Built-in permanent magnet synchronous motor with asymmetric structure

Abstract

The invention discloses a built-in permanent magnet synchronous motor with an asymmetric structure, which comprises a rotor, the rotor comprises a rotor iron core and a plurality of double-layer permanent magnets embedded in the rotor iron core, and the double-layer permanent magnets comprise a first permanent magnet and a second permanent magnet positioned on the outer side; a plurality of magnetic barriers and magnetic isolation bridges are arranged on the rotor core; a magnetic barrier is arranged between two adjacent first permanent magnets close to the outer side of the rotor, and the thickness of each magnetic barrier is gradually increased along two sides by taking the first permanent magnet group without the magnetic barrier as a starting point; a first magnetic isolation bridge and a second magnetic isolation bridge are arranged between each first permanent magnet and the outer side of the rotor and between each second permanent magnet and the outer side of the rotor respectively, one pair of first magnetic isolation bridges serves as a first magnetic isolation bridge set, and the heights of the two first magnetic isolation bridges in the first magnetic isolation bridge set are the same. And the heights of the first magnetic isolation bridge groups are gradually reduced along the two sides by taking one first magnetic isolation bridge group adjacent to the first permanent magnet group as a starting point. In this way, the harmonic content of the inductance waveform is optimized to suppress the total harmonic distortion rate, and high torque density and low torque ripple are achieved.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet motors, and more specifically to an interior permanent magnet synchronous motor with an asymmetric structure. Background Art

[0002] Permanent magnet synchronous motors have the advantages of large torque, high power density, and high efficiency, and are widely used in automatic control systems. However, the rotor structures of existing permanent magnet synchronous motors still have the following defects in terms of self-sensing performance, torque characteristics, and magnetic circuit optimization.

[0003] 1. Large torque ripple. Conventional permanent magnet synchronous motors have relatively low torque ripple and total harmonic distortion rate due to their symmetric structure, generally around 5%-10%. However, in order to achieve self-sensing of permanent magnet synchronous motors, the rotors of permanent magnet synchronous motors usually adopt an asymmetric structure, which results in significant torque ripple (≥15%) and high total harmonic distortion rate (THD) (>20%), and cannot meet the requirements of high-precision drive scenarios for torque smoothness, such as the requirement for torque fluctuation <10% in robot joint drives.

[0004] 2. Distortion of air-gap magnetic density waveform. The typical single-layer permanent magnet structure is in the shape of a straight line or a V shape, which makes the air-gap magnetic density a trapezoidal wave with a high content of low-order harmonics, increasing torque ripple and noise during low-speed operation, and increasing stator iron loss and reducing efficiency during high-speed field weakening.

[0005] 3. Local magnetic saturation. In the single-layer permanent magnet structure, the magnetic load is concentrated, and the uniform height of the magnetic isolation bridge leads to unreasonable direct-axis magnetic resistance distribution. When running at high speed, the magnetic density of the rotor yoke exceeds 1.8T, and the iron loss increases significantly.

[0006] 4. Magnetic leakage and efficiency loss. In the single-layer permanent magnet structure, the unilateral magnetic barrier layout is prone to increasing magnetic leakage. The distortion of the air-gap magnetic density leads to an increase in the harmonic content of the back electromotive force, an increase in the inverter switching loss, and a 2-3% reduction in system efficiency.

[0007] Compared with the single-layer permanent magnet structure, the traditional multi-layer permanent magnet structure can reduce air-gap harmonics and improve the utilization rate of reluctance torque. However, there are problems of increased magnetic leakage, that is, the increase in the number of permanent magnet layers leads to an increase in magnetic leakage paths, resulting in a decrease in torque density, and magnetic isolation bridge saturation, that is, the multi-layer permanent magnet structure requires multiple magnetic isolation bridges, and their saturation will exacerbate the distortion of the air-gap magnetic density, instead increasing the torque ripple.

[0008] In view of this, the present application conducts in-depth research on this basis, and thus this case is generated. Summary of the Invention

[0009] The object of the present invention is to provide an interior permanent magnet synchronous motor with an asymmetric structure, which can improve the quality of self-sensing signals while optimizing electromagnetic performance, achieve high torque density, low torque ripple and low harmonic distortion, reduce the magnetic saturation of the rotor core, reduce leakage magnetic loss, and keep the motor body operating at high speed with high efficiency.

[0010] To achieve the above object, the solution of the present invention is: an interior permanent magnet synchronous motor with an asymmetric structure, including a motor body, the motor body includes a rotor, the rotor includes a rotor core and a plurality of first permanent magnets and second permanent magnets embedded in the rotor core, each of the first permanent magnets corresponds to each of the second permanent magnets respectively, and each of the first permanent magnets is located inside the corresponding second permanent magnet, and each of the first permanent magnets and each of the second permanent magnets are sequentially arranged at intervals along the circumferential direction of the rotor core, and a plurality of magnetic barriers and magnetic isolation bridges are provided on the rotor core; A magnetic barrier is provided between every two adjacent first permanent magnets, and no magnetic barrier is provided between a pair of adjacent first permanent magnets, and each of the magnetic barriers is arranged at intervals along the circumferential direction of the rotor core; in the cross section of the rotor core, taking the two first permanent magnets without the magnetic barrier as a first permanent magnet group, the widths of each of the magnetic barriers are the same, and starting from the first permanent magnet group, the thicknesses of each of the magnetic barriers gradually increase along both sides in a manner of increasing by the same thickness difference; each of the magnetic isolation bridges is divided into a first magnetic isolation bridge and a second magnetic isolation bridge, a first magnetic isolation bridge is respectively provided between each of the first permanent magnets and the outside of the rotor, and a second magnetic isolation bridge is respectively provided between each of the second permanent magnets and the outside of the rotor, taking the two first magnetic isolation bridges adjacent to two mutually separated first permanent magnets as a first magnetic isolation bridge group, the heights of the two first magnetic isolation bridges in each first magnetic isolation bridge group are the same; starting from the first magnetic isolation bridge group corresponding to one of the first permanent magnets in the first permanent magnet group, the heights of each of the first magnetic isolation bridge groups gradually decrease along both sides in a manner of decreasing by the same height difference; and the heights of each of the second magnetic isolation bridges are the same.

[0011] In the cross section of the rotor, taking the extension line between the center of the first permanent magnet group and the axis of the rotor core as symmetry line one, each of the magnetic barriers is symmetrically arranged along symmetry line one; and, taking the extension line between the center between two first permanent magnets corresponding to one of the first magnetic isolation bridge groups adjacent to the first permanent magnet group and the axis of the rotor as symmetry line two, each of the first magnetic isolation bridges is symmetrically distributed along symmetry line two.

[0012] Each of the magnetic barriers is a rectangular magnetic barrier.

[0013] The thickness difference between every two adjacent magnetic barriers is 0.75 mm.

[0014] The width of each of the magnetic barriers is 1 mm, and the depth of each of the magnetic barriers is 57.5 mm.

[0015] Two adjacent first permanent magnets are arranged in a V-shaped layout, and two adjacent second permanent magnets are arranged in a V-shaped layout.

[0016] The height difference between every two adjacent first magnetic bridges is 0.15 mm.

[0017] The height of each of the second magnetic bridges is 0.5 mm.

[0018] Each of the first magnetic bridges is respectively disposed between one side surface of the first permanent magnet adjacent to the outer side of the rotor and the outer side of the rotor, and each of the second magnetic bridges is respectively disposed between one side surface of the second permanent magnet adjacent to the outer side of the rotor and the outer side of the rotor.

[0019] The first permanent magnets that are far from each other near the outer side of the rotor form a pair of permanent magnets. On the same end face of the rotor, the polarities of the magnetic poles of two adjacent pairs of permanent magnets are different from each other, and the polarities of the magnetic poles of each of the second permanent magnets are the same as the polarities of the corresponding first permanent magnets.

[0020] After adopting the above structure, the present invention has the following beneficial effects: By embedding magnetic barriers with gradually changing thickness between every two adjacent first permanent magnets, an asymmetric magnetic barrier distribution is formed, that is, an asymmetric magnetic circuit is formed, thereby changing the magnetic resistance distribution of the quadrature magnetic circuit, realizing the two-way regulation of the direct-axis and quadrature-axis inductances of the magnetic circuit, avoiding the limitation of single-direction inductance modulation, and at the same time increasing the amplitude of inductance fluctuation; moreover, with the double-layer design of the permanent magnets, each of the second magnetic bridges is used to stabilize the basic magnetic circuit, combined with the setting of the gradually changing height in each of the first magnetic bridges with the same height difference, to construct a hierarchical magnetic resistance system of an outer-layer stable magnetic circuit + an inner-layer fine regulation through the differential design of the inter-layer magnetic resistance, improving the regulation of the magnetic circuit, while optimizing the air-gap magnetic density distribution and suppressing harmonics, controlling the torque ripple within a lower range; compared with the prior art, the present invention changes the inductance fluctuation by changing the magnetic circuit so as to realize the self-sensing of the mechanical position of the rotor in the motor body, facilitating the acquisition of the position information of the rotor. At the same time, due to the change of the magnetic circuit and inductance in the motor body, the torque ripple is large and the torque decreases. Therefore, the present invention combines the design of the magnetic barrier to enhance the salient pole effect and suppress stray harmonics, and then combines the design of the magnetic bridge to adjust the magnetic permeability of the main magnetic circuit, optimizing the harmonic content of the inductance waveform, thereby suppressing the total harmonic distortion rate and compensating for the problems of large torque ripple and torque decrease, enabling the present invention to achieve high torque density and low torque ripple, and reducing the magnetic saturation of the rotor core and the magnetic leakage loss, so that the motor body still maintains high efficiency during high-speed operation. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the built-in permanent magnet synchronous motor of the present invention.

[0022] Figure 2 It is a size marking diagram of each magnetic barrier in the present invention.

[0023] Figure 3 It is a size marking diagram of each first magnetic isolation bridge and second magnetic isolation bridge in the present invention.

[0024] Figure 4 It is an ABC three-phase winding inductance waveform diagram of the motor body in the present invention.

[0025] Figure 5 It is an A-phase winding inductance waveform diagram of the motor body in the present invention.

[0026] Figure 6 It is an A-phase winding inductance waveform diagram of the motor body in the present invention when only magnetic barriers are provided.

[0027] Figure 7 It is an A-phase winding inductance waveform diagram of the motor body in the present invention when only the magnetic isolation bridge is changed.

[0028] Figure 8 It is an electromagnetic torque simulation diagram of the motor body in the present invention.

[0029] Figure 9 It is a back electromotive force waveform diagram of the motor body in the present invention.

[0030] Figure 10 It is an FFT analysis diagram of the inductance waveform of the motor body in the present invention.

[0031] Figure 11 It is a schematic diagram of the magnetic field line distribution of the motor body in the present invention.

[0032] Figure 12 It is a magnetic cloud diagram of the motor body in the present invention.

[0033] Figure 13 It is an eighth schematic diagram of the rotor in the present invention.

[0034] In the figure: 100 - motor body; 1 - stator core; 11 - air gap; 2 - winding coil; 4 - rotor core; 51 - first permanent magnet; 52 - second permanent magnet; 6 - magnetic barrier; 71 - first magnetic isolation bridge; 72 - second magnetic isolation bridge; 81 - symmetry line one; 82 - symmetry line two. Detailed implementation manners

[0035] In order to further explain the technical solution of the present invention, the present invention will be elaborated in detail through specific embodiments below.

[0036] An interior permanent magnet synchronous motor with an asymmetric structure, as Figure 1 shown, includes a motor body 100. The motor body 100 includes a rotor and a stator. The stator is sleeved outside the rotor in a conventional manner. The stator includes a stator core 1 and a plurality of winding coils 2. Each winding coil 2 is respectively installed in the stator core 1 in a conventional manner, and each winding coil 2 is uniformly arranged at intervals along the circumference of the stator core 1. An air gap 11 is formed between the rotor and the stator. Among them, the structure of the stator adopts the stator structure used in existing motors, and in this embodiment, the winding coil 2 can be a conventional IPMSM stator winding in the prior art. A rotating shaft is installed on the rotor. The installation structure between the rotating shaft and the rotor and the installation structure between the rotor and the stator are both conventional installation structures used in existing motors, so they will not be described in detail. It should be noted that the IPMSM winding coil adopts a symmetric 9-slot full-tooth-wound fractional-slot concentrated double-layer winding to ensure that the motor body has the characteristics of high torque density, excellent no-load electromotive force waveform, and strong field weakening ability.

[0037] For convenience of description, the side where the axis of the rotor is located is defined as the inner side, and the side opposite thereto is defined as the outer side.

[0038] In the present invention, the above-mentioned rotor is a rotor with an asymmetric arrangement. The rotor includes a rotor core 4 and a plurality of first permanent magnets 51 and second permanent magnets 52. Each first permanent magnet 51 and each second permanent magnet 52 are respectively installed in the rotor core 4. Each first permanent magnet 51 is arranged at intervals along the circumference of the rotor in sequence, and each second permanent magnet 52 is arranged at intervals along the circumference of the rotor in sequence. Each first permanent magnet 51 and each second permanent magnet 52 correspond to each other one by one. Each first permanent magnet 51 is located inside the corresponding second permanent magnet 52, and the corresponding first permanent magnet 51 and second permanent magnet 52 are arranged side by side; preferably, every two adjacent first permanent magnets 51 are arranged in a V-shaped arrangement, and every two adjacent second permanent magnets 52 are arranged in a V-shaped arrangement to further increase the reluctance torque, so that the motor body can output greater power and torque under the same volume and weight.

[0039] The above-mentioned rotor core 4 is further provided with a plurality of magnetic barriers 6, a plurality of first magnetic isolation bridges 71 and second magnetic isolation bridges 72. The distribution of each magnetic barrier 6 is as follows: a magnetic barrier 6 is arranged between every two adjacent first permanent magnets 51 close to the outer side of the rotor, and each magnetic barrier 6 is close to the air gap 11 of the motor body 100. Among them, there is no magnetic barrier 6 between a pair of first permanent magnets 51 adjacent to each other in the direction close to the outer side. Taking this pair of first permanent magnets 51 as a first permanent magnet group, each magnetic barrier 6 is arranged at intervals along the circumferential direction of the rotor core 4, and the widths of all magnetic barriers 6 are the same. Starting from the first permanent magnet group, the thicknesses of each magnetic barrier 6 gradually increase along both sides in a manner of increasing by the same thickness difference. Here, the thickness refers to the value of the magnetic barrier 6 in the inner and outer directions in the cross-section of the rotor, and the width refers to the value in the circumferential direction in the cross-section of the rotor. The following depth refers to the direction along the axis of the rotor.

[0040] The distribution of each first magnetic isolation bridge 71 and each second magnetic isolation bridge 72 is as follows: a first magnetic isolation bridge 71 is respectively arranged between each first permanent magnet 51 and the outer side of the rotor, and a second magnetic isolation bridge 72 is respectively arranged between each second permanent magnet 52 and the outer side of the rotor. More specifically, each first magnetic isolation bridge 71 is located between the side surface of the first permanent magnet 51 close to the air gap 11 of the motor body 100 and the outer side edge of the rotor, and each second magnetic isolation bridge 72 is located between the side surface of the second permanent magnet 52 close to the air gap 11 of the motor body 100 and the outer side edge of the rotor. Among them, each first magnetic isolation bridge 71 is arranged at intervals along the circumferential direction of the rotor core 4 in sequence, and each second magnetic isolation bridge 72 is arranged at intervals along the circumferential direction of the rotor core 4 in sequence. In this embodiment, two first magnetic isolation bridges 71 respectively adjacent to two mutually separated first permanent magnets 51 are used as a group of first magnetic isolation bridge groups, and two second magnetic isolation bridges 72 respectively adjacent to two mutually separated second permanent magnets 52 are used as a group of second magnetic isolation bridge groups. The heights of the two first magnetic isolation bridges 71 in each group of first magnetic isolation bridges are the same. Starting from the group of first magnetic isolation bridge groups corresponding to one of the first permanent magnets 51 in the first permanent magnet group, the heights of each group of first magnetic isolation bridge groups gradually decrease along both sides in a manner of decreasing by the same height difference. And the heights of all second magnetic isolation bridges 72 are the same. Here, the height refers to the distance between the nearest point of the second permanent magnet close to the outer side edge of the rotor and the outer side edge of the rotor.

[0041] Specifically, in the cross-section of the rotor, taking the extension line between the center between the first permanent magnet groups and the axis of the rotor as the first symmetry line 81, each magnetic barrier 6 in the rotor is symmetrically distributed along the first symmetry line 81; taking the extension line between the center between two first permanent magnets corresponding to one group of first magnetic isolation bridge groups adjacent to the first permanent magnet group and the axis of the rotor as the second symmetry line 82, each first magnetic isolation bridge 71 is symmetrically distributed along the second symmetry line 82.

[0042] Furthermore, taking the first permanent magnets 51 that are located on the outer side close to the rotor and away from each other as a pair of permanent magnets, on the same end face of the rotor, the polarities of the magnetic poles of the two adjacent pairs of permanent magnets are different from each other. The polarities of the magnetic poles of each second permanent magnet 52 are the same as those of the corresponding first permanent magnet 51. For example, if the two first permanent magnets 51 in one pair of permanent magnets are both N poles, then the two second permanent magnets 52 corresponding to the two first permanent magnets 51 are both N poles, and the two first permanent magnets 51 in the pair of permanent magnets adjacent to this pair of permanent magnets are both S poles.

[0043] Furthermore, the above-mentioned motor body 100 is a structure based on an interior permanent magnet synchronous motor, and the number of slots is an odd number of slots. For example, the motor is 8 poles and 9 slots, 10 poles and 15 slots, 12 poles and 15 slots, etc.

[0044] Furthermore, each of the above-mentioned first permanent magnets 51 and each second permanent magnet 52 are strip-shaped, and each of the first permanent magnets 51 and each second permanent magnet 52 are respectively arranged to extend from the first end face of the rotor core 4 to the second end face. Among them, every two adjacent first permanent magnets 51 are respectively in a figure-eight shape that opens towards the axis of the rotor core 4 or in a figure-eight shape that opens towards the air gap 3 of the motor body 100. Correspondingly, the arrangement of every two adjacent second permanent magnets 52 is the same as that of the corresponding first permanent magnet 51, so it will not be elaborated here; in this embodiment, each of the first permanent magnets 51 and each second permanent magnet 52 uses the permanent magnets used in existing motors, and the embedding structures of each of the first permanent magnets 51 and each second permanent magnet 52 are both conventional existing structures. For example, a number of through slots are provided on the above-mentioned rotor core 4, and each through slot is respectively arranged in one-to-one correspondence with each of the first permanent magnets 51 and the second permanent magnets 52, and each of the first permanent magnets 51 and each second permanent magnet 52 are respectively embedded in the corresponding through slots.

[0045] Furthermore, a number of through holes are provided in the above-mentioned rotor core 4, each through hole is a square hole, both ends of each through hole respectively extend along the two end faces of the rotor core 4, and each through hole respectively forms the above-mentioned magnetic barrier 6, and the depths of each magnetic barrier 6 are respectively arranged to extend from the first end face of the rotor core 4 to the second end face; preferably, in this embodiment, as Figure 2As shown, each of the above magnetic barriers 6 is a rectangular magnetic barrier. The width of each magnetic barrier 6 is 0.1 - 3 mm, preferably 1 mm for the magnetic barrier 6, at which time the influence on the magnetic field lines (inductance) is the greatest, and the depth of each magnetic barrier 6 is 57.5 mm, that is, the depth of the motor body 100; in this embodiment, the thickness difference between every two adjacent magnetic barriers 6 is 0.75 mm. That is to say, taking the built-in permanent magnet synchronous motor with 8 poles and 9 slots of the motor body 100 as an example for illustration, starting from the first permanent magnet group, the magnetic barriers 6 are respectively the first magnetic barrier, the second magnetic barrier, and the third magnetic barrier in the counterclockwise direction, and the first magnetic barrier, the second magnetic barrier, and the third magnetic barrier in the clockwise direction. That is, in this embodiment, there are two first magnetic barriers, two second magnetic barriers, two third magnetic barriers, and one fourth magnetic barrier. Among them, the thicknesses of the two first magnetic barriers are both smaller than those of the two second magnetic barriers, the thicknesses of the two second magnetic barriers are both smaller than those of the two third magnetic barriers, and the thicknesses of the two third magnetic barriers are both smaller than that of the fourth magnetic barrier. As Figure 2 shown, taking the thickness of the two first magnetic barriers as 0.75 mm and the thickness difference as 0.75 mm as an example, the thicknesses of the two second magnetic barriers are both 1.5 mm, the thicknesses of the two third magnetic barriers are both 2.25 mm, and the thickness of the fourth magnetic barrier is 3 mm.

[0046] In this way, as Figure 4 shown - as Figure 5 shown, in this embodiment, the non - symmetric magnetic barrier is set, so that the magnetic field lines of the winding coil are blocked, which can directly change the magnetic resistance distribution of the quadrature magnetic circuit, that is, the magnetic resistance of the quadrature magnetic circuit changes periodically with the mechanical angle of the rotor, so that the quadrature inductance shows a non - linear distribution in the mechanical angle domain, thereby introducing harmonic components synchronized with the mechanical angle period in the inductance waveform, providing more significant inductance fluctuation characteristics for self - sensing electricity, and at the same time, realizing the two - way collaborative regulation of the direct - axis and quadrature - axis inductances. The inductance fluctuation amplitude is increased by 50% (reaching 10.5 - 14.5 mH), and the inductance characteristics related to the mechanical angle are more significant. In addition, as Figure 6 shown, on the motor body 100, only the magnetic barriers 6 are set according to the above structure and preferred dimensions, and when the heights of each first magnetic isolation bridge 71 and each second magnetic isolation bridge 72 are the same, that is, the first magnetic isolation bridge 71 and the second magnetic isolation bridge 72 are arranged according to the traditional magnetic isolation bridge. It can be seen from the figure that only changing the magnetic barrier 6 according to the above structure can significantly increase the inductance of the quadrature axis of the inductance and reduce the direct - axis inductance.

[0047] Furthermore, each first magnetic isolation bridge 71 and each second magnetic isolation bridge 72 are magnetic isolation bridges formed of the same material as the rotor core 4. In this embodiment, each magnetic isolation bridge is made of silicon steel material respectively; in this embodiment, taking the built - in permanent magnet synchronous motor with 8 poles and 9 slots of the motor body 100 as an example for illustration, starting from one of the first magnetic isolation bridge groups adjacent to the first permanent magnet group, the heights of each first magnetic isolation bridge group gradually decrease in a manner of decreasing by the same height difference from the starting point to both sides. In this embodiment, as Figure 3As shown, the first magnetic isolation bridge group at the starting point is the first magnetic isolation bridge group 1. In the clockwise direction, they are respectively the first magnetic isolation bridge group 2, the first magnetic isolation bridge group 3, and the first magnetic isolation bridge group 4. In the counterclockwise direction, they are also respectively the first magnetic isolation bridge group 2, the first magnetic isolation bridge group 3, and the first magnetic isolation bridge group 4. That is, in this embodiment, there is one first magnetic isolation bridge group 1, two first magnetic isolation bridge groups 2, two first magnetic isolation bridge groups 3, two first magnetic isolation bridge groups 4, and one first magnetic isolation bridge group 5. Among them, the height of the first magnetic isolation bridge group 1 is greater than the height of the two first magnetic isolation bridge groups 2. The height of the two first magnetic isolation bridge groups 2 is greater than the height of the two first magnetic isolation bridge groups 3. The height of the two first magnetic isolation bridge groups 3 is greater than the height of the first magnetic isolation bridge group 4. As Figure 2 shown, taking the height of the first magnetic isolation bridge group 1 as 1 mm and the height difference as 0.15 mm as an example, the height of the two first magnetic isolation bridge groups 2 is 0.85 mm, the height of the two first magnetic isolation bridge groups 3 is 0.7 mm, the height of the two first magnetic isolation bridge groups 4 is 0.55 mm, and the height of the first magnetic isolation bridge group 5 is 0.4 mm. Among them, the height of each second magnetic isolation bridge 72 is the same, which is 0.5 mm.

[0048] Furthermore, as Figure 13 shown, h m1 and W m1 are respectively the thickness and width of the first permanent magnet. h m2 and W m2 are respectively the thickness and width of the first permanent magnet. w b and h p are respectively the thickness and width of the magnetic barrier. h p1 and h p2 are respectively the distance between the top of the first permanent magnet and the outer side of the rotor and the distance between the top of the second permanent magnet and the outer side of the rotor. l p is the distance between the tops of two adjacent first permanent magnets at the outer side of the rotor. Here, the top refers to the end point of the permanent magnet closest to the outer side of the rotor. w p is the width of the magnetic path between the magnetic barrier and the magnetic isolation bridge. Here, the change of w p has a negligible impact on the present invention, so it will not be further defined. Among them, the values of h p2 and l p are fixed and unchanged. It should be noted that the parameters of the first permanent magnet and the second permanent magnet are fixed and arranged according to the actual situation, and are not limited here.

[0049] Furthermore, in this embodiment, the distance between the ends of two mutually separated first permanent magnets 51 near the outer side of the rotor is 1.5 mm.

[0050] In this way, a double-layer structure of permanent magnets is adopted, and the heights of all the second magnetic isolation bridges are the same to stabilize the basic magnetic circuit; and each first magnetic isolation bridge gradually changes along both sides of the starting point with a gradient of 0.15 mm. Through the differential design of the interlayer magnetic resistance, a hierarchical magnetic resistance system of a stable outer-layer magnetic circuit + fine inner-layer regulation is constructed, as Figure 4-5 shown and as Figure 7 shown. By designing the first magnetic isolation bridge according to the above structure, the magnetic resistance of the direct-axis magnetic circuit is enhanced, so that the direct-axis inductance L d shows a stepped change in the mechanical angle domain, that is, the inductance fluctuation is enhanced. In this way, both the magnetic flux intensity of the main magnetic circuit is ensured, and the inductance fluctuation is increased through the difference in the interlayer magnetic resistance, improving the self-sensing accuracy; among them, Figure 7 the waveform shown is obtained when only the first magnetic isolation bridge and the second magnetic isolation bridge are changed according to the above structure, and the thicknesses of the magnetic barriers are the same.

[0051] In the present invention, by the mutual cooperation of each magnetic barrier and each magnetic isolation bridge, the direct- and quadrature-axis magnetic resistances of the motor body 100 show a non-uniform distribution related to the mechanical angle during the rotation of the rotor, that is, the magnetic circuit of the motor body 100 changes, thereby changing the inductance of the motor body 100, that is, the inductance fluctuation is significant, so that the mechanical position of the rotor can be directly observed without using a sensor for the motor body 100, realizing the self-sensing of the motor body 100. Among them, due to the asymmetric design of the motor body, the torque fluctuation and the total harmonic distortion (THD) suppression of the motor body increase greatly. Therefore, while ensuring that the torque fluctuation significantly changes the inductance, the motor body still maintains good performance. The present invention adopts the design of gradually changing the thicknesses of each magnetic barrier and the heights of each first magnetic isolation bridge to control the torque fluctuation and the total harmonic distortion (THD) of the motor. For example, when the rated power of the motor body is 2.5 N·m, the torque fluctuation is controlled within 5.54%, and the THD of the magnetic flux linkage of phase A is reduced to 5.37%.

[0052] Furthermore, in this embodiment, with the depth of the permanent magnet being 57.5 mm and the depth of the magnetic barrier being 57.5 mm, the motor body 100 obtains the Figure 3 - Figure 11 simulation diagram shown according to the parameters and values selected in Table 1, and each magnetic barrier, each first magnetic isolation bridge, and each second magnetic isolation bridge are respectively experimented according to the above optimized dimensions.

[0053] Table 1 Basic parameters of the motor

[0054] By utilizing the mutual cooperation of each magnetic barrier and each magnetic isolation bridge, while improving the quality of the self-sensing signal, the electromagnetic performance of the motor body 100 is optimized to meet the requirements of "high torque density (>2.5 N·m / kg), low torque ripple (<8%), and low harmonic distortion (THD < 8%)". Meanwhile, the motor body 100 has the following performances respectively in terms of inductance fluctuation, electromagnetic torque, back electromotive force, harmonic content, magnetic field line distribution, and magnetic flux density.

[0055] Regarding the inductance fluctuation, for the motor body obtained according to the above structure and Figure 2 the dimensions shown, as Figure 4 shown, the amplitude of the inductance fluctuation increases significantly. The optimization of the position and size of the permanent magnet double-layer structure in cooperation with the magnetic barrier makes the slope of the curve of the direct and quadrature axis inductances changing with the mechanical angle steeper, so that the motor can still output a self-sensing signal with a high signal-to-noise ratio at low speeds or in a stationary state, and is more suitable for scenarios with high-precision position detection. Among them, the inductance fluctuation range is between 10.5 - 14.5 mH, that is, the difference between the direct axis and quadrature axis inductances is significant.

[0056] Furthermore, by utilizing the mutual cooperation of each magnetic barrier and each magnetic isolation bridge, the magnetic barrier optimizes the magnetic circuit distribution and increases the proportion of reluctance torque, while the design of each magnetic isolation bridge balances the permanent magnet torque and reluctance torque. While the torque is increased, as Figure 8 shown, the simulation results show that the motor torque is 2.0140 N*m, the torque ripple is 0.0545 (SI), which is lower than 10%, and the torque curve presents a stable sine wave shape. While the torque is increased, due to the suppression of magnetic circuit harmonics by the permanent magnet double-layer structure, the gradual change of the thickness of each first magnetic isolation bridge in the inner layer weakens specific harmonics specifically, so that the torque stability of the motor body 100 is better, that is, the torque ripple does not increase significantly, and it is more suitable for application scenarios with high requirements for torque smoothness (such as robot joint drive).

[0057] Furthermore, regarding the back electromotive force, by utilizing the mutual cooperation of each magnetic barrier and each magnetic isolation bridge, as Figure 9 shown, the simulation results show that during the operation of the motor body 100 in the present invention, the distortion of the air-gap magnetic flux density is reduced, which promotes the back electromotive force waveform to be closer to a sine wave, effectively suppressing the high-order harmonic components of the back electromotive force, improving the quality of the electromotive force during motor operation, reducing the switching loss of the inverter configured for the motor body 100, and improving the system efficiency.

[0058] Furthermore, from Figure 10It can be seen that by using the mutual cooperation of each magnetic barrier and each magnetic isolation bridge, through the fine modulation of the magnetic circuit by each magnetic barrier and each magnetic isolation bridge, the harmonic components in the air-gap magnetic density are reduced, the low-order harmonics (such as the 3rd and 5th harmonics) are suppressed, and the magnetic density waveform is further optimized. From the simulation results, it can be shown that the total harmonic distortion (THD) can be controlled within 5.37%, that is, the electrical signal output by the motor body 100 is purer, the power conversion efficiency is higher, the harmonic pollution to the power grid or the drive circuit is smaller, and at the same time the proportion of the fundamental harmonic is increased to 1.6%.

[0059] Furthermore, due to the mutual cooperation of each magnetic barrier and each magnetic isolation bridge, each magnetic barrier is distributed between two adjacent first permanent magnets to guide the magnetic force line path to better meet the operating requirements of the motor body 100. The magnetic force lines in the direct and quadrature axes are more regular, reducing the magnetic leakage phenomenon. From Figure 11 it can be seen that the magnetic force line density gradient in the air-gap region more conforms to the sine law, that is, the magnetic field energy conversion is more efficient, the output ability of the motor torque is enhanced, and at the same time the additional loss caused by magnetic leakage is reduced. In addition, as Figure 12 shown, a double-layer structure of permanent magnets is adopted to share the magnetic load, combined with the setting of each first magnetic isolation bridge, so as to adjust the magnetic resistance, effectively reducing the local magnetic saturation phenomenon of the rotor core 4; due to the height gradient design of each first magnetic isolation bridge 71, the magnetic resistance distribution of the direct-axis magnetic circuit is more reasonable, avoiding the excessive concentration of magnetic density in a certain area, and effectively improving the overload capacity and efficiency of the motor body 100.

[0060] It is worth mentioning that the experimental results show that when the speed reaches 3000 r / min, the output torque is the highest and the torque ripple is the smallest, and the harmonic distortion rate is reduced to the lowest, realizing the collaborative optimization of the self-sensing function and the motor performance.

[0061] Furthermore, in terms of manufacturing of the present invention, due to the axial symmetry of the rotor and the gradient design of the heights of the magnetic barriers and the first magnetic isolation bridges, only 2 sets of basic molds are required for manufacturing the rotor, improving the processing efficiency.

[0062] In the present invention, the above-mentioned motor body 100 can be combined with existing conventional rotor mechanical angle detection methods to detect the mechanical angle of the rotor, so as to accurately determine the rotor position, such as the "Sensorless Interior Permanent Magnet Synchronous Motor and Rotor Mechanical Angle Detection Method" with the publication number CN119448618A.

[0063] The above are only the preferred embodiments of this embodiment. All equivalent changes and modifications made within the scope of the claims of the present invention shall fall within the scope of the claims of the present invention.

Claims

1. An interior permanent magnet synchronous motor with an asymmetric structure, including a motor body, the motor body includes a rotor, the rotor includes a rotor core and a plurality of first permanent magnets and second permanent magnets embedded in the rotor core, each of the first permanent magnets corresponds to each of the second permanent magnets one by one, and each of the first permanent magnets is located inside the corresponding second permanent magnet, and each of the first permanent magnets and each of the second permanent magnets are sequentially arranged at intervals along the circumferential direction of the rotor core, and a plurality of magnetic barriers and magnetic isolation bridges are provided on the rotor core; It is characterized in that: A magnetic barrier is provided between every two adjacent first permanent magnets, and there is no magnetic barrier between a pair of adjacent first permanent magnets, and each of the magnetic barriers is arranged at intervals along the circumferential direction of the rotor core; in the cross-section of the rotor core, taking the two first permanent magnets without magnetic barriers as a first permanent magnet group, the widths of all the magnetic barriers are the same, and starting from the first permanent magnet group, the thicknesses of all the magnetic barriers gradually increase along both sides in a manner of increasing by the same thickness difference; each of the magnetic isolation bridges is divided into a first magnetic isolation bridge and a second magnetic isolation bridge, a first magnetic isolation bridge is respectively provided between each of the first permanent magnets and the outer side of the rotor, and a second magnetic isolation bridge is respectively provided between each of the second permanent magnets and the outer side of the rotor, taking the two first magnetic isolation bridges adjacent to two mutually separated first permanent magnets as a first magnetic isolation bridge group, the heights of the two first magnetic isolation bridges in each first magnetic isolation bridge group are the same; starting from the first magnetic isolation bridge group corresponding to one of the first permanent magnets in the first permanent magnet group, the heights of each of the first magnetic isolation bridge groups gradually decrease along both sides in a manner of decreasing by the same height difference; and the heights of all the second magnetic isolation bridges are the same.

2. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 1, characterized in that: In the cross-section of the rotor, taking the extension line between the center of the first permanent magnet group and the axis of the rotor core as the first symmetry line, each of the magnetic barriers is symmetrically arranged along the first symmetry line; and, taking the extension line between the center of the two first permanent magnets corresponding to one of the first magnetic isolation bridge groups adjacent to the first permanent magnet group and the axis of the rotor as the second symmetry line, each of the first magnetic isolation bridges is symmetrically distributed along the second symmetry line.

3. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 1, characterized in that: All of the magnetic barriers are rectangular magnetic barriers.

4. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 3, characterized in that: The thickness difference between every two adjacent magnetic barriers is 0.75 mm.

5. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 4, characterized in that: The width of each of the magnetic barriers is 1 mm, and the depth of each of the magnetic barriers is 57.5 mm.

6. An interior permanent magnet synchronous motor with an asymmetric structure according to any one of claims 2-5, characterized in that: Two adjacent first permanent magnets are arranged in a V-shape, and two adjacent second permanent magnets are arranged in a V-shape.

7. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 6, characterized in that: The height difference between every two adjacent first magnetic isolation bridges is 0.15 mm.

8. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 7, characterized in that: The height of each of the second magnetic isolation bridges is 0.5 mm.

9. An interior permanent magnet synchronous motor with an asymmetric structure according to claim 6, characterized in that: Each of the first magnetic isolation bridges is respectively provided between the side surface of the first permanent magnet adjacent to the outer side of the rotor and the outer side of the rotor, and each of the second magnetic isolation bridges is respectively provided between the side surface of the second permanent magnet adjacent to the outer side of the rotor and the outer side of the rotor.

10. An interior permanent magnet synchronous motor with an asymmetric structure according to any one of claims 2-5, characterized in that: The first permanent magnets that are away from each other near the outer side of the rotor are permanent magnet pairs. On the same end face of the rotor, the polarities of the magnetic poles of two adjacent permanent magnet pairs are different from each other, and the polarities of the magnetic poles of each second permanent magnet are the same as the polarities of the corresponding first permanent magnets respectively.

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