A high torque density anti-leakage magnetic lightweight rotor structure and a permanent magnet synchronous motor

Abstract

The present invention discloses a high torque density anti-leakage magnetic lightweight rotor structure and a permanent magnet synchronous motor, relating to the technical field of motors; the rotor structure includes a tangential rotor which is formed by laminating rotor punching sheets; a magnetic steel groove is formed between two adjacent tangential rotors; a permanent magnet is located in the corresponding magnetic steel groove; a magnetic isolation ring, on one side of which there are more than two assembly key grooves, and each assembly key groove is embedded with a corresponding tangential rotor; a process groove is opened on the magnetic isolation ring and is located between adjacent assembly key grooves, and a clamping platform is formed between the process groove and the assembly key groove; the permanent magnet is located above the process groove and is supported by the clamping platforms on both sides of the process groove, and a through hole is formed among the top surface of the clamping platform, the side surface of the permanent magnet and the side surface of the tangential rotor. The present invention can improve the utilization rate of magnetic steel, increase the output capacity of unit magnetic steel, ensure the reliable operation of the motor, optimize the weight of the rotor part, improve the torque density of the whole machine, and realize the lightweight solution of the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and particularly to a high torque density, anti-leakage magnetic and lightweight rotor structure and a permanent magnet synchronous motor. Background Art

[0002] Driven by the global energy shortage, the motor technology is accelerating towards high efficiency. With the significant improvement in the application efficiency of rare earth materials, the permanent magnet synchronous motor industry in China has entered a booming development period. The traditional solution of an asynchronous motor with a speed reducer has increasingly shown its limitations due to its low power factor and low efficiency under light load. The introduction of a permanent magnet direct drive system has completely revolutionized this situation, ensuring that the motor can maintain a high-efficiency operating state within the full load range. At the same time, the permanent magnet synchronous motor controlled by an inverter can flexibly meet various speed regulation requirements. The direct drive design eliminates intermediate links such as speed reducers, not only improving the overall reliability of the system but also greatly simplifying subsequent maintenance and servicing work. China is a major coal-producing country, and the belt conveyors underground are transitioning from the traditional asynchronous motor + speed reducer system to the permanent magnet direct drive system.

[0003] The underground space is extremely limited, and the volume and weight of the motor are directly related to its transportation convenience, assembly complexity, and space occupancy underground. As the volume and weight of the motor increase, the requirements for the transportation device become more stringent, requiring a larger transportation space and also increasing the potential risks during transportation. The working space at the working face is limited and further compressed by large motors, which not only restricts the operating freedom of workers but also hinders the layout and installation of other operating equipment. Currently, the permanent magnet synchronous motors applied to belt conveyors generally tend to adopt a near pole-slot matching design, combined with a surface-mounted or interior-mounted magnet layout, but this design often has a high leakage magnetic coefficient. Traditionally, the motor uses a structure in which the stator core is closely fitted with the machine base, and the rotor relies on the rotor core or is directly connected to the rotor bracket. Although the technology is mature, the problems of large motor volume and heavy weight are still prominent. Therefore, the research and development of high torque density and lightweight permanent magnet motors have become an important development trend in the field of mine belt conveyors. Summary of the Invention

[0004] The purpose of the present invention is to provide a high torque density, anti-leakage magnetic and lightweight rotor structure and a permanent magnet synchronous motor, which can improve the utilization rate of magnetic steel, increase the output capacity per unit of magnetic steel, ensure the reliable operation of the motor, optimize the weight of the rotor part, improve the torque density of the whole machine, and realize the lightweight solution of the motor.

[0005] To achieve the above object, the technical solution of the present application is: A high torque density, anti-leakage magnetic and lightweight rotor structure, comprising:

[0006] A tangential rotor, which is formed by laminating rotor punching sheets; a magnet slot is formed between two adjacent tangential rotors;

[0007] A permanent magnet, located in the corresponding magnet slot;

[0008] A magnetic isolation ring, on one side of which there are more than two assembly key grooves, and each assembly key groove is embedded with a corresponding tangential rotor;

[0009] A process groove is opened on the magnetic isolation ring and is located between adjacent assembly key grooves. A clamping platform is formed between the process groove and the assembly key groove; the permanent magnet is located above the process groove and is supported by the clamping platforms on both sides of the process groove. A through hole is formed between the top surface of the clamping platform, the side surface of the permanent magnet, and the side surface of the tangential rotor.

[0010] In one embodiment, glue is applied in the process groove to bond the permanent magnet and the magnetic isolation ring into a whole.

[0011] In one embodiment, a separation groove is provided on the rotor punching sheet, and a separation groove wedge is inserted between adjacent separation grooves. The separation groove wedge divides the magnet slot into two, and a permanent magnet is placed in each magnet slot.

[0012] In one embodiment, the magnetic isolation ring is made of aluminum alloy and is of a four-in-one type, that is, there are four assembly key grooves on the magnetic isolation ring, and each assembly key groove is embedded with a tangential rotor.

[0013] In one embodiment, an opening structure and a key groove are provided on the tangential rotor. One side of the opening structure contacts the magnetic isolation ring, and the other side communicates with the key groove. A flat key is placed in the key groove.

[0014] In one embodiment, a convex platform is provided on the other side of the magnetic isolation ring. The convex platform is located in a groove on the rotor bracket, and a bolt passes through the rotor bracket, the magnetic isolation ring and is connected to the corresponding flat key.

[0015] In one embodiment, a rotor groove wedge is provided on the top surface of each permanent magnet, and both sides of the rotor groove wedge are clamped under the magnetic bridge of the tangential rotor.

[0016] In one embodiment, the side surface of the tangential rotor at the through hole is a fillet arc surface or an obtuse arc surface.

[0017] In one embodiment, a reserved groove communicating with the key groove is provided on the tangential rotor. The height of the reserved groove is 2-3 threads of the bolt; the gap between the outer wall of the flat key and the inner wall of the key groove is 20-30 silk.

[0018] In one embodiment, the rotor punching sheet is of a single-pole type, and the outer diameter of the rotor punching sheet is eccentrically processed.

[0019] A permanent magnet synchronous motor includes the above-mentioned high torque density, anti-leakage magnetic and lightweight rotor structure.

[0020] Due to the adoption of the above technical solutions, the present invention can achieve the following technical effects: The present invention designs a rotor structure and a permanent magnet synchronous motor with high torque density, anti-leakage magnetic and lightweight. Through the rotor topology structure, the leakage magnetic phenomenon of the permanent magnet is significantly reduced, thereby enhancing the main magnetic flux and further improving the torque density of the whole machine. At the same time, on the premise of ensuring excellent performance, the rotor structure realizes the lightweight of each component, promoting the overall lightweight design of the motor. It provides a motor design scheme with higher torque density, lighter overall weight and more compact volume for the underground belt conveyor in mines. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is a partial schematic diagram of the high torque density, anti-leakage magnetic and lightweight rotor structure;

[0023] Figure 2 It is a schematic diagram of the four-in-one magnetic isolation ring structure;

[0024] Figure 3 It is a schematic diagram of the rotor punching sheet structure without a separation groove;

[0025] Figure 4 It is a schematic diagram of the rotor punching sheet structure with a separation groove;

[0026] Figure 5 It is a schematic diagram of the comparison of the rotor magnetic force lines;

[0027] Figure 6 It is a schematic diagram of the comparison of the back electromotive force between the traditional structure and the anti-leakage magnetic structure.

[0028] Explanation of the numbers in the figure: 1, permanent magnet; 2, tangential rotor; 21, magnetic bridge; 22, reserved groove; 23, keyway; 24, rounded arc surface or obtuse arc surface; 25, opening structure; 26, fixing hole; 27, separation groove; 3, magnetic isolation ring; 31, process groove; 32, assembly keyway; 33, clamping platform; 34, boss; 4, rotor bracket; 5, bolt; 6, flat key; 7, through hole; 8, rotor slot wedge. Detailed Embodiments

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clear and understandable, the following further details this application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0030] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0031] In the description of this application, the meaning of "a plurality" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0032] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0033] In the description of this application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] For a permanent magnet motor, due to different rotor structures, the rotor magnetic field distributions are different. The design of the rotor structure affects the performance indexes of the motor, and different rotor structures are also adapted to different load types. For example, Figure 1 As shown, this embodiment provides a high torque density, anti-leakage magnetic and lightweight rotor structure, including:

[0035] A tangential rotor, which is formed by laminating a plurality of rotor punching sheets. Threaded pins pass through the fixing holes on the rotor punching sheets and cooperate with hex nuts to fix the rotor punching sheets; a magnetic steel groove is formed between two adjacent tangential rotors, and its groove width can be appropriately adjusted according to the manufacturing dimensions and assembly deviations of the permanent magnets, but the groove width should not be too large to avoid the movement of the permanent magnets in the groove;

[0036] A permanent magnet, located in a corresponding magnet slot;

[0037] A magnetic isolation ring, on one side of which there are more than two assembly key slots, and corresponding tangential rotors are embedded in each assembly key slot; the circumferential angle occupied by each magnetic isolation ring is 360° / N, and N magnetic isolation rings are spliced into a complete circle;

[0038] A process slot is opened on the magnetic isolation ring in contact with the bottom of the permanent magnet and is located between adjacent assembly key slots. A clamping platform is formed between the process slot and the assembly key slot; the permanent magnet is located above the process slot and is supported by the clamping platforms on both sides of the process slot. A through hole is formed between the top surface of the clamping platform, the side surface of the permanent magnet, and the side surface of the tangential rotor;

[0039] Glue is applied in the process slot to facilitate bonding the magnet steel and the magnetic isolation ring to form an integral body, improving the strength of the entire rotor and preventing the magnet steel from being thrown outwards under the action of centrifugal force and radial force during the rotation of the motor. For the detailed structure, see Figure 2 。

[0040] As a preferred implementation provided in this embodiment, as Figure 3 shown, the rotor punching sheet adopts a single-pole type, and the outer diameter is eccentrically processed to improve the sinusoidality of the magnetomotive force; according to the direction and distribution of the magnetic force lines inside the rotor (as Figure 5 shown), the opening structure in the part where the magnetic force lines are sparse is used as the basis for connecting with the magnetic isolation ring. A flat key is inserted into the key slot, and the gap between the flat key and the punching sheet is made as small as possible, that is, the gap between the outer wall of the flat key and the inner wall of the key slot is 20 - 30 silk, to avoid deformation caused by the perpendicularity of the key and the tensile force, resulting in deviation of the outer diameter of the rotor. A reserved slot is provided above the key slot, and the height of the reserved slot is 2 - 3 threads of the bolt, ensuring sufficient screwing depth of the bolt.

[0041] As a preferred implementation provided in this embodiment, as Figure 4 shown, for high-power motors, there will be a situation where the eddy current loss of the magnet steel is large, resulting in a high rotor temperature. At this time, it is considered to segment the permanent magnet. In order to reduce the eddy current loss on the surface of the permanent magnet, slots can be opened on the rotor punching sheet, and a split slot wedge is inserted to divide the space in the slot into two parts. The permanent magnet does not need to be segmented and can be directly made into two small pieces and placed into the slot.

[0042] As a preferred embodiment provided in this embodiment, the magnetic isolation ring is made of aluminum alloy material, which has high strength and low magnetic permeability and is suitable for being used as a magnetic isolation material. The magnetic isolation ring is preferably of a four-in-one type, that is, a group of four poles. This structure can reduce the number of mating key grooves with the rotor bracket. The fewer the number of key grooves, the higher its reliability, and it can reduce the assembly complexity and improve the assembly efficiency. It is also possible to consider making the magnetic isolation ring into a three-in-one, two-in-one or single-pole type. Although the assembly process is redundant, the overall accuracy is better guaranteed and can be selected according to actual working needs.

[0043] As a preferred embodiment provided in this embodiment, a rotor slot wedge is added on the permanent magnet to make the permanent magnet in surface contact with the slot wedge surface to avoid scratching the magnetic steel due to uneven stacking of the rotor laminations; both sides of the rotor slot wedge are clamped under the magnetic bridge of the tangential rotor.

[0044] As a preferred embodiment provided in this embodiment, the side surface of the tangential rotor at the through hole is a rounded arc surface or an obtuse arc surface. During the operation of the motor, the rotor laminations need to bear a large tangential force. The large rounded arc surface or obtuse arc surface can improve the structural strength at this position and avoid the laminations from deforming under force during the normal operation of the motor.

[0045] Embodiment 2

[0046] This embodiment provides a permanent magnet synchronous motor, including the high torque density anti-leakage magnetic lightweight rotor structure described in Embodiment 1.

[0047] The rotor structure of the permanent magnet synchronous motor currently applied to the mine belt conveyor usually consists of a rotor core, a permanent magnet, a rotor bracket and a shaft. The structure proposed in the present invention has a large change at the rotor, adding a magnetic isolation ring. The original thickness of the rotor bracket is split into a magnetic isolation ring plus a rotor bracket. The material density of aluminum is less than that of steel. Therefore, the weight reduction on the rotor bracket is particularly obvious, and the larger the motor frame number, the larger the rotor bracket, and the more obvious the weight reduction at the rotor bracket.

[0048] Common rotor structures of permanent magnet synchronous motors include surface-mounted type and interior-mounted type. The interior-mounted type is further divided into tangential type, radial type and hybrid type according to different magnetization directions. Different rotor structures have their different characteristics. The rotor structures of the surface-mounted type and the interior tangential type have a relatively low salient pole ratio. The surface-mounted type is approximately 1, and the tangential type is between 1.1 and 1.5. The radial type and the hybrid type have a larger salient pole ratio, and the motor has a wider torque range and overload capacity, and the proportion of reluctance torque is larger. The load characteristics of the mine belt conveyor determine that its overload requirement is not large. The scheme with too large a salient pole ratio is not applicable in terms of torque density and control difficulty. And the motor has a large number of pole pairs. For the tangential structure, the two magnetic poles are connected in parallel to provide magnetomotive force, and the advantage of high magnetic flux per pole is more obvious. Therefore, the torque density of the motor with a tangential rotor will be higher than that of the surface-mounted motor. The present invention adopts a tangential rotor structure and optimizes its topological structure to achieve high torque density.

[0049] For traditional tangential magnetic poles, the permanent magnet is embedded in the rotor core, and then the rotor core is connected to the rotor bracket. Through finite element calculation, it is known that the magnetic leakage coefficient of this structure motor is relatively large. In order to reduce the magnetic leakage coefficient, the present invention is provided with a process groove and a through hole. Below the permanent magnet is non-magnetic material (magnetic isolation ring made of aluminum alloy and air). In this embodiment, its influence on the magnetic leakage coefficient is explored. The magnetic vector potential method, magnetic density integration method, etc. are often used to calculate the magnetic leakage coefficient of the motor. The magnetic density integration method is shown in formulas (1), (2) and (3), Φ m , Φ δ are the total magnetic flux generated by the permanent magnet and the main magnetic flux passing through the stator respectively, B m , B δ are the corresponding magnetic flux densities, S m , S δ are the corresponding magnetic flux areas. The magnetic flux is decomposed into the product of magnetic density and area. l m , l δ are the total magnetic flux integration path and the main magnetic flux integration path respectively. Therefore, the magnetic flux is converted into the integral form of magnetic density with respect to its path. After calculation, its magnetic leakage coefficient is reduced from 1.136 to 1.06, a reduction of about 9%. On the premise that the stator topology remains unchanged, the comparison of the no-load back electromotive force generated by the magnetic steel under the same volume is shown in Figure 6 . The back electromotive force of the anti-magnetic leakage rotor structure proposed by the present invention is increased by about 8%. The above results all prove that the magnetic leakage coefficient of the anti-magnetic leakage structure is smaller, which means that the magnetic steel per unit volume can output a larger torque, effectively improving the torque density of the motor.

[0050]

[0051] The overall weight of the rotor structure of the present invention is lighter. There is no longer silicon steel sheet material below the rotor punching and the permanent magnet, and an opening structure is made at the place where the magnetic circuit is not affected inside, so the weight of the punching is lighter. At the same time, a magnetic isolation ring made of aluminum alloy is used between the rotor punching and the rotor bracket, which has a smaller density and lighter weight compared with the steel plate. Through the four-in-one magnetic isolation ring, the weight of each material per unit volume is calculated, and the results are shown in Table 1. The weight of the rotor structure of this invention is about 16.5% lighter than the traditional structure, achieving the goal of lightweight design of the motor.

[0052] Table 1 Comparison of rotor structure weights under the four-pole unit model

[0053] Weight / kg Traditional structure Magnetic leakage resistant structure Rotor punching sheet 9.96 6.44 Rotor bracket 5.23 4.51 Magnetic isolation ring / 1.73 Total 15.19 12.68

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A high torque density, anti-leakage magnetic, lightweight rotor structure, characterized in that, Comprising: A tangential rotor, which is formed by laminating rotor punching sheets; a magnet slot is formed between two adjacent tangential rotors; A permanent magnet, located in the corresponding magnet slot; A magnetic isolation ring, on one side of which there are more than two assembly key grooves, and each assembly key groove is embedded with a corresponding tangential rotor; A process groove, which is opened on the magnetic isolation ring and is located between adjacent assembly key grooves. A clamping platform is formed between the process groove and the assembly key groove; the permanent magnet is located above the process groove and is supported by the clamping platforms on both sides of the process groove. A through hole is formed between the top surface of the clamping platform, the side surface of the permanent magnet, and the side surface of the tangential rotor; A separation groove is provided on the rotor punching sheet, and a separation groove wedge is inserted between adjacent separation grooves. The separation groove wedge divides the magnet slot into two, and a permanent magnet is placed in each magnet slot; An opening structure and a key groove are provided on the tangential rotor. One side of the opening structure is in contact with the magnetic isolation ring, and the other side is communicated with the key groove. A flat key is placed in the key groove; a convex platform is provided on the other side of the magnetic isolation ring, and the convex platform is located in a groove on the rotor bracket. A bolt passes through the rotor bracket, the magnetic isolation ring and is connected to the corresponding flat key; The side surface of the tangential rotor at the through hole is a rounded arc surface.

2. The high-torque-density anti-leakage magnetic lightweight rotor structure according to claim 1, wherein Glue is applied in the process groove to bond the permanent magnet and the magnetic isolation ring into a whole.

3. The high-torque-density anti-leakage magnetic lightweight rotor structure according to claim 1, characterized in that, The magnetic isolation ring is made of aluminum alloy material and is of a four-in-one type, that is, there are four assembly key grooves on the magnetic isolation ring, and each assembly key groove is embedded with a tangential rotor.

4. The high torque density anti-leakage magnetic lightweight rotor structure according to claim 1, characterized in that, A rotor slot wedge is provided on the top surface of each permanent magnet, and both sides of the rotor slot wedge are clamped under the magnetic bridge of the tangential rotor.

5. A high torque density anti-leakage magnetic lightweight rotor structure according to claim 1, characterized in that, A reserved groove communicated with the key groove is provided on the tangential rotor, and the height of the reserved groove is 2-3 threads of the bolt; the gap between the outer wall of the flat key and the inner wall of the key groove is 20-30 silk.

6. A permanent magnet synchronous motor, characterized in that, Comprising the high torque density anti-leakage magnetic lightweight rotor structure according to any one of claims 1-5.

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