Cooling structure of back-wound winding high-speed permanent magnet motor and motor

Abstract

The invention relates to the technical field of high-speed permanent magnet motors, in particular to a cooling structure of a back-wound winding high-speed permanent magnet motor and a motor, and aims to reduce heat resistance of heat transfer from internal heat of the back-wound winding high-speed permanent magnet motor to a liquid-cooled casing by replacing part of outer teeth of a stator core with heat pipes. Under the conditions that the electromagnetic performance of the back-wound winding high-speed permanent magnet motor is not influenced and the volume is not increased, the cooling effect on the stator core and the back-wound winding of the back-wound winding high-speed permanent magnet motor is enhanced, so that the overall temperature of the motor is greatly reduced, and the application of the back-wound winding high-speed permanent magnet motor to the high-power and high-speed field is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed permanent magnet motors, and in particular to a cooling structure of a back-wound high-speed permanent magnet motor and a motor. Background Art

[0002] With the development of new energy vehicles, more electric / all electric aircraft, more electric / all electric ships and other emerging fields, there is a large demand for high-speed permanent magnet motors. High-speed permanent magnet motors have attracted widespread attention due to their advantages of high power density, high efficiency, small size and light weight. However, existing high-speed permanent magnet motors generally use stacked windings. Due to the long ends of the stacked windings, the axial length of the motor is increased, which gradually highlights the rotor dynamics problem and limits the increase in speed. In comparison, the back-wound winding has a special structure that surrounds the inside and outside of the stator core, so that the axial length of the winding end is very short, and the axial size of the stator is very compact, which has a significant effect on improving the critical speed of the rotor. Therefore, the back-wound winding has great application potential in the field of high-speed permanent magnet motors.

[0003] However, the small size and high power density of the back-wound high-speed permanent magnet motor also bring about the problems of limited heat dissipation area and severe heat generation. In addition, due to the use of the back-wound winding, the outer teeth of the stator core and the height of the outer back-wound winding are additionally increased in the radial direction, so that the back-wound high-speed permanent magnet motor adopts the traditional method of conducting heat from the stator core to the liquid-cooled casing. When the coolant in the liquid-cooled casing is used to dissipate heat, the heat transfer path of the radial heat transfer from the heat inside the motor to the liquid-cooled casing becomes longer, that is, the thermal resistance increases, which further aggravates the heating of the back-wound high-speed permanent magnet motor. Summary of the invention

[0004] In the first aspect, the purpose of the present invention is to provide a cooling structure for a back-wound high-speed permanent magnet motor, by using heat pipes to replace part of the outer teeth of the stator core, thereby reducing the thermal resistance of the heat transfer from the internal heat of the back-wound high-speed permanent magnet motor to the liquid cooling casing, and enhancing the cooling effect of the stator core and back-wound winding of the back-wound high-speed permanent magnet motor without affecting the electromagnetic performance of the back-wound high-speed permanent magnet motor and without increasing the volume.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A cooling structure of a back-wound high-speed permanent magnet motor comprises: a heat pipe, the heat pipe imitates the outer teeth shape of the stator core of the back-wound high-speed permanent magnet motor, when at least one heat pipe replaces the outer teeth of the stator core and is installed on the outer circumferential side wall of the stator core:

[0007] If there is only one heat pipe, the heat pipe and the outer teeth of the adjacent stator core form an outer slot;

[0008] If there are multiple heat pipes, when the heat pipe is adjacent to another heat pipe, the heat pipe and the adjacent heat pipe form an outer slot; and, at least one heat pipe is adjacent to an outer tooth of a stator core, and the heat pipe and the adjacent outer tooth of the stator core form an outer slot;

[0009] Among them, the condensing section of the heat pipe exchanges heat with the liquid-cooled casing of the back-wound high-speed permanent magnet motor.

[0010] In some disclosures, the heat pipe is detachably fixedly connected to the outer circumferential side wall of the stator core.

[0011] In some disclosures, the lower end of the heat pipe has a snap-fitting portion or a slot, and the corresponding outer circumferential side wall of the stator core has an adaptable slot or snap-fitting portion; the heat pipe and the outer circumferential side wall of the stator core are connected through the adaption of the slot and the snap-fitting portion.

[0012] In some disclosures, the gap at the connection between the engaging portion and the slot is filled with thermally conductive silicone.

[0013] In some disclosures, the length of the heat pipe is equal to the length of the stator core, and the axial end surfaces on both sides of the stator core are flush with the end surfaces of the heat pipe.

[0014] In some disclosures, the length of the heat pipe is greater than the length of the stator core, and the heat pipe extending beyond the axial end surfaces on both sides of the stator core forms a semi-enclosed structure with respect to the end of the back-wound winding.

[0015] In some disclosures, an outer wall of the condensation section of the heat pipe is formed with an arc surface that matches the inner wall of the liquid cooling casing, and the arc surface fits the inner wall of the liquid cooling casing.

[0016] On the second aspect, the purpose of the present invention is to provide a back-wound high-speed permanent magnet motor, which reduces the thermal resistance of the heat transfer from the internal heat of the back-wound high-speed permanent magnet motor to the liquid cooling casing by using heat pipes to replace part of the outer teeth of the stator core, and enhances the efficient cooling of the stator core and back-wound winding of the back-wound high-speed permanent magnet motor without affecting the electromagnetic performance of the back-wound high-speed permanent magnet motor and without increasing the volume.

[0017] To achieve the above object, the present invention provides the following technical solutions:

[0018] A back-wound high-speed permanent magnet motor comprises the cooling structure of the first aspect, when at least one heat pipe replaces the outer teeth of the stator core and is installed on the outer circumferential side wall of the stator core, the top of the cooling structure is in contact with the inner wall of the liquid cooling casing;

[0019] The liquid cooling housing has a liquid cooling channel, and the liquid cooling channel is filled with coolant;

[0020] The cooling structure conducts the heat on the stator core to the coolant in the liquid cooling casing, and the coolant dissipates the heat.

[0021] In some disclosures, the heat pipes and the outer teeth of the stator core form a structure in which the circumferential spaces are alternately arranged.

[0022] In some disclosures, a plurality of heat pipes are arranged in a group to replace a corresponding number of adjacent outer teeth of the stator core.

[0023] The present invention has at least the following beneficial effects:

[0024] 1. The present invention replaces part of the outer teeth of the conventional back-wound high-speed permanent magnet motor with a heat pipe. Since the heat pipe has extremely strong thermal conductivity, it can effectively reduce the thermal resistance of the heat transfer from the internal heat of the back-wound high-speed permanent magnet motor to the liquid cooling casing, so that the heat concentrated in the stator core and the winding can be quickly transferred to the liquid cooling casing, and the heat is taken away by the coolant in time; and the heat pipe can also quickly transfer the heat of the outer winding in the stator outer slot in contact with it to the liquid cooling casing. The combined effect of the two aspects greatly reduces the temperature rise of the back-wound high-speed permanent magnet motor.

[0025] 2. When the axial length of the heat pipe is greater than the stator core, the portion exceeding the axial end faces on both sides of the stator core can also quickly transfer the heat at the end of the back-wound winding to the coolant in the liquid-cooled casing, thereby avoiding high temperature generated by heat accumulation at the end of the back-wound winding.

[0026] 3. Since the outer teeth and outer back-wound windings of the back-wound high-speed permanent magnet motor do not contribute to the electromagnetic performance of the motor, they only play the role of structural support and connecting the effective windings on the air gap side. Therefore, when heat pipes are used to replace part of the outer teeth, they can play the role of auxiliary support of the stator in the structure, and have almost no effect on the electromagnetic performance.

[0027] Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A three-dimensional view of the cooling structure of the back-wound high-speed permanent magnet motor of the present invention;

[0029] Figure 2 This is an end view of the overall structure of the back-wound high-speed permanent magnet motor of the present invention;

[0030] Figure 3 A three-dimensional view of the stator of the back-wound high-speed permanent magnet motor of the present invention;

[0031] Figure 4 A diagram of an assembly in which a heat pipe having a length greater than that of a stator core is installed on a stator core;

[0032] Figure 5 The figure is a component diagram of the continuous heat pipe group installed on the stator core;

[0033] Figure 6 The assembly diagram is a heat pipe having the same length as the stator core installed on the stator core;

[0034] Figure 7 A three-dimensional view of the stator core with slots;

[0035] Figure 8 is a three-dimensional view of a heat pipe with a snap-fit ​​portion;

[0036] Fig. 9 is a cross-sectional view of a heat pipe with a snap-fit ​​portion;

[0037] Fig.10 This is the working principle diagram of the heat pipe;

[0038] Fig.11 To adopt Figure 3 The magnetic field line distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0039] Fig.12 This is the magnetic field line distribution diagram of a conventional back-wound high-speed permanent magnet motor;

[0040] Fig.13 To adopt Figure 3 The magnetic flux density distribution cloud diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0041] Fig.14 This is the magnetic flux density distribution cloud diagram of a conventional back-wound high-speed permanent magnet motor;

[0042] Fig.15 To adopt Figure 3 The no-load back-EMF waveform of the high-speed permanent magnet motor with the heat pipe structure shown;

[0043] Fig.16 This is the no-load back EMF waveform of a conventional back-wound high-speed permanent magnet motor;

[0044] Fig.17 To adopt Figure 3 The torque curve of the high-speed permanent magnet motor with the heat pipe structure shown;

[0045] Fig.18 It is the torque curve of the conventional back-wound high-speed permanent magnet motor;

[0046] Fig.19 This is the winding temperature distribution diagram of a conventional back-wound high-speed permanent magnet motor;

[0047] Fig. 20 This is the temperature distribution diagram of the stator core of a conventional back-wound high-speed permanent magnet motor;

[0048] Fig.21This is the overall temperature distribution diagram of a conventional back-wound high-speed permanent magnet motor;

[0049] Fig. 22 To adopt Figure 6 The winding temperature distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0050] Fig.23 To adopt Figure 6 The stator core temperature distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0051] Fig.24 To adopt Figure 6 The temperature distribution diagram of the stator and rotor of the high-speed permanent magnet motor with the heat pipe structure shown;

[0052] Fig.25 To adopt Figure 4 The winding temperature distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0053] Fig.26 To adopt Figure 4 The stator core temperature distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0054] Fig. 27 To adopt Figure 4 The temperature distribution diagram of the stator and rotor of the high-speed permanent magnet motor with the heat pipe structure shown;

[0055] Fig.28 To adopt Figure 5 The winding temperature distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0056] Fig.29 To adopt Figure 5 The stator core temperature distribution diagram of the high-speed permanent magnet motor with the heat pipe structure shown;

[0057] Fig.30 To adopt Figure 5 Temperature distribution diagram of the stator and rotor of the high-speed permanent magnet motor with heat pipe structure shown in FIG. 1; Reference numerals:

[0058] 1. Liquid-cooled housing; 2. Liquid-cooled liquid; 3. Stator core; 31. Slot; 4. External teeth; 5. Internal teeth of stator; 6. External slot; 7. Internal slot; 8. Back-wound winding; 9. End of back-wound winding; 10. Heat pipe; 101. Condensation section of heat pipe 10; 102. Evaporation section of heat pipe 10; 103. Pipe wall of heat pipe 10; 104. Cavity of heat pipe 10; 105. Capillary wick of heat pipe 10; 106. Clamping part of heat pipe 10; 11. Rotating shaft; 12. Permanent magnet; 13. Sheath DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0060] The back-wound high-speed permanent magnet motor generally comprises a stator core 3, wherein the stator inner teeth 5 and the outer teeth 4 of the stator core 3 are respectively provided with inner slots 7 and outer slots 6 which are axially distributed, and the winding is back-wound in the inner slots 7 and the outer slots 6, specifically, one side of each back-wound coil constituting the back-wound winding 8 is in the inner slot 7, and the other side is in the outer slot 6 opposite to the inner slot 7; in the prior art, the positions of the outer slots 6 and the inner slots 7 between the stator inner teeth 5 of the stator core 3 correspond to each other, and the inner slots 7 and the outer slots 6 on the inner and outer sides of the stator core 3 can be designed to have different numbers of tooth slots, but the number of inner slots 7 should be an integer multiple of the number of outer slots 6. Of course, in some occasions, the number of inner slots 7 can be equal to the number of outer slots 6; and the outer teeth 4 and the outer back-wound winding 8 of the back-wound high-speed permanent magnet motor do not contribute to the electromagnetic performance of the back-wound high-speed permanent magnet motor, and they only play the role of structural support and connecting the effective winding on the air gap side. Of course, in some cases, insulating paper is laid in the outer slot 6 and the inner slot 7 respectively, or insulating material is sprayed on the outside of the inner slot 7 and the outer slot 6 as a whole, and then a back-wound winding 8 with a high slot fill rate is wound in the outer slot 6 and the inner slot 7.

[0061] Heat pipe 10, in general, has a cavity 104 wrapped by a shell, and a capillary wick 105 is attached to the inner wall of the cavity 104, and the capillary wick 105 is filled with liquid working medium; the section of the heat pipe 10 in contact with the component that needs to dissipate heat is used as the evaporation section 102, and the section of the other end in contact with the refrigerant is used as the condensation section 101. When one end (evaporation section 102) of the heat pipe 10 is heated, the liquid working medium in the capillary wick evaporates and vaporizes, and the steam flows to the other end (condensation section 101) under a small pressure difference, releases heat and condenses into liquid, and the liquid then flows back to the evaporation section 102 along the porous material by the action of capillary force. In this way, the cycle continues, and the heat is transferred from one end (evaporation section 102) of the heat pipe 10 to the other end (condensation section 101), realizing heat transfer; acetone, methanol or water are generally selected for the liquid working medium.

[0062] Embodiment 1:

[0063] In the present application, a cooling structure of a back-wound high-speed permanent magnet motor is disclosed, comprising: a heat pipe 10, the heat pipe 10 imitates the shape of the outer teeth 4 of the stator core 3 of the back-wound high-speed permanent magnet motor, when at least one heat pipe 10 replaces the outer teeth 4 of the stator core 3 and is installed on the outer circumferential side wall of the stator core 3:

[0064] If there is only one heat pipe 10 , the heat pipe 10 and the outer teeth 4 of the adjacent stator core 3 form an outer slot 6 ;

[0065] If there are multiple heat pipes 10, when the heat pipe 10 is adjacent to another heat pipe 10, the heat pipe 10 and the adjacent heat pipe 10 form an outer slot 6; and, at least one heat pipe 10 is adjacent to the outer teeth 4 of the stator core 3, and the heat pipe 10 and the adjacent outer teeth 4 of the stator core 3 form an outer slot 6;

[0066] The condensing section of the heat pipe 10 exchanges heat with the inner side of the liquid-cooled casing 1 of the back-wound high-speed permanent magnet motor.

[0067] That is, in the present application, the heat pipe 10 is made to imitate the shape of the outer teeth 4 of the stator core 3, and the outer teeth 4 of part of the stator core 3 on the back-wound winding high-speed permanent magnet motor are replaced with the heat pipe 10, so that the heat pipe 10 and the outer teeth 4 of the adjacent core form an outer slot 6; the outer slot 6 formed at this time can achieve the original function, such as fixing and accommodating the back-wound winding 8; after replacing the outer teeth 4 of part of the stator core 3, the evaporation section 102 of the heat pipe 10 is in contact with the stator core 3, and the condensation section 101 of the heat pipe 10 is in contact with the liquid cooling casing 1. Since the heat pipe 10 has a very strong thermal conductivity, it can effectively The thermal resistance of the heat transfer from the internal heat of the back-wound high-speed permanent magnet motor to the liquid-cooled casing 1 is reduced, so that the heat concentrated in the stator core 3 and the winding can be quickly transferred to the liquid-cooled casing 1, and the heat is taken away by the coolant in time; and the heat pipe 10 can also quickly transfer the heat of the outer winding in the stator outer slot 6 in contact with it to the liquid-cooled casing 1. The combined effect of the two aspects greatly reduces the temperature rise of the back-wound high-speed permanent magnet motor; at this stage, when the heat pipe 10 is used to replace part of the outer teeth 4, it can play a role in assisting the support of the stator core 3 in structure, and has basically no effect on the electromagnetic performance of the back-wound high-speed permanent magnet motor.

[0068] With respect to the prior art, insulating paper is laid on the outer slot 6 or the inner slot 7, or insulating material is sprayed on the outer surface of the inner slot 7 and the outer slot 6, and then a back-wound winding 8 with a high slot fill rate is wound in the outer slot 6 and the inner slot 7; since the thickness of the insulating paper and the insulating layer are both relatively thin, the effect on the heat transfer of the winding to the stator core 3 and the heat pipe 10 is relatively small, that is, it can be considered that the outer winding in the outer slot 6 is equivalent to being in close contact with the heat pipe 10.

[0069] like Figures 8 to 10As shown, in the present application, the heat pipe 10 imitates the shape of the outer teeth 4 of the stator core 3 of the back-wound winding high-speed permanent magnet motor. Specifically, the end parallel surface of the back-wound winding high-speed permanent magnet motor is used as the cross-section, and the heat pipe 10 is similar to the cross-sectional shape of the outer teeth 4 of the stator core 3, such as both having a similar "T"-shaped cross-section. The purpose is that the heat pipe 10 imitates the shape of the outer teeth 4 of the stator core 3, so that when the outer teeth 4 of the stator core 3 are replaced, the heat pipe 10 is installed on the stator core 3, and will not cause damage to the outer slot 6 structure formed between the original outer teeth 4 of the adjacent stator cores 3, thereby satisfying the original function of the back-wound winding high-speed permanent magnet motor, such as the winding is back-wound in the inner slot 7 and the outer slot 6.

[0070] like Figures 8 to 10 As shown, the heat pipe 10 includes an evaporation section 102 and a condensation section 101 fixedly connected to the evaporation section 102; wherein the heat pipe 10 has a cavity 104 wrapped by a shell, and a capillary wick 105 is attached to the inner wall of the cavity 104, and the capillary wick 105 is filled with a liquid working medium; the evaporation section 102 is in contact with the stator core 3, and when the evaporation section 102 of the heat pipe 10 is heated, the liquid working medium in the capillary wick evaporates and vaporizes, and the steam flows to the condensation section 101 under a small pressure difference to release heat and condense into liquid, and the liquid then flows back to the evaporation section 102 along the porous material by the action of capillary force, and the cycle is repeated, and the heat is transferred from the evaporation section 102 of the heat pipe 10 to the condensation section 101 to achieve heat transfer; for the liquid working medium, acetone, methanol or water is generally selected; wherein Fig.10 In FIG. 1 , the arrow in the capillary wick indicates the flow direction of the liquid medium; the arrow in the cavity 104 indicates the movement direction of the evaporated gas.

[0071] Regarding the preparation of the heat pipe 10 , for example, the material of the wall 104 of the heat pipe 10 is preferably copper, and the manufacturing process thereof is preferably 3D printing technology, so as to meet the size requirements of different parts of the heat pipe 10 according to demand.

[0072] 3D printing technology refers to a high-tech technology that converts digital models into physical entities by stacking them layer by layer. It uses computer-aided design (CAD) software to generate three-dimensional models, and then sends these models to 3D printers for "printing". During the 3D printing process, the user first selects suitable printing materials, such as plastic, metal or ceramic, and then uses the software to layer the design model and calculate the fine structure of each layer. Then, the 3D printer will stack layers of solid materials together according to predetermined paths and specifications to finally build a complete object. 3D printing technology belongs to the existing technology and will not be repeated here.

[0073] In some cases, such as Figure 3As shown, the length of the heat pipe 10 is greater than the length of the stator core 3, and the heat pipe 10 that exceeds the axial end surfaces on both sides of the stator core 3 forms a semi-enclosed structure for the back-wound winding end 9; the part that exceeds the axial end surfaces on both sides of the stator core 3 can also quickly transfer the heat of the back-wound winding end 9 to the liquid cooling casing 1, avoiding the high temperature generated by the back-wound winding end 9 due to heat accumulation. At this stage, by replacing part of the stator outer teeth 4 of the conventional back-wound high-speed permanent magnet motor with a heat pipe 10, the thermal resistance of the heat path for heat transfer from the back-wound high-speed permanent magnet motor to the liquid-cooled casing 1 can be effectively reduced, so that the heat concentrated in the stator core 3 and the back-wound winding 8 is quickly transferred to the evaporation section 102 of the heat pipe 10, and the heat is transferred to the liquid-cooled casing 1 through the phase change of the working medium in the heat pipe 10; at the same time, the heat pipe 10 can also transfer the heat of the outer winding in the outer slot 6 to the liquid-cooled casing 1. The combined effect of the two aspects can greatly reduce the temperature gradient of the back-wound high-speed permanent magnet motor, avoid local overheating, and reduce the temperature rise of the back-wound high-speed permanent magnet motor.

[0074] Of course, regarding the contact mode between the heat pipe 10 and the liquid cooling housing 1 , the outer wall of the condensation section of the heat pipe 10 is formed with an arc surface that matches the inner wall of the liquid cooling housing 1 , and the arc surface fits the inner wall of the liquid cooling housing 1 .

[0075] In the present application, the heat pipe 10 replaces the outer teeth 4 of the stator core 3 and is installed on the outer circumferential side wall of the stator core 3. In some cases, the heat pipe 10 can be directly fixedly connected to the stator core 3 by gluing or welding in advance, such as Figure 2 The overall structure diagram of the motor is shown, and the heat pipe is fixedly connected in this way.

[0076] For example, in some cases, the heat pipe 10 can be pre-connected to the stator core 3 by fitting the card slot with the card engaging portion, and the heat pipe 10 and the stator core 3 can be directly connected in a detachable fixed manner. Figure 6-7 As shown, the heat pipe 10 has a snap-fitting portion 106 at the lower end, and the corresponding outer circumferential side wall of the stator core 3 has an adaptive snap-fitting groove 31; for example, in some occasions, a single heat pipe 10 has a snap-fitting groove at the lower end of the heat pipe 10, and the corresponding outer circumferential side wall of the stator core 3 has an adaptive snap-fitting portion.

[0077] Of course, with respect to the cross section of the slot 31, in some cases, the cross section of the slot 31 can be made into a constricted shape, such as a dovetail groove. At this time, the purpose of such a design is that the engaging portion of the evaporation section 102 of the heat pipe 10 is adapted to the shape of the slot 31 on the outside of the stator core 3, so that the heat pipe 10 can be well fixed on the stator core 3 through the matching of the dovetail groove. In addition, the contact gap between the evaporation section 102 of the heat pipe 10 and the slot 31 is also filled with thermal conductive silicone, so that the contact thermal resistance between the stator core 3 and the heat pipe 10 can be reduced. With respect to the engaging portion 106 of the evaporation section 102 of the heat pipe 10, in the present application, the shape of the evaporation section 102 of the heat pipe 10 itself can be changed, such as being transformed into an engaging portion matching the dovetail groove.

[0078] It should be noted that the above-mentioned heat pipe 10 is connected to the stator core 3 by adapting the slot and the locking part. Considering that the heat pipe 10 is embedded in the outside of the stator core 3, and the stator core 3 is a part of the magnetic circuit of the back-wound high-speed permanent magnet motor, in order to reduce the impact on the electromagnetic performance of the back-wound high-speed permanent magnet motor, the depth of the slot 31 should not be too large. At this time, it is necessary to determine the depth of the slot 31 according to the size of the back-wound high-speed permanent magnet motor. For example, when the radial length of the stator yoke is 15 mm, the depth of the slot 31 is preferably between 1 mm and 2 mm. This embodiment does not strictly limit the depth of the slot 31, and should be reasonably designed on the basis of fixing the heat pipe 10.

[0079] Embodiment 2:

[0080] A back-wound high-speed permanent magnet motor includes the cooling structure of the first embodiment, when at least one heat pipe 10 replaces the outer teeth 4 of the stator core 3 and is installed on the outer circumferential side wall of the stator core 3, the top of the cooling structure is in contact with the inner wall of the liquid cooling casing 1;

[0081] The liquid cooling housing 1 has a liquid cooling channel therein, and the liquid cooling channel is filled with a coolant 2;

[0082] The cooling structure conducts the heat on the stator core 3 to the liquid cooling housing 1 , and the coolant 2 in the liquid cooling housing 1 dissipates the heat.

[0083] At this time, the evaporation section 102 of the heat pipe 10 is in contact with the stator core 3, and the condensation section 101 of the heat pipe 10 is in contact with the liquid cooling casing 1. Since the heat pipe 10 has extremely strong thermal conductivity, it can effectively reduce the thermal resistance of the heat transfer from the internal heat of the back-wound high-speed permanent magnet motor to the liquid cooling casing 1, so that the heat concentrated in the stator core 3 and the winding can be quickly transferred to the liquid cooling casing 1, and the heat is taken away by the coolant in time; and the heat pipe 10 can also quickly transfer the heat of the outer winding in the stator outer slot 6 in contact with it to the liquid cooling casing 1. The combined effect of the two aspects greatly reduces the temperature rise of the back-wound high-speed permanent magnet motor; at this stage, when the heat pipe 10 is used to replace part of the stator outer teeth 4, it can play a role in auxiliary support of the stator core 3 in structure, and has almost no effect on the electromagnetic performance.

[0084] Regarding the number of external teeth 4 of the stator core 3 replaced by the heat pipe 10, in the present application, the maximum number of external teeth 4 of the stator core 3 after the heat pipe 10 is replaced is less than the total number of external teeth 4 of the stator core 3, that is, at least one external tooth 4 of the stator core 3 needs to be retained, that is, the reason is that the external teeth 4 play a structural role in supporting the stator. When the number of external teeth 4 of the stator core 3 is reduced, especially when the number of external teeth is too small, it may cause uneven force on the stator of the back-wound high-speed permanent magnet motor, thereby causing adverse consequences such as increased vibration of the motor;

[0085] Regarding the layout of the heat pipe 10 replacing the outer teeth 4 of the stator core 3, in the present application, the outer teeth 4 of the stator core 3 at any position can be randomly replaced. For example, in some cases, it is assumed that the number of inner slots 7 of the stator core 3 is equal to the number of outer slots 6, such as Figure 3 and Figure 4 As shown, the number of external teeth 4 of the stator core 3 is 12, and the number of heat pipes 10 is 12. The number of external teeth 4 of the stator core 3 and the number of heat pipes 10 are the same as the number of internal teeth of the stator core 3, and the number of internal teeth of the stator core 3 is 24. In this figure, the heat pipes 10 alternately replace the external teeth 4 of the stator core 3. The heat pipes 10 and the external teeth 4 of the stator core 3 form a structure alternately arranged in a circumferential space. The heat pipes 10 and the adjacent external teeth 4 of the stator core 3 form external grooves 6. By evenly and widely arranging the heat pipes 10 on the stator core 3, the heat pipe 10 arrangement structure is conducive to ensuring that the heat generated by the stator core 3 of the back-wound high-speed permanent magnet motor is quickly transferred to the heat pipes 10 and then to the liquid-cooled casing 1.

[0086] For example, in some cases, it is assumed that the number of inner slots 7 of the stator core 3 is equal to the number of outer slots 6, such as Figure 5As shown, the number of external teeth 4 of the stator core 3 is 6, the number of heat pipes 10 is 18, and the number of internal teeth of the stator core 3 is 24; in this diagram, the heat pipes 10 are distributed in a decentralized and concentrated manner, that is, a continuous heat pipe group, and each three heat pipes 10 are grouped together. One heat pipe 10 group replaces three or more adjacent external teeth 4 of the stator core 3, and the remaining heat pipe 10 groups are evenly distributed along the circumference of the stator core 3 and replace adjacent external teeth 4. At this time, the arrangement structure of the heat pipes 10 is conducive to further reducing the thermal resistance in the heat transfer process of the stator core and enhancing the heat dissipation capacity of the motor.

[0087] Of course, in some cases, the length of the heat pipe 10 along the axial direction of the stator core 3 is set, such as in some occasions, such as Figure 6 As shown, the length of the heat pipe 10 is equal to the length of the stator core 3, and the axial end faces on both sides of the stator core 3 are flush with the end faces of the heat pipe 10, which can reduce the processing difficulty of the heat pipe 10 and facilitate the installation of the heat pipe 10.

[0088] The liquid cooling housing 1 has a liquid cooling channel filled with a coolant 2. Depending on the usage conditions, the coolant is preferably No. 65 coolant, pure water, oil, ethylene glycol, etc. The liquid cooling channel is preferably in a "Z" shape or a spiral shape.

[0089] In order to verify the conclusion that the heat pipe 10 has little effect on the electromagnetic performance of the motor, the present invention adopts Figure 3 The electromagnetic performance of the heat pipe structure shown in the figure and the back-wound high-speed permanent magnet motor without heat pipe is compared and analyzed. The electromagnetic performance under no-load and load conditions is compared as follows.

[0090] Figure 11-16 The simulation results of magnetic field lines, magnetic flux density distribution and no-load back EMF of the two motors are given respectively. Fig.11 , 12 It can be seen that after the heat pipe 10 is installed, the magnetic lines of force of the motor are evenly distributed and have a reasonable trend, which is basically consistent with the distribution trend of the magnetic lines of force of a conventional motor without the heat pipe 10 installed. Fig.13 , 14 It can be seen that the motor magnetic flux distribution and magnetic flux size are highly consistent when the heat pipe 10 is installed and when it is not installed. Fig.15 , 16 It can be seen that the no-load back EMF effective values ​​of the two motors are 151 V and 149.8 V respectively, which are basically the same. Therefore, the installation of the heat pipe 10 has basically no effect on the no-load electromagnetic performance of the back-wound high-speed permanent magnet motor.

[0091] Fig.17 , 18The electromagnetic torque curves of the two motors under load are given respectively, and the drive current of the motors is set to 120A at this time. It can be seen that the average electromagnetic torques of the motors with and without the heat pipe 10 are 17.2539Nm and 17.1264Nm respectively, that is, the electromagnetic torques are basically the same, and the torque fluctuations are also basically the same. Therefore, replacing part of the stator outer teeth 4 with the heat pipe 10 has little effect on the motor load torque.

[0092] In summary, the cooling structure of the present invention has little effect on the electromagnetic performance of the back-wound high-speed permanent magnet motor.

[0093] In addition, in order to verify the cooling effect of the cooling structure, the following Figure 4-6 The temperature field of the motor with the cooling structure shown is simulated and analyzed, and for comparison, the temperature field simulation results of a conventional back-wound winding motor that does not adopt the cooling structure of the present invention are also given.

[0094] Figure 19-21 The temperature distribution of the winding, core and the whole of a conventional back-wound motor without the cooling structure of the present invention is given. Figure 22-24 The invention provides a method of using 12 heat pipes and the heat pipe length is equal to the iron core (corresponding to the invention Figure 6 ) of the motor winding, core and overall temperature field distribution, Figure 25-27 A method of using 12 heat pipes and having a heat pipe length greater than the iron core (corresponding to the present invention) is provided. Figure 4 ) of the motor winding, core and overall temperature field distribution, Figure 28-30 The invention provides a method of using 18 heat pipes and the heat pipe length is greater than the iron core (corresponding to the invention Figure 5 )'s motor windings, core and overall temperature field distribution.

[0095] contrast Fig.19 , 22 , 25, and 28 show the temperature distribution diagrams of the winding 8. It can be seen that when the heat pipe 10 is not installed, the maximum temperature of the winding 8 is 90.9°C; when 12 heat pipes 10 of the same length as the stator core 3 are installed, the maximum temperature of the winding drops significantly to 76.2°C, which is 14.7°C lower than when the heat pipe 10 is not installed; when 12 heat pipes 10 of a length greater than the stator core 3 are installed, the maximum temperature of the winding drops to 72.4°C, which is 14.7°C lower than when the heat pipe 10 is not installed. Figure 6 With the cooling structure shown, the maximum temperature of the winding 8 drops by 3.8°C, which indicates that increasing the length of the heat pipe 10 and increasing the contact area with the winding are effective in reducing the temperature of the winding 8; when 18 heat pipes 10 are installed, the maximum temperature of the winding 8 drops to 68.9°C, which is a significant decrease of 22°C compared with the case where the heat pipe 10 is not installed.

[0096] contrast Fig. 20 ,23 , 26, and 29 show the temperature distribution diagrams of the stator core 3. It can be seen that the change in the maximum temperature of the stator core 3 is basically consistent with the change in the maximum temperature of the winding 8. The maximum temperature of the stator core 3 without the heat pipe 10 is 92.0°C, while the corresponding Figure 6 , 4 The maximum temperatures of the stator cores of the cooling structures shown in Figure 5 are 76.1°C, 74.0°C, and 68.8°C, respectively. The maximum temperatures of the stator cores of the three cooling structures are all reduced by more than 15°C. Figure 5 The cooling structure shown has the largest temperature drop, with the stator core temperature dropping by up to 21.2°C.

[0097] contrast Fig.21 , 24 , 27, and 30 show the overall temperature distribution of the motor. It can be seen that the highest temperature of the motor appears on the rotor sheath 13. The highest temperature of the motor without heat pipe is 133.5℃, while the corresponding Figure 6 , 4 The maximum temperatures of the motors with the cooling structures shown in Figure 5 are 122.2°C, 121.2°C, and 116.2°C respectively. The maximum temperatures of the motors with the three cooling structures all drop by more than 11°C. Figure 5 The maximum temperature drop of the motor with the cooling structure shown is significantly higher than Figure 4 , 6 The two cooling structures shown are 17.3° C., indicating that increasing the number of heat pipes 10 can further enhance the heat dissipation capacity of the motor.

[0098] In summary, using heat pipes instead of the stator outer teeth 4 can significantly reduce the temperature of the winding 8, the stator core 3 and the rotor, and the temperature rise can be further reduced by extending the length of the heat pipes 10 and increasing the number of heat pipes 10, which verifies that the cooling structure of the present invention can significantly reduce the heat generation of the back-wound winding motor.

[0099] In summary, in the conventional back-wound high-speed permanent magnet motor with casing liquid cooling, the heat of the stator core 3 and the winding is first transferred to the outer teeth 4 of the stator core 3, and then transferred to the liquid-cooled casing 1 by the stator outer teeth 4. Since the material of the stator outer teeth 4 is a core material such as silicon steel sheets, its thermal conductivity is poor, so the thermal resistance of the back-wound high-speed permanent magnet motor stator to the outside heat transfer is large, so the back-wound high-speed permanent magnet motor has a serious problem of heating. The present invention is structurally equivalent to replacing part of the stator outer teeth 4 of the back-wound high-speed permanent magnet motor with a heat pipe 10. Since the principle of the heat pipe 10 is to conduct heat by utilizing the vapor-liquid phase change process of the liquid, its thermal conductivity is extremely strong, far higher than that of iron core materials such as silicon steel sheets, so it can effectively reduce the thermal resistance of the heat transfer from the internal heat of the back-wound high-speed permanent magnet motor to the liquid cooling housing 1, so that the heat concentrated in the stator core 3 and the winding can be quickly transferred to the liquid cooling housing 1; and the heat pipe 10 can also quickly transfer the heat of the outer winding in the stator outer slot 6 in close contact with it to the liquid cooling housing 1. The combined effect of the two aspects can quickly transfer the heat in the stator core 3 and the winding to the liquid cooling housing 1, and the coolant can take away the heat in time, thereby greatly reducing the temperature rise of the back-wound high-speed permanent magnet motor. The heat pipe 10 of this embodiment plays a role in supporting the stator in structure, and has little effect on the electromagnetic performance.

[0100] It should be noted that the terms "comprises", "includes" or any other variations thereof in this article are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0101] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can also be a centered element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a centered element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and are not intended to be the only implementation method.

[0102] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0103] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation 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.

Claims

1. A cooling structure for a back-wound high-speed permanent magnet motor, characterized in that: include: A heat pipe (10), the heat pipe (10) imitates the shape of the outer teeth (4) of the stator core (3) of a back-wound high-speed permanent magnet motor, when at least one heat pipe (10) replaces the outer teeth (4) of the stator core (3) and is installed on the outer circumferential side wall of the stator core (3): If there is only one heat pipe (10), the heat pipe (10) and the outer teeth (4) of the adjacent stator core (3) form an outer slot (6); If there are multiple heat pipes (10), when a heat pipe (10) is adjacent to another heat pipe (10), the heat pipe (10) and the adjacent heat pipe (10) form an outer groove (6); and, if at least one heat pipe (10) is adjacent to an outer tooth (4) of a stator core (3), the heat pipe (10) and the adjacent outer tooth (4) of the stator core (3) form an outer groove (6); The condensing section of the heat pipe (10) performs heat exchange with the liquid cooling casing (1) of the back-wound high-speed permanent magnet motor.

2. The cooling structure of a back-wound high-speed permanent magnet motor according to claim 1, characterized in that: The heat pipe (10) is detachably fixedly connected to the outer circumferential side wall of the stator core (3).

3. The cooling structure of a back-wound high-speed permanent magnet motor according to claim 2, characterized in that: The lower end of the heat pipe (10) has a snap-fitting portion or a snap-fitting slot, and the outer circumferential side wall of the corresponding stator core (3) has a matching snap-fitting slot or snap-fitting portion; the heat pipe (10) and the outer circumferential side wall of the stator core (3) are connected via the matching snap-fitting slot and the snap-fitting portion.

4. The cooling structure of a back-wound high-speed permanent magnet motor according to claim 3, characterized in that: The gap between the engaging portion and the slot is filled with thermally conductive silica gel.

5. The cooling structure of a back-wound high-speed permanent magnet motor according to claim 1, characterized in that: The length of the heat pipe (10) is equal to the length of the stator core (3), and the axial end faces on both sides of the stator core (3) are flush with the end faces of the heat pipe (10).

6. The cooling structure of a back-wound high-speed permanent magnet motor according to claim 1, characterized in that: The length of the heat pipe (10) is greater than the length of the stator core (3), and the heat pipe (10) extending beyond the axial end surfaces on both sides of the stator core (3) forms a semi-enclosed structure with respect to the end (9) of the back-wound winding (8).

7. The cooling structure of a back-wound high-speed permanent magnet motor according to claim 1, characterized in that: The outer wall of the condensation section of the heat pipe (10) is formed with an arc surface that matches the inner wall of the liquid cooling casing (1), and the arc surface fits the inner wall of the liquid cooling casing (1).

8. A back-wound high-speed permanent magnet motor, characterized in that: Comprising a cooling structure as claimed in any one of claims 1 to 7, when at least one heat pipe (10) replaces the outer teeth (4) of the stator core (3) and is installed on the outer circumferential side wall of the stator core (3), the top of the cooling structure is in contact with the inner wall of the liquid cooling housing (1); The liquid cooling housing (1) has a liquid cooling channel therein, and the liquid cooling channel is filled with cooling liquid (2); The cooling structure conducts the heat in the stator core (3) and the back-wound winding (8) to the coolant in the liquid-cooled casing (1), and the coolant dissipates heat.

9. The back-wound high-speed permanent magnet motor according to claim 8, characterized in that: The heat pipes (10) and the outer teeth (4) of the stator core (3) form a structure in which the circumferential spaces are alternately arranged.

10. The back-wound high-speed permanent magnet motor according to claim 9, characterized in that: The plurality of heat pipes (10) form a group of outer teeth (4) that replace a corresponding number of adjacent stator cores (3).

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