Motor and direct-drive rotary table

Abstract

The utility model discloses a motor and a direct-drive rotary table, and the motor comprises a rotor assembly which comprises a rotor yoke and permanent magnets, the rotor yoke is provided with an annular groove, and the permanent magnets comprise an outer radial magnetic flux permanent magnet, an inner radial magnetic flux permanent magnet and an axial magnetic flux permanent magnet; the stator assembly comprises a stator yoke and a coil winding, the stator yoke is annular, one end of the stator yoke extends in the axial direction and extends into the annular groove, the other end of the stator yoke is installed on the cooling plate, and the coil winding is wound on the stator yoke; the coil winding includes a first side facing the outer radial flux permanent magnets, a second side facing the axial flux permanent magnets, a third side facing the inner radial flux permanent magnets, and a fourth side facing the cooling plate. According to the utility model, one side of the coil winding is directly cooled by the cooling plate, so that the extreme heat dissipation of the motor is realized, the other three sides participate in electromagnetic reaction and provide electromagnetic torque, and the annular winding is utilized in an extreme manner, so that the cooling efficiency of the motor is greatly enhanced, and the torque density of the motor is greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to motor technical field, in particular to a motor and direct drive rotary table. BACKGROUND

[0002] Numerical control rotary table adopts direct drive motor, avoids the precision loss of transmission mechanism such as worm gear, ball screw, gear reducer, and is matched with high-precision servo driver and position sensor, and will have the characteristics of high precision, high reliability, fast response, high efficiency and low noise, and the direct drive rotary table has the above-mentioned obvious advantages, and has become the preferred of high-grade four-axis and five-axis numerical control machine tool.

[0003] In addition to high precision, the excellent performance of the direct drive rotary table also requires high load capacity, that is, the motor of the direct drive rotary table should have high torque output capacity, or the direct drive rotary table with higher torque output capacity will be more competitive under the same installation space and quality requirements, and the high-torque motor requires higher heat dissipation effect, so how to make the supporting motor of the direct drive rotary table have higher torque and better heat dissipation effect has become a hot topic. UTILITY MODEL CONTENTS

[0004] The utility model discloses a motor and direct drive rotary table.

[0005] The utility model discloses the technical scheme that the technical problem is solved to it is:

[0006] First, a motor, comprising:

[0007] Rotor assembly, including rotor yoke and permanent magnet, the rotor yoke extends to the second end face along the axial direction from the first end face, the first end face is equipped with the annular groove extending to the second end face along the axial direction, the annular groove is cut off before extending to the second end face, the permanent magnet includes the outer radial magnetic flux permanent magnet of setting in the outer diameter direction inner wall surface of the annular groove, the inner radial magnetic flux permanent magnet of setting in the inner diameter direction inner wall surface of the annular groove and the axial magnetic flux permanent magnet of setting in the axial direction inner wall surface of the annular groove;

[0008] Stator assembly, including stator yoke and coil winding, the stator yoke is annular, one end of the stator yoke extends along the axial direction and stretches into the annular groove, the other end of the stator yoke is installed on the cooling plate, the coil winding is around the stator yoke, the coil winding includes the first side towards the outer radial magnetic flux permanent magnet, the second side towards the axial magnetic flux permanent magnet, the third side towards the inner radial magnetic flux permanent magnet and the fourth side towards the cooling plate.

[0009] With reference to the first aspect, in some implementations of the first aspect, the outer radial flux permanent magnet, the axial flux permanent magnet and the inner radial flux permanent magnet located in the same radial section form a group of permanent magnets, a plurality of groups of the permanent magnets are arranged along the circumferential direction of the annular slot, each group of the permanent magnets forms a U-shaped space in the annular slot, the magnetic pole directions of each group of the permanent magnets towards the inner side of the U-shaped space are the same, and the magnetic poles of the plurality of groups of the permanent magnets along the circumferential direction of the annular slot are alternately arranged as N poles and S poles.

[0010] With reference to the first aspect and the above implementation, in some implementations of the first aspect, the middle part of the rotor yoke is provided with an axle hole.

[0011] With reference to the first aspect and the above implementation, in some implementations of the first aspect, the cooling plate comprises a cooling water cover and a water cover plate, the stator yoke is installed on the cooling water cover, the cooling water cover is provided with a cooling water groove at a position corresponding to the stator yoke, the water cover plate is connected to the cooling water cover and covers the cooling water groove, and the cooling water cover and / or the water cover plate are provided with an inlet and an outlet in communication with the cooling water groove.

[0012] With reference to the first aspect and the above implementation, in some implementations of the first aspect, the cooling water groove is arranged on the side surface of the cooling water cover away from the stator yoke, and the cooling water groove is an annular groove extending along the circumferential direction of the stator yoke.

[0013] With reference to the first aspect and the above implementation, in some implementations of the first aspect, the middle part of the cooling water cover is provided with a through hole corresponding to the axle hole, and the water cover plate is installed on the cooling water cover from the side away from the stator yoke and covers the through hole.

[0014] With reference to the first aspect and the above implementation, in some implementations of the first aspect, the stator yoke is provided with a plurality of radial winding grooves, the plurality of radial winding grooves are arranged along the circumferential direction of the stator yoke, the radial winding groove comprises an outer circumferential surface groove, a first end surface groove, an inner circumferential surface groove and a second end surface groove along the winding direction, the coil winding comprises a plurality of annular winding units wound in each radial winding groove, a first side of the annular winding unit is located in the outer circumferential surface groove, a second side of the annular winding unit is located in the first end surface groove, a third side of the annular winding unit is located in the inner circumferential surface groove, and a fourth side of the annular winding unit is located in the second end surface groove.

[0015] With reference to the first aspect and the above implementation manners, in some implementation manners of the first aspect, the stator yoke comprises a radial yoke ring and an axial yoke iron, the radial yoke ring comprises a plurality of first laminations arranged in layers, the first laminations comprise annular sheets, outer circumferential wings of the annular sheets are provided to extend outward in the radial direction, inner circumferential wings of the annular sheets are provided to extend inward in the radial direction, the outer circumferential face grooves are formed between adjacent outer circumferential wings, the inner circumferential face grooves are formed between adjacent inner circumferential wings, and the axial yoke iron comprises a plurality of second laminations arranged in layers, the axial yoke iron is connected to both ends of the radial yoke ring corresponding to the outer circumferential wings and the inner circumferential wings, and first end face grooves and second end face grooves are formed at both ends of the radial yoke ring.

[0016] With reference to the first aspect and the above implementation manners, in some implementation manners of the first aspect, the radial yoke ring and the axial yoke iron are provided with axial holes, and the radial yoke ring and the axial yoke iron are connected to the cooling plate through the pull rods arranged in the axial holes.

[0017] The second aspect discloses a direct-drive rotating table comprising the motor of any implementation manner of the first aspect.

[0018] The technical scheme has at least one of the following advantages or beneficial effects: the axial+radial three-dimensional magnetic flux multi-air-gap permanent magnet synchronous motor has axial magnetic field and radial magnetic field, and at least three surface stators and rotor air gaps, the motor has a motor electromechanical energy exchange place, the magnetic field energy storage level is determined by the air gap area, and the motor torque density is directly determined; the motor air gap is improved from the traditional single surface (radial magnetic flux) or multi-surface (axial magnetic flux) to three surfaces, the motor electromechanical energy exchange place is effectively improved, and the motor torque density is improved; the effective coil side number of the winding is improved from two to at least three, the winding coil is fully utilized, the participation of the winding coil in the electromagnetic field is improved from 1 / 2 to 3 / 4, the motor torque density is improved by 50%, and the motor torque density is also improved by 50%.

[0019] The winding of the motor is the main heat source of the motor, one side of the coil winding of the motor is directly cooled by the cooling plate, the motor is extremely cooled, the other three sides are involved in electromagnetic reaction, and the electromagnetic torque is provided. The annular winding is extremely utilized. The three-dimensional structure of the motor changes the heat dissipation path of the traditional motor, realizes the extreme heat dissipation effect of the directly cooled motor winding, and greatly enhances the cooling efficiency of the motor, so that the motor torque density is greatly improved.

[0020] Additional aspects and advantages of the present application will be set forth in part in the following description, will become apparent from the description, or will be learned through practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 is a schematic structural diagram of one embodiment of the motor of the present application;

[0023] Figure 2 is Figure 1 is an axial view of the rotor assembly of one embodiment shown in FIG.

[0024] Figure 3 is Figure 1 is a cross-sectional view of the rotor assembly of one embodiment shown in FIG.

[0025] Figure 4 is Figure 1 is an axial view of the rotor assembly of one embodiment shown in FIG.

[0026] Figure 5 is Figure 1 is an axial view of the rotor assembly of one embodiment shown in FIG.

[0027] Figure 6 is Figure 1 is a cross-sectional view of the stator assembly of one embodiment shown in FIG.

[0028] Figure 7 is Figure 1 is a schematic structural diagram of the stator yoke of one embodiment shown in FIG.

[0029] Figure 8 is Figure 1 is a schematic structural diagram of the radial yoke ring of one embodiment shown in FIG.

[0030] Figure 9 is Figure 1 is a schematic structural diagram of the axial yoke iron of one embodiment shown in FIG.

[0031] Figure 10 is Figure 1 is a schematic structural diagram of the annular winding unit of one embodiment shown in FIG.

[0032] Figure 11 is a schematic structural diagram of one embodiment of the direct-drive rotary table of the present application. DETAILED DESCRIPTION

[0033] The detailed description of the embodiments of the present application will be given in this part, and the preferred embodiments of the present application are shown in the drawings, the drawings are used to supplement the description of the text part, so that people can intuitively and visually understand each technical feature and the overall technical scheme of the present application, but it cannot be understood as a limitation on the protection scope of the present application.

[0034] In the present application, if the direction (up, down, left, right, front and back) is described, it is only for the convenience of describing the technical scheme of the present application, and is not intended to indicate or imply that the technical features referred to must have a specific orientation, structure and operation in a specific orientation, so it cannot be understood as a limitation on the present application.

[0035] In the present application, the meaning of "several" is one or more, the meaning of "multiple" is more than two, and "greater than", "less than", "more than" and the like are not included in the number; "above", "below", "within" and the like are understood to include the number. In the description of the present application, if "first" and "second" are described, they are only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0036] In the present application, unless otherwise explicitly limited, the words "set", "install", "connect" and the like should be broadly understood, for example, they can be directly connected, or indirectly connected through an intermediate medium; can be fixedly connected, or can be detachably connected, or can be integrally formed; can be mechanically connected, or can be electrically connected or capable of communicating with each other; can be the communication or interaction relationship between two elements. The skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical scheme.

[0037] Referring to Figures 1-6 The embodiment of the present application provides a motor, which comprises a rotor assembly 100 and a stator assembly 200, the rotor assembly 100 comprises a rotor yoke 101 and a permanent magnet, the rotor yoke 101 extends from a first end face 102 to a second end face 103 along an axial direction, the first end face 102 is provided with an annular groove 104 extending to the second end face 103 along the axial direction, the annular groove 104 is cut off before extending to the second end face 103, and the permanent magnet comprises an outer radial flux permanent magnet 105 arranged on an outer radial inner wall surface of the annular groove 104, an inner radial flux permanent magnet 106 arranged on an inner radial inner wall surface of the annular groove 104 and an axial flux permanent magnet 107 arranged on an axial inner wall surface of the annular groove 104.

[0038] The stator assembly 200 comprises a stator yoke 201 and a coil winding, the stator yoke 201 is annular, one end of the stator yoke 201 extends in the axial direction and extends into the annular slot 104, the other end of the stator yoke 201 is mounted to the cooling plate 202, the coil winding is wound on the stator yoke 201, the coil winding comprises a first side 203 facing the outer radial magnetic flux permanent magnet 105, a second side 204 facing the axial magnetic flux permanent magnet 107, a third side 205 facing the inner radial magnetic flux permanent magnet 106 and a fourth side 206 facing the cooling plate 202.

[0039] The technical scheme of the utility model discloses an axial + radial three-dimensional magnetic flux multi-gap permanent magnet synchronous motor, which is a motor that simultaneously has an axial magnetic field and a radial magnetic field and has at least three surface stators and rotor air gaps. The stator and rotor air gaps in the motor are places for electromechanical energy exchange of the motor, and the level of magnetic field energy storage is determined by the size of the air gap area, which directly determines the torque density of the motor. The utility model improves the air gap of the motor from the traditional single surface (radial magnetic flux) or multiple surfaces (axial magnetic flux) to three surfaces, effectively improves the electromechanical energy exchange place in the motor, and thus achieves the effect of improving the torque density of the motor. The utility model improves the effective coil side number of the winding from two in the traditional motor to at least three, which fully utilizes the coil side number of the winding, so that the participation of the winding coil in the electromagnetic field in the motor is improved from 1 / 2 in the traditional motor to 3 / 4, which is improved by 50%, and the torque density of the motor is also improved by 50% accordingly.

[0040] The winding of the motor is the main heat source of the motor, one side of the coil winding of the utility model is directly cooled by the cooling plate 202, so that the extreme heat dissipation of the motor is realized, and the other three sides all participate in electromagnetic reaction to provide electromagnetic torque. The annular winding is extremely utilized. The innovative three-dimensional structure of the utility model changes the heat dissipation path of the traditional motor, realizes the extreme heat dissipation effect of directly cooling the winding of the motor, and thus greatly enhances the cooling efficiency of the motor and greatly improves the torque density of the motor.

[0041] Specifically, referring to Figure 1 、 Figure 5The coil winding is essentially a concentrated winding, and generally, round copper wire or flat copper wire is used to conveniently use an automatic winding machine to wind the coil winding into the slot of the stator core. The first edge 203, the second edge 204 and the third edge 205 of the coil winding are all effective element edges of the coil winding, all participate in the electromechanical energy exchange of the electromagnetic field, and provide electromagnetic torque. In summary, the total of three effective edge windings of the motor of the case, together with the semi-enclosed three-dimensional structure of the rotor described above, collectively correspond to three motors participating in electromagnetic reaction, while the windings of the conventional motor are all two effective edges, and the other two only serve the connection function and do not participate in the electromechanical energy conversion. The number of effective coil edges is increased from two in the conventional motor to three in the case, making full use of the number of coil edges of the winding, so that the participation of the winding coil in the electromagnetic field in the motor is increased from 1 / 2 in the conventional motor to 3 / 4, which is increased by 50%. Similarly, the torque density of the motor can also be increased by 50%. In addition, after adopting the back-wound winding, the height of the coil end is greatly reduced, releasing the valuable space in the motor, so that the power and torque of the motor can be increased by filling more effective materials in the motor. At the same time, the fourth edge 206 of the ring winding is directly forced to cool by the cooling plate 202, thereby achieving the ultimate heat dissipation of the motor. At this point, each edge of the coil winding plays an indispensable important role, while the conventional motor whether it is a concentrated winding or a distributed winding, only has two edges participating in electromagnetic reaction and providing electromagnetic torque, and the other two edges only serve the connection function. Therefore, the structure of the present application in which all four edges play an extreme role is the core of the present application.

[0042] In general, the present application proposes such a new motor topology, which is equivalent to a special structure of a stator, and three permanent magnet rotors form a permanent magnet synchronous motor as a whole. The motor has unique ultimate heat dissipation capability and axial + radial three-dimensional magnetic flux multi-air-gap characteristics. Since a motor has multiple electromechanical energy exchange sites, the overall power density and torque density of the motor can be greatly improved.

[0043] In some embodiments, referring to Figure 4 , the outer radial flux permanent magnet 105, the axial flux permanent magnet 107 and the inner radial flux permanent magnet 106 located in the same radial section form a group of permanent magnets, and a plurality of groups of permanent magnets are arranged along the circumference of the annular slot 104. Each group of permanent magnets forms a U-shaped space in the annular slot 104, and the magnetic pole directions of each group of permanent magnets towards the inner side of the U-shaped space are the same. The magnetic poles of the plurality of groups of permanent magnets along the circumference of the annular slot 104 are alternately distributed as N and S poles. The rotor assembly 100 is a rotating element of the motor and an execution element for converting electrical energy into mechanical energy, as shown in Figure 2 , the rotor assembly 100 is composed of the axial flux permanent magnet 107, the outer radial flux permanent magnet 105 and the inner radial flux permanent magnet 106 to form a semi-enclosed three-dimensional structure, which is equivalent to three rotors as a whole.

[0044] In other words, the axial flux permanent magnets 107 are divided into P N-poles and P S-poles, and are equally spaced along the circumference, while the outer radial flux permanent magnets 105 are also divided into P N-poles and P S-poles, and the inner radial flux permanent magnets 106 are also divided into P N-poles and P S-poles, and are also equally spaced along the circumference. In particular, in the same dimension, the polarities of all the axial and radial permanent magnets are the same, i.e. they are either N-poles or S-poles at the same time. Here, P is the pole pair number of the motor. In this case, P = 5, as shown in the specific embodiment. Figure 4

[0045] The outer radial flux permanent magnets 105, the axial flux permanent magnets 107 and the inner radial flux permanent magnets 106 can be connected to the rotor yoke 101 in various ways, for example, the permanent magnets are attached to the surface of the rotor yoke 101; or the permanent magnets are embedded in the grooves on the surface of the rotor yoke 101; or the permanent magnets are embedded in the interior of the rotor yoke 101. The magnetic steel can also be a Halbach array magnetic steel.

[0046] In some embodiments, in order to ensure that the motor has superior performance, the material of the rotor yoke 101 is selected to be soft magnetic stainless steel or electrical pure iron with excellent magnetic conductivity; and the permanent magnets are selected to be high-performance high-grade sintered neodymium-iron-boron materials.

[0047] In some embodiments, referring to Figures 1-4 , the middle part of the rotor yoke 101 is provided with an axle hole 108, which can be used to install a rotating shaft or the like to realize direct drive function.

[0048] The cooling plate 202 can be air-cooled or water-cooled, for example, in some embodiments, the cooling plate 202 is provided with cooling fins on the side away from the stator yoke 201, and the heat generated by the coil winding during operation can be forcibly cooled by the cooling plate 202 cooperating with the fourth side 206, thereby achieving extreme heat dissipation of the motor.

[0049] In some embodiments, referring to Figure 1 , Figure 6 , the cooling plate 202 includes a cooling water cover 207 and a water cover plate 208, the stator yoke 201 is installed on the cooling water cover 207, the cooling water cover 207 is provided with a cooling water tank 209 at the position corresponding to the stator yoke 201, the water cover plate 208 is connected to the cooling water cover 207 and covers the cooling water tank 209, and the cooling water cover 207 and / or the water cover plate 208 are provided with an inlet 210 and an outlet 211 communicating with the cooling water tank 209. The water cover plate 208 and the cooling water cover 207 together constitute a liquid cooling structure of the motor, and the inlet 210 and the outlet 211 are provided on the cooling water cover 207 and / or the water cover plate 208. During use, the cooling liquid flows into the inlet 210, flows through the cooling water tank 209 and then flows out of the outlet 211, which is used to carry away the heat generated by the motor loss. ​

[0050] Further, referring to Figure 1 , Figure 6 In some embodiments, the cooling water tank 209 is arranged on the side surface of the cooling water cover 207 away from the stator yoke 201, and the cooling water tank 209 is an annular water tank extending along the circumferential direction of the stator yoke 201. The annular water tank extends along the distribution direction of the coil winding, and the annular water tank corresponds to the distribution position of the coil winding, so that the heat generated by the coil winding loss can be quickly taken away.

[0051] In some embodiments, referring to Figure 1 , Figure 6 The cooling water cover 207 is provided with a through hole 212 corresponding to the shaft hole 108, and the cooling water cover 207 is annular. The sealing cover plate 208 is arranged on the cooling water cover 207 away from the stator yoke 201, and covers the through hole 212. The cooling water cover 207 simultaneously plays the role of sealing the shaft hole 108 and the through hole, so as to prevent water vapor, dust and other impurities from entering the motor.

[0052] In some embodiments, referring to Figure 5 , Figure 7 , Figure 10 The stator yoke 201 is provided with a plurality of radial winding grooves, and the plurality of radial winding grooves are arranged along the circumferential direction of the stator yoke 201. The radial winding groove includes an outer circumferential surface groove 213, a first end surface groove 214, an inner circumferential surface groove 215 and a second end surface groove 216 along the winding direction. The coil winding includes a plurality of annular winding units 217 wound in each radial winding groove. The first side 203 of the annular winding unit 217 is located in the outer circumferential surface groove 213, the second side 204 of the annular winding unit 217 is located in the first end surface groove 214, the third side 205 of the annular winding unit 217 is located in the inner circumferential surface groove 215, and the fourth side 206 of the annular winding unit 217 is located in the second end surface groove 216. For example, in the embodiment shown in Figure 5 , Figure 7 The stator yoke 201 is provided with 12 radial winding grooves, and 12 annular winding units 217 are distributed in the radial winding grooves. According to a specific wiring method, a symmetrical multi-phase motor winding is formed to participate in electromagnetic reaction of the motor.

[0053] The annular winding unit 217 is essentially a concentrated winding, and generally uses round copper wire or flat copper wire to facilitate the use of an automatic winding machine to wind the coil winding into the radial winding groove of the stator yoke 201.

[0054] Further, in some embodiments, referring to Figure 7 , Figure 8 , Figure 9The stator yoke 201 comprises a radial yoke ring 218 and an axial yoke iron 219, the radial yoke ring 218 comprises a plurality of first stamping sheets arranged in a stack, the first stamping sheet comprises an annular sheet, the outer edge of the annular sheet is provided with an outer peripheral wing fin extending outward in the radial direction, the inner edge of the annular sheet is provided with an inner peripheral wing fin extending inward in the radial direction, the outer peripheral wing fins between adjacent ones form an outer peripheral surface groove 213, the inner peripheral wing fins between adjacent ones form an inner peripheral surface groove 215, the axial yoke iron 219 comprises a plurality of second stamping sheets arranged in a stack, the axial yoke iron 219 is connected to both ends of the radial yoke ring 218 corresponding to the outer peripheral wing fins and the inner peripheral wing fins, and forms a first end surface groove 214 and a second end surface groove 216 at both ends of the radial yoke ring 218. Wherein, the materials of the axial yoke iron 219 and the radial yoke ring 218 can be high-performance cold-rolled silicon steel sheets stacked.

[0055] In some embodiments, referring to Figure 6 、 Figure 8 、 Figure 9 The radial yoke ring 218 and the axial yoke iron 219 are provided with an axial hole 220, and the radial yoke ring 218 and the axial yoke iron 219 are connected to the cooling plate 202 through a pull rod 221 arranged in the axial hole 220. The cooling plate 202 not only plays a role in cooling the motor, but also plays a key role in fixing the stator assembly 200. In order to ensure the mechanical strength, high yield strength stainless steel is specially selected.

[0056] The stator yoke 201 of the utility model has rich and varied structure forms, rich design space, very free manufacturing process, and can all produce good effects.

[0057] Referring to Figure 11 The embodiment of the utility model further provides a direct drive rotary table, which comprises the motor in any one of the above embodiments.

[0058] Specifically, referring to Figure 11 The direct drive rotary table comprises a machine base 301, a rotating shaft 302 and a slewing disc 303, the slewing disc 303 is connected with the rotating shaft 302, and the rotating shaft 302 is directly driven by the motor.

[0059] In the description of the present specification, the description of the terms "example", "embodiment" or "some embodiments" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the utility model. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0060] Of course, the present application is not limited to the above-mentioned embodiments, and those skilled in the art can make equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. An electric machine characterized in that, The application relates to a rotor assembly and a stator assembly. The rotor assembly comprises a rotor yoke and permanent magnets, the rotor yoke extends along an axial direction from a first end surface to a second end surface, the first end surface is provided with an annular groove extending along the axial direction to the second end surface, the annular groove is truncated before extending to the second end surface, the permanent magnets comprise outer radial flux permanent magnets arranged on the outer radial inner wall surface of the annular groove, inner radial flux permanent magnets arranged on the inner radial inner wall surface of the annular groove and axial flux permanent magnets arranged on the axial inner wall surface of the annular groove. The stator assembly comprises a stator yoke and a coil winding, the stator yoke is annular, one end of the stator yoke extends along the axial direction and extends into the annular groove, the other end of the stator yoke is mounted on a cooling plate, the coil winding is wound on the stator yoke, the coil winding comprises a first side facing the outer radial flux permanent magnets, a second side facing the axial flux permanent magnets, a third side facing the inner radial flux permanent magnets and a fourth side facing the cooling plate.

2. The electric machine of claim 1, wherein, The outer radial flux permanent magnets, the axial flux permanent magnets and the inner radial flux permanent magnets located in the same radial section form a group of permanent magnets, a plurality of groups of the permanent magnets are arranged along the circumferential direction of the annular groove, each group of the permanent magnets forms a U-shaped space in the annular groove, the magnetic pole directions of each group of the permanent magnets facing the inner side of the U-shaped space are the same, and the magnetic poles of the plurality of groups of the permanent magnets along the circumferential direction of the annular groove are alternately distributed in N and S poles.

3. The electric machine of claim 1, wherein, The middle part of the rotor yoke is provided with a shaft hole.

4. The electric machine of claim 3, wherein, The cooling plate comprises a cooling water cover and a water sealing cover plate, the stator yoke is mounted on the cooling water cover, the cooling water cover is provided with a cooling water groove at a position corresponding to the stator yoke, the water sealing cover plate is connected to the cooling water cover and covers the cooling water groove, and the cooling water cover and / or the water sealing cover plate are provided with an inlet and an outlet communicating with the cooling water groove.

5. The electric machine of claim 4, wherein, The cooling water groove is arranged on the side surface of the cooling water cover away from the stator yoke, and the cooling water groove is an annular water groove extending along the circumferential direction of the stator yoke.

6. The electric machine of claim 5, wherein, The middle part of the cooling water cover is provided with a through hole corresponding to the shaft hole, and the water sealing cover plate is mounted on the cooling water cover from the side away from the stator yoke and covers the through hole.

7. The electric machine of claim 1, wherein, The stator yoke is provided with a plurality of radial winding grooves, the plurality of radial winding grooves are arranged along the circumferential direction of the stator yoke, the radial winding grooves comprise an outer circumferential surface groove, a first end surface groove, an inner circumferential surface groove and a second end surface groove along the winding direction, the coil winding comprises a plurality of annular winding units wound in the radial winding grooves, the first side of the annular winding unit is located in the outer circumferential surface groove, the second side of the annular winding unit is located in the first end surface groove, the third side of the annular winding unit is located in the inner circumferential surface groove, and the fourth side of the annular winding unit is located in the second end surface groove.

8. The electric machine of claim 7, wherein, The stator yoke comprises a radial yoke ring and an axial yoke iron, the radial yoke ring comprises a plurality of first laminated sheets, the first laminated sheets comprise annular sheets, the outer edges of the annular sheets are provided with outwardly extending outer peripheral fins, the inner edges of the annular sheets are provided with inwardly extending inner peripheral fins, the outer peripheral fins between adjacent ones of the annular sheets form the outer peripheral surface slots, the inner peripheral fins between adjacent ones of the annular sheets form the inner peripheral surface slots, the axial yoke iron comprises a plurality of second laminated sheets, the axial yoke iron is connected to both ends of the radial yoke ring corresponding to the outer peripheral fins and the inner peripheral fins, and forms first end surface slots and second end surface slots at both ends of the radial yoke ring.

9. The electric machine of claim 8, wherein, The radial yoke ring and the axial yoke iron are provided with axial holes, and the radial yoke ring and the axial yoke iron are connected to the cooling plate through pull rods arranged in the axial holes.

10. A direct drive rotary table, characterized by, The motor comprises the motor of any one of claims 1-9.

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