Permanent magnet and method for manufacturing a permanent magnet for a permanent magnet electric machine

Abstract

The embodiment of the present application relates to a kind of permanent magnet for permanent magnet motor and its manufacturing method, which includes the permanent magnet motor of pole number 2P;The permanent magnet is the hollow annular permanent magnet with predetermined thickness, the annular permanent magnet includes 2P trapezoidal magnetic poles, 2P trapezoidal magnetic poles include P N pole and P S pole, the P N pole and P S pole are evenly distributed on the annular permanent magnet and symmetrically distributed along the axial direction of the annular permanent magnet.The technical scheme of the embodiment of the present application provides the annular permanent magnet structure with trapezoidal magnetic pole distribution, based on the relationship between the cogging torque period in permanent magnet motor and the number of stator slot and pole number, by calculating the angle of inclined pole, and using corresponding magnetizing fixture for magnetizing, the trapezoidal magnetic pole distribution of axially symmetric distribution annular magnet can be realized, the cogging torque fundamental wave is eliminated, so that the purpose of weakening cogging torque while not producing axial electromagnetic force is realized.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more particularly to a permanent magnet for a permanent magnet motor and a method for manufacturing the same. Background Technology

[0002] Currently, permanent magnet motors are widely used in various industries due to their high efficiency and high power density. However, the interaction between the permanent magnet and the stator slots in permanent magnet motors generates cogging torque, which further leads to increased motor torque pulsation, vibration, and noise. For surface-mount motors using toroidal permanent magnets, measures to reduce cogging torque include: 1. Stator skew: While stator skew can effectively reduce cogging torque, it also generates additional axial force and makes mass production using automated winding equipment impossible; 2. Rotor skew: Rotor skew can effectively reduce cogging torque, but it generates additional axial electromagnetic force, affecting the lifespan of the motor bearings. Summary of the Invention

[0003] Based on the above-mentioned situation of the prior art, the purpose of this invention is to provide a permanent magnet for a permanent magnet motor and a method for manufacturing the same, which can effectively reduce cogging torque without generating additional axial electromagnetic force.

[0004] To achieve the above objectives, according to one aspect of the present invention, a permanent magnet for a permanent magnet motor is provided, the permanent magnet motor comprising a permanent magnet motor with a pole number of 2P;

[0005] The permanent magnet includes a hollow annular permanent magnet body with a predetermined thickness. The permanent magnet formed after magnetizing the annular permanent magnet body includes 2P trapezoidal magnetic poles. The 2P trapezoidal magnetic poles include P N poles and P S poles. The P P poles and P S poles are evenly distributed on the annular permanent magnet and are symmetrically distributed along the axial direction of the annular permanent magnet.

[0006] Where P is a natural number greater than or equal to 1.

[0007] Furthermore, each trapezoid in the 2P trapezoidal magnetic poles has the same skew angle θ. sk .

[0008] Furthermore, the permanent magnet is a one-piece molded structure. By employing a corresponding magnetizing fixture, this one-piece molded structure is magnetized to form 2P trapezoidal magnetic poles, each trapezoid having the same oblique pole angle θ. sk .

[0009] Furthermore, the slant polar angle θ sk The number of poles and slots is determined based on the number of permanent magnet motors used.

[0010] Furthermore, the slant polar angle θ is determined according to the following formula.sk :

[0011] θ sk =360° / LCM

[0012] Wherein, LCM is the least common multiple of the number of slots Z and the number of poles 2P of the permanent magnet motor.

[0013] According to a second aspect of the present invention, a permanent magnet motor is provided, characterized in that it includes a stator, coils, permanent magnets, and a rotor core; the permanent magnet motor includes an inner rotor permanent magnet motor, an outer rotor permanent magnet motor, or a brushed motor;

[0014] The permanent magnet includes the permanent magnet as described in the first aspect of the present invention.

[0015] Furthermore, the core of the inner rotor permanent magnet motor has a columnar structure and is coaxially arranged with the permanent magnet in the hollow part of the permanent magnet;

[0016] The stator includes slots, and the winding coils are placed in the stator slots. The stator and the core and permanent magnet of the inner rotor permanent magnet motor are coaxially arranged around the permanent magnet.

[0017] Furthermore, the housing of the external rotor permanent magnet motor is coaxially disposed around the permanent magnet with the permanent magnet.

[0018] The stator includes a columnar structure with slots, and the winding coils are arranged in the stator slots. The stator and the permanent magnet are coaxially arranged in the hollow part of the permanent magnet.

[0019] Furthermore, the permanent magnet of the brushed motor is coaxially disposed in the housing of the brushed motor, and the rotor of the brushed motor is a cylindrical structure including slots, with the winding coils placed in the slots of the rotor; the rotor of the brushed motor is coaxially disposed in the hollow part of the permanent magnet.

[0020] According to a third aspect of the present invention, a magnetizing jig for processing permanent magnets as described in the first aspect of the present invention is provided, comprising a magnetizing pole head and a yoke; wherein,

[0021] The magnetizing pole head is a columnar structure, and the yoke is a columnar structure with a central hole. The magnetizing pole head is coaxially disposed in the central hole of the yoke.

[0022] At least one of the magnetizing pole head and the yoke is provided with multiple grooves, all of which are inclined grooves and form a trapezoidal shape in pairs. The inclined groove angle of the groove is consistent with the inclined pole angle of the permanent magnet.

[0023] According to a fourth aspect of the present invention, a method for manufacturing a permanent magnet as described in the first aspect of the present invention is provided, comprising:

[0024] Obtain the number of slots Z and the number of poles 2P of the permanent magnet motor corresponding to this permanent magnet application;

[0025] Calculate the least common multiple (LCM) of the number of slots Z and the number of poles 2P;

[0026] The slant polar angle θ is calculated using the following formula based on the least common multiple (LCM). sk :

[0027] θ sk =360° / LCM

[0028] Based on the calculated polar angle θ sk The permanent magnet body is magnetized using a magnetizing fixture so that the magnetized permanent magnet has 2P trapezoidal magnetic poles, each trapezoid having a skew pole angle θ. sk ;

[0029] The magnetizing clamp includes the magnetizing clamp as described in claim 10.

[0030] Furthermore, the permanent magnet is installed into the permanent magnet motor after being magnetized; or, the permanent magnet is installed into the permanent magnet motor and then magnetized.

[0031] In summary, this invention provides a permanent magnet for a permanent magnet motor and a method for manufacturing the same. The permanent magnet motor includes a 2P pole type. The permanent magnet is a hollow annular permanent magnet with a predetermined thickness, comprising 2P trapezoidal magnetic poles, including P N poles and P S poles. The P N poles and P S poles are evenly distributed and symmetrically arranged along the axial direction of the annular permanent magnet. This invention provides an annular permanent magnet structure with trapezoidal pole distribution. Based on the relationship between the cogging torque period and the number of stator slots and poles in a permanent magnet motor, by calculating the skew angle and using appropriate magnetizing fixtures, an axially symmetrical trapezoidal pole distribution of the annular magnet can be achieved, eliminating the fundamental wave of the cogging torque. This achieves the goal of reducing cogging torque without generating axial electromagnetic force. This invention effectively reduces cogging torque (by more than 90%), while the output torque decreases only slightly, and no additional axial electromagnetic force is generated. Combining the flexible magnetization feature of toroidal permanent magnets, magnetization can be achieved simply by using appropriate magnetization fixtures, thus realizing the trapezoidal magnetic pole distribution of the toroidal magnets, making it suitable for mass production. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the permanent magnet provided in the embodiment of the present invention. Figure 1 ;

[0033] Figure 2 This is a schematic diagram of the structure of the permanent magnet provided in the embodiment of the present invention. Figure 2;

[0034] Figure 3 This is a schematic diagram of the structure of the magnetizing clamp provided in an embodiment of the present invention;

[0035] Figure 4 This is a two-dimensional topology diagram of a permanent magnet as an inner rotor in a 6-slot 4-pole permanent magnet motor, provided in an embodiment of the present invention.

[0036] Figure 5 This is a three-dimensional structural schematic diagram of the permanent magnet provided in this embodiment of the invention as an inner rotor applied to a 6-slot 4-pole permanent magnet motor;

[0037] Figure 6 This is a schematic diagram comparing the cogging torque of a permanent magnet motor when using a conventional permanent magnet structure and the permanent magnet provided in the embodiment of the present invention.

[0038] Figure 7 This is a schematic diagram showing the angular relationship between the cogging torque and the slant pole angle of the trapezoidal magnetic pole distribution provided in an embodiment of the present invention.

[0039] Explanation of reference numerals in the attached diagram: 1-Stator; 2-Coil; 3-Ring magnet; 4-Rotor core. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0041] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of the present invention should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in one or more embodiments of the present invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0042] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings. An embodiment of the present invention provides a permanent magnet for a permanent magnet motor. Figure 1 and Figure 2 All of these show schematic diagrams of the permanent magnet's structure. For example... Figure 1 and Figure 2 As shown, the permanent magnet includes a hollow annular permanent magnet body with a predetermined thickness, which can be 1-6 mm. The permanent magnet formed after magnetizing the annular permanent magnet body includes 2P trapezoidal magnetic poles (P is a natural number greater than or equal to 1). The number of magnetic poles is the same as the number of poles in the permanent magnet motor used with the permanent magnet. The annular permanent magnet body can be manufactured through processes such as sintering, bonding, hot pressing, and injection molding. The 2P trapezoidal magnetic poles include P N poles and P S poles. The P P poles and P S poles are evenly distributed and symmetrically arranged along the axial direction of the annular permanent magnet. Figure 1 Taking a permanent magnet with four trapezoidal magnetic poles as an example, a schematic diagram of its structure is shown, which includes two N poles and two S poles, with the N and S poles spaced apart and evenly distributed on the annular body of the permanent magnet. According to an optional embodiment of the invention, other numbers of magnetic poles may be included, the same as the number of magnetic poles in a permanent magnet motor. Each trapezoid in the 2P trapezoidal magnetic poles has the same skew angle θ. sk .like Figure 2 As shown, the angle formed by the projection of the lines connecting the upper and lower ends of each magnetic pole to the central axis of the magnetic ring onto the end face of the magnetic ring is the tilt angle θ. sk The angles occupied by the two ends of each trapezoidal magnetic pole are 180 / P-θ. sk With 180 / P+θ sk , where P is the number of permanent magnet pole pairs.

[0043] The permanent magnet is a one-piece molded structure. It can be magnetized using a suitable magnetizing fixture to form 2P trapezoidal magnetic poles, where each trapezoid has the same skew angle θ. sk The oblique polar angle θ sk It can be determined based on the number of poles and slots of the permanent magnet motor used.

[0044] According to some embodiments, the slant polar angle θ can be determined according to the following formula. sk :

[0045] θ sk =360° / LCM

[0046] Wherein, LCM is the least common multiple of the number of slots Z and the number of poles 2P of the permanent magnet motor.

[0047] An embodiment of the present invention also provides a permanent magnet motor, including a stator, coils, a permanent magnet, and a rotor core, wherein the permanent magnet is the same as the one provided in the above embodiments. The rotor core has a columnar structure and is coaxially disposed with the permanent magnet in the hollow portion of the permanent magnet; the stator contains slots, and the winding coils are disposed in the slots, with the stator coaxially disposed around the permanent magnet. The permanent magnet includes the permanent magnet described in the above embodiments of the present invention. The permanent magnet motor can be an inner rotor permanent magnet motor, an outer rotor permanent magnet motor, or a brushed motor. The annular permanent magnet can serve as an inner rotor, an outer rotor, and a stator in the permanent magnet motor.

[0048] When the permanent magnet motor is an internal rotor permanent magnet motor, the internal rotor core is a columnar structure and is coaxially arranged with the permanent magnet in the hollow part of the permanent magnet; the stator contains slots, the winding coils are placed in the stator slots, and the stator is coaxially arranged with the internal rotor core and the permanent magnet around the permanent magnet.

[0049] When the permanent magnet motor is an external rotor permanent magnet motor, the external rotor housing is coaxially arranged with the permanent magnet on the periphery of the permanent magnet; the stator is a columnar structure containing slots, the winding coils are arranged in the stator slots, and the stator is coaxially arranged with the permanent magnet in the hollow part of the permanent magnet.

[0050] When the permanent magnet motor is a brushed motor, the permanent magnet is coaxially mounted in the motor housing. The brushed motor rotor is a cylindrical structure containing slots, and the winding coils are housed in these slots. The brushed motor rotor is coaxially mounted in the hollow portion of the permanent magnet. An embodiment of the present invention also provides a magnetizing clamp. Figure 3 The diagram shows the structure of the magnetizing clamp, which has a slant pole angle θ. sk And it has the same number of poles as a toroidal permanent magnet. For example... Figure 3 As shown, the magnetizing fixture includes a magnetizing pole head 1, slots 2, a permanent magnet 3, and a yoke 4. The pole head and yoke are made of solid silicon steel or stacked silicon steel sheets. The magnetizing pole head has a columnar structure, and the yoke has a columnar structure with a central hole. The magnetizing pole head is coaxially positioned in the central hole of the yoke. At least one of the magnetizing pole head or yoke has multiple slots, all of which are inclined slots forming a trapezoidal shape in pairs. The inclined angle of the slots matches the inclined pole angle of the permanent magnet. The number of slots is related to the number of magnetized poles, and the number of magnetized poles is equal to the number of slots. The following detailed explanation uses a permanent magnet as an inner rotor in a 6-slot, 4-pole permanent magnet motor as an example. Figure 4 The diagram shows a two-dimensional topology of a 6-slot, 4-pole permanent magnet motor, where the permanent magnet provided in this embodiment of the invention is used as an inner rotor. Figure 5 The diagram shows a three-dimensional structural schematic of a permanent magnet, as an inner rotor, applied to a 6-slot 4-pole permanent magnet motor according to an embodiment of the present invention. Figure 4 and5 As shown, the permanent magnet motor includes a stator 5, a coil 6, a ring-shaped permanent magnet 7, and a rotor core 8. The rotor core 8 is located in the hollow portion of the ring-shaped permanent magnet 7 and is coaxially arranged. The stator 5 is also coaxially arranged with the ring-shaped permanent magnet 7 and the rotor core 8. The coil 6 is wound around the stator 5. This permanent magnet motor has 6 slots and 4 poles, i.e., the number of slots Z = 6 and the number of poles 2P = 4. The least common multiple of the number of slots and the number of poles is 12. Therefore, using the formula...

[0051] θ sk =360° / LCM

[0052] Determine the slant polar angle: θ sk =360° / 12 = 30°.

[0053] Magnetization can be performed using the corresponding magnetization clamps provided in the above embodiments of the present invention.

[0054] An embodiment of the present invention also provides a method for manufacturing a permanent magnet, comprising the following steps:

[0055] Obtain the number of slots Z and the number of poles 2P of the permanent magnet motor corresponding to this permanent magnet application;

[0056] Calculate the least common multiple (LCM) of the number of slots Z and the number of poles 2P;

[0057] The slant polar angle θ is calculated using the following formula based on the least common multiple (LCM). sk :

[0058] θ sk =360° / LCM

[0059] Based on the calculated polar angle θ sk The permanent magnet body is magnetized using a magnetizing fixture so that the magnetized permanent magnet has 2P trapezoidal magnetic poles, each trapezoid having a skew pole angle θ. sk ;

[0060] The magnetizing clamp includes the magnetizing clamp described in the above embodiments of the present invention.

[0061] According to certain alternative embodiments, the permanent magnet can be installed into the permanent magnet motor after being magnetized; or the permanent magnet can be installed into the permanent magnet motor, i.e., assembled into the rotor (as the rotor), stator housing (as the stator, etc.) and then magnetized.

[0062] Figure 6 The diagram shows a comparison of the cogging torque of a permanent magnet motor when using a conventional permanent magnet structure and when using a permanent magnet provided in an embodiment of the present invention. Figure 7 The diagram shows the angular relationship between the cogging torque and the slant pole angle of the trapezoidal magnetic pole distribution provided in an embodiment of the present invention. Figure 6The horizontal axis represents the motor's mechanical angles, and the vertical axis represents the cogging torque. Figure 7 The horizontal axis represents the skew angle, and the vertical axis represents the peak-to-peak value of the cogging torque. Figure 6 and Figure 7 As can be seen, as the slant angle gradually increases from 0° to 50°, the cogging torque first decreases and then increases, reaching its minimum value at a slant angle of 30°. For the 6-slot, 4-pole permanent magnet motor in the above embodiment, when the slant angle θ... sk When the angle is 30°, the cogging torque is reduced by 90%, achieving good results.

[0063] In summary, this invention relates to a permanent magnet for a permanent magnet motor and a method for manufacturing the same. The permanent magnet motor includes a 2P-pole permanent magnet. The permanent magnet is a hollow annular permanent magnet with a predetermined thickness, comprising 2P trapezoidal magnetic poles, including P N poles and P S poles. The P N poles and P S poles are evenly distributed and symmetrically arranged along the axial direction of the annular permanent magnet. This invention provides an annular permanent magnet structure with trapezoidal pole distribution. Based on the relationship between the cogging torque period and the number of stator slots and poles in a permanent magnet motor, by calculating the skew angle and using appropriate magnetizing fixtures, an axially symmetrical trapezoidal pole distribution of the annular magnet can be achieved, eliminating the fundamental wave of the cogging torque. This achieves the goal of reducing the cogging torque without generating axial electromagnetic force. This invention effectively reduces the cogging torque (by more than 90%), while the output torque decreases only slightly, and no additional axial electromagnetic force is generated. Combining the flexible magnetization feature of toroidal permanent magnets, magnetization can be achieved simply by using appropriate magnetization fixtures, thus realizing the trapezoidal magnetic pole distribution of the toroidal magnets, making it suitable for mass production.

[0064] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A permanent magnet for a permanent magnet motor, characterized in that, The permanent magnet motor includes a number of poles. Permanent magnet motor; The permanent magnet includes a hollow annular permanent magnet body with a predetermined thickness, and the permanent magnet formed after magnetizing the annular permanent magnet body includes... A trapezoidal magnetic pole, The trapezoidal magnetic poles include indivual Extremes and indivual Extreme, the indivual Extremes and indivual The poles are evenly distributed at intervals on the ring-shaped permanent magnet and are symmetrically distributed along the axial direction of the ring-shaped permanent magnet. The Each trapezoidal magnetic pole has the same skew angle. The slant polar angle The skew angle is determined based on the number of poles and slots of the permanent magnet motor used, using the following formula. : in, For natural numbers greater than or equal to 1, Number of slots in a permanent magnet motor With extreme numbers The least common multiple of .

2. The permanent magnet according to claim 1, characterized in that, The permanent magnet is a one-piece molded structure. It is magnetized using a suitable magnetizing fixture to form... A trapezoidal magnetic pole, wherein each trapezoid has the same skew angle. .

3. A permanent magnet motor, characterized in that, It includes a stator, coils, permanent magnets, and a rotor core; the permanent magnet motor includes an inner rotor permanent magnet motor, an outer rotor permanent magnet motor, or a brushed motor; The permanent magnet includes the permanent magnet as described in claim 1 or 2.

4. The permanent magnet motor according to claim 3, characterized in that, The core of the internal rotor permanent magnet motor is a columnar structure and is coaxially arranged with the permanent magnet in the hollow part of the permanent magnet. The stator includes slots, and the winding coils are placed in the stator slots. The stator and the core and permanent magnet of the inner rotor permanent magnet motor are coaxially arranged around the permanent magnet.

5. The permanent magnet motor according to claim 3, characterized in that, The housing of the external rotor permanent magnet motor is coaxially disposed around the permanent magnet. The stator includes a columnar structure with slots, and the winding coils are arranged in the stator slots. The stator and the permanent magnet are coaxially arranged in the hollow part of the permanent magnet.

6. The permanent magnet motor according to claim 3, characterized in that, The permanent magnet of the brushed motor is coaxially disposed in the housing of the brushed motor, and the rotor of the brushed motor is a cylindrical structure including wire slots, with the winding coils placed in the rotor wire slots; the rotor of the brushed motor is coaxially disposed in the hollow part of the permanent magnet.

7. A magnetizing fixture for processing permanent magnets as described in claim 1 or 2, characterized in that, Includes magnetized pole head and yoke; among which, The magnetizing pole head is a columnar structure, and the yoke is a columnar structure with a central hole. The magnetizing pole head is coaxially disposed in the central hole of the yoke. At least one of the magnetizing pole head and the yoke is provided with multiple grooves, all of which are inclined grooves and form a trapezoidal shape in pairs. The inclined groove angle of the groove is consistent with the inclined pole angle of the permanent magnet.

8. A method for manufacturing a permanent magnet as described in claim 1 or 2, characterized in that, include: Obtain the number of slots in the permanent magnet motor corresponding to this permanent magnet application. Sum of extreme numbers ; Calculate the number of slots Sum of extreme numbers Least Common Multiple ; According to the least common multiple Calculate the slant polar angle using the following formula. : Based on the calculated polar angle The permanent magnet body is magnetized using a magnetizing fixture so that the magnetized permanent magnet has 2P trapezoidal magnetic poles, each trapezoid having a skewed pole angle. ; The magnetizing clamp includes the magnetizing clamp as described in claim 7.

9. The method according to claim 8, characterized in that, After magnetizing the permanent magnet, it is installed into the permanent magnet motor; or... After the permanent magnet is installed into the permanent magnet motor, it is magnetized.

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