A magnetic gear composite pseudo direct drive motor for robot joint drive

Abstract

The present invention discloses a magnetic gear composite pseudo-direct drive motor for robot joint drive, comprising an outer permanent magnet rotor, a modulation rotor, and an inner stator, which are concentrically nested from the outside to the inside in the radial direction. The inner stator comprises a first inner permanent magnet ring, an armature stator, and a second inner permanent magnet ring, which are coaxially arranged from front to back in the axial direction. Air gaps exist between the outer permanent magnet rotor and the modulation rotor, and between the modulation rotor and the first inner permanent magnet ring, the armature stator, and the second inner permanent magnet ring. The first inner permanent magnet ring and the second inner permanent magnet ring each comprise a magnetic conductive block, a permanent magnet, and a magnetic isolation ring. The magnetic conductive blocks and the permanent magnets are alternately arranged circumferentially. The first inner permanent magnet ring and the second inner permanent magnet ring are connected to the armature stator via the magnetic isolation ring. The axial arrangement of the inner permanent magnet ring and the armature stator enables the motor to have a higher air gap flux density and a more flexible magnetic gear reduction ratio design, expanding the application prospects of the motor in the field of robot joint drive.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic gear composite pseudo direct drive motors, and in particular relates to a magnetic gear composite pseudo direct drive motor for robot joint driving. Background Art

[0002] Motors and reducers are the core components of robotic joint modules. Traditional robotic joint modules typically connect motors to mechanical gear reducers to amplify torque and achieve low-speed, high-torque transmission. However, the meshing of mechanical gears can easily generate friction, heat, and vibration noise. These problems become more severe due to wear and tear over time, affecting the proper functioning of the reducer.

[0003] To address these issues, Huang Hailin et al. proposed a Halbach continuous-pole pseudo-direct-drive motor, comprising an armature stator with 18 tooth slots, 18 pairs of Halbach permanent magnets embedded in the slots, a modulating rotor with 22 magnetic modulation blocks, and a four-pole continuous-pole permanent magnet rotor. The Halbach permanent magnets, modulating rotor, and permanent magnet rotor constitute the magnetic field modulation magnetic gear section with a reduction ratio of 5.5; the armature stator, modulating rotor, and permanent magnet rotor constitute the motor section (Huang Hailin, Li Dawei, Kong Wubing, and Qu Ronghai. “Torque Performance of Pseudo Direct-Drive Machine with Halbach Consequent Pole” in 2018 IEEE Energy Conversion Congress and Exposition (ECCE), Sep. 2018, pp. 3286-3293). During operation, current flows through the outer armature stator, driving the permanent magnet rotor. This also applies a magnetic drag torque to the modulating rotor. This torque, amplified by the magnetic gear effect, acts on the modulating rotor, where it, along with the magnetic drag torque, drives the load and operates at a specific reduction ratio, achieving low-speed, high-torque, contactless transmission. However, the motor's stator slot-mounted permanent magnets limit the design of the magnetic gear reduction ratio. Furthermore, the slotted permanent magnets lack back iron, which reduces the magnetic gear's maximum transmittable torque to a certain extent.

[0004] Chinese invention patent publication number CN112713737A discloses a two-stage magnetic gear transmission motor for robot joint drive. A magnetic field modulation magnetic gear is integrated into the inner stator shaft hole of an outer rotor vernier motor, fixed by a magnetic isolation ring to form a radial composite structure. The outer permanent magnet rotor of the vernier motor and the high-speed rotor of the magnetic field modulation magnetic gear are fixedly connected. When the motor is operating, current flows into the armature stator, driving the outer permanent magnet rotor of the vernier motor and the high-speed rotor of the magnetic field modulation magnetic gear to rotate at a certain reduction ratio, achieving a first-stage reduction by utilizing the principle of the vernier motor. The high-speed rotor then drives the modulation rotor to rotate at a low speed through the magnetic gear effect, achieving a second-stage reduction. This motor achieves contactless transmission and has the characteristics of low speed and high torque. It also overcomes the problem of low transmission ratio of the first-stage magnetic gear. However, the three-layer air gap structure of this motor will undoubtedly increase the size and processing difficulty of the joint motor, and the amount of permanent magnets used is relatively large.

[0005] At present, the magnetic gear composite motors for robot joint drive have the problems of large size and complex structure, and some solutions are not conducive to the design of magnetic gear reduction ratio due to structural limitations. Therefore, a magnetic gear composite pseudo-direct drive motor for robot joint drive is proposed, which can overcome the above defects and is expected to promote the development of magnetic transmission in the field of robot joint drive, which has practical significance and good application prospects. Summary of the Invention

[0006] In order to at least solve one of the shortcomings of the existing technology, the present invention provides a magnetic gear composite pseudo-direct drive motor for robot joint drive, which can realize contactless transmission of robot joints and has the characteristics of low speed, high torque and compact structure. The magnetic gear reduction ratio is flexible in design, which greatly expands the application prospects of the motor in the field of robot joint drive.

[0007] To achieve the purpose of the present invention, the present invention provides a magnetic gear composite pseudo direct drive motor for robot joint drive, comprising an outer permanent magnet rotor, a modulation rotor and an inner stator which are concentrically nested in sequence from the outside to the inside in the radial direction;

[0008] The inner stator includes a first inner permanent magnet ring, an armature stator, and a second inner permanent magnet ring, which are coaxially arranged from front to back in the axial direction. There are air gaps between the outer permanent magnet rotor and the modulation rotor, and between the modulation rotor and the first inner permanent magnet ring, the armature stator, and the second inner permanent magnet ring. The first inner permanent magnet ring and the second inner permanent magnet ring both include magnetic conductive blocks, permanent magnets, and magnetic isolation rings. The magnetic conductive blocks and permanent magnets are alternately arranged circumferentially. The first inner permanent magnet ring and the second inner permanent magnet ring are connected to the armature stator through magnetic isolation rings.

[0009] There is an air gap between the outer permanent magnet rotor and the modulation rotor, and there is also an air gap between the modulation rotor and the first inner permanent magnet ring, the armature stator, and the second inner permanent magnet ring. The axial arrangement of the first inner permanent magnet ring, the armature stator, and the second inner permanent magnet ring makes the distance between the modulation rotor and the three equal.

[0010] Preferably, the outer rotor permanent magnet comprises an iron yoke and a first permanent magnet with alternating polarity and radial magnetization, which are concentrically nested in sequence from the outside to the inside in the radial direction.

[0011] Preferably, the modulation rotor comprises a plurality of magnetic modulation blocks, which are tile-shaped units made of magnetic conductive material, and the plurality of tile-shaped units are evenly arranged along the circumference to form the modulation rotor.

[0012] Preferably, the number of pole pairs P of the outer permanent magnet rotor is o , the number of magnetic blocks Z of the modulating rotor m , and the number of pole pairs P of the inner permanent magnet ring i The following relationship is satisfied: Z m =P o +P i , that is, the number of pole pairs generated by the external permanent magnet is P o The magnetic field is modulated by the modulating rotor to produce a pole pair number Z m -P o The magnetic field, and the number of pole pairs of the internal permanent magnet P i Matching, thus generating torque.

[0013] Preferably, different reduction ratios are designed by adjusting the number of pole pairs of the inner permanent magnet ring and the number of magnetic modulation blocks of the modulation rotor.

[0014] Preferably, the first inner permanent magnet ring and the second inner permanent magnet ring both comprise magnetic conductive blocks and permanent magnets alternately arranged circumferentially. The permanent magnets are magnetized circumferentially, and adjacent permanent magnets are magnetized in opposite directions, thereby introducing a magnetic concentration effect.

[0015] Preferably, the axial length of the magnetic conductive block is shorter than that of the permanent magnet, and the shorter magnetic conductive block corresponds one-to-one to the salient pole teeth of the magnetic isolation ring. One side of the magnetic isolation ring contains a plurality of evenly arranged salient pole teeth corresponding to the shorter magnetic conductive block, and the other side is connected to the armature stator. The magnetic isolation ring plays the role of magnetic isolation, positioning, fixing and connection.

[0016] The magnetic blocks and permanent magnets are arranged alternately, and the axial length of the magnetic blocks is set to be smaller than that of the permanent magnets. This is to allow the shorter magnetic blocks to match the salient pole teeth of the magnetic isolation ring. Such a structure can play a role in fixing, supporting and positioning, and facilitates the installation of the magnetic blocks and permanent magnets.

[0017] Preferably, the magnetic isolation ring is made of magnetic isolation material.

[0018] The second inner permanent magnet ring has the same structure as the first inner permanent magnet ring, both comprising a magnetic block, permanent magnets, and a magnetic isolation ring. They are symmetrically distributed about the armature stator. The axial arrangement of the inner permanent magnet ring and the armature stator frees the inner permanent magnet ring from the constraints of the stator slots, allowing for more flexible reduction ratio design.

[0019] Preferably, the axial length L of the outer permanent magnet rotor and the modulation rotor is a The axial length L1 of the first inner permanent magnet ring and the second inner permanent magnet ring and the axial length L2 of the armature stator satisfy L a =2*L1+L2, that is, the permanent magnet ring and the armature stator are arranged axially, and the sum of their axial lengths is equal to the axial length of the outer permanent magnet rotor or the modulation rotor.

[0020] Preferably, different reduction ratios are designed by adjusting the number of pole pairs of the inner permanent magnet ring and the number of magnetic modulation blocks of the modulation rotor.

[0021] Preferably, the outer permanent magnet rotor, the modulation rotor, the first inner permanent magnet ring and the second inner permanent magnet ring together constitute a magnetic field modulation magnetic gear part, the outer permanent magnet rotor and the armature stator together constitute a permanent magnet synchronous motor part, and the permanent magnet synchronous motor and the magnetic field modulation magnetic gear share an outer permanent magnet rotor.

[0022] Preferably, the magnetic gear composite pseudo direct drive motor is applied in the field of robot joint drive. Three-phase sinusoidal alternating current is introduced into the armature stator, and the electromagnetic torque is generated by the magnetic field of the external permanent magnet rotor, and the external permanent magnet rotor is driven to rotate at a synchronous speed. The external permanent magnet rotor amplifies the electromagnetic torque through the magnetic gear effect and transmits it to the modulation rotor. The external permanent magnet rotor is subjected to a reverse torque from the magnetic gear effect, which offsets the electromagnetic torque. Therefore, the external permanent magnet rotor is in an idling state, and the modulation rotor is connected to the robot joint load, driving the load to move at low speed and high torque.

[0023] Compared with the existing technology, the present invention can at least bring the following beneficial effects:

[0024] (1) The novel magnetic gear composite pseudo direct drive motor proposed in the present invention arranges the inner permanent magnet ring and the armature stator axially, thereby improving the air gap magnetic permeability of the permanent magnet synchronous motor part, thereby greatly improving the air gap magnetic density of the motor, and thus improving the electromagnetic torque of the motor.

[0025] (2) The novel magnetic gear composite pseudo direct drive motor proposed in the present invention has an axially placed inner permanent magnet ring structure, which frees it from the limitation of the number of stator slots, improves the flexibility of the reduction ratio selection of the magnetic gear part, and greatly expands the application prospects of the motor.

[0026] (3) The new type of magnetic gear composite pseudo direct drive motor proposed in the present invention has a motor part and a magnetic gear part that share an external permanent magnet rotor. It has a compact structure, a high utilization rate of permanent magnets, and only two layers of air gaps. It does not significantly increase the processing difficulty of the magnetic gear composite motor and can meet the requirements of robot joint motors for small size, high torque and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0028] Figure 1 It is a three-dimensional diagram of the overall structure of an embodiment of the present invention, in which the inner permanent magnet ring adopts the form of an exploded diagram.

[0029] Figure 2 Schematic cross-sectional view of the magnetic gear portion in an embodiment of the present invention.

[0030] Figure 3 Schematic diagram of the cross section of the motor part in an embodiment of the present invention.

[0031] Figure 4 It is a three-dimensional diagram of the inner stator in an embodiment of the present invention.

[0032] Figure 5 It is a stereoscopic diagram of the internal and external permanent magnet rotors and the modulation rotor in an embodiment of the present invention.

[0033] Figure 6 1 is an exploded view of the inner permanent magnet ring in an embodiment of the present invention.

[0034] The accompanying drawings in the present invention are:

[0035] 1: External permanent magnet rotor, including 101 iron yoke and 102 first permanent magnet.

[0036] 2: Modulate the rotor.

[0037] 3: The first inner permanent magnet ring includes 301 a first magnetic conductive block, 302 a second permanent magnet and 303 a first magnetic isolation ring.

[0038] 4: The second inner permanent magnet ring includes a second magnetic conductive block 401, a third permanent magnet 402 and a second magnetic isolation ring 403.

[0039] 5: Armature stator, including 501 stator core and 502 armature winding. DETAILED DESCRIPTION

[0040] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0041] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0042] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0043] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0044] like Figure 1 As shown, the present invention provides a magnetic gear composite pseudo direct drive motor for robot shutdown, comprising an outer permanent magnet rotor 1, a modulation rotor 2 and an inner stator which are concentrically nested from the outside to the inside in the radial direction; the inner stator comprises a first inner permanent magnet ring 3, an armature stator 5 and a second inner permanent magnet ring 4 which are coaxially arranged from front to back in the axial direction; there is an air gap between the outer permanent magnet rotor 1 and the modulation rotor 2, which is called the outer air gap of the motor, with a length of h1, and there is also an air gap between the modulation rotor 2 and the first inner permanent magnet ring 3, the armature stator 5 and the second inner permanent magnet ring 4, which is called the inner air gap of the motor, with a length of h1. That is, the provided magnetic gear composite pseudo direct drive motor has a double-layer air gap structure.

[0045] In some embodiments of the present invention, the above-mentioned magnetic gear composite pseudo direct drive motor, the outer permanent magnet rotor 1 includes an iron yoke 101 and a plurality of first permanent magnets 102 located inside the iron yoke 101. Preferably, the number of permanent magnet pole pairs P o =5, radial magnetization is adopted, and the magnetization directions of adjacent first permanent magnets 102 are opposite; the material used for the first permanent magnets 102 is neodymium iron boron.

[0046] The modulation rotor 2 includes a plurality of magnetic adjustment blocks, and the magnetic adjustment blocks are evenly arranged along the circumference. In some embodiments of the present invention, the modulation rotor 2 includes Z m= 26 magnetic modulation blocks are evenly arranged along the circumference, which can modulate the magnetic field with a small number of pole pairs generated by the outer permanent magnet rotor 1 to generate a magnetic field with a large number of pole pairs, and interact with the magnetic field with the same number of pole pairs generated by the inner permanent magnet ring to transmit torque, that is, the number of pole pairs of the outer permanent magnet P o , Modulate the number of rotor magnetic blocks Z m and the number of pole pairs of the inner permanent magnet ring P i Between: Z m =P o +P i .

[0047] In some embodiments of the present invention, the first inner permanent magnet ring 3 comprises a plurality of first conductive blocks 301, a plurality of second permanent magnets 302 and a first magnetic isolation ring 303, wherein the first conductive blocks 301 and the second permanent magnets 302 are alternately arranged, and the axial length of the first conductive blocks 301 is smaller than the axial length of the second permanent magnets 302, and the shorter first conductive blocks 301 correspond to the salient pole teeth of the first magnetic isolation ring 303; among the plurality of second permanent magnets 302, the second permanent magnets 302 are magnetized along the circumferential direction, and the magnetization directions of two adjacent second permanent magnets 302 are opposite, such as Figure 2 Preferably, the number of pole pairs P of the first inner permanent magnet ring 3 is i =21, each pair of poles contains 2 permanent magnets and 2 magnetic blocks, and the circumferential angle occupied by each pair of poles is:

[0048]

[0049] like Figure 6 As shown, the first magnetic isolation ring 303 has 2*P i A salient pole tooth is used to correspond to the shorter first magnetic conductive block 301 on the first inner permanent magnet ring 3, and is used to support and position the first inner permanent magnet ring 3. In addition, the first magnetic isolation ring 303 also serves to isolate the magnetic field and the excitation magnetic field generated by the first inner permanent magnet ring 3; after the first magnetic isolation ring 303 has a side with salient pole teeth and is integrated with the second permanent magnet 302 and the first magnetic conductive block 301, it can be axially connected to the stator core 501 through the other side of the first magnetic isolation ring 303. The modular structure of the first inner permanent magnet ring 3 facilitates the installation and maintenance of the motor, and is also convenient for flexible adjustment of the pole pair number of the first inner permanent magnet ring 3, expanding the choice of reduction ratio of the magnetic gear compound motor.

[0050] In some embodiments of the present invention, the second inner permanent magnet ring 4 includes a second magnetic conductive block 401, a third permanent magnet 402 and a second magnetic isolation ring 403. Its structure and configuration are completely consistent with the first inner permanent magnet ring 3, and it is symmetrical with the first inner permanent magnet ring 3 about the armature stator, and together constitute the multi-pole stator part of the magnetic field modulation magnetic gear.

[0051] The armature stator 5 includes a stator core 501 and an armature winding 502. In some embodiments of the present invention, the stator core 501 is made of laminated silicon steel sheets and has a 12-slot structure. In addition, there are concave annular structures on both sides of the stator core 501 near the stator teeth, which are used to position and support the annular inner permanent magnet ring. The height of the concave structure is consistent with the height of the yoke of the magnetic isolation ring. The armature winding 502 is wound with copper wire using a concentrated winding and star-connected winding method. A total of three-phase windings A, B, and C are provided, and each phase winding is wound around four teeth in series.

[0052] like Figure 2 As shown, the outer permanent magnet rotor 1, the modulation rotor 2, the first inner permanent magnet ring 3 and the second inner permanent magnet ring 4 together constitute the magnetic gear part of the magnetic gear composite pseudo direct drive motor. In some embodiments of the present invention, combined with the specific values ​​of the relevant parameters given above, its working principle is: the outer permanent magnet rotor 1 generates a pole pair number P o =5 magnetic field modulated by the rotor Z m = Magnetic field modulation of 26 magnetic blocks, generating multi-pole pair Z m -P o = 21, which generates a pole pair number P with the inner permanent magnet ring. i =21, that is, Z m -P o =P i , thus being able to function as a magnetic gear. The outer permanent magnet rotor 1 acts as a high-speed rotor, and the modulation rotor 2 acts as a low-speed rotor. They rotate in the same direction, while the inner permanent magnet ring is stationary. Therefore, the reduction ratio G of the magnetic gear is:

[0053]

[0054] In some embodiments of the present invention, Figure 3 As shown, the outer permanent magnet rotor 1, the modulation rotor 2 and the armature stator 5 together constitute the motor part of the magnetic gear composite pseudo direct drive motor, wherein the speed n of the outer permanent magnet rotor 2 is r =3000rpm, pole pair number P o =5, the armature winding 502 is passed through an electric frequency Three-phase sinusoidal alternating current, with current i d = 0, the armature magnetic field and the magnetic field generated by the external permanent magnet rotor 1 interact to produce a constant torque. Therefore, the working principle of the motor part of the proposed motor is similar to that of the surface-mounted permanent magnet synchronous motor. The difference is that the motor part of the proposed motor has an additional intermediate modulation rotor 2 to contribute to the average air gap magnetic permeance.

[0055] like Figure 4 and Figure 5As shown, the outer permanent magnet rotor 1 and the modulation rotor 2 are the rotor parts of the proposed magnetic gear composite pseudo direct drive motor. The outer permanent magnet rotor 1 is a high-speed rotor, and the modulation rotor 2 is a low-speed rotor. Their axial lengths are the same, both L a The first inner permanent magnet ring 3, the armature stator 5 and the second inner permanent magnet ring 4 constitute the inner stator, and their axial lengths are L1, L2 and L1, respectively, and the three are arranged in axial order, L a , the relationship between L1 and L2 satisfies: L a =2*L1+L2.

[0056] The working principle of the magnetic gear composite pseudo direct drive motor for robot joint driving provided by the above embodiment of the present invention is: when a three-phase sinusoidal AC current of a certain frequency is applied to the armature winding 502, the armature magnetic field and the excitation magnetic field with the same number of pole pairs interact to generate an electromagnetic torque T e , and drives the outer permanent magnet rotor 1 to rotate at synchronous speed n r When the outer permanent magnet rotor 1 and the modulation rotor 2 have a certain mechanical angle difference, due to the magnetic gear effect, the outer permanent magnet rotor 1 will be subjected to a torque T1 that is equal to and opposite to the electromagnetic torque, that is, it satisfies: T e =-T1.

[0057] Therefore, the outer permanent magnet rotor 1 is in an idling state during normal operation. At the same time, the modulation rotor 2 is subjected to a torque T2 amplified by the magnetic gear effect and rotates in the same direction as the outer permanent magnet rotor 1 at a certain reduction ratio G. Therefore, the torque T2 and speed n2 of the modulation rotor 2 satisfy:

[0058]

[0059] The modulating rotor 2 drives the robot joint load to operate with the output torque T2, which can achieve contactless, low-speed and high-torque output.

[0060] The motor provided in the aforementioned embodiment of the present invention adopts a structure in which the inner permanent magnet ring and the armature stator are axially arranged, so that the magnetic gear composite pseudo-direct drive motor proposed in the present invention has a higher air gap magnetic density and can make the magnetic gear reduction ratio design more flexible, thereby expanding the application prospects of the motor in the field of robot joint drive.

[0061] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A magnetic gear composite pseudo direct drive motor for robot joint drive, characterized in that: It includes an outer permanent magnet rotor, a modulation rotor and an inner stator which are concentrically nested in sequence from the outside to the inside in the radial direction; The inner stator includes a first inner permanent magnet ring, an armature stator and a second inner permanent magnet ring which are coaxially arranged from front to back in the axial direction. There is an air gap between the outer permanent magnet rotor and the modulation rotor, and between the modulation rotor and the first inner permanent magnet ring, the armature stator and the second inner permanent magnet ring; the first inner permanent magnet ring and the second inner permanent magnet ring both include magnetic conductive blocks, permanent magnets and magnetic isolation rings, the magnetic conductive blocks and permanent magnets are arranged alternately in the circumferential direction, and the first inner permanent magnet ring and the second inner permanent magnet ring are connected to the armature stator through the magnetic isolation ring, wherein the first inner permanent magnet ring and the second inner permanent magnet ring both include multiple magnetic conductive blocks and multiple permanent magnets arranged alternately in the circumferential direction, the axial length of the magnetic conductive blocks is shorter than that of the permanent magnets, one side of the magnetic isolation ring includes multiple salient pole teeth, which correspond one-to-one to the magnetic conductive blocks, and the other side is connected to the armature stator.

2. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 1, characterized in that: The outer permanent magnet rotor includes an iron yoke and a radially magnetized first permanent magnet which are concentrically nested in sequence from the outside to the inside in the radial direction.

3. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 1, characterized in that: The modulation rotor includes a plurality of magnetic modulation blocks, and the magnetic modulation blocks are evenly arranged along the circumference.

4. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 3, characterized in that: Number of pole pairs of the external permanent magnet rotor , the number of magnetic blocks of the modulating rotor , and the number of pole pairs of the inner permanent magnet ring The following relations are satisfied: .

5. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 3, characterized in that: Different reduction ratios can be designed by adjusting the number of pole pairs of the inner permanent magnet ring and the number of magnetic modulation blocks of the modulating rotor.

6. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 1, characterized in that: The permanent magnets are magnetized circumferentially, and adjacent permanent magnets are magnetized in opposite directions.

7. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 1, characterized in that: The axial length of the outer permanent magnet rotor and the modulating rotor is The axial lengths of the first inner permanent magnet ring and the second inner permanent magnet ring are , the axial length of the armature stator is , their relationship satisfies the following formula: .

8. The magnetic gear composite pseudo direct drive motor for robot joint drive according to claim 1, characterized in that: The outer permanent magnet rotor, the modulation rotor, the first inner permanent magnet ring and the second inner permanent magnet ring constitute a magnetic field modulation magnetic gear part, the outer permanent magnet rotor and the armature stator constitute a permanent magnet synchronous motor part, and the permanent magnet synchronous motor and the magnetic field modulation magnetic gear share an outer permanent magnet rotor.

9. Application of the magnetic gear composite pseudo direct drive motor according to any one of claims 1 to 8 in the field of robot joint drive, characterized in that: Three-phase sinusoidal alternating current is supplied to the armature stator, which reacts with the external permanent magnet rotor to generate electromagnetic torque and drive the external permanent magnet rotor to rotate. The external permanent magnet rotor transmits the electromagnetic torque to the modulation rotor through the magnetic gear effect generated by the modulation rotor and the inner permanent magnet magnetic ring, and finally drives the robot joint load to rotate. The reverse torque from the magnetic gear effect on the external permanent magnet rotor is offset by the electromagnetic torque, and the external permanent magnet rotor is in an idling state.

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