Rotor of permanent magnet motor and design method thereof

Abstract

The invention discloses a rotor of a permanent magnet motor and a design method thereof, M independent rotor cores (2) are installed on a fixing ring (1), and permanent magnets (3) are arranged between adjacent rotor cores (2). A rotor iron core magnetic isolation bridge structure is completely omitted, air gaps between the permanent magnets and the rotor iron core in the magnetic flux direction are reduced, magnetic resistance is reduced, and the unit power consumption is reduced. And meanwhile, the rotor iron core punching sheet is modularized, unitized and spliced, so that compared with a whole-circle punching sheet, the rotor iron core and permanent magnet fixing structure is small in size, flexible in mold opening, low in cost and capable of being assembled and adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a rotor of a permanent magnet motor and a design method thereof. Background Art

[0002] In the context of low-carbon and environmental protection, permanent magnet motors have achieved rapid development due to their high efficiency and energy-saving technical characteristics. At the same time, due to their high prices, they are difficult to promote on a large scale in the industrial field.

[0003] Permanent magnet motors are expensive, one of the main reasons being the high price of permanent magnet materials. During the motor design process, reducing the amount of permanent magnet material used is an important consideration.

[0004] To reduce the amount of permanent magnet material, one of the structural solutions is to reduce permanent magnet leakage and improve the utilization rate of permanent magnet material. Figure 1 As shown in the figure, the traditional structural design idea currently used is to control the leakage of permanent magnets by minimizing the width and length of the rotor punching magnetic bridge while ensuring the mechanical strength of the rotor. The leakage coefficient is an important parameter that reflects the utilization rate of permanent magnets. Its value is the ratio of the total magnetic flux provided by the permanent magnet to the main magnetic flux (effective magnetic flux). In order to ensure a good structural performance, the maximum leakage coefficient is about 1.4.

[0005] At present, most permanent magnet motor rotors are full-circle structures. The structure of the permanent magnet motor rotor plates is complex, especially the magnetic isolation bridge part. Due to its small size, the material selection, processing, and life assurance of the punch plate mold are relatively high. At the same time, the manufacturing cost of the full-circle composite mold is high, and the investment cost is high for the unfinalized research and development stage.

[0006] At present, the permanent magnets and rotor core magnet (permanent magnet) slots of embedded permanent magnet motors are square structures. In order to facilitate assembly, a gap of 0.3-0.4 on both sides needs to be left. In order to reduce mechanical noise and friction damage, the permanent magnets need to be filled with glue and fixed during assembly.

[0007] From the perspective of electromagnetics, in order to avoid magnetic flux leakage between the poles, a magnetic isolation bridge that is as narrow and long as possible is used; from the perspective of structural strength and actual processing technology, the magnetic bridge cannot be too narrow. The design needs to balance these two parameters: better magnetic isolation effect requires less magnetic steel, weak structural strength, short fatigue life, and the motor rotor deforms and is damaged in the short term due to the difference in speed; increasing the width of the magnetic isolation bridge will increase the magnetic flux leakage of the permanent magnet, the unit power consumption will be large, and the cost of the motor will increase. Summary of the invention

[0008] In view of the technical problems in the prior art that the unit power consumption and cost of permanent magnets in a permanent magnet motor rotor are relatively high, the present invention provides a permanent magnet motor rotor and a design method thereof.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A rotor of a permanent magnet motor comprises a fixing ring 1, M independent rotor cores 2 are mounted on the fixing ring 1, and permanent magnets 3 are arranged between adjacent rotor cores 2.

[0011] Preferably, a positioning block 4 is also included for assembling the rotor core 2 .

[0012] Preferably, the positioning block 4 is fixed to the fixing ring 1 via a fixing device 5 .

[0013] Preferably, the fixing device 5 includes bolts or rivets.

[0014] Preferably, the rotor core 2 is a trapezoidal structure that is wider at the top and narrower at the bottom, that is, the length of the first upper side 21 of the rotor core 2 is greater than the length of the first lower side 22, and the first side 23 and the second side 24 of the rotor core 2 are oblique sides.

[0015] Preferably, the permanent magnet 3 is a trapezoidal structure that is narrow at the top and wide at the bottom, that is, the length of the second upper side 31 of the permanent magnet 3 is smaller than the length of the second lower side 32, and the third side 33 and the fourth side 34 of the permanent magnet 3 are oblique sides.

[0016] Preferably, the third side 33 of the permanent magnet 3 is parallel to the second side 24 of the rotor core 2 , and the fourth side 34 of the permanent magnet 3 is parallel to the first side 23 of the rotor core 2 .

[0017] Preferably, the included angle between the first lower edge 22 and the first side edge 23 in the rotor core 2 is α, and the included angle between the second lower edge 32 and the fourth side edge 34 in the permanent magnet 3 is β, then α+β=180°.

[0018] The present invention also provides a permanent magnet motor rotor design method, which is used to design the permanent magnet motor rotor, and specifically comprises the following steps:

[0019] S1: Designing the matching structure of the permanent magnet 3 and the rotor core 2;

[0020] S2: The rotor core 2 is mounted on the outer surface of the fixing ring 1 through the corresponding positioning blocks 4 and fixing devices 5;

[0021] S3: insert the permanent magnet 3 into the gap formed by the two rotor cores 2, align and tighten them by means of the fixing device 5.

[0022] Preferably, in S1, the coordination design is:

[0023] The rotor core 2 is a trapezoidal structure that is wide at the top and narrow at the bottom, that is, the length of the first upper side 21 of the rotor core 2 is greater than the length of the first lower side 22; the permanent magnet 3 is a trapezoidal structure that is narrow at the top and wide at the bottom, that is, the length of the second upper side 31 of the permanent magnet 3 is less than the length of the second lower side 32;

[0024] Furthermore, the third side 33 of the permanent magnet 3 is parallel to the second side 24 of the rotor core 2 , and the fourth side 34 of the permanent magnet 3 is parallel to the first side 23 of the rotor core 2 .

[0025] In summary, due to the adoption of the above technical solution, compared with the prior art, the present invention has at least the following beneficial effects:

[0026] The present invention completely eliminates the rotor core magnetic isolation bridge structure, reduces the air gap between the permanent magnet and the rotor core in the magnetic flux direction, reduces the magnetic resistance, and reduces the unit power consumption. At the same time, the rotor core punching sheet is modular, unitized, and spliced. Compared with the full-circle punching sheet, the structure is smaller in size, flexible in mold opening, low in cost, and can be assembled and adjusted to fix the rotor core and permanent magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the rotor structure of an existing permanent magnet motor.

[0028] Figure 2 The figure is a schematic diagram of a simple structure of a rotor of a permanent magnet motor according to an exemplary embodiment of the present invention.

[0029] Figure 3 Schematic diagram of the structure of a rotor core and a permanent magnet according to an exemplary embodiment of the present invention.

[0030] Figure 4 Schematic diagram of magnetic lines of force of a permanent magnet according to an exemplary embodiment of the present invention.

[0031] Figure 5 Schematic diagram of a rotor design method for a permanent magnet motor according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0033] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 on the present invention.

[0034] like Figure 2 As shown, the present invention provides a rotor of a permanent magnet motor, comprising a magnetic isolation fixing ring 1, a rotor core 2, a permanent magnet 3, a dovetail positioning block 4 and a fixing device 5.

[0035] In this embodiment, the magnetic isolation fixing ring 1 is a circular structure and can be made of stainless steel. M dovetail-shaped positioning blocks 4 are evenly distributed along the circumference on the outer surface of the magnetic isolation fixing ring 1, and the dovetail-shaped positioning blocks 4 are fixed to the outer surface of the magnetic isolation fixing ring 1 through fixing devices 5.

[0036] In this embodiment, the fixing device 5 can be a bolt, a rivet or a pull rod.

[0037] In this embodiment, when the rotor core 2 needs to be installed on the magnetic isolation fixing ring 1, the dovetail positioning block 4 needs to be inserted into the dovetail groove of the rotor core 2 (reserved), so as to play a role in fixing the installation while ensuring the neatness of the rotor core 2.

[0038] The manufacturing process of the rotor core 2 is as follows: the rotor punching sheets are initially in the shape of thin sheets with a thickness of 0.5, which are stacked into a long strip of designed length, neatly riveted (using a stacking riveting process) to form the rotor core 2.

[0039] The basic principle of permanent magnet motor generating magnetic torque is that the magnetic flux generated by the permanent magnet must pass through the stator and rotor cores to generate magnetic torque. Figuratively speaking, the magnetic flux must link the stator and rotor like a closed rubber band to be effective magnetic flux, which is the magnetic flux defined in electrical engineering.

[0040] Therefore, the present invention adopts a modular rotor core 2 design, that is, each rotor core 2 is independent, the rotor core 2 has no interconnected magnetic isolation bridges, the magnetic poles are relatively independent, and there is no short-circuit magnetic flux (leakage magnetic flux) that the magnetic flux leaks from the magnetic isolation bridge in the traditional structure, so as to achieve the purpose of improving the utilization rate of the permanent magnet. In addition, the size of a single rotor core 2 is small, and there are almost no local weak points that affect the overall strength of the punching sheet and the mold. There can be a good balance in material selection and processing, and the mold opening is flexible and the cost is low.

[0041] In this embodiment, the structure of each rotor core 2 is the same, so the structure of any rotor core 2 is used for description.

[0042] like Figure 3 As shown, the length of the first upper side 21 of the rotor core 2 is greater than the length of the first lower side 22, and the first side 23 and the second side 24 of the rotor core 2 are oblique sides, that is, the rotor core 2 is a trapezoidal structure with a wide top and a narrow bottom. A gap with a narrow top and a wide bottom is formed between the two rotor cores 2.

[0043] In this embodiment, a permanent magnet 3 is arranged in the gap between two adjacent rotor cores 2, the length of the second upper side 31 of the permanent magnet 3 is smaller than the length of the second lower side 32, and the third side 33 and the fourth side 34 of the permanent magnet 3 are hypotenuses, that is, the permanent magnet 3 is a trapezoidal structure that is narrow at the top and wide at the bottom.

[0044] In this embodiment, since the rotor core 2 is trapezoidal, the gap formed by the two rotor cores 2 is also a trapezoidal structure. When the permanent magnet 3 is inserted into the gap, the two sides of the gap are tightened outward, so that the permanent magnet 3 and the rotor core 2 fit closely, reducing magnetic resistance and improving magnetic conductivity. The straight slot is not as good as the trapezoidal one in terms of adjustability.

[0045] like Figure 4 As shown, since the length of the second lower side 32 is greater than the length of the second upper side 31, the flux linkage (magnetic flux lines that close the magnetic flux lines linking the stator and rotor cores 2) path through the bottom of the permanent magnet 3 is long and the magnetic resistance is large, thereby improving the balance between magnetic potential and magnetic resistance.

[0046] In this embodiment, the size of the permanent magnet 3 and the size of the gap formed by the two rotor cores 2 are matched sizes, that is, after the permanent magnet 3 is placed in the gap, there is substantially no gap between the third side 33 of the permanent magnet 3 and the second side 24 of the rotor core 2, and there is substantially no gap between the fourth side 34 of the permanent magnet 3 and the first side 23 of the rotor core 2. The advantage of such a structural design is to ensure that the permanent magnet 3 and the rotor core 2 are in close contact with each other without air gaps, so as to achieve the purpose of reducing the magnetic resistance of the magnetic circuit and improving the magnetic conductivity.

[0047] Therefore, the third side 33 of the permanent magnet 3 is parallel to the second side 24 of the rotor core 2, and the fourth side 34 of the permanent magnet 3 is also parallel to the first side 23 of the rotor core 2. The angle between the first lower side 22 and the first side 23 of the rotor core 2 is α, and the angle between the second lower side 32 and the fourth side 34 of the permanent magnet 3 is β, then α+β=180°.

[0048] In order to ensure that the dimensions after assembly are strictly matched, the same precision error needs to be controlled. The mold processing of the rotor core 2 is generally a wire cutting slow wire walking method, which can well control the dimensional accuracy. The processing method of the permanent magnet 3 is also a wire cutting method, and the conventional method is a fast wire walking method, which has good control over the slope size requirements and can meet the design intent required by the present invention.

[0049] Based on the above-mentioned rotor of a permanent magnet motor, such as Figure 5 As shown, the present invention also provides a rotor of a permanent magnet motor, which specifically includes the following steps:

[0050] S1: Design the structure of the permanent magnet 3 and the rotor core 2 to match each other.

[0051] In this embodiment, a modular rotor core 2 design is adopted, that is, each rotor core 2 is independent, and the rotor core 2 has no interconnected magnetic isolation bridges, and the magnetic poles are relatively independent, and there is no short-circuit magnetic flux (leakage magnetic flux) that the magnetic flux leaks from the magnetic isolation bridge in the traditional structure, so as to achieve the purpose of improving the utilization rate of the permanent magnet. In addition, the size of a single rotor core 2 is small, and there are almost no local weak points that affect the overall strength of the punching sheet and the mold. There can be a good balance in terms of material selection and processing, and the mold opening is flexible and the cost is low.

[0052] In this embodiment, the manufacturing process of the rotor core 2 is as follows: the rotor punching sheets are initially in the shape of thin sheets with a thickness of 0.5, which are stacked into a long strip of designed length, neatly riveted (using a stacking riveting process) to form the rotor core 2.

[0053] In this embodiment, the length of the first upper side 21 of the rotor core 2 is greater than the length of the first lower side 22, and the first side 23 and the second side 24 of the rotor core 2 are oblique sides, that is, the rotor core 2 is a trapezoidal structure that is wide at the top and narrow at the bottom.

[0054] The length of the second upper side 31 of the permanent magnet 3 is smaller than that of the second lower side 32 , and the third side 33 and the fourth side 34 of the permanent magnet 3 are oblique sides, that is, the permanent magnet 3 is a trapezoidal structure that is narrow at the top and wide at the bottom.

[0055] The size of the permanent magnet 3 and the size of the gap formed by the two rotor cores 2 are matched sizes, that is, after the permanent magnet 3 is placed in the gap, there is basically no gap between the third side 33 of the permanent magnet 3 and the second side 24 of the rotor core 2, and there is basically no gap between the fourth side 34 of the permanent magnet 3 and the first side 23 of the rotor core 2. The advantage of such a structural design is to ensure that the permanent magnet 3 and the rotor core 2 are in close contact with each other without air gaps, so as to achieve the purpose of reducing the magnetic resistance of the magnetic circuit and improving the magnetic conductivity.

[0056] Therefore, the third side 33 of the permanent magnet 3 is parallel to the second side 24 of the rotor core 2, and the fourth side 34 of the permanent magnet 3 is also parallel to the first side 23 of the rotor core 2. The angle between the first lower side 22 and the first side 23 of the rotor core 2 is α, and the angle between the second lower side 32 and the fourth side 34 of the permanent magnet 3 is β, then α+β=180°.

[0057] In this embodiment, in order to ensure the dimensional accuracy of the rotor core 2 and to ensure a good mutual constraint relationship with the permanent magnet, it is still necessary to perform punching processing using a traditional mold opening method.

[0058] For example, the mold processing of the rotor core 2 is generally a slow-wire cutting method, which can well control the dimensional accuracy. The processing method of the permanent magnet 3 is also a slow-wire cutting method, and the conventional method is a fast-wire cutting method, which has good control over the slope size requirements and can meet the design intent required by the present invention.

[0059] S2: The designed and produced rotor core 2 is preliminarily installed on the outer surface of the magnetic isolation fixing ring 1 through the corresponding dovetail positioning blocks 4 and fixing devices 5.

[0060] S3: Insert the designed and produced permanent magnet 3 into the gap formed by the two rotor cores 2, align and tighten them by means of the fixing device 5, and ensure that the permanent magnet 3 and the two rotor cores 2 are in close contact with each other without air gaps, so as to achieve the purpose of reducing the magnetic resistance of the magnetic circuit and improving the magnetic conductivity.

[0061] In this embodiment, the fixing device 5 may be a bolt or the like, the purpose of which is to ensure that the permanent magnet 3 and the two rotor cores 2 are in close contact with each other without air gaps. This belongs to the existing fixing structure and is not the focus of the present invention.

[0062] In this embodiment, the permanent magnet and the rotor core are pre-tightened and fixed, and no glue filling is required, which reduces the glue filling process measures. During the motor assembly process or later maintenance, if the permanent magnet needs to be removed, the fixing device 5 can be loosened to conveniently remove the permanent magnet, which is conducive to rework and maintenance work such as motor disassembly and assembly.

[0063] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A rotor of a permanent magnet motor, comprising a fixing ring (1), characterized in that: M independent rotor cores (2) are mounted on the fixing ring (1), and permanent magnets (3) are arranged between adjacent rotor cores (2).

2. A rotor for a permanent magnet motor as claimed in claim 1, characterized in that: It also includes a positioning block (4) for assembling the rotor core (2).

3. A rotor for a permanent magnet motor as claimed in claim 2, characterized in that: The positioning block (4) is fixed to the fixing ring (1) via a fixing device (5).

4. A rotor for a permanent magnet motor as claimed in claim 3, characterized in that: The fixing device (5) comprises bolts and rivets.

5. The rotor of a permanent magnet motor according to claim 1, characterized in that: The rotor core (2) is a trapezoidal structure that is wider at the top and narrower at the bottom, that is, the length of the first upper side (21) of the rotor core (2) is greater than the length of the first lower side (22), and the first side (23) and the second side (24) of the rotor core (2) are oblique sides.

6. A rotor for a permanent magnet motor as claimed in claim 1, characterized in that: The permanent magnet (3) is a trapezoidal structure that is narrow at the top and wide at the bottom, that is, the length of the second upper side (31) of the permanent magnet (3) is smaller than the length of the second lower side (32), and the third side (33) and the fourth side (34) of the permanent magnet (3) are oblique sides.

7. A rotor for a permanent magnet motor as claimed in claim 6, characterized in that: The third side (33) of the permanent magnet (3) is parallel to the second side (24) of the rotor core (2), and the fourth side (34) of the permanent magnet (3) is parallel to the first side (23) of the rotor core (2).

8. A rotor for a permanent magnet motor as claimed in claim 6, characterized in that: The included angle between the first lower edge (22) and the first side edge (23) in the rotor core (2) is α, and the included angle between the second lower edge (32) and the fourth side edge (34) in the permanent magnet (3) is β, then α+β=180°.

9. A method for designing a rotor of a permanent magnet motor, characterized in that: The method for designing a rotor of a permanent magnet motor according to any one of claims 1 to 8 comprises the following steps: S1: Designing the matching structure of the permanent magnet 3 and the rotor core 2; S2: The rotor core (2) is mounted on the outer surface of the fixing ring (1) through corresponding positioning blocks (4) and fixing devices (5); S3: inserting the permanent magnet (3) into the gap formed by the two rotor cores (2), aligning and tightening them closely, and then pre-tightening them by means of a fixing device (5).

10. A method for designing a rotor of a permanent magnet motor as claimed in claim 9, characterized in that: In S1, the coordination design is: The rotor core (2) is a trapezoidal structure that is wide at the top and narrow at the bottom, i.e., the length of the first upper side (21) of the rotor core (2) is greater than the length of the first lower side (22); the permanent magnet (3) is a trapezoidal structure that is narrow at the top and wide at the bottom, i.e., the length of the second upper side (31) of the permanent magnet (3) is less than the length of the second lower side (32); Furthermore, the third side (33) of the permanent magnet (3) is parallel to the second side (24) of the rotor core (2), and the fourth side (34) of the permanent magnet (3) is parallel to the first side (23) of the rotor core (2).

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