A split stator permanent magnet based harmonic distortion suppression permanent magnet motor

Abstract

This invention discloses a harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation, comprising a stator, a split stator permanent magnet excitation structure, a rotor made of stacked silicon steel sheets, armature windings, and a non-magnetic shaft. The stator and rotor respectively employ split permanent magnet and salient pole structures. When the rotor rotates, two radially outward-magnetized permanent magnets and two radially inward-magnetized permanent magnets on the stator teeth always face the rotor salient poles, forming the main magnetic circuit path within the motor. The air gap between these four permanent magnets and the rotor salient poles forms four reluctances. These four reluctances, together with the permanent magnets and the stator and rotor cores, form a differential magnetic circuit structure, which can reduce the disturbance of high-order harmonics in the air gap magnetic field on the harmonic distribution, effectively suppress harmonic distortion in the air gap magnetic field, improve torque output capability, and reduce torque ripple. This invention has the advantages of high output torque, low torque ripple, and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of motor design, and more particularly to a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet. Background Technology

[0002] With the development of the motor industry, permanent magnet motors have been widely used in industrial and transportation fields due to their advantages such as high efficiency, high power density, and high reliability. Permanent magnet motors are generally classified into rotor permanent magnet motors and stator permanent magnet motors according to the position of the permanent magnet, with rotor permanent magnet motors being the earlier and more mature type. In recent decades, with the continuous development of permanent magnet materials and power electronics technology, stator permanent magnet motors have exhibited high reliability and high torque density, thus attracting widespread attention and research from researchers.

[0003] Stator permanent magnet motors utilize permanent magnet excitation, eliminating copper losses in the excitation armature winding, resulting in higher efficiency and suitability for high-speed operation and high-temperature conditions. They also eliminate frictional noise and electrical sparks associated with electrically excited armature windings, leading to higher reliability. Their rotors are lightweight with low rotational inertia, resulting in faster acceleration and deceleration responses. The stator armature windings are mostly concentrated, facilitating manufacturing and providing better electromagnetic isolation and fault tolerance. Furthermore, they have smaller armature winding coefficients, lower inductance, and shorter electrical time constants.

[0004] However, traditional stator permanent magnet motors have high harmonic content in the air gap magnetic field, resulting in large torque ripple. This torque ripple causes noise and vibration, leading to positioning errors. Therefore, suppressing harmonic distortion of the air gap magnetic field and reducing torque ripple has become a research hotspot in the field of stator permanent magnet motors.

[0005] In recent years, scholars both domestically and internationally have conducted extensive research on suppressing air gap harmonic distortion in stator permanent magnet motors. Among these studies, Professor Lin Mingyao of Southeast University proposed that asymmetrical rotor teeth can effectively improve the air gap structure, but the asymmetrical tooth structure easily causes rotor eccentricity; Professor Jin Taishi of Hanyang University proposed the method of chamfering permanent magnets to suppress air gap harmonic distortion, however, chamfering permanent magnets leads to difficulties in permanent magnet forming; and scholar Li Taobo of Shandong University proposed the method of optimizing rotor tooth surfaces to reduce air gap harmonic content. All of these methods can effectively suppress harmonic distortion, but they all optimize stator permanent magnet motors from the perspective of changes in motor structural parameters, which can easily lead to complex motor structures, posing significant challenges in both manufacturing processes and large-scale production. Summary of the Invention

[0006] To address the above problems, this invention proposes a harmonic distortion suppression type permanent magnet motor based on a split stator permanent magnet.

[0007] To achieve the purpose of this invention, a harmonic distortion suppression type permanent magnet motor based on split stator permanent magnet is provided, comprising: a rotor and a stator, wherein the rotor and stator are coaxially sleeved;

[0008] The rotor includes: a non-magnetic shaft, a rotor yoke, and a plurality of rotor salient poles; the non-magnetic shaft and the rotor yoke are coaxially sleeved; the rotor yoke and the plurality of rotor salient poles are integrally formed; the plurality of rotor salient poles are evenly arranged circumferentially on the inner annular surface of the rotor yoke.

[0009] The stator includes: a plurality of stator teeth, a stator yoke, a plurality of split stator permanent magnets, a plurality of armature windings, and a plurality of stator slots; the plurality of stator teeth are uniformly arranged circumferentially on the inner ring surface of the stator yoke, and the plurality of stator teeth and the stator yoke are integrally formed; the plurality of split stator permanent magnets are arranged on the arc-shaped inner ring surface of the stator teeth; the stator slots are cavities formed between adjacent stator teeth; the armature windings are wound on the stator teeth and placed in the stator slots; an air gap is left between the plurality of split stator permanent magnets and the plurality of rotor salient poles.

[0010] When the rotor rotates, there are always four split stator permanent magnets facing the rotor salient poles. The split stator permanent magnets and the rotor salient poles form four magnetic reluctances in the air gap. These four magnetic reluctances, together with the split stator permanent magnets, rotor yoke, rotor salient poles, stator teeth, and stator yoke, form a differential magnetic circuit structure, which reduces the disturbance of high-order spatial harmonics in the air gap magnetic field on the harmonic distribution.

[0011] When the rotor rotates, the split permanent magnets on the stator teeth always have two radially outward magnetized permanent magnets and two radially inward magnetized permanent magnets facing the rotor salient poles, forming the main magnetic circuit path inside the motor.

[0012] Furthermore, the plurality of split stator permanent magnets include: a plurality of split stator permanent magnets magnetized radially outward and a plurality of split stator permanent magnets magnetized radially inward, and the pole arc coefficients of the plurality of split stator permanent magnets are equal.

[0013] Furthermore, the number of the split stator permanent magnets disposed on the arc-shaped inner ring surface of each stator tooth is an integer multiple of four.

[0014] Furthermore, four split stator permanent magnets are disposed on the arc-shaped inner ring surface of each stator tooth.

[0015] Furthermore, the number Z of rotor salient poles r The number of pole pairs p of the split stator permanent magnet PM And the number of pole pairs P of the spatial armature magnetic field generated when a three-phase sinusoidal alternating current is injected into the armature winding. a The three satisfy the following formula: pa =p PM -Z r .

[0016] Furthermore, on the inner arc of each stator tooth, the polarities of adjacent split stator permanent magnets are opposite; one split stator permanent magnet is provided at each end of the inner arc of each stator tooth, and one split stator permanent magnet is provided at intervals on both sides of the central axis of each stator tooth; the distance between the two middle split stator permanent magnets on the inner arc of each stator tooth and the central axis of the stator tooth is equal; the interval between the two split stator permanent magnets on both sides of the central axis of the stator tooth is equal; and overall, the polarities of adjacent split stator permanent magnets are opposite.

[0017] Furthermore, it also includes: several DC excitation windings;

[0018] Each of the stator teeth has a split stator permanent magnet at each end of its arc-shaped inner ring, and a split stator permanent magnet is also provided at intervals on both sides of the central axis of each stator tooth; the two middle split stator permanent magnets on the arc-shaped inner ring of each stator tooth are equidistant from the central axis of the stator tooth; the intervals between the two split stator permanent magnets on both sides of the central axis of the stator tooth are equal.

[0019] On the inner arc of each stator tooth, the polarities of the two split stator permanent magnets near the central axis of the stator tooth are the same; the polarities of the two split stator permanent magnets located on the same side of the central axis of the stator tooth are opposite; between adjacent stator teeth, the polarities of the split stator permanent magnets at both ends are the same.

[0020] A DC excitation winding is provided between each pair of split stator permanent magnets located on the same side of the central axis of the stator teeth.

[0021] Furthermore, the number of splits of the stator teeth is 2, that is, each stator tooth has two split stator teeth, which are located on both sides of the central axis of the stator teeth respectively; two split stator permanent magnets with opposite polarities are provided on the arc-shaped inner ring of each split stator tooth; and overall, the polarities of adjacent split stator permanent magnets are opposite.

[0022] Furthermore, the number of splits of the stator teeth is 4, that is, each stator tooth has four split stator teeth; each split stator tooth has a split stator permanent magnet on its arc-shaped inner ring; and adjacent split stator permanent magnets have opposite polarities.

[0023] Furthermore, the number of stator teeth is 4, that is, each stator tooth has four split stator teeth; each split stator tooth has one split stator permanent magnet on its arc-shaped inner ring; the two middle split stator permanent magnets on each stator tooth have the same polarity and are opposite to the polarity of the split stator permanent magnets at both ends; between adjacent stator teeth, the polarity of the adjacent split stator permanent magnets at both ends is the same;

[0024] A pair of DC excitation windings are provided between the split stator permanent magnets with opposite polarities. The DC excitation winding closer to the non-magnetic shaft is the DC excitation winding of the permanent magnet's S pole, and the DC excitation winding farther from the non-magnetic shaft is the DC excitation winding of the permanent magnet's N pole.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] (1) In this invention, both the split stator permanent magnet and the armature winding are placed on the stator. When the rotor salient pole is running, it drives the surrounding fluid to move, which is beneficial to the heat dissipation of the permanent magnet and the armature winding. The probability of the permanent magnet undergoing irreversible demagnetization due to high temperature is reduced.

[0027] (2) The rotor structure of the present invention is the same as that of the traditional double salient pole motor. It is made of silicon steel sheets stacked together. There are no permanent magnets on the rotor. The structure is simple, suitable for high-speed operation, and has high reliability.

[0028] (3) The present invention uses a differential magnetic circuit structure to suppress spatial harmonic distortion in the air gap magnetic field, which can reduce the content of high-order useless harmonics, increase the fundamental amplitude, and effectively reduce cogging torque and torque pulsation.

[0029] (4) Compared with traditional stator permanent magnet motors, this invention does not introduce structural parameter adjustments that would increase the difficulty of manufacturing processes. Moreover, by setting a gap between every two split stator permanent magnets, the magnetic resistance between adjacent permanent magnets is increased without increasing the air gap length, effectively reducing magnetic leakage between permanent magnets and improving the utilization rate of permanent magnets. At the same time, another structure of this invention is a stator permanent magnet motor with a DC excitation winding on the stator. By passing a DC current in a fixed direction into the DC excitation winding on the stator, a stable electric excitation magnetic field is generated in the air gap. This field can interact with the permanent magnet magnetic field generated by the split stator permanent magnets on the stator, thereby enhancing or weakening the permanent magnet magnetic field, thus obtaining a larger torque output or a wider speed range. It is suitable for field weakening control and has a wider range of applications. It has good development prospects in electric vehicles, robotic arms and other applications that require low speed, high torque and high quality torque output. Attached Figure Description

[0030] Figure 1This is a schematic cross-sectional view along the axis of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, according to one embodiment.

[0031] Figure 2 This is a schematic diagram of the radial cross-section of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, according to one embodiment.

[0032] Figure 3 This is a three-dimensional exploded view of the stator of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, according to one embodiment.

[0033] Figure 4 This is a schematic cross-sectional view of a hybrid excitation structure of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, according to one embodiment.

[0034] Figure 5 This is a schematic cross-sectional view of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, where the stator teeth are split into two according to one embodiment.

[0035] Figure 6 This is a schematic cross-sectional view of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, with the stator teeth split into 4.

[0036] Figure 7 This is a cross-sectional schematic diagram of a hybrid excitation structure of a harmonic distortion suppression permanent magnet motor based on a split stator permanent magnet, where the stator teeth are split into 4.

[0037] Reference numerals in the attached figures: 1-rotor, 2-stator, 101-non-magnetic shaft, 102-rotor yoke, 103-rotor salient pole, 201-stator tooth, 202-stator yoke, 203-split stator permanent magnet, 204-armature winding, 205-DC excitation winding, 206-stator slot, 207-split stator tooth, 401-DC excitation winding of permanent magnet S pole, 402-DC excitation winding of permanent magnet N pole. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] To achieve high-quality torque output from a stator permanent magnet synchronous motor, this invention, based on the exploration of novel stator permanent magnet synchronous motors and motor air gap harmonic suppression technologies, discloses a harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation. Its armature winding is located on the stator and has a brushless structure, resulting in high operational stability. When three-phase sinusoidal alternating current is applied to the armature winding, a rotating armature magnetic field is generated in the air gap, which couples with the permanent magnet magnetic field modulated by the rotor salient poles, achieving electromechanical energy conversion. To suppress high-order unwanted harmonics, this invention uses each stator tooth and its corresponding rotor salient pole as a magnetic circuit unit. A total of four permanent magnets and their corresponding rotor salient poles form a differential magnetic circuit structure, reducing high-order harmonics and increasing the fundamental frequency amplitude. The differential magnetic circuit structure suppresses spatial harmonic distortion within the air gap magnetic field; the harmonic distortion suppression capability is jointly determined by the pole arc coefficients of the split stator permanent magnets and the rotor salient poles. The rotor is made of stacked silicon steel sheets. It has no permanent magnets or armature windings, making it simple and robust, and suitable for high-speed applications.

[0041] refer to Figure 1 , Figure 2 , Figure 3 As shown, a harmonic distortion suppression type permanent magnet motor based on split stator permanent magnet includes: a rotor 1 and a stator 2, wherein the rotor 1 and the stator 2 are coaxially sleeved.

[0042] The rotor 1 includes: a non-magnetic shaft 101, a rotor yoke 102, and a plurality of rotor salient poles 103; the non-magnetic shaft 101 and the rotor yoke 102 are coaxially sleeved; the rotor yoke 102 and the plurality of rotor salient poles 103 are integrally formed; the plurality of rotor salient poles 103 are evenly arranged circumferentially on the inner annular surface of the rotor yoke 102.

[0043] The stator 2 includes: a plurality of stator teeth 201, a stator yoke 202, a plurality of split stator permanent magnets 203, a plurality of armature windings 204, and a plurality of stator slots 206; the plurality of stator teeth 201 are uniformly arranged circumferentially on the annular inner ring surface of the stator yoke 202, and the plurality of stator teeth 201 and the stator yoke 202 are integrally formed; the plurality of split stator permanent magnets 203 are disposed on the arc-shaped inner ring surface of the stator teeth 201; the stator slots 206 are cavities formed between adjacent stator teeth 201; the armature windings 204 are wound on the stator teeth 201 and placed in the stator slots 206; a gap is left between the plurality of split stator permanent magnets 203 and the plurality of rotor salient poles 103.

[0044] In one embodiment, the plurality of split stator permanent magnets 203 include: a plurality of radially outwardly magnetized split stator permanent magnets 203 and a plurality of radially inwardly magnetized split stator permanent magnets 203, and the pole arc coefficients of the plurality of split stator permanent magnets 203 are equal.

[0045] Among them, the armature winding 204 adopts a fractional slot concentrated winding connection method, which can generate a rotating armature magnetic field when a three-phase sinusoidal alternating current is applied.

[0046] like Figure 2 As shown, in one embodiment, radially magnetized, oppositely oriented split stator permanent magnets 203 are arranged at intervals to form a split stator permanent magnet array. When the rotor 1 rotates, four split stator permanent magnets 203 are always facing the rotor salient pole 103, forming the main magnetic circuit path within the motor. The split stator permanent magnets 203 and the rotor salient pole 103 form four magnetic reluctances in the air gap. These four magnetic reluctances, together with the split stator permanent magnets 203, rotor yoke 102, rotor salient pole 103, stator teeth 201, and stator yoke 202, form a differential magnetic circuit structure, reducing the disturbance of high-order spatial harmonics in the air gap magnetic field on the harmonic distribution. The armature winding 204 is embedded in the stator slot 206. An armature magnetic field is generated by applying a three-phase sinusoidal alternating current to the armature winding 204. This armature magnetic field is modulated by the rotor teeth 103. The air gap utilizes the coupling of different armature magnetic field tooth harmonics with the stator permanent magnet magnetic field to generate output torque.

[0047] In one embodiment, the number of split stator permanent magnets 203 disposed on the arc-shaped inner ring surface of each stator tooth 201 is an integer multiple of four.

[0048] The number m of the split stator permanent magnets 203 attached to the surface of each stator tooth 201 satisfies the following:

[0049] m = 4k (k ∈ Z) * )

[0050] In one embodiment, Figure 2As shown, each of the stator teeth 201 has four split stator permanent magnets 203 disposed on the arc-shaped inner ring surface.

[0051] The number of rotor salient poles 103 is Z r The number of pole pairs p of the split stator permanent magnet 203 PM And the number of pole pairs P of the spatial armature magnetic field generated when a three-phase sinusoidal alternating current is injected into the armature winding 204. a The three satisfy the following formula: p a =p PM -Z r .

[0052] This scheme uses a differential magnetic circuit structure to suppress spatial harmonic distortion in the air gap magnetic field. The harmonic distortion suppression capability is jointly determined by the pole arc coefficient of the split stator permanent magnet 203 and the rotor salient pole 103.

[0053] On the inner arc of each stator tooth 201, the polarities of adjacent split stator permanent magnets 203 are opposite; one split stator permanent magnet 203 is provided at each end of the inner arc of each stator tooth 201, and one split stator permanent magnet 203 is provided at intervals on both sides of the central axis of each stator tooth 201; the distance between the two middle split stator permanent magnets 203 on the inner arc of each stator tooth 201 and the central axis of the stator tooth 201 is equal; the interval between the two split stator permanent magnets 203 on both sides of the central axis of the stator tooth 201 is equal; and overall, the polarities of adjacent split stator permanent magnets 203 are opposite.

[0054] In one embodiment, such as Figure 4 As shown, a harmonic distortion suppression type permanent magnet motor based on split stator permanent magnet also includes: several DC excitation windings 205.

[0055] Each of the stator teeth 201 has a split stator permanent magnet 203 at each end of its arc-shaped inner ring, and a split stator permanent magnet 203 is arranged at intervals on both sides of the central axis of each stator tooth 201; the distance between the two middle split stator permanent magnets 203 on the arc-shaped inner ring of each stator tooth 201 and the central axis of the stator tooth 201 is equal; the interval between the two split stator permanent magnets 203 on both sides of the central axis of the stator tooth 201 is equal.

[0056] On the inner arc of each stator tooth 201, the two split stator permanent magnets 203 near the central axis of the stator tooth 201 have the same polarity; the two split stator permanent magnets 203 located on the same side of the central axis of the stator tooth 201 have opposite polarities; between adjacent stator teeth 201, the polarities of the split stator permanent magnets 203 adjacent at both ends are the same.

[0057] A DC excitation winding 205 is provided between each pair of split stator permanent magnets 203 located on the same side of the central axis of the stator teeth 201.

[0058] The above embodiment adopts a hybrid excitation structure. By placing a DC excitation coil in the interval of the split stator permanent magnets 203 as a DC excitation winding 205, and by passing a DC current in a fixed direction into the DC excitation winding 205, a stable electric excitation magnetic field is generated in the air gap. This magnetic field can interact with the permanent magnet magnetic field generated by the split stator permanent magnets 203 on the stator 2, thereby enhancing or weakening the permanent magnet magnetic field, thus obtaining a larger torque output or a wider speed range, which is suitable for field weakening control.

[0059] As a preferred embodiment, the two split stator permanent magnets 203 between the DC excitation windings 205 have the same polarity.

[0060] When the above-mentioned new motor structure is adopted, torque ripple can be reduced and motor output reliability can be improved with a very small reduction in total output torque.

[0061] In one embodiment, such as Figure 5 As shown, the stator tooth 201 has two splits, that is, each stator tooth 201 has two split stator teeth 207, which are located on both sides of the central axis of the stator tooth 201 respectively; each split stator tooth 207 has two split stator permanent magnets 203 with opposite polarities on its arc-shaped inner ring; and overall, the polarities of adjacent split stator permanent magnets 203 are opposite.

[0062] In one embodiment, such as Figure 6 As shown, the stator tooth 201 has 4 splits, that is, each stator tooth 201 has four split stator teeth 207; each split stator tooth 207 has a split stator permanent magnet 203 on its arc-shaped inner ring; the polarities of adjacent split stator permanent magnets 203 are opposite.

[0063] In one embodiment, such as Figure 7As shown, the stator tooth 201 has four splits, meaning each stator tooth 201 has four split stator teeth 207; each split stator tooth 207 has one split stator permanent magnet 203 on its inner arc-shaped ring; the two middle split stator permanent magnets 203 on each stator tooth 201 have the same polarity, and their polarities are opposite to those of the split stator permanent magnets 203 at both ends; between adjacent stator teeth 201, the polarities of the adjacent split stator permanent magnets 203 at both ends are the same.

[0064] A pair of DC excitation windings 205 are provided between the split stator permanent magnets 203 with opposite polarities. The DC excitation winding 401 closer to the non-magnetic shaft 101 is the S pole of the permanent magnet, and the DC excitation winding 402 farther away from the non-magnetic shaft 101 is the N pole of the permanent magnet.

[0065] The above embodiment adopts a hybrid excitation structure, in which DC excitation windings 205 can be placed in the gaps of the stator teeth 207 with opposite polarities. At this time, the permanent magnets between the DC excitation windings 205 have the same polarity. By passing a DC current in a fixed direction into the stator DC excitation winding, a stable electric excitation magnetic field is generated in the air gap. This magnetic field can interact with the permanent magnet magnetic field generated by the split stator permanent magnets 203 on the stator 2, thereby enhancing or weakening the permanent magnet magnetic field, thus obtaining a larger torque output or a wider speed range, which is suitable for field weakening control.

[0066] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] It should be noted that the terms "first," "second," and "third" used in the embodiments of this application are merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first," "second," and "third" can be interchanged in a specific order or sequence where permitted. It should be understood that the objects distinguished by "first," "second," and "third" can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in an order other than those illustrated or described herein.

[0068] The terms "comprising" and "having," and any variations thereof, in this application are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps or modules is not limited to the steps or modules listed, but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to such processes, methods, products, or devices.

[0069] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation, characterized in that, include: The rotor (1) and stator (2) are coaxially fitted together. The rotor (1) includes: a non-magnetic shaft (101), a rotor yoke (102), and a plurality of rotor salient poles (103); the non-magnetic shaft (101) and the rotor yoke (102) are coaxially sleeved; the rotor yoke (102) and the plurality of rotor salient poles (103) are integrally formed; the plurality of rotor salient poles (103) are uniformly arranged circumferentially on the inner annular surface of the rotor yoke (102); The stator (2) includes: a plurality of stator teeth (201), a stator yoke (202), a plurality of split stator permanent magnets (203), a plurality of armature windings (204), and a plurality of stator slots (206); the plurality of stator teeth (201) are uniformly arranged circumferentially on the annular inner ring surface of the stator yoke (202), and the plurality of stator teeth (201) and the stator yoke (202) are integrally formed; the plurality of split stator permanent magnets (203) are arranged on the arc-shaped inner ring surface of the stator teeth (201); the stator slots (206) are cavities formed between adjacent stator teeth (201); the armature windings (204) are wound on the stator teeth (201) and placed in the stator slots (206); an air gap is left between the plurality of split stator permanent magnets (203) and the plurality of rotor salient poles (103); The positional relationship between the plurality of rotor salient poles (103) and the plurality of split stator permanent magnets (203) satisfies the following: when the rotor (1) rotates, there are always four of the split stator permanent magnets (203) facing the four rotor salient poles (103) respectively; at this time, the four split stator permanent magnets (203) and the four rotor salient poles (103) facing them respectively form four magnetic reluctances in the air gap. The four magnetic reluctances, together with the plurality of split stator permanent magnets (203), the rotor yoke (102), the plurality of rotor salient poles (103), the plurality of stator teeth (201) and the stator yoke (202), form a differential magnetic circuit structure to reduce the disturbance of the high-order spatial harmonics in the air gap magnetic field to the harmonic distribution.

2. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 1, characterized in that, The plurality of split stator permanent magnets (203) include: a plurality of radially outwardly magnetized split stator permanent magnets (203) and a plurality of radially inwardly magnetized split stator permanent magnets (203), and the polar arc coefficients of the plurality of split stator permanent magnets (203) are equal.

3. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 2, characterized in that, The number of the split stator permanent magnets (203) disposed on the arc-shaped inner ring surface of each stator tooth (201) is an integer multiple of four.

4. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 3, characterized in that, Four split stator permanent magnets (203) are provided on the arc-shaped inner ring surface of each stator tooth (201).

5. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 4, characterized in that, The number of rotor salient poles (103) Z r The number of pole pairs p of the split stator permanent magnet (203) PM And the number of pole pairs P of the spatial armature magnetic field generated when a three-phase sinusoidal alternating current is injected into the armature winding (204). a The three satisfy the following formula: p a =p PM -Z r .

6. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 5, characterized in that, On the inner arc of each stator tooth (201), the polarities of adjacent split stator permanent magnets (203) are opposite; one split stator permanent magnet (203) is provided at each end of the inner arc of each stator tooth (201), and one split stator permanent magnet (203) is provided at intervals on both sides of the central axis of each stator tooth (201); the distance between the two middle split stator permanent magnets (203) on the inner arc of each stator tooth (201) and the central axis of the stator tooth (201) is equal; the interval between the two split stator permanent magnets (203) on both sides of the central axis of the stator tooth (201) is equal; and overall, the polarities of adjacent split stator permanent magnets (203) are opposite.

7. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 5, characterized in that, It also includes: several DC excitation windings (205); Each of the stator teeth (201) has a split stator permanent magnet (203) at each end of its arc-shaped inner ring, and a split stator permanent magnet (203) is provided on each side of the central axis of each stator tooth (201) at intervals; the two middle split stator permanent magnets (203) on the arc-shaped inner ring of each stator tooth (201) are equidistant from the central axis of the stator tooth (201); the intervals between the two split stator permanent magnets (203) on each side of the central axis of the stator tooth (201) are equal; On the inner arc of each stator tooth (201), the two split stator permanent magnets (203) near the central axis of the stator tooth (201) have the same polarity; the two split stator permanent magnets (203) located on the same side of the central axis of the stator tooth (201) have opposite polarities; between adjacent stator teeth (201), the polarities of the split stator permanent magnets (203) adjacent at both ends are the same. The split stator permanent magnets (203) are located on the same side of the central axis of each pair of stator teeth (201). A DC excitation winding (205) is provided between them.

8. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 5, characterized in that, The stator tooth (201) has two splits, meaning that each stator tooth (201) has two split stator teeth (207), which are located on both sides of the central axis of the stator tooth (201). Each split stator tooth (207) has two split stator permanent magnets (203) with opposite polarities on its arc-shaped inner ring. Overall, adjacent split stator permanent magnets (203) have opposite polarities.

9. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 5, characterized in that, The stator tooth (201) has 4 splits, that is, each stator tooth (201) has four split stator teeth (207); each split stator tooth (207) has one split stator permanent magnet (203) on its arc-shaped inner ring; the polarities of adjacent split stator permanent magnets (203) are opposite.

10. A harmonic distortion suppression permanent magnet motor based on split stator permanent magnet excitation according to claim 5, characterized in that, The stator teeth (201) are split into four segments, meaning each stator tooth (201) has four split stator teeth (207); each split stator tooth (207) has one split stator permanent magnet (203) on its inner arc-shaped ring; the two middle split stator permanent magnets (203) on each stator tooth (201) have the same polarity and are opposite to the polarity of the split stator permanent magnets (203) at both ends; between adjacent stator teeth (201), the polarity of the adjacent split stator permanent magnets (203) at both ends is the same. A pair of DC excitation windings (205) are provided between the two split stator permanent magnets (203) with opposite polarities. The DC excitation winding (401) closer to the non-magnetic shaft (101) is the DC excitation winding (402) of the permanent magnet's S pole, and the DC excitation winding (402) farther away from the non-magnetic shaft (101) is the DC excitation winding (402) of the permanent magnet's N pole.

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