A magnetic powder core applied to a motor and a preparation method thereof and the motor

Abstract

The application provides a magnetic powder core applied to a motor and a preparation method and the motor, and relates to the technical field of motors.The magnetic powder core comprises a first magnet, a winding coil, a second magnet and a shell.The winding coil is arranged around the first magnet, the second magnet is sleeved outside the winding coil, and the shell wraps the second magnet.The magnetic permeability of the second magnet decreases from the winding coil to the shell in the direction, and the magnetic permeability decreases in the first magnet layer, the second magnet layer and the third magnet layer in turn.The material of the first magnet layer, the second magnet layer and the third magnet layer comprises iron-silicon-aluminum alloy powder and a silicon dioxide coating layer covering the iron-silicon-aluminum alloy powder.The application can solve the technical problem that the radial magnetic permeability gradient changes in the prior art through a multi-layer heterogeneous magnetic powder system, which easily causes magnetic field distortion and a sharp increase in eddy current loss.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a magnetic powder core for use in motors, its preparation method, and the motor itself. Background Technology

[0002] In the field of motors, magnetic cores are key components for converting electrical energy into magnetic energy. Traditional motors mostly use laminated silicon steel cores, but these cores suffer from high eddy current losses and are bulky and heavy at high frequencies (e.g., 50kHz~500kHz), making them unsuitable for the high power density requirements of motors used in new energy vehicles and industrial servos. Magnetic powder cores, due to their advantages of low eddy current losses and high frequency adaptability, have become a research hotspot.

[0003] In existing magnetic powder core technologies, radial permeability gradients are often used to reduce eddy current losses. This is generally achieved through multilayer heterogeneous magnetic powder design (such as layered pressing of Fe-Ni, Fe-Si-Al, Fe-Si, etc.). However, this approach has the following drawbacks: First, the process is complex: the procurement and mixing of various magnetic powders is cumbersome, and layered loading can easily lead to uneven mixing between layers. Second, the permeability gradient is discontinuous: the magnetic properties of different magnetic powders vary significantly, resulting in a step-like abrupt change in the magnetic field and a high magnetic field distortion rate, which increases eddy current losses. Third, the interfacial voids and thermal resistance are large: due to poor matching of various magnetic powder particles, voids remain between layers, resulting in high interfacial thermal resistance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a magnetic powder core for use in motors, a method for preparing the same, and a motor, aiming to solve the technical problem in the prior art that the radial permeability gradient change formed by multilayer heterogeneous magnetic powder systems easily causes magnetic field distortion and a surge in eddy current losses.

[0005] A first aspect of the present invention is to provide a magnetic powder core for use in an electric motor, the magnetic powder core comprising:

[0006] First magnet, winding coil, second magnet, outer casing;

[0007] The winding coil is arranged around the first magnet, the second magnet is sleeved on the outside of the winding coil, and the outer shell encloses the second magnet;

[0008] The permeability of the second magnet decreases in a gradient from the winding coil to the outer shell, including a first magnet layer, a second magnet layer, and a third magnet layer with sequentially decreasing permeability. The materials of the first magnet layer, the second magnet layer, and the third magnet layer all include iron-silicon-aluminum alloy powder and a silicon dioxide coating layer covering the iron-silicon-aluminum alloy powder.

[0009] Compared with the prior art, the application has the beneficial effects that: the magnetic powder core applied to the motor provided by the application adopts single iron-silicon-aluminum alloy powder, the density gradient and the thickness gradient of the silicon dioxide coating layer are synergistically controlled by setting the particle size and pressure parameters of the iron-silicon-aluminum alloy powder, the magnetic permeability is smoothly transitioned, and the magnetic field distortion rate is reduced, thereby solving the technical problems in the prior art that the radial magnetic permeability gradient change is formed by a multi-layer heterogeneous magnetic powder system, which easily causes the magnetic field distortion and the surge of eddy current loss.

[0010] According to an aspect of the above technical solution, the thicknesses of the first magnet layer, the second magnet layer and the third magnet layer are 4mm-6mm, 4mm-6mm and 3mm-5mm respectively, the magnetic permeabilities thereof are 80-110, 60-80 and 30-60 respectively, the particle sizes of the iron-silicon-aluminum alloy powder corresponding to the first magnet layer, the second magnet layer and the third magnet layer are 8um-12um, 7um-10um and 5um-8um respectively, and the thicknesses of the silicon dioxide coating layers are 50nm-80nm, 100nm-120nm and 150nm-200nm respectively.

[0011] According to an aspect of the above technical solution, the magnetic permeability of the first magnet is 120-130, the first magnet comprises iron-nickel alloy powder, E-15 epoxy resin and KH-560 coupling agent, the particle size of the iron-nickel alloy powder is 12um-15um, the mass ratio of the iron-nickel alloy powder to the E-15 epoxy resin is (90-95):8, the KH-560 coupling agent accounts for 1wt%-5wt% of the first magnet, and the mass fraction of nickel in the iron-nickel alloy powder is 75wt%-85wt%.

[0012] According to an aspect of the above technical solution, the winding coil is coated with a heat-conducting insulating coating, a compatible interface layer is arranged inside the shell, so that the first magnet, the winding coil, the second magnet and the shell are tightly attached, the inner diameter of the winding coil is 18.1mm-22.1mm, the outer diameter is 28mm-32mm, the length is 50mm-70mm, the number of turns is 55-70, the heat-conducting insulating coating comprises 25wt%-48wt% boron nitride particles, 50wt%-70wt% silicone resin and 0.1wt%-2wt% KH-550 coupling agent, and the thickness of the heat-conducting insulating coating is 80um-120um.

[0013] According to an aspect of the above technical solution, the inner diameter of the shell is 48mm-52mm, the length is 52mm-72mm, and the wall thickness is 3mm-4mm; the compatibility interface layer comprises 89wt%-92wt% E-15 epoxy resin, 1wt%-5wt% KH-560 coupling agent, and 1wt%-10wt% boron nitride microparticles; the thickness of the compatibility interface layer is 40um-60um, and the particle size of the boron nitride microparticles is 4um-6um.

[0014] The second aspect of the application provides a preparation method of a magnetic powder core applied to a motor, which is used for preparing the magnetic powder core applied to the motor, and comprises the following steps:

[0015] The coil winding coated with the heat-conducting insulating coating is wound to form a winding coil;

[0016] The first magnet is injection molded and attached to the inner wall of the winding coil;

[0017] The second magnet is three-layer gradient-pressed and attached to the outer wall of the winding coil;

[0018] The shell with the compatibility interface layer in the inside is wrapped around the second magnet, and solidified to obtain the magnetic powder core.

[0019] Further, the preparation method of the second magnet comprises the following steps:

[0020] The iron-silicon-aluminum alloy powder with a particle size of 8um-12um is dispersed in 2wt%-7wt% silica sol, and after ball milling reaction for 20min-40min, drying at 70℃-90℃ for 1h-3h, and roasting at 400℃-600℃ for 0.5h-2h, the first coated particle is obtained by passing through a 120-mesh sieve;

[0021] The iron-silicon-aluminum alloy powder with a particle size of 7um-10um is dispersed in 4wt%-8wt% silica sol, and after ball milling reaction for 50min-70min, drying at 70℃-90℃ for 1h-3h, and roasting at 400℃-600℃ for 0.5h-2h, the second coated particle is obtained by passing through a 150-mesh sieve;

[0022] The iron-silicon-aluminum alloy powder with a particle size of 5um-8um is dispersed in 7wt%-9wt% silica sol, and after ball milling reaction for 80min-100min, drying at 70℃-90℃ for 1h-3h, and roasting at 400℃-600℃ for 0.5h-2h, the third coated particle is obtained by passing through a 200-mesh sieve;

[0023] The solid-liquid ratio of the iron-silicon-aluminum alloy powder and the silica sol is 1g:(0.1-1)mL, the ball-to-material ratio of the ball milling reaction is (4-6):1, and the rotation speed is 200r / min-400r / min;

[0024] A three-section partition mold is adopted, adjacent cavities are separated by annular bosses, and the third coated particle, the second coated particle and the first coated particle are sequentially loaded, and each section is pre-pressed at 1MPa~3MPa for 1s~5s to fix;

[0025] The pressure is started step by step in sequence, the pressure of the first coated particle, the second coated particle and the third coated particle is 11MPa~13MPa, 8MPa~10MPa and 5MPa~7MPa respectively, the holding time is 10s~20s, 8s~17s and 5s~15s respectively, after the pressing is completed, the nitrogen degreasing is carried out at 200℃~400℃ for 80min~100min, and the first magnet layer, the second magnet layer and the third magnet layer are formed.

[0026] Further, the preparation method of the heat-conducting and insulating coating comprises:

[0027] 25wt%~48wt% boron nitride particles, 50wt%~70wt% silicone resin and 0.1wt%~2wt% KH-550 coupling agent are added to deionized water for stirring, vacuum defoaming, to obtain a coating slurry, wherein the solid-liquid ratio is 1g: (1~2)mL, the stirring speed is 400r / min~600r / min, the stirring time is 30min~50min, the vacuum defoaming pressure is-0.08MPa~-0.1MPa, and the vacuum defoaming time is 10min~20min;

[0028] The coating slurry is coated on the surface of the coil, and the heat-conducting and insulating coating is obtained by curing at 150℃~200℃ for 30min~50min.

[0029] The preparation method of the compatible interface layer comprises:

[0030] 89wt%~92wt% E-15 epoxy resin, 1wt%~5wt% KH-560 coupling agent and 1wt%~10wt% boron nitride particles are added to ethyl acetate for uniform stirring, to obtain a spraying slurry, wherein the solid-liquid ratio is 1g: (1~3)mL, the stirring speed is 700r / min~900r / min, and the stirring time is 10min~30min;

[0031] The spraying slurry is sprayed on the inner wall of the shell, and the shell with the compatible interface layer is obtained by curing at 90℃~110℃ for 20min~40min.

[0032] Further, the curing step comprises:

[0033] The curing temperature is set to 100℃~140℃, and the first-stage curing is completed by curing for 60min~100min;

[0034] The curing temperature is set to 140-180 DEG C, and the curing time is 100-140 min, to complete the second curing;

[0035] The curing temperature is set to 180-220 DEG C, and the curing time is 130-170 min, to complete the third curing.

[0036] The third aspect of the present application provides an electric machine, which comprises the magnetic powder core applied to the electric machine. BRIEF DESCRIPTION OF DRAWINGS

[0037] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings, in which:

[0038] Fig. 1 is a top view of the magnetic powder core in the present application;

[0039] Fig. 2 is a structural schematic view of the winding coil, the first magnet and the second magnet in the present application;

[0040] Fig. 3 is a structural schematic view of the winding coil in the present application;

[0041] In the figure: winding coil 1, first magnet 2, second magnet 3, shell 4, first magnet layer 30, second magnet layer 31, third magnet layer 32. DETAILED DESCRIPTION

[0042] In order to make the objects, features and advantages of the present application more apparent and easily understood, the specific embodiments of the present application are described in detail below in conjunction with the accompanying drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0043] Please refer to Figs. 1-3 , which shows a magnetic powder core applied to an electric machine provided by the present application, which comprises:

[0044] First magnet 2, winding coil 1, second magnet 3, shell 4;

[0045] The winding coil 1 is arranged around the first magnet 2, the second magnet 3 is sleeved outside the winding coil 1, and the shell 4 wraps the second magnet 3;

[0046] The magnetic permeability of the second magnet 3 changes along the radial direction, and decreases from the winding coil 1 to the shell 4;

[0047] The winding coil 1 is coated with a heat-conducting insulating coating, and the shell 4 is internally provided with a compatibility interface layer, so that the first magnet 2, the winding coil 1, the second magnet 3, and the shell 4 are tightly attached.

[0048] Further, the second magnet 3 comprises a first magnet layer 30, a second magnet layer 31, and a third magnet layer 32 with decreasing magnetic permeability in sequence, the first magnet layer 30, the second magnet layer 31, and the third magnet layer 32 all comprise iron-silicon-aluminum alloy powder and a silica coating layer covering the iron-silicon-aluminum alloy powder, and the thicknesses of the first magnet layer 30, the second magnet layer 31, and the third magnet layer 32 are 4mm-6mm, 4mm-6mm, and 3mm-5mm respectively, and the magnetic permeabilities of the first magnet layer 30, the second magnet layer 31, and the third magnet layer 32 are 80-110, 60-80, and 30-60 respectively.

[0049] Further, the particle sizes of the corresponding iron-silicon-aluminum alloy powder of the first magnet layer 30, the second magnet layer 31, and the third magnet layer 32 are 8μm-12μm, 7μm-10μm, and 5μm-8μm respectively, and the thicknesses of the silica coating layer are 50nm-80nm, 100nm-120nm, and 150nm-200nm respectively.

[0050] It should be noted that the second magnet 3 only uses one kind of basic magnetic powder (iron-silicon-aluminum alloy powder), and the structural differences in density are formed by setting the particle size and pressing pressure, and the magnetic permeability gradient is realized in combination with the thickness of the coating layer, without the need for multiple magnetic powders to form the second magnet 3 with a decreasing magnetic permeability gradient, that is, when the density is high, the magnetic powder is in close contact and the coating layer is thin (strong magnetic coupling), forming the first magnet layer 30 with high magnetic permeability, and when the density is low and the coating layer is thick (weak magnetic coupling), forming the third magnet layer 32 with low magnetic permeability.

[0051] Furthermore, by setting three layers, the magnetic permeability is smoothly transitioned from the inside to the outside, the magnetic field is uniformly distributed, the magnetic field is guided to flow back, and local magnetic saturation is avoided. The low-magnetic-permeability magnet of the third magnet layer 32 forms a magnetic resistance barrier, reduces the leakage magnetic field to the shell 4, and at the same time improves the anti-saturation capability under large current.

[0052] Further, the magnetic permeability of the first magnet 2 is 120-130, and the first magnet 2 comprises iron-nickel alloy powder, E-15 epoxy resin, and KH-560 coupling agent, the particle size of the iron-nickel alloy powder is 12μm-15μm, the mass ratio of the iron-nickel alloy powder to the E-15 epoxy resin is (90-95):8, the KH-560 coupling agent accounts for 1wt%-5wt% of the first magnet 2, and in the iron-nickel alloy powder, the mass fraction of nickel is 75wt%-85wt%.

[0053] That is, the high magnetic permeability of the first magnet 2 concentrates the magnetic field of the winding coil in the center of the magnetic circuit, reduces the magnetic resistance, and improves the inductance.

[0054] Further, the inner diameter of the winding coil 1 is 18.1mm~22.1mm, the outer diameter is 28mm~32mm, the length is 50mm~70mm, the number of turns is 55~70, and the heat-conducting insulation coating includes 25wt%~48wt% boron nitride particles, 50wt%~70wt% silicone resin, and 0.1wt%~2wt% KH-550 coupling agent, and the thickness of the heat-conducting insulation coating is 80μm~120μm.

[0055] The winding coil 1 forms a magnetic field source by a densely wound coil to provide excitation for the magnetic powder core, and the flaky boron nitride particles in the heat-conducting insulation coating improve heat conduction, and the flaky boron nitride particles form a continuous heat-conducting network through face-to-face lapping to quickly transfer the heat generated by the energization of the coil to the second magnet 3 and then conduct the heat out through the shell 4. The boron nitride particles are uniformly dispersed in the silicone resin matrix, wrap the surface of the coil, and fill the resin gaps to form a non-porous insulation barrier to block the electrical path of the coil to the first magnet 2 and the second magnet 3. The KH-550 coupling agent is used to enhance the interfacial bonding between the boron nitride particles and the silicone resin and reduce thermal resistance.

[0056] Further, the inner diameter of the shell 4 is 48mm~52mm, the length is 52mm~72mm, the wall thickness is 3mm~4mm, the compatible interface layer includes 89wt%~92wt% E-15 epoxy resin, 1%~5wt% KH-560 coupling agent, and 1wt%~10wt% boron nitride particles, the thickness of the compatible interface layer is 40μm~60μm, and the particle size of the boron nitride particles is 4μm~6μm.

[0057] The material of the shell 4 is aluminum alloy, which serves as a heat dissipation terminal to conduct heat out, and the compatible interface layer is selected to be compatible with the material of the shell 4 and the binder of the second magnet 3, which is E-15 epoxy resin.

[0058] In addition, the first magnet 2 and the winding coil 1 are attached by an injection molding process. During injection molding, the molten E-15 epoxy resin and the silicone resin of the heat-conducting insulation coating of the winding coil 1 interface swell and fuse, eliminating micro voids. The silicone resin of the winding coil 1 will chemically adhere to the silica coating layer of the second magnet 3 (-Si-O- bond), reducing the gap. In addition, after the second magnet 3 is pressed, the shell 4 is fitted while hot (150℃). The compatible interface layer microflows under pressure to fill the gap, undergoes a condensation reaction with the silica coating layer (containing Si-OH) of the second magnet 3, and chemically bonds with the aluminum alloy shell 4 (Al-OH). After cooling, the elastic deformation compensates for thermal expansion and contraction, further reducing the gap.

[0059] Correspondingly, the application further provides a preparation method of the magnetic powder core applied to the motor, for preparing the magnetic powder core applied to the motor, and the preparation method comprises steps S10-S13.

[0060] Step S10, winding the coil with the surface coated with the heat-conducting insulating coating to form a winding coil;

[0061] Specifically, the polyimide enameled copper wire is wound at a single layer and 5N-6N tension for 55 turns-70 turns to form the winding coil.

[0062] Further, the polyimide enameled copper wire is pre-cleaned with anhydrous ethanol to remove surface oil stains, dried, and then wound, and the winding coil needs to be heated in a 100℃ oven for 30 min to eliminate winding stress.

[0063] Then, 25wt%-48wt% boron nitride particles, 50wt%-70wt% silicone resin, and 0.1wt%-2wt% KH-550 coupling agent are added into deionized water for stirring, vacuum defoaming, to obtain a coating slurry, wherein the solid-liquid ratio is 1g:(1-2)mL, the stirring speed is 400r / min-600r / min, the stirring time is 30min-50min, the vacuum defoaming pressure is-0.08MPa--0.1MPa, and the vacuum defoaming time is 10min-20min.

[0064] The coating slurry is coated on the surface of the coil, and cured at 150℃-200℃ for 30min-50min to obtain the coil with the surface coated with the heat-conducting insulating coating.

[0065] The heating rate is 4℃ / min-6℃ / min.

[0066] Step S11, injection molding a first magnet and adhering to the inner wall of the winding coil;

[0067] Specifically, the iron-nickel alloy powder and the E-15 epoxy resin are mixed, and the KH-560 coupling agent is added, and the injection molding material is prepared by double screw mixing;

[0068] The iron-nickel alloy powder needs to be pre-dried at 80℃ for 2h, and the agglomerated particles are removed through a 200-mesh sieve, the process conditions of the double screw mixing are a temperature of 90℃-110℃, a speed of 100r / min-300r / min, and a time of 10min-20min, and the particle size of the injection molding material is 3mm-5mm.

[0069] Then, the injection molding material is preheated at 100-120°C for 20-40 minutes, the winding coil with heat-conducting insulating coating is preheated at 70-90°C for 10-30 minutes, and then is placed in an injection molding die, and is injection molded at an injection molding temperature of 150-160°C, an injection molding pressure of 5-15 MPa, and a pressure maintaining time of 12-25 seconds, and is cooled and solidified at 110-130°C for 50-70 minutes to form the first magnet closely adhering to the winding coil.

[0070] It should be noted that the preheating of the injection molding material is to improve the fluidity, and the preheating of the winding coil with heat-conducting insulating coating is to activate the surface active groups of the heat-conducting insulating coating, so that the molten E-15 epoxy resin and the silicone resin of the heat-conducting insulating coating of the coil are interfacially swelled and fused, and micro voids are eliminated.

[0071] Step S12, three layers of gradient pressing the second magnet and adhering to the outer wall of the winding coil;

[0072] The particle sizes of the iron-silicon-aluminum alloy powders corresponding to the first magnet layer, the second magnet layer, and the third magnet layer are 8-12 μm, 7-10 μm, and 5-8 μm, respectively, and the powders are vacuum dried at 80°C for 1 hour, respectively, to avoid the generation of bubbles during pressing, and are passed through 120-mesh, 150-mesh, and 200-mesh screens, respectively, to remove large-particle agglomerates.

[0073] Specifically, the iron-silicon-aluminum alloy powder with a particle size of 8-12 μm is dispersed in 2-7 wt% silica sol, ball-milled for 20-40 minutes, dried at 70-90°C for 1-3 hours, calcined at 400-600°C for 0.5-2 hours, and passed through a 120-mesh screen to obtain the first coated particle.

[0074] The iron-silicon-aluminum alloy powder with a particle size of 7-10 μm is dispersed in 4-8 wt% silica sol, ball-milled for 50-70 minutes, dried at 70-90°C for 1-3 hours, calcined at 400-600°C for 0.5-2 hours, and passed through a 150-mesh screen to obtain the second coated particle.

[0075] The iron-silicon-aluminum alloy powder with a particle size of 5-8 μm is dispersed in 7-9 wt% silica sol, ball-milled for 80-100 minutes, dried at 70-90°C for 1-3 hours, calcined at 400-600°C for 0.5-2 hours, and passed through a 200-mesh screen to obtain the third coated particle.

[0076] The solid-liquid ratio of the iron-silicon-aluminum alloy powder to the silica sol is 1 g to (0.1-1) mL, the ball-to-material ratio of the ball-milling reaction is (4-6) to 1, and the rotation speed is 200-400 r / min.

[0077] A three-section partition mold is adopted, adjacent cavities are separated by annular bosses, and the third coating particles, the second coating particles and the first coating particles are sequentially loaded, and each section is pre-pressed at 1MPa~3MPa for 1s~5s to fix;

[0078] Among them, the coaxiality of the three-section partition mold is ≤0.02mm, the surface roughness Ra of the cavity is ≤0.8μm, the thickness of the annular boss is 0.3mm, and after pressure relief, the annular boss is ejected, and the three-layer compact is connected into one after high-temperature nitrogen degreasing.

[0079] Step-by-step pressure is sequentially started, the pressure of the first coating particles, the second coating particles and the third coating particles is 11MPa~13MPa, 8MPa~10MPa and 5MPa~7MPa respectively, the holding time is 10s~20s, 8s~17s and 5s~15s respectively, after the pressing is completed, nitrogen degreasing at 200℃~400℃ for 80min~100min is performed to form the first magnet layer, the second magnet layer and the third magnet layer.

[0080] Among them, the nitrogen degreasing at 200℃~400℃ is used to remove residual organic matter.

[0081] Step S13, the shell with a compatible interface layer inside is wrapped around the second magnet, and solidified to obtain a magnetic powder core.

[0082] Specifically, 89wt%~92wt% E-15 epoxy resin, 1%~5wt% KH-560 coupling agent and 1wt%~10wt% boron nitride microparticles are added into ethyl acetate, and stirred uniformly to obtain a spraying slurry, wherein the solid-liquid ratio is 1g: (1~3)mL, the stirring speed is 700r / min~900r / min, and the stirring time is 10min~30min.

[0083] Then, the spraying slurry is sprayed on the inner wall of the shell, and pre-solidified at 90℃~110℃ for 20min~40min to obtain a shell with a compatible interface layer inside.

[0084] Among them, the spraying pressure is 0.4MPa, the distance is 15cm, the time is 10s, and the walking gun speed is 90mm / s~110mm / s, and the wet film thickness is 70μm~90μm.

[0085] In addition, the shell needs to be roughened and then sprayed with the slurry.

[0086] Among them, the roughening treatment is sandblasting treatment, the sand particle size is 60μm, the sandblasting pressure is 0.4MPa, the distance is 15cm, the time is 10s, the roughness Ra is 2.0μm~3.2μm. After sandblasting, ultrasonic cleaning with anhydrous ethanol for 10min (power 300W) and 80℃ hot air drying for 30min are performed.

[0087] In addition, the second magnet (150℃ residual heat) is pressed into the shell, 2.5MPa pressure is applied for 10min, so that the compatible interface layer fills the gap.

[0088] In addition, the step of curing comprises:

[0089] The curing temperature is set to 100℃-140℃, and the curing time is 60min-100min, so that the E-15 epoxy resin in the first magnet is completely cured.

[0090] The curing temperature is set to 140℃-180℃, and the curing time is 100min-140min, so that the silica coating layer structure in the second magnet is crystallized or densified to improve stability, and the Si-OH groups of the compatible interface layer and the silica coating layer of the second magnet and the Al-OH groups of the shell aluminum alloy are condensed to form chemical bonds (such as -Si-O-Al- bonds), so that the compatible interface layer is upgraded from physical adhesion to chemical bonding, the bonding strength is improved, and the continuity of the heat dissipation path is strengthened.

[0091] The curing temperature is set to 180℃-220℃, and the curing time is 130min-170min, so that the internal stress of the whole is eliminated.

[0092] The rising and falling rates of the curing temperature are both 4℃ / min-6℃ / min.

[0093] In addition, the application also provides a motor comprising the above-mentioned magnetic powder core for the motor.

[0094] The technical solutions of the application will be described in detail below with specific embodiments.

[0095] Embodiment 1

[0096] The application embodiment 1 provides a magnetic powder core for a motor, which comprises:

[0097] The first magnet, the winding coil, the second magnet, and the shell.

[0098] The winding coil is arranged around the first magnet, the second magnet is arranged outside the winding coil, and the shell is wrapped around the second magnet.

[0099] The magnetic permeability of the second magnet changes along the radial direction, and decreases from the winding coil to the shell.

[0100] The winding coil is coated with a heat-conducting insulating coating, and the shell is provided with a compatible interface layer, so that the first magnet, the winding coil, the second magnet, and the shell are tightly adhered.

[0101] Further, the second magnet comprises a first magnet layer, a second magnet layer and a third magnet layer in turn, the material of the first magnet layer, the second magnet layer and the third magnet layer comprises iron-silicon-aluminum alloy powder and a silica coating layer covering the iron-silicon-aluminum alloy powder, the thickness of the first magnet layer, the second magnet layer and the third magnet layer is 5mm, 5mm and 4mm respectively, and the magnetic permeability of the first magnet layer, the second magnet layer and the third magnet layer is 95, 70 and 48 respectively.

[0102] Further, the particle size of the iron-silicon-aluminum alloy powder corresponding to the first magnet layer, the second magnet layer and the third magnet layer is 10μm, 8μm and 7μm respectively, and the thickness of the silica coating layer is 60nm, 110nm and 180nm respectively.

[0103] Further, the magnetic permeability of the first magnet is 125, the first magnet comprises iron-nickel alloy powder, E-15 epoxy resin and KH-560 coupling agent, the particle size of the iron-nickel alloy powder is 14μm, the mass ratio of the iron-nickel alloy powder to the E-15 epoxy resin is 92:8, the KH-560 coupling agent accounts for 3wt% of the first magnet, and the mass percentage of nickel in the iron-nickel alloy powder is 80wt%.

[0104] Further, the inner diameter of the winding coil is 20.1mm, the outer diameter is 30mm, the length is 60mm, the number of turns is 63, the heat-conducting insulating coating layer comprises 39wt% boron nitride particles, 60wt% silicone resin and 1wt% KH-550 coupling agent, and the thickness of the heat-conducting insulating coating layer is 100μm.

[0105] Further, the inner diameter of the shell is 50mm, the length is 66mm, and the wall thickness is 3mm, the compatibility interface layer comprises 90wt% E-15 epoxy resin, 3wt% KH-560 coupling agent and 7wt% boron nitride particles, the thickness of the compatibility interface layer is 50μm, and the particle size of the boron nitride particles is 5μm.

[0106] The material of the shell is aluminum alloy.

[0107] Correspondingly, the embodiment also provides a preparation method of the magnetic powder core applied to the motor.

[0108] Step S10, a coil winding with a heat-conducting insulating coating layer on the surface is formed into a winding coil.

[0109] Specifically, a polyimide enameled copper wire is single-layer tightly wound for 63 turns at a tension of 5N-6N to form the winding coil.

[0110] Further, the polyimide enameled copper wire is pre-cleaned with anhydrous ethanol to remove surface oil stains, dried, and then wound, and the winding coil needs to be kept in a 100 DEG C oven for 30 min to eliminate winding stress.

[0111] Then, the boron nitride particles, the silicone resin, and the KH-550 coupling agent are added into deionized water for stirring, vacuum degassing, to obtain a coating slurry, wherein the solid-liquid ratio is 1g:1.5mL, the stirring speed is 500r / min, the stirring time is 40min, the vacuum degassing pressure is-0.09MPa, and the vacuum degassing time is 15min.

[0112] The coating slurry is coated on the surface of the coil, and cured at 180 DEG C for 40min to obtain a coil coated with a heat-conducting and insulating coating on the surface.

[0113] The temperature rising rate is 5 DEG C / min.

[0114] Step S11, injection molding the first magnet and adhering to the inner wall of the winding coil;

[0115] Specifically, the iron-nickel alloy powder and the E-15 epoxy resin are mixed, and the KH-560 coupling agent is added to prepare the injection molding material by double screw mixing.

[0116] The iron-nickel alloy powder needs to be pre-dried at 80 DEG C for 2h, and the agglomerated particles are removed through a 200-mesh sieve. The process conditions for double screw mixing are temperature 100 DEG C, rotation speed 200r / min, and time 15min. The particle size of the injection molding material is 4mm.

[0117] Then, the injection molding material is preheated at 110 DEG C for 30min, and the winding coil with the heat-conducting and insulating coating is preheated at 80 DEG C for 20min and then placed in the injection molding mold. The injection molding is performed at an injection molding temperature of 160 DEG C, an injection molding pressure of 9MPa, and a pressure maintaining time of 18s. After cooling, the first magnet is formed by curing at 120 DEG C for 60min and closely adhering to the winding coil.

[0118] Step S12, three-layer gradient pressing the second magnet and adhering to the outer wall of the winding coil;

[0119] The particle sizes of the iron-silicon-aluminum alloy powders corresponding to the first magnet layer, the second magnet layer, and the third magnet layer are 10um, 8um, and 7um, respectively. The powders are vacuum dried at 80 DEG C for 1h to avoid air bubbles during pressing. The powders are passed through a 120-mesh sieve, a 150-mesh sieve, and a 200-mesh sieve, respectively, to remove large agglomerates.

[0120] Specifically, the 10-micron iron-silicon-aluminum alloy powder is dispersed in 5wt% silica sol, ball-milled for 30 minutes, dried at 80°C for 2 hours, baked at 500°C for 1 hour, and sieved through a 120-mesh sieve to obtain first coated particles, wherein the solid-liquid ratio of the iron-silicon-aluminum alloy powder to the silica sol is 1g:0.5mL;

[0121] The 8-micron iron-silicon-aluminum alloy powder is dispersed in 6.5wt% silica sol, ball-milled for 60 minutes, dried at 80°C for 2 hours, baked at 500°C for 1 hour, and sieved through a 150-mesh sieve to obtain second coated particles, wherein the solid-liquid ratio of the iron-silicon-aluminum alloy powder to the silica sol is 1g:0.6mL;

[0122] The 7-micron iron-silicon-aluminum alloy powder is dispersed in 8wt% silica sol, ball-milled for 90 minutes, dried at 80°C for 2 hours, baked at 500°C for 1 hour, and sieved through a 200-mesh sieve to obtain third coated particles, wherein the solid-liquid ratio of the iron-silicon-aluminum alloy powder to the silica sol is 1g:0.7mL, the ball-to-material ratio of the ball-milling reaction is 5:1, and the rotation speed is 300r / min;

[0123] A three-section partition mold is used, adjacent mold cavities are separated by annular bosses, and the third coated particles, the second coated particles, and the first coated particles are sequentially loaded, and each section is pre-pressed at 2MPa for 3s to be fixed;

[0124] The coaxiality of the three-section partition mold is ≤0.02mm, the surface roughness Ra of the mold cavity is ≤0.8μm, the thickness of the annular boss is 0.3mm, the annular boss is ejected after pressure relief, and the three-layer green compacts are integrated and then degreased by high-temperature nitrogen.

[0125] The pressure is started step by step in sequence, the pressure of the first coated particles, the second coated particles, and the third coated particles is 12MPa, 9MPa, and 6MPa respectively, the pressure holding time is 15s, 12s, and 10s respectively, and after the pressing is completed, the first magnet layer, the second magnet layer, and the third magnet layer are formed by nitrogen degreasing at 300°C for 90 minutes.

[0126] In step S13, the shell with the compatibility interface layer in the inside is wrapped around the second magnet, and the magnetic powder core is obtained after curing.

[0127] Specifically, the E-15 epoxy resin, the KH-560 coupling agent, and the boron nitride microparticles are added into ethyl acetate, and stirred uniformly to obtain a spraying slurry, wherein the solid-liquid ratio is 1g:2mL, the stirring speed is 800r / min, and the stirring time is 20 minutes.

[0128] Then, the spraying slurry is sprayed on the inner wall of the shell, pre-cured at 100°C for 30 minutes, and the shell with the compatibility interface layer in the inside is obtained.

[0129] The spraying pressure is 0.4 MPa, the distance is 15 cm, the time is 10 s, the spraying speed is 100 mm / s, and the wet film thickness is 80 mu m.

[0130] In addition, the shell needs to be roughened and then sprayed with slurry.

[0131] The roughening treatment is sandblasting treatment, the sand particle size is 60 mu m, the sandblasting pressure is 0.4 MPa, the distance is 15 cm, the time is 10 s, and the roughness Ra is 2.0-3.2 mu m. After sandblasting, the shell is ultrasonically cleaned with anhydrous ethanol for 10 min (power 300 W) and dried with hot air at 80 DEG C for 30 min.

[0132] In addition, the second magnet (150 DEG C residual heat) is pressed into the shell, a pressure of 2.5 MPa is applied for 10 min, so that the compatible interface layer fills the gap.

[0133] In addition, the solidification step comprises:

[0134] The solidification temperature is set to 120 DEG C, and solidification is performed for 80 min to complete the first-stage solidification.

[0135] The solidification temperature is set to 160 DEG C, and solidification is performed for 120 min to complete the second-stage solidification.

[0136] The solidification temperature is set to 200 DEG C, and solidification is performed for 150 min to complete the third-stage solidification.

[0137] The solidification temperature is set to 200 DEG C, and solidification is performed for 150 min to complete the third-stage solidification.

[0138] Example 2

[0139] The magnetic powder core provided by the embodiment 2 of the application is applied to a motor, and is different from the magnetic powder core applied to a motor in the embodiment 1 in that:

[0140] The thicknesses of the first magnet layer, the second magnet layer and the third magnet layer are 6 mm, 4 mm and 3 mm respectively.

[0141] Example 3

[0142] The magnetic powder core provided by the embodiment 3 of the application is applied to a motor, and is different from the magnetic powder core applied to a motor in the embodiment 1 in that:

[0143] The thicknesses of the first magnet layer, the second magnet layer and the third magnet layer are 4 mm, 6 mm and 3 mm respectively.

[0144] Example 4

[0145] The application embodiment 4 provides a magnetic powder core applied to a motor.

[0146] Thicknesses of the first magnet layer, the second magnet layer and the third magnet layer are 4mm, 4mm and 5mm respectively.

[0147] Embodiment 5

[0148] The application embodiment 5 provides a magnetic powder core applied to a motor, and the magnetic powder core applied to the motor in the embodiment is different from the magnetic powder core applied to the motor in the embodiment 1.

[0149] Thicknesses of the first magnet layer, the second magnet layer and the third magnet layer are 5mm, 5mm and 5mm respectively.

[0150] Embodiment 6

[0151] The application embodiment 6 provides a magnetic powder core applied to a motor, and the magnetic powder core applied to the motor in the embodiment is different from the magnetic powder core applied to the motor in the embodiment 1.

[0152] Pressures of the first coated particle, the second coated particle and the third coated particle are 13MPa, 10MPa and 5MPa respectively.

[0153] Embodiment 7

[0154] The application embodiment 7 provides a magnetic powder core applied to a motor, and the magnetic powder core applied to the motor in the embodiment is different from the magnetic powder core applied to the motor in the embodiment 1.

[0155] Pressures of the first coated particle, the second coated particle and the third coated particle are 11MPa, 8MPa and 7MPa respectively.

[0156] Embodiment 8

[0157] The application embodiment 8 provides a magnetic powder core applied to a motor, and the magnetic powder core applied to the motor in the embodiment is different from the magnetic powder core applied to the motor in the embodiment 1.

[0158] Particle sizes of the first magnet layer, the second magnet layer and the third magnet layer are 12um, 10um and 8um respectively.

[0159] Embodiment 9

[0160] The application embodiment 9 provides a magnetic powder core applied to a motor, and the magnetic powder core applied to the motor in the embodiment is different from the magnetic powder core applied to the motor in the embodiment 1.

[0161] The particle sizes of the iron-silicon-aluminum alloy powders corresponding to the first magnet layer, the second magnet layer and the third magnet layer are 8 microns, 7 microns and 5 microns respectively.

[0162] Embodiment 10

[0163] The application provides the magnetic powder core applied to the motor, and the magnetic powder core applied to the motor in the embodiment 10 is different from the magnetic powder core applied to the motor in the embodiment 1 in that:

[0164] The thicknesses of the silicon dioxide coating layers corresponding to the first magnet layer, the second magnet layer and the third magnet layer are 50 nm, 100 nm and 150 nm respectively.

[0165] Embodiment 11

[0166] The application provides the magnetic powder core applied to the motor, and the magnetic powder core applied to the motor in the embodiment 11 is different from the magnetic powder core applied to the motor in the embodiment 1 in that:

[0167] The thicknesses of the silicon dioxide coating layers corresponding to the first magnet layer, the second magnet layer and the third magnet layer are 80 nm, 120 nm and 200 nm respectively.

[0168] Embodiment 12

[0169] The application provides the magnetic powder core applied to the motor, and the magnetic powder core applied to the motor in the embodiment 12 is different from the magnetic powder core applied to the motor in the embodiment 1 in that:

[0170] The heat-conducting insulating coating layer comprises 48% boron nitride particles, 50wt% silicone resin and 2wt% KH-550 coupling agent.

[0171] Embodiment 13

[0172] The application provides the magnetic powder core applied to the motor, and the magnetic powder core applied to the motor in the embodiment 13 is different from the magnetic powder core applied to the motor in the embodiment 1 in that:

[0173] The heat-conducting insulating coating layer comprises 30% boron nitride particles, 69.9wt% silicone resin and 0.1wt% KH-550 coupling agent.

[0174] Embodiment 14

[0175] The application provides the magnetic powder core applied to the motor, and the magnetic powder core applied to the motor in the embodiment 14 is different from the magnetic powder core applied to the motor in the embodiment 1 in that:

[0176] The compatible interface layer comprises 89wt% E-15 epoxy resin, 5wt% KH-560 coupling agent, and 6wt% boron nitride particles.

[0177] Example 15

[0178] The magnetic powder core for a motor provided by the embodiment 15 of the present application is different from the magnetic powder core for a motor in the embodiment 1 in that:

[0179] The compatible interface layer comprises 92wt% E-15 epoxy resin, 1wt% KH-560 coupling agent, and 7wt% boron nitride particles.

[0180] Comparative Example 1

[0181] The magnetic powder core for a motor provided by the comparative example 1 of the present application is different from the magnetic powder core for a motor in the embodiment 1 in that:

[0182] The multi-layer heterogeneous magnetic powder design is designed, and the materials of the first magnetic layer, the second magnetic layer and the third magnetic layer are iron-silicon alloy powder (3wt% silicon), iron-silicon-aluminum alloy powder (8.5wt% silicon, 5wt% aluminum) and iron powder respectively, and the magnetic permeability gradient is 100 / 80 / 60.

[0183] Comparative Example 2

[0184] The magnetic powder core for a motor provided by the comparative example 2 of the present application is different from the magnetic powder core for a motor in the embodiment 1 in that:

[0185] There is no magnetic permeability gradient, the iron-silicon-aluminum alloy powder has a particle size of 10μm, is not coated with a silicon dioxide coating layer, has a thickness of the thickness of the second magnetic layer, and is pressed at a pressure of 10MPa, and the magnetic permeability is 70.

[0186] Comparative Example 3

[0187] The magnetic powder core for a motor provided by the comparative example 3 of the present application is different from the magnetic powder core for a motor in the embodiment 1 in that:

[0188] There is no thermal conductive insulating coating.

[0189] Comparative Example 4

[0190] The magnetic powder core for a motor provided by the comparative example 4 of the present application is different from the magnetic powder core for a motor in the embodiment 1 in that:

[0191] There is no compatible interface layer.

[0192] Please refer to Table 1 below, which shows the parameters corresponding to the above-mentioned examples and comparative examples of the present application. The test method of magnetic permeability: using a soft magnetic alternating current magnetic property test system (B-H analyzer), the initial magnetic permeability is tested under a 1 kHz sinusoidal alternating magnetic field. The test method of iron loss: using an iron loss tester, the unit volume iron loss is measured under a sinusoidal alternating magnetic field with a magnetic flux density B m =0.25T, a frequency of 500 kHz. The test method of overall thermal conductivity: using the transient plane source method (TPS), the magnetic powder core is placed in a thermal constant analyzer, and the effective thermal conductivity is calculated by the transient thermal response of the heating probe. The test method of insulation resistance: using a high resistance meter (megohmmeter), the insulation resistance between the winding coil and the first magnet / second magnet is measured under a direct current voltage of 500V. The test method of magnetic field distortion rate: using a three-dimensional magnetic field distribution tester, five test points are selected at equal intervals in the radial direction of the magnetic powder core, and the alternating magnetic field strength (1 kHz, B m =0.25T) is measured, and the maximum deviation percentage of the magnetic field strength at each point from the average magnetic field is calculated. The test method of inductance change rate after vibration resistance: the magnetic powder core is assembled into a simulated motor stator slot and placed on a vibration test table, with an acceleration of 15g, a frequency range of 10Hz-2000Hz, and a duration of 100h. The inductance is measured using a precision inductance tester (such as an LCR bridge) before and after vibration, and the change rate is calculated.

[0193] Table 1:

[0194]

[0195] According to Table 1, the single iron-silicon-aluminum magnetic powder of the present application, through the thickness gradient of the silicon dioxide coating layer and the synergistic control of the pressing pressure gradient, compared with Comparative Example 1 (multilayer heterogeneous magnetic powder), the magnetic field uniformity is improved, the magnetic field distortion is reduced, the iron loss is reduced, and the electromagnetic performance under high frequency working conditions is significantly optimized.

[0196] Further, through the flow filling of the thermal conductive insulation layer and the chemical combination of the compatible interface layer, the overall thermal conductivity of the magnetic powder core is improved, the continuity of the heat dissipation path is guaranteed, the coil temperature rise is effectively reduced, and the thermal reliability requirements of high power density motors are met.

[0197] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like 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 application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0198] The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A magnetic powder core applied to an electric machine, characterized by, The magnetic powder core comprises: a first magnet, a winding coil, a second magnet, and a shell; the winding coil is arranged around the first magnet, the second magnet is sleeved outside the winding coil, and the shell wraps the second magnet; the magnetic permeability of the second magnet decreases from the winding coil to the shell, and the second magnet comprises a first magnet layer, a second magnet layer, and a third magnet layer with decreasing magnetic permeability, and the first magnet layer, the second magnet layer, and the third magnet layer are all composed of iron-silicon-aluminum alloy powder and a silica coating layer covering the iron-silicon-aluminum alloy powder.

2. The magnetic powder core for use in an electric motor according to claim 1, characterized by, The thickness of the first magnet layer, the second magnet layer, and the third magnet layer is 4mm-6mm, 4mm-6mm, and 3mm-5mm respectively, the magnetic permeability thereof is 80-110, 60-80, and 30-60 respectively, the particle size of the corresponding iron-silicon-aluminum alloy powder of the first magnet layer, the second magnet layer, and the third magnet layer is 8μm-12μm, 7μm-10μm, and 5μm-8μm respectively, and the thickness of the silica coating layer is 50nm-80nm, 100nm-120nm, and 150nm-200nm respectively.

3. The magnetic powder core for use in a motor according to claim 1, characterized by, The magnetic permeability of the first magnet is 120-130, and the first magnet comprises iron-nickel alloy powder, E-15 epoxy resin, and KH-560 coupling agent, the particle size of the iron-nickel alloy powder is 12μm-15μm, the mass ratio of the iron-nickel alloy powder to the E-15 epoxy resin is (90-95):8, and the KH-560 coupling agent accounts for 1wt%-5wt% of the first magnet, and in the iron-nickel alloy powder, the mass fraction of nickel is 75wt%-85wt%.

4. The magnetic powder core for application to an electric motor according to claim 1, characterized by The surface of the winding coil is coated with a heat-conducting insulating coating, and the shell is provided with a compatibility interface layer, so that the first magnet, the winding coil, the second magnet, and the shell are tightly attached, the inner diameter of the winding coil is 18.1mm-22.1mm, the outer diameter is 28mm-32mm, the length is 50mm-70mm, and the number of turns is 55-70, and the heat-conducting insulating coating comprises 25wt%-48wt% boron nitride particles, 50wt%-70wt% silicone resin, and 0.1wt%-2wt% KH-550 coupling agent, and the thickness of the heat-conducting insulating coating is 80μm-120μm.

5. The magnetic powder core for use in an electric motor according to claim 4, characterized by The inner diameter of the shell is 48mm-52mm, the length is 52mm-72mm, and the wall thickness is 3mm-4mm, and the compatibility interface layer comprises 89wt%-92wt% E-15 epoxy resin, 1wt%-5wt% KH-560 coupling agent, and 1wt%-10wt% boron nitride particles, and the thickness of the compatibility interface layer is 40μm-60μm, and the particle size of the boron nitride particles is 4μm-6μm.

6. A method for producing a magnetic powder core for an electric machine, characterized by, The preparation method is used for preparing the magnetic powder core for the motor according to any one of claims 1-5, and the preparation method comprises: coiling a winding coil coated with a heat-conducting insulating coating to form a winding coil; injection molding a first magnet and attaching the inner wall of the winding coil; Three layers of gradient pressing second magnet and adhere to the outer wall of the winding coil; The second magnet is wrapped with a shell provided with a compatibility interface layer, and is cured to obtain a magnetic powder core.

7. The method of producing a magnetic powder core for use in a motor according to claim 6, characterized by, The preparation method of the second magnet comprises: Fe-Si-Al alloy powder with a particle size of 8-12 μm is dispersed in 2-7 wt% silica sol, ball-milled for 20-40 min, dried at 70-90 ℃ for 1-3 h, calcined at 400-600 ℃ for 0.5-2 h, and sieved through a 120-mesh sieve to obtain first coated particles; Fe-Si-Al alloy powder with a particle size of 7-10 μm is dispersed in 4-8 wt% silica sol, ball-milled for 50-70 min, dried at 70-90 ℃ for 1-3 h, calcined at 400-600 ℃ for 0.5-2 h, and sieved through a 150-mesh sieve to obtain second coated particles; Fe-Si-Al alloy powder with a particle size of 5-8 μm is dispersed in 7-9 wt% silica sol, ball-milled for 80-100 min, dried at 70-90 ℃ for 1-3 h, calcined at 400-600 ℃ for 0.5-2 h, and sieved through a 200-mesh sieve to obtain third coated particles; The solid-liquid ratio of the Fe-Si-Al alloy powder to the silica sol is 1 g:(0.1-1) mL, the ball-to-material ratio of the ball-milling reaction is (4-6):1, and the rotation speed is 200-400 r / min; A three-section partition mold is used, adjacent mold cavities are separated by annular bosses, and the third coated particles, the second coated particles and the first coated particles are sequentially loaded, and each section is fixed by pre-pressing at 1-3 MPa for 1-5 s; The pressure is sequentially started, the pressure of the first coated particles, the second coated particles and the third coated particles is 11-13 MPa, 8-10 MPa and 5-7 MPa respectively, the pressure holding time is 10-20 s, 8-17 s and 5-15 s respectively, and after the pressing is completed, the first magnet layer, the second magnet layer and the third magnet layer are formed by nitrogen degreasing at 200-400 ℃ for 80-100 min.

8. The method of producing a magnetic powder core for use in a motor according to claim 6, characterized by, The preparation method of the heat-conducting and insulating coating comprises: 25-48 wt% boron nitride particles, 50-70 wt% silicone resin and 0.1-2 wt% KH-550 coupling agent are added to deionized water and stirred to obtain a coating slurry, wherein the solid-liquid ratio is 1 g:(1-2) mL, the stirring speed is 400-600 r / min, the stirring time is 30-50 min, the vacuum degassing pressure is-0.08 to-0.1 MPa, and the vacuum degassing time is 10-20 min; The coating slurry is coated on the surface of the coil, and is cured at 150-200 ℃ for 30-50 min to obtain a coil coated with a heat-conducting and insulating coating on the surface; The preparation method of the compatibility interface layer comprises: The 89wt%-92wt% E-15 epoxy resin, 1wt%-5wt% KH-560 coupling agent and 1wt%-10wt% boron nitride microparticles are added into ethyl acetate and stirred uniformly to obtain a spraying slurry, wherein the solid-liquid ratio is 1g:(1-3)mL, the stirring speed is 700r / min-900r / min, and the stirring time is 10min-30min; The spraying slurry is sprayed on the inner wall of the shell, and cured at 90°C-110°C for 20min-40min to obtain a shell with a compatible interface layer inside.

9. The method of producing a magnetic powder core for use in a motor according to claim 6, characterized by, The curing step comprises: The curing temperature is set to 100°C-140°C, and the curing is performed for 60min-100min to complete a first-stage curing; The curing temperature is set to 140°C-180°C, and the curing is performed for 100min-140min to complete a second-stage curing; The curing temperature is set to 180°C-220°C, and the curing is performed for 130min-170min to complete a third-stage curing.

10. An electric machine characterized by The motor comprises the magnetic powder core for a motor according to any one of claims 1-5.

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