Lightweight Halbach permanent magnet motor non-yoke rotor

Abstract

The invention relates to a lightweight Halbach permanent magnet motor non-yoke rotor, which comprises a rotor casing, Halbach permanent magnets are mounted on the inner periphery of the rotor casing, a permanent magnet positioning structure is arranged on the rotor casing, each Halbach permanent magnet is of an annular structure and consists of a plurality of layers of Halbach permanent magnets, outer positioning grooves are formed in the outer peripheries of the Halbach permanent magnets, and inner positioning grooves are formed in the inner peripheries of the Halbach permanent magnets; the Halbach permanent magnets are composed of tangential magnetizing permanent magnets and radial magnetizing permanent magnets which are sequentially arranged at intervals, the top surfaces of the tangential magnetizing permanent magnets are larger than the bottom surfaces of the tangential magnetizing permanent magnets, and top surface chamfers are arranged on the two sides of the tops of the tangential magnetizing permanent magnets; the radial magnetizing permanent magnets are isosceles trapezoids, the bottom faces of the radial magnetizing permanent magnets are larger than the top faces of the radial magnetizing permanent magnets, and the two side edges of the tangential magnetizing permanent magnets are tightly attached to the two side edges of the radial magnetizing permanent magnets. The permanent magnets are fixed through the mechanical positioning strips, compared with fixing only through glue, reliability is high, and the motor rotor fixing device is still suitable for a motor rotor with the high rotating speed.

Description

Technical Field

[0001] This invention belongs to the field of motor technology and relates to a lightweight Halbach permanent magnet motor with a yokeless rotor. Background Technology

[0002] Permanent magnet motors, characterized by high torque density and high efficiency, have found widespread application in new energy vehicles, aerospace, and industrial robots. Aircraft electrification is a crucial development direction in aviation technology, particularly in the field of electric aircraft, represented by eVTOL (electrical vehicle vertical rotation), where electrification development is booming. Unlike traditional powered aircraft, electric aircraft directly drive propellers or ducted fans to generate thrust, offering significant advantages such as high energy efficiency, green operation, environmental friendliness, and quiet operation. As the core of aircraft electrification, the motor system faces higher requirements in terms of power density, torque density, efficiency, and safety and reliability. For example, the power density of propulsion motor systems needs to be 2-3 times that of electric drives in new energy vehicles, and the torque density needs to be more than 7 times that of electric drives in new energy vehicles. Meeting these requirements necessitates research in various aspects, including motor electromagnetic topology, cooling, lightweight structure, integrated design, and the application of new electrical materials.

[0003] Patent CN 111600407 A discloses a lightweight, low-loss permanent magnet motor rotor, such as... Figure 1 , Figure 2 As shown, this rotor features a special squirrel-cage damping winding, end plates, a rotor support, and vents. The damping winding bars and end plates, made of conductors, work in conjunction with positioning slots on the surface of the permanent magnets to effectively suppress eddy current losses in the rotor permanent magnets caused by stator harmonic magnetic fields. They also serve to fix the permanent magnets in place. At higher motor speeds, the sheath enhances rotor strength. The rotor yoke vents further enhance heat dissipation. This patent solves the problems of suppressing rotor permanent magnet losses and protecting the permanent magnets caused by stator harmonic magnetic fields. However, during operation, load changes and magnetic field harmonics can induce currents in the squirrel-cage damping windings, resulting in stray losses, reduced overall motor efficiency, localized overheating, and potential demagnetization of the permanent magnets. The squirrel-cage windings also cause a decrease in the motor's power factor. Furthermore, the squirrel-cage windings occupy a portion of the air gap space of the permanent magnets, leading to a decrease in the permanent magnet pole arc coefficient and a certain degree of reduction in the air gap magnetic flux density. Summary of the Invention

[0004] The purpose of this invention is to provide a lightweight Halbach permanent magnet motor rotor without a magnetic yoke, which can solve the above-mentioned problems and ensure reliable fixation of the rotor permanent magnet.

[0005] According to the technical solution provided by the present invention: a lightweight Halbach permanent magnet motor rotor without magnetic yoke includes a rotor housing, Halbach permanent magnets are installed on the inner circumference of the rotor housing, and a permanent magnet positioning structure is provided on the rotor housing.

[0006] As a further improvement of the present invention, the Halbach permanent magnet has a ring-shaped structure and is composed of several layers of Halbach permanent magnets. The outer periphery of the Halbach permanent magnet has an outer positioning groove, and the inner periphery of the Halbach permanent magnet has an inner positioning groove. The Halbach permanent magnet is composed of tangentially magnetized permanent magnets and radially magnetized permanent magnets arranged at intervals. The top surface of the tangentially magnetized permanent magnet is larger than the bottom surface, and the top two sides of the tangentially magnetized permanent magnet have top surface chamfers. The radially magnetized permanent magnet is an isosceles trapezoid, with the bottom surface of the radially magnetized permanent magnet being larger than the top surface. The two sides of the tangentially magnetized permanent magnet are in close contact with the two sides of the radially magnetized permanent magnet. The top two sides of the tangentially magnetized permanent magnet and the sides of the radially magnetized permanent magnet form an outer positioning groove, and the bottom two sides of the radially magnetized permanent magnet and the two sides of the tangentially magnetized permanent magnet form an inner positioning groove.

[0007] As a further improvement of the present invention, the permanent magnet positioning structure includes a housing positioning protrusion and a positioning strip. The housing positioning protrusion is evenly distributed on the inner wall of the rotor housing. A pressure plate is installed on the top of the rotor housing. The upper and lower ends of the Halbach permanent magnet abut against the pressure plate and the bottom of the rotor housing, respectively. The upper and lower ends of the positioning strip are installed between the pressure plate and the bottom of the rotor housing, and the positioning strip is embedded in the inner positioning groove.

[0008] As a further improvement of the present invention, the lower part of the pressure plate is provided with an upper positioning groove and the bottom of the rotor housing is provided with a lower positioning groove; the upper and lower ends of the positioning strip are located in the upper positioning groove and the lower positioning groove.

[0009] As a further improvement of the present invention, a protective sleeve groove is provided on the outer periphery of the rotor housing, and an anti-expansion sleeve is embedded in the protective sleeve groove.

[0010] As a further improvement of the present invention, the Halbach permanent magnet has a ring-shaped structure, which is composed of several radially wedge-shaped units. The radially wedge-shaped unit includes a central magnetized permanent magnet and a side magnetized permanent magnet. The side magnetized permanent magnets are located on both sides of the central magnetized permanent magnet. The axial cross-section of the central magnetized permanent magnet is quadrilateral, including the outer periphery of the central magnetized permanent magnet and the inner periphery of the central magnetized permanent magnet. The outer periphery of the central magnetized permanent magnet is larger than the inner periphery of the central magnetized permanent magnet.

[0011] As a further improvement of the present invention, an intermediate magnetized permanent magnet is provided between the center magnetized permanent magnet and the edge magnetized permanent magnet.

[0012] As a further improvement of the present invention, the permanent magnet positioning structure includes a positioning strip and a pressure plate. The positioning strip adopts a split mechanism and is composed of a first positioning strip and a second positioning strip. The pressure plate is installed on the top of the rotor housing. The lower part of the pressure plate is provided with an upper positioning groove, and the bottom of the rotor housing is provided with a lower positioning groove. One end of the first positioning strip is fixed to the upper positioning groove, and the other end is fixed to the outer periphery of the magnetized permanent magnet on one side. One end of the second positioning strip is fixed to the lower positioning groove, and the other end is fixed to the outer periphery of the magnetized permanent magnet on the other side.

[0013] As a further improvement of the present invention, the permanent magnet positioning structure includes a pressure plate, an upper limit angle is provided at the lower edge of the pressure plate, and a lower limit angle is provided at the bottom of the rotor housing; a side limit surface is provided on the inner periphery of the side magnetized permanent magnet, and the side limit surface is in contact with the upper limit angle and the lower limit angle.

[0014] The positive and progressive effects of this invention are as follows: 1. This invention uses mechanical positioning strips to fix the permanent magnet, which is more reliable than fixing with glue alone, and is still applicable to motor rotors with high speeds; 2. The positioning strip of this invention is designed in the corner area where the permanent magnet is easy to demagnetize, so as not to affect the rotor pole arc coefficient. At the same time, the positioning strip is insulated to prevent the formation of a squirrel cage and avoid adverse effects on motor efficiency, power factor and rotor pole arc coefficient. 3. This invention designs the Halbach permanent magnet in a partially or entirely wedge-shaped structure with a larger outer side and a smaller inner side in the axial direction. Combined with segmented positioning strips or wedge-shaped protrusions arranged on the rotor housing and pressure plate, the permanent magnet is effectively fixed mechanically. Even when the adhesive for the permanent magnet fails, the rotor permanent magnet can still be reliably fixed. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0016] Figure 2 This is a cross-sectional view of Embodiment 1 of the present invention.

[0017] Figure 3 These are exploded views and partial enlarged views of Embodiment 1 of the present invention.

[0018] Figure 4 This is a schematic diagram of the trapezoidal Halbach array and positioning strip 8 in Embodiment 1 of the present invention.

[0019] Figure 5 This is an axial sectional view of Embodiment 2 of the present invention.

[0020] Figure 6 This is an exploded view of the structure of Embodiment 2 of the present invention.

[0021] Figure 7This is a cross-sectional view of the Halbach permanent magnet and the permanent magnet positioning structure according to Embodiment 2 of the present invention.

[0022] Figure 8 This is an axial sectional view of Embodiment 3 of the present invention.

[0023] Figure 9 This is a schematic diagram of the Halbach permanent magnet and its positioning structure, and the radial magnetization of the Halbach permanent magnet, according to Embodiment 3 of the present invention.

[0024] Figure 10 This is a schematic diagram of the oblique magnetization of a three-sided magnetized permanent magnet according to an embodiment of the present invention. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein. Furthermore, terms such as "comprising" and "having" mean that in addition to those already listed in "comprising" and "having," other unlisted contents may also be included; for example, a process, method, system, product, or device may include a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0028] Due to the angle of the drawing, some parts may not be drawn, but their positions and connections can be understood from the text descriptions.

[0029] like Figure 1 As shown, the present invention is a lightweight Halbach permanent magnet motor rotor without a magnetic yoke, including a rotor housing 5, a Halbach permanent magnet 4 installed on the inner circumference of the rotor housing 5, and a permanent magnet positioning structure provided on the rotor housing 5.

[0030] Example 1 The Halbach permanent magnet 4 has a ring-shaped structure and is composed of several layers of Halbach permanent magnets. The layered structure helps suppress eddy current losses. In this embodiment, the Halbach permanent magnet 4 consists of four layers of Halbach permanent magnets. Figure 4 As shown, the Halbach permanent magnet 4 has an outer positioning groove 403 on its outer periphery and an inner positioning groove 404 on its inner periphery. The Halbach permanent magnet 4 consists of tangentially magnetized permanent magnets 401 and radially magnetized permanent magnets 402 arranged at intervals. The tangentially magnetized permanent magnet 401 is an isosceles trapezoid, with its top surface larger than its bottom surface, and chamfered edges on both sides of its top surface. The radially magnetized permanent magnet 402 is also an isosceles trapezoid, with its bottom surface larger than its top surface, and chamfered edges on both sides of its bottom surface. The two sides of the tangentially magnetized permanent magnet 401 are in close contact with the two sides of the radially magnetized permanent magnet 402. The chamfered edges on the top surfaces of the tangentially magnetized permanent magnet 401 and the sides of the radially magnetized permanent magnet 402 form an outer positioning groove 403. The chamfered edges on the bottom surfaces of the radially magnetized permanent magnet 402 and the two sides of the tangentially magnetized permanent magnet 401 form an inner positioning groove 404. The magnetization direction of the Halbach permanent magnet 4 is as follows: Figure 6 As shown.

[0031] The top and bottom surfaces of the tangentially magnetized permanent magnet 401 and the radially magnetized permanent magnet 402 are either flat or curved. Using a flat surface makes it easier to process, while using a curved surface results in a higher fit between the Halbach permanent magnet 4 and the rotor housing 5, and an equal distance between the Halbach permanent magnet 4 and the stator.

[0032] The permanent magnet positioning structure includes housing positioning protrusions 503 and positioning strips 8. The housing positioning protrusions 503 are evenly distributed on the inner wall of the rotor housing 5. The housing positioning protrusions 503 are arranged vertically and are triangular in shape to match the outer positioning groove 403.

[0033] The pressure plate 2 is installed on the top of the rotor housing 5 by fixing screws 1. The upper and lower ends of the Halbach permanent magnet 4 abut against the pressure plate 2 and the bottom of the rotor housing 5 respectively. The upper and lower ends of the positioning strip 8 are installed between the pressure plate 2 and the bottom of the rotor housing 5, and the positioning strip 8 is embedded in the inner positioning groove 404.

[0034] The pressure plate 2 has an upper positioning groove at its lower part, and the rotor housing 5 has a lower positioning groove 501 at its bottom. Figure 3 As shown; the upper positioning groove and the lower positioning groove 501 are blind grooves, and their shape is a triangle that matches the positioning strip 8. The upper and lower ends of the positioning strip 8 are located in the upper positioning groove and the lower positioning groove 501.

[0035] The positioning strip 8 is made of titanium alloy or other lightweight materials. The surface of the positioning strip 8 is electroplated with epoxy or passivated for insulation treatment to prevent it from forming a squirrel cage structure with the pressure plate 2 and the rotor housing 5, which would affect the motor efficiency and power factor. The positioning strip 8 must have a certain rigidity to overcome the repulsive force between permanent magnets and the centrifugal force of the rotor, and its deformation must be within acceptable limits.

[0036] The rotor housing 5 is made of aluminum alloy or magnesium-aluminum alloy, such as Figure 2 As shown, the rotor housing 5 has a protective sleeve groove on its outer periphery ( Figure 2 (Two layers are shown). Anti-expansion sleeves 3 are embedded in the sleeve groove. Anti-expansion sleeves 3 are made of carbon fiber material. A certain pre-tightening force is applied during the carbon fiber winding process to suppress the high-temperature expansion of the rotor housing 5 when the motor is working. Due to the difference in thermal expansion coefficients between the permanent magnet and the rotor housing 5, a gap is generated between the rotor housing 5 and the permanent magnet array 4, which makes it difficult for the permanent magnet to dissipate heat. The anti-expansion sleeves 3 can ensure that the rotor housing 5 is always in close contact with the permanent magnet array 4. At the same time, the outer circle protrusion of the rotor housing 5 between multiple anti-expansion sleeves 3 also provides a path for the permanent magnet to dissipate heat, which is equivalent to heat dissipation fins.

[0037] like Figure 2 As shown, the rotor shaft 6 is mounted in the rotor housing 5 via a double-row ball bearing 7.

[0038] Example 2 like Figure 5 , Figure 7As shown, the Halbach permanent magnet 4 has a ring-shaped structure, which is composed of several radially wedge-shaped units. The radially wedge-shaped unit includes a center-magnetized permanent magnet 405 and a side-magnetized permanent magnet 406. The side-magnetized permanent magnet 406 is located on both sides of the center-magnetized permanent magnet 405. One side-magnetized permanent magnet 406 is located between the pressure plate 2 and the center-magnetized permanent magnet 405, and the other side-magnetized permanent magnet 406 is located between the bottom of the rotor housing 5 and the center-magnetized permanent magnet 405. The axial cross-section of the center-mounted permanent magnet 405 is quadrilateral, including the outer periphery of the center-mounted permanent magnet 405, the inner periphery of the center-mounted permanent magnet 405, the edge of the pressure plate of the center-mounted permanent magnet 405, and the bottom edge of the shell of the center-mounted permanent magnet 405. The outer periphery of the center-mounted permanent magnet 405 is attached to the inner wall of the rotor housing 5, the inner periphery of the center-mounted permanent magnet 405 is located on the air gap side, the edge of the pressure plate of the center-mounted permanent magnet 405 faces the pressure plate 2, and the bottom edge of the shell of the center-mounted permanent magnet 405 faces the bottom of the rotor housing 5. The outer periphery of the center-mounted permanent magnet 405 is larger than the inner periphery of the center-mounted permanent magnet 405. The axial cross-section of the edge magnetized permanent magnet 406 is quadrilateral, including the outer periphery of the edge magnetized permanent magnet 406, the inner periphery of the edge magnetized permanent magnet 406, the contact edge of the edge magnetized permanent magnet 406, and the center edge of the edge magnetized permanent magnet 406. The outer periphery of the edge magnetized permanent magnet 406 is attached to the inner wall of the rotor housing 5, the inner periphery of the edge magnetized permanent magnet 406 is located on the air gap side, the contact edge of the edge magnetized permanent magnet 406 is in close contact with the pressure plate 2 or the bottom of the rotor housing 5, and the center edge of the edge magnetized permanent magnet 406 is in close contact with the edge of the pressure plate of the center magnetized permanent magnet 405 or the bottom edge of the housing of the center magnetized permanent magnet 405.

[0039] To improve and reduce eddy current losses, an intermediate magnetized permanent magnet 407 is provided between the center magnetized permanent magnet 405 and the edge magnetized permanent magnet 406. The axial cross-section of the intermediate magnetized permanent magnet 407 is quadrilateral, including the outer periphery, the inner periphery, the side, and the center edge. The outer periphery of the intermediate magnetized permanent magnet 407 is attached to the inner wall of the rotor housing 5, the inner periphery is located on the air gap side, and the side is attached to the center edge of the edge magnetized permanent magnet 406. The outer periphery is larger than the inner periphery. In this embodiment, there is one intermediate magnetized permanent magnet 407. In other embodiments, several intermediate magnetized permanent magnets 407 are provided between the center magnetized permanent magnet 405 and the edge magnetized permanent magnet 406. The 407s can also be combined into the 406 as required by the design.

[0040] The permanent magnet positioning structure includes a positioning strip 8 and a pressure plate 2. The positioning strip 8 adopts a split mechanism, such as... Figure 6As shown, it consists of a first positioning strip 801 and a second positioning strip 802. A pressure plate 2 is mounted on the top of the rotor housing 5 using fixing screws 1. The pressure plate 2 has an upper positioning groove at its lower part, and the rotor housing 5 has a lower positioning groove 501 at its bottom. One end of the first positioning strip 801 is fixed to the upper positioning groove with glue, and the other end is fixed to the outer periphery of a magnetized permanent magnet 406 on one side with glue. One end of the second positioning strip 802 is fixed to the lower positioning groove 501 with glue, and the other end is fixed to the outer periphery of a magnetized permanent magnet 406 on the other side with glue. The upper and lower positioning grooves 801 are blind grooves, with a triangular shape adapted to the first and second positioning strips 801 and 802. The split structure of the positioning strips 8 further reduces the possibility of forming a cage, and the shortened length of the positioning strips 8 reduces deformation.

[0041] The radial wedge unit reliably clamps the rotor in the axial direction, and the permanent magnet positioning structure prevents the permanent magnets from popping out under mutual repulsion. For the internal rotor motor, this can effectively enhance the ability to resist centrifugal force, increase the upper limit of rotor speed, and ensure rotor safety and reliability.

[0042] The rotor housing 5 is made of aluminum alloy or magnesium-aluminum alloy, the anti-expansion sleeve 3 is made of carbon fiber or glass fiber composite material, and the positioning strip 8 is made of titanium alloy or stainless steel.

[0043] Example 3 like Figure 8 As shown, based on Embodiment 2, the first positioning strip 801 and the second positioning strip 80 are removed. Instead, an upper limit angle 201 is provided at the lower edge of the pressure plate 2, and a lower limit angle 502 is provided at the bottom of the rotor housing 5; correspondingly, a side-position limiting surface is provided on the inner circumference of the side-position magnetized permanent magnet 406, and the side-position limiting surface contacts the upper limit angle 201 and the lower limit angle 502. In this embodiment, the magnetization direction of the radial wedge unit is as follows... Figure 9 As shown.

[0044] In other embodiments, the magnetization direction of the radial wedge unit is as follows: Figure 10 As shown, the magnetization direction of the edge-magnetized permanent magnet 406 is inclined towards the middle, forming a certain magnetic concentration effect, changing the distribution of the air gap magnetic field at the rotor end, enhancing the air gap magnetic density, and further improving the power density of the permanent magnet motor.

[0045] With the above structure, it is possible to place barrier strips in the corner areas of the permanent magnet that are prone to demagnetization, or to design part or all of the permanent magnet as a wedge-shaped structure with a larger outer side and a smaller inner side. This effectively protects the permanent magnet without affecting the rotor pole arc coefficient of the motor, thus improving the utilization rate of the magnet.

[0046] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A lightweight Halbach permanent magnet motor rotor without a magnetic yoke, comprising a rotor housing (5), characterized in that, Halbach permanent magnets (4) are installed on the inner circumference of the rotor housing (5), and a permanent magnet positioning structure is provided on the rotor housing (5).

2. The lightweight Halbach permanent magnet motor with a yokeless rotor as described in claim 1, characterized in that, The Halbach permanent magnet (4) has a ring-shaped structure and is composed of several layers of Halbach permanent magnets. The outer circumference of the Halbach permanent magnet (4) is provided with an outer positioning groove (403), and the inner circumference of the Halbach permanent magnet (4) is provided with an inner positioning groove (404). The Halbach permanent magnet (4) is composed of tangentially magnetized permanent magnets (401) and radially magnetized permanent magnets (402) arranged at intervals. The top surface of the tangentially magnetized permanent magnet (401) is larger than the bottom surface, and the top two sides of the tangentially magnetized permanent magnet (401) are... The top surface is chamfered; the radially magnetized permanent magnet (402) is an isosceles trapezoid, the bottom surface of the radially magnetized permanent magnet (402) is larger than the top surface, the two sides of the tangentially magnetized permanent magnet (401) are in close contact with the two sides of the radially magnetized permanent magnet (402), the top chamfers on both sides of the top of the tangentially magnetized permanent magnet (401) and the sides of the radially magnetized permanent magnet (402) form an outer positioning groove (403), and the bottom chamfers on both sides of the bottom of the radially magnetized permanent magnet (402) and the sides of the tangentially magnetized permanent magnet (401) form an inner positioning groove (404).

3. The lightweight Halbach permanent magnet motor with a yoke-less rotor as described in claim 2, characterized in that, The permanent magnet positioning structure includes a housing positioning protrusion (503) and a positioning strip (8). The housing positioning protrusion (503) is evenly distributed on the inner wall of the rotor housing (5). A pressure plate (2) is installed on the top of the rotor housing (5). The upper and lower ends of the Halbach permanent magnet (4) abut against the pressure plate (2) and the bottom of the rotor housing (5) respectively. The upper and lower ends of the positioning strip (8) are installed between the pressure plate (2) and the bottom of the rotor housing (5). The positioning strip (8) is embedded in the inner positioning groove (404).

4. The lightweight Halbach permanent magnet motor with a yoke-less rotor as described in claim 3, characterized in that, The pressure plate (2) has an upper positioning groove at the bottom and the rotor housing (5) has a lower positioning groove (501) at the bottom; the positioning strip (8) is located in the upper positioning groove and the lower positioning groove (501) at both ends.

5. The lightweight Halbach permanent magnet motor with a yokeless rotor as described in claim 1, characterized in that, The outer periphery of the rotor housing (5) is provided with a protective sleeve groove, and an anti-expansion sleeve (3) is embedded in the protective sleeve groove.

6. The lightweight Halbach permanent magnet motor with a yokeless rotor as described in claim 1, characterized in that, The Halbach permanent magnet (4) has a ring structure and is composed of several radially wedged units. The radially wedged units include a central magnetized permanent magnet (405) and a side magnetized permanent magnet (406). The side magnetized permanent magnet (406) is located on both sides of the central magnetized permanent magnet (405). The axial cross-section of the central magnetized permanent magnet (405) is quadrilateral, including the outer periphery of the central magnetized permanent magnet (405) and the inner periphery of the central magnetized permanent magnet (405). The outer periphery of the central magnetized permanent magnet (405) is larger than the inner periphery of the central magnetized permanent magnet (405).

7. The lightweight Halbach permanent magnet motor with a yokeless rotor as described in claim 6, characterized in that, An intermediate magnetized permanent magnet (407) is provided between the center magnetized permanent magnet (405) and the edge magnetized permanent magnet (406).

8. The lightweight Halbach permanent magnet motor with a yokeless rotor as described in claim 6, characterized in that, The permanent magnet positioning structure includes a positioning strip (8) and a pressure plate (2). The positioning strip (8) adopts a split mechanism and is composed of a first positioning strip (801) and a second positioning strip (802). The pressure plate (2) is installed on the top of the rotor housing (5). The pressure plate (2) has an upper positioning groove at the bottom and a lower positioning groove (501) at the bottom of the rotor housing (5). One end of the first positioning strip (801) is fixed in the upper positioning groove, and the other end is fixed on the outer periphery of the magnetized permanent magnet (406) on one side. One end of the second positioning strip (802) is fixed in the lower positioning groove (501), and the other end is fixed on the outer periphery of the magnetized permanent magnet (406) on the other side.

9. The lightweight Halbach permanent magnet motor with a yokeless rotor as described in claim 6, characterized in that, The permanent magnet positioning structure includes a pressure plate (2), with an upper limit angle (201) set at the lower edge of the pressure plate (2) and a lower limit angle (502) set at the bottom of the rotor housing (5); the inner circumference of the side-position magnetized permanent magnet (406) is provided with a side-position limiting surface, which is in contact with the upper limit angle (201) and the lower limit angle (502).

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