are along the radial direction of the rotor; under the same pole, each permanent magnet in the two permanent magnet groups is the same N pole or S pole, and the magnetization directions of the adjacent two-pole permanent magnets are opposite.

[0007] Preferably, each permanent magnet in the two permanent magnet groups consists of one or more permanent magnets, or is further divided into multiple permanent magnets along the axial direction.

[0008] Preferably, the permanent magnet slots 4 corresponding to the main magnetic flux permanent magnet group 9 are of a straight-line, arc-shaped, V-shaped or U-shaped structure. When the permanent magnet slots 4 are of a straight-line, a main magnetic flux permanent magnet 5 is embedded in each permanent magnet slot 4; when the permanent magnet slots 4 are of an arc-shaped structure, a main magnetic flux permanent magnet 5 is embedded in each permanent magnet slot 4; when the permanent magnet slots 4 are of a V-shaped structure, two main magnetic flux permanent magnets 5 are symmetrically placed on both sides of each permanent magnet slot 4; when the permanent magnet slots 4 are of a U-shaped structure, two or three main magnetic flux permanent magnets 5 are embedded in each permanent magnet slot 4. If two main magnetic flux permanent magnets 5 are embedded, they are symmetrically placed on both sides of each permanent magnet slot 4; if three main magnetic flux permanent magnets 5 are embedded, in addition to being symmetrically placed on both sides of each permanent magnet slot 4, another main magnetic flux permanent magnet 5 is embedded on the bottom side.

[0009] Preferably, the functional permanent magnets 6 embedded in the surface of the rotor core 3 are arranged in the circumferential direction along the ends of the permanent magnet slots 4 .

[0010] Preferably, the width of the magnetic bridge 7 increases or decreases along the permanent magnet slot 4 toward the center of the circle.

[0011] Beneficial effects of the present invention: The built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface of the present invention forms a series magnetic circuit relationship with the permanent magnets at the center of each pole by embedding permanent magnets at the positions corresponding to each permanent magnet slot on the rotor surface, thereby avoiding the problem of part of the original magnetic flux being short-circuited directly on the rotor core through the magnetic bridge, reducing the problem of permanent magnet leakage of the motor and the local saturation of the rotor core caused by the magnetic flux short-circuit. The direction of the magnetic flux in the magnetic bridge changes from the original direct closure on the rotor side along the circumferential direction to passing through the air gap along the radial direction, providing the main magnetic flux for the operation of the motor; the decoupling of the mechanical strength and electromagnetic performance of the built-in permanent magnet synchronous motor is realized, and when the motor is designed to work at high speed or high torque conditions, the width of the magnetic bridge can be increased according to demand without adversely affecting the electromagnetic performance of the motor. Because the permanent magnets embedded in the surface of the motor rotor are located in the direction of the end of the permanent magnet slot with a magnetic barrier function, they do not interfere with the magnetic conductive structure of the rotor core that provides a path for the armature reaction, so the salient pole ratio of the motor structure will not be reduced, and the influence of the supporting structural components such as the magnetic bridge on the motor reluctance torque is avoided. Two groups of permanent magnets in specially arranged positions work together to provide the permanent magnetic field required by the motor, with a higher magnetic field intensity; because the permanent magnets embedded on the surface and the magnetic bridges at the ends of the permanent magnet slots regulate the rotor flux path, the sinusoidality of the magnetic field generated by the motor's permanent magnets is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The invention relates to a built-in permanent magnet synchronous motor with a permanent magnet embedded in the rotor surface;

[0013] Figure 2 yes Figure 1 A partial enlarged view of

[0014] Figure 3 It is a distribution diagram of magnetic lines of force on the rotor core of the magnetic field generated by the permanent magnets of the internal permanent magnet synchronous motor with the permanent magnets embedded in the rotor surface of the present invention;

[0015] Figure 4 It is a distribution diagram of magnetic lines of force on the rotor core of the magnetic field generated by the permanent magnets of a conventional built-in permanent magnet synchronous motor. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0018] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0019] Specific implementation method 1: The following is combined Figures 1 to 4 The present embodiment is described. The present embodiment describes an internal permanent magnet synchronous motor with a permanent magnet embedded in the rotor surface, comprising a stator core 1, a stator winding 2, a rotor core 3 and a rotating shaft 8. Inside the stator core 1, the rotor core 3 is fixed on the rotating shaft 8, and the stator winding 2 is arranged on the stator core 1.

[0020] N layers of permanent magnet slots 4 are provided under each pole of the rotor core 3, and each slot runs through the entire motor axially. A main flux permanent magnet 5 is placed in each slot, and the main flux permanent magnet 5 under each pole constitutes a main flux permanent magnet group 9 that provides the main permanent magnetic flux. Corresponding to both sides of the ends of each permanent magnet slot 4, functional permanent magnets 6 are embedded on the surface of the rotor core 3, and the functional permanent magnets 6 under each pole constitute a functional permanent magnet group 10 that changes the magnetic flux path. A magnetic bridge 7 is arranged between the functional permanent magnets 6 embedded on the surface and the permanent magnet slots 4. The magnetic field generated by the main flux permanent magnet group 9 passes through the magnetic bridge 7, the functional permanent magnet group 10, and the magnetic field generated by the functional permanent magnet group 10 directly through the air gap from the rotor into the stator.

[0021] n is a positive integer. The larger n is, the more it helps to enhance the influence of the permanent magnet embedded on the surface on the magnetic field path. However, the more complex the structure is, the more likely it is that n will be. The specific number can be determined based on actual conditions and is generally between 2 and 5.

[0022] Each permanent magnet in the two permanent magnet groups, the main flux permanent magnet group 9 and the functional permanent magnet group 10, adopts a straight-line, arc-shaped, V-shaped or U-shaped structure, and the magnetic field directions of the two permanent magnet groups are along the radial direction of the rotor; under the same pole, each permanent magnet in the two permanent magnet groups is the same N pole or S pole, and the magnetization directions of the adjacent two-pole permanent magnets are opposite.

[0023] The permanent magnet slots 4 corresponding to the main magnetic flux permanent magnet group 9 are of a straight-line, arc-shaped, V-shaped or U-shaped structure. When the permanent magnet slots 4 are of a straight-line, a main magnetic flux permanent magnet 5 is embedded in each permanent magnet slot 4; when the permanent magnet slots 4 are of an arc-shaped structure, a main magnetic flux permanent magnet 5 is embedded in each permanent magnet slot 4; when the permanent magnet slots 4 are of a V-shaped structure, two main magnetic flux permanent magnets 5 are symmetrically placed on both sides of each permanent magnet slot 4; when the permanent magnet slots 4 are of a U-shaped structure, two or three main magnetic flux permanent magnets 5 are embedded in each permanent magnet slot 4. If two main magnetic flux permanent magnets 5 are embedded, they are symmetrically placed on both sides of each permanent magnet slot 4; if three main magnetic flux permanent magnets 5 are embedded, in addition to being symmetrically placed on both sides of each permanent magnet slot 4, another main magnetic flux permanent magnet 5 is embedded on the bottom side.

[0024] As for the arrangement of the functional permanent magnet 6 in the form of a straight line, arc, V or U structure, it is the same as that of the main flux permanent magnet 5. The difference is that the functional permanent magnet 6 is embedded in the surface of the rotor core 3. The functional permanent magnet 6 embedded in the surface of the rotor core 3 is only arranged in the circumferential direction along the end of the permanent magnet slot 4, and does not affect the structure of the rotor core 3 between the two permanent magnet slots 4.

[0025] Each permanent magnet in the two permanent magnet groups is composed of one or more permanent magnets, or is further divided into multiple permanent magnets along the axial direction.

[0026] The width of the magnetic bridge 7 increases or decreases along the permanent magnet slot 4 toward the center of the circle.

[0027] by Figure 1 As shown in the figure, n=4, the permanent magnet slot 4 is arc-shaped, and the functional permanent magnet 6 is straight-shaped. This is a specific embodiment. The motor is composed of a stator core 1, a stator winding 2, a rotor core 3, a permanent magnet slot 4, a main flux permanent magnet 5 providing a main permanent magnetic field, a surface-embedded functional permanent magnet 6, a magnetic bridge 7, and a rotating shaft 8. The four main flux permanent magnets 5 providing the main permanent magnetic field under each pole constitute a main flux permanent magnet group 9 providing the main permanent magnetic flux, and the eight surface-embedded functional permanent magnets 6 constitute a functional permanent magnet group 9 for changing the magnetic flux path. A functional permanent magnet group 10; inside the stator core 1, a rotor core 3 is fixed on a rotating shaft 8, and a stator winding 2 is arranged on the stator core 1; each pole of the rotor core 3 is provided with 4 permanent magnet slots 4, and each slot runs through the entire motor along the axial direction, and 8 functional permanent magnets 6 are embedded in the end of each permanent magnet slot 4 on the surface of the rotor core 3, and a magnetic bridge 7 is arranged between the permanent magnet slots 4 and the functional permanent magnets 6 on the rotor surface, with 8 under each pole; and 4 permanent magnets 5 are placed in the 4 permanent magnet slots 4 under each pole.

[0028] Working principle: When the motor of the present invention is working, the permanent magnets embedded in the positions corresponding to the permanent magnet slots on the rotor surface are located on the side of the magnetic bridge facing the air gap, and form a series magnetic circuit relationship with the permanent magnets in the permanent magnet slots at the center of each pole. Figure 3 , 4By comparison, it can be seen that the direction of the magnetic flux in the magnetic bridge changes from being directly closed on the rotor side in the circumferential direction in the conventional topology to passing through the air gap in the radial direction, changing the original leakage flux that is directly short-circuited on the rotor core into the main flux for energy exchange, improving the permanent magnet leakage of the motor and the local saturation of the rotor core caused by the short circuit of the permanent magnet flux on the rotor surface; due to the change in the direction of the magnetic flux path in the magnetic bridge, when the width of the magnetic bridge is increased to ensure that the motor can work at high speed or high torque conditions, it will not have an adverse effect on the electromagnetic performance of the motor, and the decoupling of the mechanical strength and electromagnetic performance of the built-in permanent magnet synchronous motor is achieved. Since two sets of mutually coordinated permanent magnets are used to coordinately provide the permanent magnetic field required by the motor, and the permanent magnets embedded on the surface and the magnetic bridge at the end of the permanent magnet slot play a role in regulating the rotor flux path, the sinusoidality of the synthetic magnetic field generated by the permanent magnets of the motor is improved, and the magnetic field strength is enhanced. The permanent magnets on the surface of the motor rotor are embedded in the end positions of the permanent magnet slots that act as magnetic barriers, so the magnetic conductivity of the armature reaction path on the rotor core is not affected, so the salient pole ratio of the motor is not reduced, and the problem of weakening the motor reluctance torque due to the introduction of supporting mechanical structures such as magnetic bridges is avoided. Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention as defined by the attached claims. It should be understood that different dependent claims and features described herein can be combined in a manner different from that described in the original claims. It can also be understood that the features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface, It is characterized in that The invention comprises a stator core (1), a stator winding (2), a rotor core (3) and a rotating shaft (8); inside the stator core (1), a rotor core (3) is fixed on the rotating shaft (8), and the stator winding (2) is arranged on the stator core (1); The invention is characterized in that n layers of permanent magnet slots (4) are arranged under each pole of the rotor core (3), each slot axially penetrates the entire motor, a main flux permanent magnet (5) is placed in each slot, the main flux permanent magnet (5) under each pole constitutes a main flux permanent magnet group (9) providing main permanent magnetic flux, functional permanent magnets (6) are embedded on the surface of the rotor core (3) at both sides of the ends of each permanent magnet slot (4), the functional permanent magnets (6) under each pole constitute a functional permanent magnet group (10) for changing the magnetic flux path, a magnetic bridge (7) is arranged between the functional permanent magnet (6) embedded on the surface and the permanent magnet slot (4), the magnetic field generated by the main flux permanent magnet group (9) directly enters the stator from the rotor through the air gap via the magnetic bridge (7), the functional permanent magnet group (10) and the magnetic field generated by the functional permanent magnet group (10), and n is between 2 and 5.

2. According to claim 1, a built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface, It is characterized in that Each permanent magnet in the two permanent magnet groups, the main magnetic flux permanent magnet group (9) and the functional permanent magnet group (10), adopts a straight-line, arc-shaped, V-shaped or U-shaped structure, and the magnetic field directions of the two permanent magnet groups are along the radial direction of the rotor; under the same pole, each permanent magnet in the two permanent magnet groups is the same N pole or S pole, and the magnetization directions of the adjacent two-pole permanent magnets are opposite.

3. According to claim 2, a built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface, It is characterized in that Each permanent magnet in the two permanent magnet groups is composed of one or more permanent magnets, or is further divided into multiple permanent magnets along the axial direction.

4. According to claim 2, a built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface, It is characterized in that The permanent magnet slots (4) corresponding to the main magnetic flux permanent magnet group (9) are of straight-line, arc-shaped, V-shaped or U-shaped structure. When the permanent magnet slots (4) are straight-line, a main magnetic flux permanent magnet (5) is embedded in each permanent magnet slot (4); when the permanent magnet slots (4) are arc-shaped, a main magnetic flux permanent magnet (5) is embedded in each permanent magnet slot (4); when the permanent magnet slots (4) are V-shaped, two sides of each permanent magnet slot (4) are symmetrical. Two main magnetic flux permanent magnets (5) are placed; when the permanent magnet slot (4) is U-shaped, two or three main magnetic flux permanent magnets (5) are embedded in each permanent magnet slot (4); if two main magnetic flux permanent magnets (5) are embedded, they are symmetrically placed on both sides of each permanent magnet slot (4); if three main magnetic flux permanent magnets (5) are embedded, in addition to being symmetrically placed on both sides of each permanent magnet slot (4), another main magnetic flux permanent magnet (5) is embedded on the bottom side.

5. According to claim 1, a built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface, It is characterized in that Functional permanent magnets (6) embedded in the surface of the rotor core (3) are arranged in a circumferential direction along the ends of the permanent magnet slots (4).

6. According to claim 1, a built-in permanent magnet synchronous motor with permanent magnets embedded in the rotor surface, It is characterized in that The width of the magnetic bridge (7) increases or decreases along the permanent magnet slot (4) toward the center of the circle.

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