Lightweight permanent magnet synchronous motor for electric aircraft

Abstract

The utility model discloses a lightweight permanent magnet synchronous motor for an electric aircraft. An electromagnetic structure in the motor comprises a stator iron core, an armature winding, a permanent magnet, a rotor magnet yoke and a rotor bracket, the stator iron core is of an annular columnar structure, stator grooves penetrating through the axial direction are evenly formed in the end face of the stator iron core in the circumferential direction, and armature windings are arranged in the stator grooves. A rotor magnet yoke is arranged to be of an annular thin-wall structure, a plurality of pole permanent magnets which are sequentially connected are evenly pasted to the outer ring wall face of the rotor magnet yoke in the circumferential direction, and an excitation assembly of an annular columnar structure is formed by the pole permanent magnets. The rotor magnet yoke and the permanent magnets of each pole adhered to the outer side wall of the rotor magnet yoke are mounted on the inner side of the stator iron core through the rotor bracket, and the permanent magnets of each pole and the inner side wall of the stator iron core form an annular thin-wall gap, so that the rotor magnet yoke, the permanent magnets of each pole and the rotor bracket rotate relative to the stator iron core; the permanent magnet of each pole is of a segmented structure and is divided into four segments which are arranged in a central symmetry mode, and the four segments comprise the two samarium cobalt permanent magnets located in the middle and the two neodymium iron boron permanent magnets located on the two sides. According to the technical scheme of the utility model, the problem that as most of the existing aviation permanent magnet synchronous motors adopt high-speed and high-electromagnetic-load design, the temperature rise of the motors is too high, and the stable operation of the motors is greatly threatened is solved.

Description

Technical Field

[0001] This utility model relates to, but is not limited to, the field of aerospace technology, and particularly to a lightweight permanent magnet synchronous motor for electric aircraft. Background Technology

[0002] Aircraft electrification, which replaces engines with electric motors, can reduce high-altitude environmental pollution and is a development direction and research focus for next-generation aircraft. Electric motors are one of its key technologies. Aircraft have strict requirements for spatial structure and are extremely sensitive to the weight of various systems. Electric motors typically have high power and low speed, making it difficult to reduce their size and weight.

[0003] Compared to other types of motors, permanent magnet synchronous motors (PMSMs) offer advantages such as high power density and efficiency. Their rotor structures are also easier to optimize, making them promising candidates for use in electric aircraft. Currently, most aviation PMSMs employ high-speed and high electromagnetic load designs, which can easily lead to excessive temperature rise, posing a significant threat to stable operation. For high-speed PMSMs, additional gearboxes are required, increasing maintenance costs and frequency. Furthermore, some motors, in pursuit of lightweight design and high torque density, have extremely complex magnetic circuit structures that are difficult to industrialize. Utility Model Content

[0004] The purpose of this utility model is to solve the above-mentioned technical problems. This utility model provides a lightweight permanent magnet synchronous motor for electric aircraft, which solves the problem that existing aviation permanent magnet synchronous motors, due to their high-speed and high electromagnetic load designs, are prone to excessive temperature rise, posing a great threat to the stable operation of the motor.

[0005] The technical solution of this utility model: This utility model embodiment provides a lightweight permanent magnet synchronous motor for electric aircraft. The electromagnetic structure of the lightweight permanent magnet synchronous motor includes: stator core 1, armature winding 2, permanent magnet 3, rotor yoke 4, and rotor support 5.

[0006] The stator core 1 is configured as an annular columnar structure, and the end face of the stator core 1 is uniformly provided with stator slots that penetrate the axial direction along the circumference. The armature winding 2 is arranged in the stator slot.

[0007] The rotor yoke 4 is configured as an annular thin-walled structure. Multiple permanent magnets 3 are uniformly and sequentially bonded to the outer annular wall of the rotor yoke 4 along the circumferential direction. The excitation assembly with an annular columnar structure is formed by the permanent magnets 3. The rotor yoke 4 and the permanent magnets 3 bonded to its outer wall are installed on the inner side of the stator core 1 through the rotor support 5. The permanent magnets 3 and the inner wall of the stator core 1 form an annular thin-walled gap, so that the rotor yoke 4, each permanent magnet 3 and the rotor support 5 rotate relative to the stator core 1.

[0008] Each permanent magnet 3 is configured as a segmented structure, consisting of four segments arranged in a centrally symmetrical manner, including two samarium cobalt permanent magnet segments 32 located in the middle, and two neodymium iron boron permanent magnet segments 31 located on both sides.

[0009] Optionally, in the lightweight permanent magnet synchronous motor for electric aircraft as described above, in each pole permanent magnet 3, the two middle samarium cobalt permanent magnets 32 occupy at least 75% of the volume of the pole permanent magnet 3, and the two middle samarium cobalt permanent magnets 32 are 0.5 mm longer in the radial direction than the two neodymium iron boron permanent magnets 31 located on both sides.

[0010] Optionally, in the lightweight permanent magnet synchronous motor for electric aircraft as described above, among the permanent magnets 3 per pole, the samarium cobalt permanent magnet 32 ​​has better high-temperature resistance than the neodymium iron boron permanent magnet 31, the remanence of the neodymium iron boron permanent magnet 31 is higher than that of the samarium cobalt permanent magnet 32, and the density of the neodymium iron boron permanent magnet 31 is lower than that of the samarium cobalt permanent magnet 32.

[0011] The magnetization angle of the neodymium iron boron permanent magnet 31 is 55°, and the magnetization angle of the samarium cobalt permanent magnet 32 ​​is 25°.

[0012] Optionally, in the lightweight permanent magnet synchronous motor for electric aircraft as described above,

[0013] The permanent magnets 3 arranged along the outer ring wall of the rotor yoke 4 have two types of permanent magnets, N pole and S pole. The two types of permanent magnets are arranged alternately along the circumference to form an excitation assembly with a ring column structure.

[0014] Optionally, in the lightweight permanent magnet synchronous motor for electric aircraft as described above,

[0015] The outer ring wall of the rotor yoke 4 is uniformly provided with multiple concave grooves along the circumference. Each groove is located in the middle of the corresponding permanent magnet 3 to accommodate two samarium cobalt permanent magnets 32 in the middle two sections of the permanent magnet 3. The inner ring of the rotor yoke 4 is uniformly provided with multiple semi-circular grooves along the circumference. Each semi-circular groove is located in the middle of the permanent magnet 3, that is, each semi-circular groove is located at the weak point of the magnetic field in the corresponding permanent magnet 3, which is used to reduce the weight of the rotor yoke.

[0016] The number of rotor yokes 4 and the number of semi-circular slots in the rotor yoke 4 are the same as the number of permanent magnets 3, and are arranged accordingly.

[0017] Optionally, in the lightweight permanent magnet synchronous motor for electric aircraft as described above,

[0018] The outer sides of the two neodymium iron boron permanent magnets 31 located on both sides of the permanent magnet 3 are shaped into rounded chamfers, forming an uneven air gap with the inner side of the stator core 1.

[0019] Optionally, in the lightweight permanent magnet synchronous motor for electric aircraft as described above,

[0020] The armature winding 2 adopts a fractional slot concentrated winding structure to shorten the winding end length. The fractional slot concentrated winding structure is a winding form with less than 1 slot per pole per phase. The number of slots per pole per phase is defined as the ratio of the number of slots to the product of the number of poles and the number of phases. The pole-slot configuration of the motor is 40 poles and 48 slots, with 0.4 slots per pole per phase. Increasing the minimum non-zero order is beneficial for reducing electromagnetic noise.

[0021] The beneficial effects of this utility model are as follows: This utility model provides a lightweight permanent magnet synchronous motor for electric aircraft. In its electromagnetic structure, on the one hand, it employs a combination of magnetic poles made of different materials. Furthermore, by setting a segmented structure for the combined magnetic poles, and by controlling the density and material properties of each segment, the weight of the permanent magnet 3 is reduced while ensuring the performance of the permanent magnet 3 and the reliability of the permanent magnet synchronous motor. Specifically, the permanent magnet synchronous motor can still operate even when the neodymium iron boron permanent magnet material fails. On the other hand, the two structures in each permanent magnet 3... By setting different magnetization angles for the permanent magnets, the weight of the rotor yoke can be reduced. Within a certain magnetization angle range, the larger the magnetization angle of the samarium cobalt permanent magnet, the lower the no-load back EMF distortion rate, while the amplitude remains basically unchanged. Furthermore, compared to the traditional structure of cutting the poles of the entire permanent magnet, the electromagnetic structure of the permanent magnet synchronous motor provided by this utility model only cuts the poles of the neodymium iron boron permanent magnet 31, which reduces the scrap rate of the permanent magnet while reducing the cogging torque. In addition, by adopting a fractional-slot concentrated winding with q = 0.4 slots per pole per phase, the overall performance of the motor is better and the end weight is reduced. The electromagnetic structure of the lightweight permanent magnet synchronous motor for electric aircraft provided by this utility model embodiment has strong feasibility and high engineering application value. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solution of this utility model and do not constitute a limitation on the technical solution of this utility model.

[0023] Figure 1 A schematic diagram of the electromagnetic structure of a lightweight permanent magnet synchronous motor for electric aircraft provided for an embodiment of this utility model;

[0024] Figure 2 for Figure 1 A partially enlarged schematic diagram of the electromagnetic structure of a lightweight permanent magnet synchronous motor for electric aircraft provided in the embodiment shown.

[0025] Figure 3 for Figure 1The illustrated embodiment provides a schematic diagram of the magnetization of the N-pole permanent magnet and the S-pole permanent magnet in the electromagnetic structure of a lightweight permanent magnet synchronous motor for electric aircraft.

[0026] Figure 4 A schematic diagram showing the effect of the magnetization angle of the samarium cobalt permanent magnet in each pole on the no-load back electromotive force and the magnetic flux density of the rotor yoke in the electromagnetic structure of the lightweight permanent magnet synchronous motor for electric aircraft provided in this embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram comparing the effects of a lightweight permanent magnet synchronous motor for electric aircraft with four permanent magnet segments per pole and only samarium cobalt permanent magnets per pole under load, as provided in an embodiment of this utility model.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Stator core; 2. Armature winding; 3. Permanent magnet; 4. Rotor yoke; 5. Rotor support; 31. Neodymium iron boron permanent magnet; 32. Samarium cobalt permanent magnet. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0031] As explained in the background section, permanent magnet synchronous motors (PMSMs) have excellent application prospects in electric aircraft due to their advantages such as high power density and high efficiency. However, most current aviation PMSMs adopt high-speed and high electromagnetic load designs, which easily lead to excessive motor temperature rise, posing a significant threat to stable motor operation. For high-speed PMSMs, a gearbox is also required, increasing maintenance costs and frequency. In addition, some motors, in order to achieve lightweight and high torque density, have extremely complex magnetic circuit structures that are difficult to industrialize.

[0032] To address the aforementioned issues, this utility model provides a lightweight permanent magnet synchronous motor for electric aircraft. Based on an electromagnetic design perspective, the motor is redesigned using an achievable magnetic circuit structure, resulting in reduced weight and high practicality. This invention has significant practical application value in the field of electric aircraft drive motors.

[0033] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they will not be described again in some embodiments.

[0034] Figure 1 This is a schematic diagram of the electromagnetic structure of a lightweight permanent magnet synchronous motor for electric aircraft, provided as an embodiment of the present invention. Figure 2 for Figure 1 The illustrated embodiment provides a partially enlarged schematic diagram of the electromagnetic structure of a lightweight permanent magnet synchronous motor for electric aircraft. (See attached diagram.) Figure 1 and Figure 2 As shown, the electromagnetic structure of the lightweight permanent magnet synchronous motor for electric aircraft provided in this embodiment of the present invention includes: stator core 1, armature winding 2, permanent magnet 3, rotor yoke 4, and rotor support 5.

[0035] like Figure 1 and Figure 2 In the electromagnetic structure of the lightweight permanent magnet synchronous motor shown, the stator core 1 is set as an annular columnar structure, and the end face of the stator core 1 is uniformly provided with stator slots that penetrate the axial direction along the circumference. The armature winding 2 is arranged in the stator slot.

[0036] In this embodiment of the present invention, the rotor yoke 4 is configured as an annular thin-walled structure. Multiple permanent magnets 3 are uniformly and sequentially bonded to the outer annular wall of the rotor yoke 4 in the circumferential direction. The excitation assembly with an annular columnar structure is formed by the permanent magnets 3. The rotor yoke 4 and the permanent magnets 3 bonded to its outer wall are installed on the inner side of the stator core 1 through the rotor support 5. The permanent magnets 3 and the inner wall of the stator core 1 form an annular thin-walled gap, so that the rotor yoke 4, each permanent magnet 3 and the rotor support 5 rotate relative to the stator core 1.

[0037] In this embodiment of the present invention, each permanent magnet 3 is configured as a segmented structure, consisting of four centrally symmetrical segments, including two samarium cobalt permanent magnet segments 32 located in the middle and two neodymium iron boron permanent magnet segments 31 located on both sides.

[0038] In one implementation of this utility model embodiment, such as Figure 2 As shown, in each pole permanent magnet 3, the two middle sections of samarium cobalt permanent magnet 32 ​​occupy at least 75% of the volume of the pole permanent magnet 3, and the two middle sections of samarium cobalt permanent magnet 32 ​​are 0.5 mm longer in the radial direction than the two neodymium iron boron permanent magnets 31 located on both sides.

[0039] In one embodiment of this utility model, among the permanent magnets 3, the samarium cobalt permanent magnet 32 ​​has better high-temperature resistance than the neodymium iron boron permanent magnet 31, the remanence of the neodymium iron boron permanent magnet 31 is higher than that of the samarium cobalt permanent magnet 32, and the density of the neodymium iron boron permanent magnet 31 is lower than that of the samarium cobalt permanent magnet 32.

[0040] In practice, the magnetization angle of the neodymium iron boron permanent magnet 31 is 55°, and the magnetization angle of the samarium cobalt permanent magnet 32 ​​is 25°. The magnetization angle of the samarium cobalt permanent magnet 32 ​​is smaller than that of the neodymium iron boron permanent magnet 31, so as not to affect the performance of the permanent magnet synchronous motor.

[0041] It should be noted that the advantages of the permanent magnet 3 with the above-described structure in this embodiment are: the density of the neodymium iron boron permanent magnet 31 is lower than that of the samarium cobalt permanent magnet 32, which can reduce the weight of each pole permanent magnet 3 and the overall excitation assembly. Furthermore, when the motor temperature is too high and causes irreversible demagnetization of the neodymium iron boron permanent magnet 31, the samarium cobalt permanent magnet 32 ​​in the permanent magnet 3 can continue to provide magnetic energy, improving the reliability of the motor operation.

[0042] In one implementation of this utility model, Figure 3 for Figure 1 The illustrated embodiment provides a schematic diagram of the magnetization of N-pole and S-pole permanent magnets in the electromagnetic structure of a lightweight permanent magnet synchronous motor for electric aircraft. In this implementation, the permanent magnets 3 arranged along the outer ring wall of the rotor yoke 4 have both N-pole and S-pole permanent magnets, which are sequentially and alternately arranged circumferentially to form an excitation assembly with a ring-shaped columnar structure.

[0043] In one implementation of this utility model embodiment, reference is made to... Figure 1 and Figure 2 As shown, the outer ring wall of the rotor yoke 4 is uniformly provided with multiple concave grooves along the circumference. Each groove is located in the middle of the corresponding permanent magnet 3 to accommodate two samarium cobalt permanent magnets 32 in the middle two sections of the permanent magnet 3. In addition, the inner ring of the rotor yoke 4 is uniformly provided with multiple semi-circular grooves along the circumference. Each semi-circular groove is located in the middle of the permanent magnet 3, that is, each semi-circular groove is located at the weak point of the magnetic field in the corresponding permanent magnet 3, which is used to reduce the weight of the rotor yoke.

[0044] In this implementation, the number of rotor yokes 4 and the number of semi-circular slots in rotor yoke 4 are the same as the number of permanent magnets 3, and are set accordingly.

[0045] In one embodiment of this utility model, the outer sides of the two neodymium iron boron permanent magnets 31 located on both sides of the permanent magnet 3 are shaped into rounded chamfers, forming an uneven air gap with the inner side of the stator core 1. Based on the specific structural design in this embodiment, the cogging torque can be reduced, and the scrap rate of the permanent magnet can be reduced.

[0046] In one implementation of this utility model, the armature winding 2 adopts a fractional slot concentrated winding structure to shorten the winding end length. The fractional slot concentrated winding structure is a winding form in which the number of slots per pole per phase is less than 1. The number of slots per pole per phase is defined as the ratio of the number of slots to the product of the number of poles and the number of phases. The pole-slot combination of the lightweight permanent magnet synchronous is 40 poles and 48 slots, with 0.4 slots per pole per phase. Increasing the minimum non-zero order is beneficial for reducing electromagnetic noise.

[0047] Furthermore, in this embodiment of the present invention, the stator core 1 is made of a soft magnetic alloy material 1J22 with higher magnetic saturation and a stack thickness of 0.2mm, which is beneficial to reducing the weight of the stator core; the rotor yoke 4 is made of high-strength alloy steel 40CrNiMoA.

[0048] The lightweight permanent magnet synchronous motor for electric aircraft provided in this embodiment of the invention features an electromagnetic structure that, on the one hand, employs a combination of magnetic poles made of different materials. By setting a segmented structure for the combined magnetic poles, and considering the density and material properties of each segment, the weight of the permanent magnet 3 is reduced while ensuring the performance of the permanent magnet 3 and the reliability of the permanent magnet synchronous motor. Specifically, the permanent magnet synchronous motor can still operate even when the neodymium iron boron permanent magnet material fails. On the other hand, different permanent magnet structures are used in each pole of the permanent magnet 3. The magnetization angle can reduce the weight of the rotor yoke. Within a certain magnetization angle range, the larger the magnetization angle of the samarium cobalt permanent magnet, the lower the no-load back EMF distortion rate, while the amplitude remains basically unchanged. Furthermore, compared to the traditional structure of cutting the poles of the entire permanent magnet, the electromagnetic structure of the permanent magnet synchronous motor provided by this invention separately cuts the poles of the neodymium iron boron permanent magnet 31, reducing the cogging torque and also lowering the scrap rate of the permanent magnet. Moreover, by adopting a fractional-slot concentrated winding with q = 0.4 slots per pole per phase, the overall performance of the motor is better, and the end weight is reduced. The electromagnetic structure of the lightweight permanent magnet synchronous motor for electric aircraft provided by this invention has strong feasibility and high engineering application value.

[0049] The following implementation example illustrates the implementation effect of the lightweight permanent magnet synchronous motor for electric aircraft provided by this utility model embodiment.

[0050] Implementation Example

[0051] Figure 4 A schematic diagram showing the effect of the magnetization angle of the samarium cobalt permanent magnet in each pole on the no-load back electromotive force and the magnetic flux density of the rotor yoke in the electromagnetic structure of the lightweight permanent magnet synchronous motor for electric aircraft provided in this embodiment of the present invention. Figure 5 This is a schematic diagram comparing the effects of a lightweight permanent magnet synchronous motor for electric aircraft with four permanent magnet segments per pole and only samarium cobalt permanent magnets per pole under load, as provided in an embodiment of this utility model.

[0052] Reference Figures 1 to 5 This embodiment proposes an electromagnetic structure for a lightweight permanent magnet synchronous motor for electric aircraft. The present invention will be further described below with reference to the accompanying drawings.

[0053] (1) The electromagnetic part of the motor mainly includes stator core 1, armature winding 2, permanent magnet 3, rotor yoke 4, and rotor support 5; among which the permanent magnet 3 includes two types of permanent magnets with different materials and structures, namely neodymium iron boron permanent magnet 31 and samarium cobalt permanent magnet 32.

[0054] (2) A fractional-slot concentrated winding with 0.4 slots per pole per phase is adopted, and the pole-slot configuration of the motor is 40 poles and 48 slots.

[0055] (3) In this embodiment, the armature winding 2 is made of round wire, but it can also be designed as flat wire.

[0056] (4) The stator core 1 is made of soft magnetic alloy 1J22 with a magnetic saturation of 2.4T and a stack thickness of 0.2mm.

[0057] (5) Figure 2 As shown, each permanent magnet is divided into 3 segments. The two segments on the sides are neodymium iron boron permanent magnets 31, and the two segments in the middle are samarium cobalt permanent magnets 32. The two segments of samarium cobalt permanent magnets 32 and the two segments of neodymium iron boron permanent magnets 31 have the same volume. The two segments of samarium cobalt permanent magnets 32 need to occupy more than 0.75 of the volume of each permanent magnet to ensure that the no-load back EMF has a high sinusoidal characteristic when only samarium cobalt permanent magnets 32 are working.

[0058] (7) The samarium cobalt permanent magnet 32 ​​is Sm2Co7-33H with a temperature resistance of 350° and a high density, while the neodymium iron boron permanent magnet 31 is N50UH with a higher remanence, a temperature resistance of 180° and a lower density. The two together form a single-pole permanent magnet 3 to provide magnetic flux.

[0059] (8) Grooves are cut in the sparse magnetic field on the inner side of the rotor yoke 4 to reduce weight. The material of the rotor yoke 4 is alloy steel 40CrNiMoA.

[0060] (9) A 0.5mm thick groove is made radially inward on the outer ring side of the rotor yoke 4 to place the samarium cobalt permanent magnet 32, which can fix the samarium cobalt permanent magnet 32 ​​and prevent it from shifting during operation.

[0061] (10) The outer side of the neodymium iron boron permanent magnet 31 is shaved to produce an uneven air gap, which is beneficial to the reduction of the cogging torque.

[0062] (11) such as Figure 3 As shown, the magnetization angle of neodymium iron boron permanent magnet 31 is 55°, and the magnetization angle of samarium cobalt permanent magnet 32 ​​is 25°. The magnetization angle is the angle between the arrow and the vertical direction.

[0063] (11) such as Figure 4 As shown, the magnetization angle of the samarium cobalt permanent magnet 32 ​​should not be too large. When the magnetization angle is larger, the magnetic flux density of the rotor yoke 4 is smaller, which is beneficial for weight reduction, but the no-load back EMF is smaller, the motor performance is reduced, and it decreases linearly after 25°. At the same time, the motor strength is worse.

[0064] (12) such as Figure 5 As shown, under rated load, when the output torque is the same, compared with the combined action of samarium cobalt permanent magnet 32 ​​and neodymium iron boron permanent magnet 31 in each pole, when only samarium cobalt permanent magnet 32 ​​is in action, the current increases by about 26%, and the current density increases to 24.4 A / mm2. With the adoption of a reasonable cooling method, the motor can work for a short time, which improves the reliability of motor operation.

[0065] Although the embodiments disclosed in this utility model are as described above, the content is only for the purpose of facilitating understanding of this utility model and is not intended to limit this utility model. Any person skilled in the art to which this utility model pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this utility model, but the patent protection scope of this utility model shall still be determined by the scope defined in the appended claims.

Claims

1. A lightweight permanent magnet synchronous motor for electric aircraft, characterized in that, The electromagnetic structure of the lightweight permanent magnet synchronous motor includes: stator core (1), armature winding (2), permanent magnet (3), rotor yoke (4), and rotor support (5); The stator core (1) is configured as an annular columnar structure, and the end face of the stator core (1) is uniformly provided with stator slots that penetrate the axial direction along the circumference, and armature windings (2) are arranged in the stator slots. The rotor yoke (4) is configured as an annular thin-walled structure. Multiple permanent magnets (3) are uniformly attached to the outer annular wall of the rotor yoke (4) in sequence. The excitation assembly with an annular columnar structure is formed by the permanent magnets (3). The rotor yoke (4) and the permanent magnets (3) attached to its outer wall are installed on the inner side of the stator core (1) through the rotor bracket (5). The permanent magnets (3) and the inner wall of the stator core (1) form an annular thin-walled gap, so that the rotor yoke (4), each permanent magnet (3) and the rotor bracket (5) rotate relative to the stator core (1). Each permanent magnet (3) is configured as a segmented structure, consisting of four segments arranged in a centrally symmetrical manner, including two samarium cobalt permanent magnet segments (32) located in the middle, and two neodymium iron boron permanent magnet segments (31) located on both sides.

2. The lightweight permanent magnet synchronous motor for electric aircraft according to claim 1, characterized in that, In each pole permanent magnet (3), the two middle samarium cobalt permanent magnets (32) occupy at least 75% of the volume of the pole permanent magnet (3), and the two middle samarium cobalt permanent magnets (32) are 0.5 mm longer in the radial direction than the two neodymium iron boron permanent magnets (31) on both sides.

3. The lightweight permanent magnet synchronous motor for electric aircraft according to claim 1, characterized in that, In each of the permanent magnets (3), the samarium cobalt permanent magnet (32) has better high temperature resistance than the neodymium iron boron permanent magnet (31), the remanence of the neodymium iron boron permanent magnet (31) is higher than that of the samarium cobalt permanent magnet (32), and the density of the neodymium iron boron permanent magnet (31) is lower than that of the samarium cobalt permanent magnet (32). The magnetization angle of the neodymium iron boron permanent magnet (31) is 55°, and the magnetization angle of the samarium cobalt permanent magnet (32) is 25°.

4. The lightweight permanent magnet synchronous motor for electric aircraft according to claim 1, characterized in that, The permanent magnets (3) arranged along the outer ring wall of the rotor yoke (4) have two types of permanent magnets, N pole and S pole. The two types of permanent magnets, N pole and S pole, are arranged alternately along the circumference to form an excitation assembly with a ring column structure.

5. The lightweight permanent magnet synchronous motor for electric aircraft according to claim 1, characterized in that, The outer ring wall of the rotor yoke (4) is uniformly provided with multiple concave grooves along the circumference. Each groove is located in the middle of the corresponding permanent magnet (3) to accommodate two samarium cobalt permanent magnets (32) in the middle two sections of the permanent magnet (3). The inner ring of the rotor yoke (4) is uniformly provided with multiple semi-circular grooves along the circumference. Each semi-circular groove is located in the middle of the permanent magnet (3), that is, each semi-circular groove is located at the weak point of the magnetic field in the corresponding permanent magnet (3) to reduce the weight of the rotor yoke. The number of rotor yokes (4) and the number of semi-circular slots in the rotor yoke (4) are the same as the number of permanent magnets (3), and are set accordingly.

6. The lightweight permanent magnet synchronous motor for electric aircraft according to claim 1, characterized in that, The outer sides of the two neodymium iron boron permanent magnets (31) located on both sides of the permanent magnet (3) are shaped into a rounded chamfer structure, forming an uneven air gap with the inner side of the stator core (1).

7. The lightweight permanent magnet synchronous motor for electric aircraft according to any one of claims 1 to 6, characterized in that, The armature winding (2) adopts a fractional slot concentrated winding structure to shorten the winding end length. The fractional slot concentrated winding structure is a winding form in which the number of slots per pole per phase is less than 1. The number of slots per pole per phase is defined as the ratio of the number of slots to the product of the number of poles and the number of phases. The lightweight permanent magnet synchronous motor has a pole-slot configuration of 40 poles and 48 slots, with 0.4 slots per pole per phase. Increasing the minimum non-zero order helps reduce electromagnetic noise.

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