A high torque quality alternating pole permanent magnet motor

Abstract

The present invention relates to an alternating-pole permanent magnet motor with high torque quality. By setting the outer peripheral surface of the air gap of the permanent magnet group and the rotor teeth corresponding to the air gap into a continuous wavy curved surface structure along the circumferential direction, the magnetic flux harmonic content of the air gap is increased. In the alternating-pole permanent magnet motor, radial magnetic flux harmonics and tangential magnetic flux harmonics of the same order interact with each other to generate an average torque, which further increases the average torque of the alternating-pole permanent magnet motor and expands the application range and efficiency of the alternating-pole permanent magnet motor.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet motors, and in particular to an alternating-pole permanent magnet motor with high torque quality. Background Art

[0002] Permanent magnet motors have the advantages of high torque density and high efficiency, and are widely used in aerospace, industrial production, robot joints, etc. The amount of permanent magnets is a key factor in determining the cost of motors, so how to efficiently use permanent magnets and produce excellent torque quality is of great practical significance.

[0003] Compared with traditional permanent magnet motors, alternating pole permanent magnet motors can significantly reduce the amount of permanent magnets used and can also obtain better electromagnetic performance, becoming a hot research topic. The patent application with publication number CN113036962 A proposes a low-cost and lightweight alternating pole permanent magnet motor. By splicing permanent magnets, the magnetic flux generated by the permanent magnets on both sides does not pass through the yoke of the rotor core, reducing the amount of the core and improving the power density. However, the rotor outer peripheral surface of the low-cost and lightweight alternating pole permanent magnet motor disclosed in the patent application with publication number CN113036962 A is a flat circumferential structure, which limits the length of the air gap between the rotor and the stator. In addition, the structure of the low-cost and lightweight alternating pole permanent magnet motor is to increase the average torque of the alternating pole permanent magnet motor by increasing the fundamental wave content of the excitation, and the increase in the average torque is also limited, which limits the application scope and efficiency of the alternating pole permanent magnet motor. Therefore, how to further increase the average torque of the alternating pole permanent magnet motor is a technical problem that the alternating pole permanent magnet motor needs to solve. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to improve the average torque of an alternating-pole permanent magnet motor. In order to overcome the defects of the above prior art, the present invention provides an alternating-pole permanent magnet motor with high torque quality.

[0005] The present invention provides an alternating-pole permanent magnet motor with high torque quality, comprising a stator and a rotor, wherein the rotor is coaxially rotatably arranged in the stator, an air gap exists between the rotor and the stator, the rotor comprises a rotating shaft, a rotor core and a plurality of permanent magnet groups, the rotor core is sleeved on the rotating shaft, the rotor core comprises a plurality of rotor teeth evenly arranged along the circumference of the rotor core and a rotor yoke formed between two adjacent rotor teeth, the permanent magnet groups are arranged on the rotor yoke, the permanent magnet groups and the rotor teeth are alternately arranged and distributed along the circumference of the rotor core, and the outer peripheral surfaces of the permanent magnet groups and the rotor teeth corresponding to the air gap present a continuous wavy curved surface along the circumference.

[0006] Compared with the prior art, the present invention has the following advantages: by setting the outer peripheral surface of the air gap corresponding to the permanent magnet group and the rotor teeth to a continuous wavy curved surface structure along the circumferential direction, the content of magnetic flux harmonics in the air gap is increased, and the radial magnetic flux harmonics and tangential magnetic flux harmonics of the same order interact with each other to produce an average torque. Therefore, the increase in the magnetic flux harmonic content in the air gap further increases the average torque of the alternating-pole permanent magnet motor, thereby expanding the application range and efficiency of the alternating-pole permanent magnet motor.

[0007] In a possible implementation, the permanent magnet group includes a central permanent magnet and lateral permanent magnets located on both sides of the central permanent magnet, the magnetization direction of the central permanent magnet is radial magnetization pointing radially outward, the magnetization direction of the lateral permanent magnets is tangential magnetization, and the magnetization directions of the two lateral permanent magnets point to the central permanent magnet respectively.

[0008] Compared with the existing technology, the permanent magnet group composed of a radially magnetized middle permanent magnet and two lateral permanent magnets with the magnetization direction pointing to the middle permanent magnet can improve the fundamental wave content, increase the magnetic field concentration effect of the permanent magnet group, and enable the alternating pole permanent magnet motor to produce a higher average torque.

[0009] In a possible implementation, the permanent magnet group includes a central permanent magnet and lateral permanent magnets located on both sides of the central permanent magnet, the magnetization direction of the central permanent magnet is radially outward parallel magnetization, the magnetization direction of the lateral permanent magnets is tangential magnetization, and the magnetization directions of the two lateral permanent magnets point to the central permanent magnet respectively.

[0010] Compared with the prior art, a permanent magnet group that uses a middle permanent magnet magnetized radially outward and two lateral permanent magnets with their magnetization directions pointing toward the middle permanent magnet can achieve the effect of optimizing the magnetic field distribution and has an air gap magnetic flux distribution that is closer to a sinusoidal state, thereby increasing the magnetic flux harmonics at the air gap and enabling the alternating-pole permanent magnet motor to produce a higher average torque.

[0011] In a possible implementation manner, the arc angle occupied by the middle permanent magnet is greater than the arc angle occupied by the lateral permanent magnets, and the arc angles occupied by the two lateral permanent magnets are equal.

[0012] Compared with the prior art, the above technical solution ensures the consistency of the magnetic flux density generated by the permanent magnets on both sides, so that the magnetic flux density of the lateral permanent magnet directly enters or flows out of the lateral permanent magnet through the side of the rotor tooth without passing through the rotor yoke, thereby increasing the harmonic content of the magnetic flux density at the air gap.

[0013] In a possible implementation manner, the outer peripheral surfaces of the permanent magnet group and the rotor teeth corresponding to the air gap are continuous sinusoidal wave surfaces along the circumferential direction.

[0014] Compared with the existing technology, the technical solution of using a continuous sinusoidal wave surface along the circumferential direction on the outer circumference of the permanent magnet group and the rotor tooth corresponding to the air gap can reduce the generation of unnecessary miscellaneous magnetic flux harmonics, reduce the torque fluctuation, and help to improve the average torque of the alternating pole permanent magnet motor.

[0015] In a possible implementation manner, the number of periods of the continuous sinusoidal wave surface on the outer circumference of the rotor composed of the permanent magnet group and the rotor teeth is 3 times the number of pole pairs.

[0016] Compared with the prior art, the technical solution of adopting a pole pair number that is three times the period number of the rotor on the outer circumference and a continuous sinusoidal wave surface along the circumferential direction of the rotor outer circumference can increase the content of the third magnetic flux harmonic generated in the air gap, and based on the property that the third magnetic flux harmonic will not produce torque fluctuations with other orders of magnetic waves, while improving the average torque of the alternating pole permanent magnet synchronous motor, the performance and life of the alternating pole permanent magnet synchronous motor are improved.

[0017] In a possible implementation manner, the shape of the outer peripheral surface of the permanent magnet group corresponding to the air gap is expressed as: ; The outer peripheral surface shape of the rotor tooth portion corresponding to the air gap is expressed as: ; In the formula, represents the initial radius of the permanent magnet group, The amplitude expressed as the shape increase of the permanent magnet group, represents the number of pole pairs, Indicates the angle of the arc from the starting point, ranging from .

[0018] Compared with the prior art, the above-mentioned technical solution obtains a sinusoidal wave surface with a period of three times the number of pole pairs on the outer circumference of the rotor composed of the permanent magnet group and the rotor teeth, which increases the content of the third magnetic flux harmonic in the generated air gap.

[0019] In a possible implementation manner, the ratio of the pole pitch angle occupied by the permanent magnet group is 0.35-0.75.

[0020] Compared with the prior art, the technical solution of limiting the ratio of the pole pitch angles occupied by the permanent magnet group can improve the magnetic field concentration effect of the permanent magnet group and maximize the utilization of the magnetic flux density generated by the permanent magnet.

[0021] In a possible implementation, the stator includes a stator core and a stator winding, the stator core includes a stator ring and a plurality of stator teeth circumferentially and evenly connected to the inner circumferential wall of the stator ring, and the stator winding is wound on the stator teeth.

[0022] The air gap is located between the ends of the stator teeth and the ends of the rotor teeth. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a specific embodiment of the present invention;

[0024] Figure 2 It is a plan view of the permanent magnet group and the rotor teeth of the present invention;

[0025] Figure 3 The finite element analysis data diagram of the present invention and the existing alternating-pole permanent magnet motor is shown.

[0026] Description of reference numerals:

[0027] 1. Stator; 11. Stator winding; 12. Stator core; 121. Stator teeth; 122. Stator ring; 2. Rotor; 21. Permanent magnet group; 211. Lateral permanent magnet; 212. Middle permanent magnet; 22. Rotor core; 221. Rotor teeth; 222. Rotor yoke; 3. Air gap. DETAILED DESCRIPTION

[0028] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present invention, and are not intended to limit the protection scope of the embodiments of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0029] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" 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 a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0030] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The magnetic field in the air gap 3 of the alternating pole permanent magnet motor includes a fundamental magnetic field and a series of harmonic magnetic fields. The interaction of these magnetic fields generates electromagnetic force, among which the tangential force generates a tangential torque. The radial magnetic flux and tangential magnetic flux of the same order harmonics generated during the operation of the alternating pole permanent magnet motor interact to generate an average torque, while radial magnetic flux harmonics and tangential magnetic flux harmonics of different orders will generate torque fluctuations. There is a close relationship between the magnetic flux harmonics in the air gap 3 of the alternating pole permanent magnet motor and the average torque. The presence of magnetic flux harmonics of different orders will cause torque fluctuations and vibration noise. The present invention reduces the torque fluctuations by increasing the content of the third magnetic flux harmonics.

[0033] See also Figure 1 As shown, the embodiment of the present invention discloses an alternating pole permanent magnet motor with high torque quality, comprising a stator 1 and a rotor 2, wherein the rotor 2 is coaxially rotatably arranged in the stator 1, and an air gap 3 exists between the rotor 2 and the stator 1. This specific embodiment takes a three-phase inner rotor alternating pole permanent magnet motor as an example, wherein:

[0034] The stator 1 includes a stator core 12 and a stator winding 11. The stator core 12 includes a stator ring 122 and a plurality of stator teeth 121 circumferentially and evenly connected to the inner wall of the stator ring 122. In this specific embodiment, the stator winding 11 is a three-phase armature winding, including phase A, phase B and phase C. In the mechanical space of 360° of the stator circumference, each phase of the stator winding is wound on the corresponding stator tooth according to a set connection rule.

[0035] The rotor 2 includes a rotating shaft (not shown in the figure), a rotor core 22 and a plurality of permanent magnet groups 21. In this specific embodiment, 7 permanent magnet groups 21 are provided. The rotor core 22 is sleeved on the rotating shaft. The rotor core 22 has a plurality of rotor teeth 221 evenly arranged along the circumference of the rotor core 22 and a rotor yoke 222 formed between two adjacent rotor teeth 221. The permanent magnet groups 21 are provided on the rotor yoke 222 to achieve that the permanent magnet groups 21 are arranged in sequence in the order of N poles and rotor teeth 221 in the circumferential direction. In the mechanical space of 360° along the circumference of the rotor, an alternating distribution of 7 permanent magnets and rotor teeth is formed. The permanent magnet groups 21 and the rotor teeth 221 are alternately arranged and distributed along the circumference of the rotor core 22, and the number of the permanent magnet groups 21 and the number of the rotor teeth 221 are equal. The magnetic field in the air gap of the alternating-pole permanent magnet motor includes a fundamental magnetic field and a series of harmonic magnetic fields. The interaction of these magnetic fields produces electromagnetic force, among which the tangential force will produce tangential torque. The radial magnetic flux of the harmonics of the same order generated during the operation of the alternating-pole permanent magnet motor interacts with the tangential magnetic flux to produce an average torque. The outer circumferential surface of the permanent magnet group 21 and the rotor tooth portion 221 corresponding to the air gap 3 in this embodiment presents a continuous wavy curved surface; for this reason, there is no height difference in the radial direction between the outer circumferential surface of the lateral permanent magnet 211 along the circumferential direction and the outer circumferential surface of the adjacent rotor tooth portion. Compared with the flat outer circumferential surface structure in the prior art, the continuous wavy curved surface helps to increase the content of magnetic flux harmonics in the air gap 3. At this time, the magnetic flux harmonic content in the air gap of the alternating-pole permanent magnet motor is greatly increased. After Fourier series decomposition, the fundamental magnetic flux and the third magnetic flux harmonic are significantly improved. In the permanent magnet motor, the radial magnetic flux harmonics and the tangential magnetic flux harmonics of the same order interact to produce an average torque. Therefore, the structure in which the outer circumferential surface of the permanent magnet group 21 and the rotor tooth portion 221 corresponding to the air gap 3 presents a continuous wavy curved surface along the circumferential direction can improve the average torque of the alternating-pole permanent magnet motor.

[0036] The radial flux density and tangential flux density of the same order harmonics generated during the operation of the alternating-pole permanent magnet motor interact to produce an average torque, but the radial flux density harmonics and tangential flux density harmonics of different orders will produce torque fluctuations, and the presence of different-order flux density harmonics will cause torque fluctuations and vibration noise. For example, the solution disclosed in the patent application of the prior art CN113036962 A, while increasing the fundamental content of the excitation to increase the average torque of the alternating-pole permanent magnet motor, will inevitably generate additional 5th and 7th harmonics. The radial flux density and tangential flux density of these different-order harmonics interact to produce torque fluctuations, thereby affecting the performance and life of the alternating-pole permanent magnet synchronous motor.

[0037] In order to further improve the average torque of the alternating-pole permanent magnet motor and prevent the generation of additional torque fluctuations that affect the stability and life of the alternating-pole permanent magnet motor, another contribution made by this specific embodiment is that the outer peripheral surface of the permanent magnet group 21 and the rotor tooth portion 221 corresponding to the air gap 3 is set to be a continuous sinusoidal wave surface along the circumferential direction, thereby reducing the generation of unnecessary miscellaneous harmonics and reducing the generation of torque fluctuations.

[0038] Existing literature shows that: unlike the 5th and 7th magnetic flux harmonics, the 3rd magnetic flux harmonic does not generate torque fluctuations with other order magnetic flux harmonics. Therefore, in order to increase the 3rd magnetic flux harmonic content of the air gap magnetic flux harmonic and suppress other order magnetic flux harmonics, in this specific embodiment, preferably, the number of periods of the continuous sinusoidal wave surface on the outer periphery of the rotor 2 composed of the permanent magnet group 21 and the rotor teeth 221 is set to 3 times the number of pole pairs, that is, the outer periphery of the rotor circumference / the outer periphery of the rotor 2 composed of the permanent magnet group 21 and the rotor teeth 221 = , It represents the pole pair number of the rotor and conforms to the shape of a sinusoidal function; therefore, the permanent magnet group based on this shape will increase the content of the third magnetic flux harmonic in the air gap, and based on the property that the third magnetic flux harmonic will not produce torque fluctuations with other order magnetic flux harmonics, while improving the average torque of the alternating pole permanent magnet synchronous motor, the performance and life of the alternating pole permanent magnet synchronous motor are improved.

[0039] Specifically, in order to obtain a sinusoidal wave surface with a period number of 3 times the number of pole pairs on the outer circumference of the rotor composed of the permanent magnet group and the rotor teeth, the shape of the outer circumference of the permanent magnet group 21 corresponding to the air gap 3 is expressed as: The shape of the outer peripheral surface of the rotor tooth portion 221 corresponding to the air gap 3 is expressed as: ; In the formula, represents the initial radius of the permanent magnet group 21, such as Figure 2 As shown, the initial radius of the permanent magnet group 211 is the side of the permanent magnet 211 that is in contact with the rotor teeth as the starting position. The amplitude expressed as the shape increase of the permanent magnet group 21, represents the pole pair number, Indicates the angle of the arc from the starting point, ranging from .

[0040] In this specific embodiment, the number of pole pairs of the rotor 2 is , thereby obtaining the surface shape of the rotor 2, increasing the content of the third magnetic flux harmonic in the generated air gap magnetic flux harmonic, thereby generating a higher average torque. In addition, the third magnetic flux harmonic does not generate torque fluctuations, thereby increasing the average torque without increasing the torque fluctuations.

[0041] In order to further improve the average torque of the alternating-pole permanent magnet motor, the permanent magnet group 21 in this specific embodiment includes a central permanent magnet 212 and lateral permanent magnets 211 located on both sides of the central permanent magnet 212. Figure 1 As shown, the permanent magnet group 21 is composed of lateral permanent magnets 211, middle permanent magnets 212, and lateral permanent magnets 212 spliced ​​along the circumferential direction. This specific embodiment preferably uses a surface-mounted permanent magnet group, which is beneficial to increase the content of magnetic flux harmonics in the air gap and improve the average torque of the alternating-pole permanent magnet motor.

[0042] Furthermore, in order to increase the content of magnetic flux harmonics at the air gap so that the alternating-pole permanent magnet motor generates higher torque, the magnetization direction of the middle permanent magnet 212 is radial magnetization directed radially outward or parallel magnetization directed radially outward, the magnetization direction of the lateral permanent magnets 211 is tangential magnetization, and the magnetization directions of the two lateral permanent magnets 211 point to the middle permanent magnet 212 respectively; Figure 2 As shown, in this specific embodiment, the magnetization direction of the intermediate permanent magnet 212 is radially outward parallel magnetization, which achieves the effect of optimizing the magnetic field distribution and has an air gap magnetic flux distribution that is closer to a sinusoidal distribution, thereby increasing the magnetic flux harmonics at the air gap and enabling the alternating pole permanent magnet motor to generate a higher average torque.

[0043] At the same time, combined with the technical solution that the arc angle occupied by the middle permanent magnet 212 is greater than the arc angle occupied by the lateral permanent magnet 211, and the arc angles occupied by the two lateral permanent magnets 211 are equal, the consistency of the magnetic flux density generated by the permanent magnets on both sides is ensured, so that the magnetic flux density of the lateral permanent magnet directly enters or flows out of the lateral permanent magnet through the side of the rotor tooth without passing through the rotor yoke, thereby increasing the harmonic content of the magnetic flux density at the air gap.

[0044] In addition, in order to improve the magnetic field concentration effect of the permanent magnet group 21 and maximize the use of the magnetic flux density generated by the permanent magnet, the ratio of the pole pitch angle occupied by the permanent magnet group 21 is 0.7, wherein the rotor pole pitch angle , represents the number of pole pairs, then the angle occupied by each permanent magnet group 21 is equal to the pole pitch angle of the rotor By limiting the ratio of the pole pitch angle occupied by the permanent magnet group, the technical solution can avoid the deviation between the magnetic pole axis of the permanent magnet group and the central axis of the rotor, so that the magnetic flux density in the air gap is evenly distributed.

[0045] The structure of the alternating-pole permanent magnet motor of the specific embodiment of the present invention can effectively increase the content of the third magnetic flux harmonic in the air gap 3, thereby improving the average torque generated. Moreover, based on the surface shape structure of the rotor 2 composed of the permanent magnet group 21 and the rotor tooth portion 221, the third magnetic flux harmonic generated by the permanent magnet group 21 will not generate torque fluctuations with other order magnetic flux harmonics, thereby achieving the maintenance of torque fluctuations and the improvement of average torque, and realizing high torque quality of the alternating-pole permanent magnet motor.

[0046] Comparative experiment

[0047] Analyzed objects:

[0048] The permanent magnet motor of the present invention has the following structure: the permanent magnet group 21 is arranged in the order of the N pole and the rotor tooth 221 in the circumferential direction, and the outer circumferential surfaces of the permanent magnet group 21 and the rotor tooth 221 are sinusoidal wave surfaces;

[0049] Comparison object: A low-cost and lightweight alternating-pole permanent magnet motor proposed in the patent application with publication number CN113036962 A; comprising a coaxially sleeved stator and an alternating-pole rotor, an air gap between the stator and the alternating-pole rotor, an armature winding wound on the stator, and an alternating-pole rotor comprising permanent magnet poles and iron core poles uniformly and alternately arranged along the circumferential direction, each permanent magnet pole comprising three permanent magnets spliced ​​along the circumferential direction, in conjunction with the specification of the patent application Figure 1 It can be seen that the outer circumference of the alternating-pole rotor is a flat circle.

[0050] The difference between the present invention and the comparative object is that the comparative object adopts a flat circular surface formed by the combination of a permanent magnet group and a rotor tooth, while the outer circumferential surface of the permanent magnet group 21 and the rotor tooth portion 221 adopted in the present invention is a sinusoidal wave surface, and the number of periods is 3 times the number of pole pairs. The structural difference between the present invention and the comparative object will make the third magnetic flux harmonic of the magnetic flux harmonic of the air gap 3 of the permanent magnet motor in this patent scheme higher than that of the comparative object, thereby generating an average torque without causing torque fluctuation, thereby increasing the average torque of the permanent magnet motor and reducing torque fluctuation.

[0051] The above simulation object is analyzed by finite element method, and the data graph about torque is obtained as follows: Figure 3 As shown, it can be obtained from Figure 3It can be seen that the torque fluctuation generated by the alternating pole rotor structure of the permanent magnet poles and the core poles uniformly and alternately arranged along the circumferential direction in the comparative object is large, and its torque fluctuation is between 1.625-1.675. The technical solution of the present invention adopting the outer circumferential surface of the permanent magnet group and the rotor teeth presenting a sinusoidal waving surface combined with a period number of 3 times the number of pole pairs, generates a torque fluctuation between 1.75-1.775. Compared with the comparative object, the outer circumferential surface of the permanent magnet group and the rotor teeth of the present invention presents a sinusoidal waving surface, which increases the content of the third magnetic flux harmonic in the air gap of the alternating pole permanent magnet motor, increases the torque of the alternating pole permanent magnet motor, and generates a small torque fluctuation, increases the average torque of the alternating pole permanent magnet motor, and reduces the torque fluctuation of the alternating pole permanent magnet motor. Therefore, the average torque of the alternating pole permanent magnet motor of the present invention is higher than the torque of the comparative object, and the torque fluctuation of the alternating pole permanent magnet motor of the present invention is smaller than the torque fluctuation of the comparative object.

[0052] In general, the present invention adopts a continuous wavy curved surface structure along the circumferential direction of the outer peripheral surface of the air gap 3 corresponding to the permanent magnet group 21 and the rotor tooth portion 221, which helps to increase the content of magnetic flux harmonics in the air gap 3. At this time, the magnetic flux harmonic content in the air gap of the alternating-pole permanent magnet motor is greatly increased. After Fourier series decomposition, the fundamental magnetic flux and the third magnetic flux harmonics are significantly improved, and in the permanent magnet motor, the radial magnetic flux harmonics and the tangential magnetic flux harmonics of the same order interact to produce an average torque; further, the radial magnetic flux and the tangential magnetic flux of the same order harmonics generated during the operation of the alternating-pole permanent magnet motor interact to produce an average torque, but the radial magnetic flux harmonics and the tangential magnetic flux harmonics of different orders will produce torque fluctuations. The existence of magnetic flux harmonics of different orders will cause torque fluctuations and vibration noise. For this reason, the present invention adopts a continuous wavy curved surface structure with sinusoidal fluctuations to reduce the generation of unnecessary miscellaneous-order harmonics and reduce the generation of torque fluctuations. At the same time, the magnetic flux harmonics in the air gap are decomposed by Fourier to produce Each order magnetic flux harmonic is a sinusoidal function of the corresponding frequency, thereby improving the quality of the generated magnetic flux harmonic. At the same time, combined with the number of periods of the rotor 2 composed of the permanent magnet group 21 and the rotor tooth portion 221 on the periphery being 3 times the number of pole pairs, the content of the 3rd magnetic flux harmonic in the air gap 3 can be effectively increased, thereby avoiding torque fluctuations with other order magnetic flux harmonics and improving the average torque of the alternating-pole permanent magnet motor. Furthermore, according to the property that the 3rd magnetic flux harmonic does not generate torque fluctuations with other order magnetic flux harmonics, in order to increase the 3rd magnetic flux harmonic content of the air gap magnetic flux harmonic, the present invention adopts a continuous sinusoidal wave surface to set the number of periods on the periphery of the rotor 2 composed of the permanent magnet group 21 and the rotor tooth portion 221 to 3 times the number of pole pairs, thereby increasing the content of the 3rd magnetic flux harmonic in the air gap, thereby achieving the improvement of the average torque of the alternating-pole permanent magnet synchronous motor without additionally increasing torque fluctuations, thereby improving the performance and life of the alternating-pole permanent magnet synchronous motor.

[0053] In the description of the embodiments of the present invention, it should be noted that in the description of the present invention, the terms "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0054] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A high torque quality alternating pole permanent magnet motor, characterized in that: The invention comprises a stator (1) and a rotor (2), wherein the rotor (2) is coaxially rotatably arranged in the stator (1), an air gap (3) is present between the rotor (2) and the stator (1), the rotor (2) comprises a rotating shaft, a rotor core (22) and a plurality of permanent magnet groups (21), the rotor core (22) is sleeved on the rotating shaft, the rotor core (22) comprises a plurality of rotor teeth (221) evenly arranged along the circumference of the rotor core (22) and a rotor yoke (222) formed between two adjacent rotor teeth (221), the permanent magnet groups (21) are arranged on the rotor yoke (222), the permanent magnet groups (21) and the rotor teeth (221) are alternately arranged and distributed along the circumference of the rotor core (22), and the outer peripheral surfaces of the permanent magnet groups (21) and the rotor teeth (221) corresponding to the air gap (3) present a continuous wavy curved surface along the circumference; The outer peripheral surfaces of the permanent magnet group (21) and the rotor tooth portion (221) corresponding to the air gap (3) are continuous sinusoidal wave curved surfaces along the circumferential direction; The number of periods of the rotor (2) composed of the permanent magnet group (21) and the rotor teeth (221) on the outer circumference is 3 times the number of pole pairs.

2. The alternating-pole permanent magnet motor with high torque quality according to claim 1, characterized in that: The permanent magnet group (21) comprises a central permanent magnet (212) and lateral permanent magnets (211) located on both sides of the central permanent magnet (212); the magnetization direction of the central permanent magnet (212) is radial magnetization directed radially outward; the magnetization direction of the lateral permanent magnets (211) is tangential magnetization; and the magnetization directions of the two lateral permanent magnets (211) are respectively directed toward the central permanent magnet (212).

3. The alternating-pole permanent magnet motor with high torque quality according to claim 1, characterized in that: The permanent magnet group (21) comprises a central permanent magnet (212) and lateral permanent magnets (211) located on both sides of the central permanent magnet (212); the magnetization direction of the central permanent magnet (212) is radially outward parallel magnetization; the magnetization direction of the lateral permanent magnets (211) is tangential magnetization; and the magnetization directions of the two lateral permanent magnets (211) are respectively directed toward the central permanent magnet (212).

4. The alternating-pole permanent magnet motor with high torque quality according to claim 2 or 3, characterized in that: The circular arc angle occupied by the middle permanent magnet (212) is greater than the circular arc angle occupied by the lateral permanent magnets (211), and the circular arc angles occupied by the two lateral permanent magnets (211) are equal.

5. The alternating-pole permanent magnet motor with high torque quality according to claim 1, characterized in that: The shape of the outer peripheral surface of the permanent magnet group (21) corresponding to the air gap (3) is expressed as: The shape of the outer peripheral surface of the rotor tooth portion (221) corresponding to the air gap (3) is expressed as: ; In the formula, represents the initial radius of the permanent magnet group (21), The amplitude is expressed as the shape increase of the permanent magnet group (21), represents the pole pair number, Indicates the angle of the arc from the starting point, ranging from .

6. The alternating-pole permanent magnet motor with high torque quality according to claim 1, characterized in that: The ratio of the pole pitch angle occupied by the permanent magnet group (21) is 0.35-0.

75.

7. The alternating-pole permanent magnet motor with high torque quality according to claim 1, characterized in that: The stator (1) comprises a stator core (12) and a stator winding (11); the stator core (12) comprises a stator ring (122) and a plurality of stator teeth (121) uniformly connected to the inner wall of the stator ring (122) in the circumferential direction; and the stator winding (11) is wound on the stator teeth (121).

8. The alternating-pole permanent magnet motor with high torque quality according to claim 7, characterized in that: The air gap (3) is located between the end of the stator tooth (121) and the end of the rotor tooth (221).

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