Water-cooled single-stator single-rotor DCB axial flux permanent magnet motor

Abstract

The application discloses a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor, and belongs to the field of axial flux permanent magnet motors. The water-cooled single-stator single-rotor DCB axial flux permanent magnet motor comprises a front end cover, an inner bearing, a rotor assembly, a DCB stator assembly, an outer bearing and a rear end cover which are coaxially and parallelly arranged on a central shaft in sequence. The DCB stator assembly comprises a DCB stator and a stator core, and the two are filled with insulating material. The stator core is in a flat circular ring structure, the inner and outer diameters of the stator core are adapted to the DCB stator, and the stator core is integrally embedded in the rear end cover. A cooling pipeline is coaxially arranged at an axial idle space formed by the inner diameter of the flat circular ring stator core in the rear end cover, and the cooling pipeline is aligned with the inner end portion of the DCB stator. The water-cooled single-stator single-rotor DCB axial flux permanent magnet motor can greatly improve the motor torque density, power density and operation efficiency, and simultaneously optimize the magnetic circuit, improve the heat dissipation capacity and reduce the motor cost.

Description

Technical Field

[0001] This invention relates to the field of axial flux permanent magnet motor technology, and more particularly to a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor. Background Technology

[0002] Axial flux permanent magnet motors based on printed circuit board (PCB) stator windings have become the preferred motor type in the aforementioned fields due to their technical advantages such as short axial dimensions, high power density, flattenable structure, and ability to achieve rapid mass production. Among them, axial flux permanent magnet motors with a single stator and single rotor structure, which form a single-sided axial air gap structure by arranging a single PCB stator and a single rotor coaxially and parallel to each other, further combine the characteristics of simple structure and high axial space utilization, and have been widely used.

[0003] However, the existing single-stator, single-rotor PCB-type axial flux permanent magnet motors still have many technical defects, making it difficult to meet the application requirements for higher power density, torque density, and operating efficiency. Specifically, these defects are as follows: First, the existing PCB stator consists only of PCB windings and non-magnetic, non-conductive insulating support material, abandoning the traditional silicon steel sheet stator core structure. Although this design can eliminate cogging effect and reduce torque pulsation to some extent, it significantly increases the magnetic reluctance of the motor's magnetic circuit, resulting in a significant reduction in air gap magnetic flux density and insufficient no-load back EMF amplitude, severely restricting the motor's output capacity. Second, the insulating support material of the PCB windings has poor thermal conductivity. During motor operation, the heat generated by the windings can only be slowly dissipated through copper foil conduction combined with air convection, resulting in low heat dissipation efficiency and a tendency for heat accumulation. This directly restricts further improvement in motor power density and becomes the core technical bottleneck for performance breakthroughs in this type of motor. Summary of the Invention

[0004] The purpose of this invention is to provide a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor to solve the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention provides a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor, comprising a front end cover, an inner bearing, a rotor assembly, a DCB stator assembly, an outer bearing, and a rear end cover, which are coaxially and parallelly sleeved on a central shaft in sequence. The DCB stator assembly includes a DCB stator and a stator core, with insulating material filling the space between them. The DCB stator includes a DCB substrate and winding coils arranged on the upper and lower sides of the DCB substrate. The winding coils adopt a concentrated winding. The inner and outer ends of the concentrated winding are connected by a chain-like effective conductor. The effective conductor is led out through motor leads embedded in the DCB substrate, and the motor leads are located inside the ring formed by the inner ends of the concentrated winding. The stator core is a flat circular ring structure. Its inner and outer diameters are adapted to the DCB stator and are embedded in the rear end cover. Cooling pipes are arranged coaxially in the axial unused space enclosed by the inner diameter of the flat circular ring stator core inside the rear end cover, and the cooling pipes are aligned with the inner end of the DCB stator.

[0006] Preferably, the cooling pipe is a circular or arc-shaped structure that coincides with the central axis of the permanent magnet motor. The cooling pipe has an inlet and an outlet at both ends, and is sealed by a water channel cover.

[0007] Preferably, the DCB substrate adopts a copper-ceramic-copper sandwich eutectic bonding structure, and the ceramic material of the DCB substrate is selected from any one of alumina, aluminum nitride, silicon nitride or silicon carbide. The copper foils on both sides of the DCB substrate are masked and etched to obtain the winding coils, and the winding coils on both sides of the ceramic are connected by holes.

[0008] Preferably, the stator core is a hollow cylindrical structure adapted to the DCB stator, made of silicon steel sheets of 0.10–0.35 mm, and the structure is shaped by laser welding or epoxy resin impregnation and curing after winding.

[0009] Preferably, the DCB stator is formed by axially stacking one or more DCB plates, and the winding coils on adjacent DCB plates are connected in series or in parallel.

[0010] Preferably, the rotor assembly includes a rotor back iron and permanent magnets. The permanent magnets are bonded to the side of the rotor back iron facing the DCB stator by epoxy structural adhesive or acrylic adhesive, and the magnetic poles of the permanent magnets are arranged alternately.

[0011] Preferably, an air gap is left between the DCB stator assembly and the rotor assembly, forming a single-sided air gap structure.

[0012] Preferably, the insulating material filled between the DCB stator and the stator core is epoxy resin or ceramic plate.

[0013] Therefore, the present invention employs the above-mentioned water-cooled single-stator single-rotor DCB axial flux permanent magnet motor, which has the following beneficial effects: 1. DCB (Direct Bonded Copper) substrate has high thermal conductivity, large current carrying capacity, high operating temperature, low coefficient of thermal expansion and good mechanical strength, which breaks through the technical bottleneck of improving the performance of axial flux permanent magnet motors from the root, and greatly improves the torque density, power density and operating efficiency of the motor. 2. Adding a high-permeability stator core at the DCB stator effectively reduces the magnetic reluctance of the motor's magnetic circuit, increases the air gap magnetic field strength, and significantly improves the no-load back EMF amplitude and output power of the motor; at the same time, the improvement in magnetic circuit efficiency can save the amount of permanent magnets used and reduce the cost of motor raw materials. 3. The axial space at the inner diameter of the stator core is rationally planned, and a cooling pipe is set inside the rear end cover. This structure does not occupy the axial space of the motor and corresponds precisely to the inner end of the DCB stator, thus creating an efficient heat transfer path and greatly improving the heat dissipation capacity of the motor in a limited space. This overcomes the shortcomings of traditional PCB winding motors, which have difficulty in improving performance due to heat dissipation difficulties. 4. The DCB stator winding adopts a concentrated winding, and the ends are connected to the effective conductors through a chain, which can reduce the radial occupancy distance at the winding ends and increase the effective conductor length; the motor leads are built into the DCB board, which further increases the effective conductor length, increases the magnetic flux linked by the winding coils, improves the fundamental wave amplitude of the air gap magnetic flux density and the amplitude of the no-load back EMF, and thus enhances the output capability of the motor. 5. The core components of the motor are arranged coaxially and in parallel. The stator core and DCB stator are precisely matched, and the cooling pipes and rear end cover are integrated and embedded. This achieves synergistic innovation in material properties and structural design. The overall structure is compact and has high space utilization, making it suitable for application scenarios with high requirements for motor axial dimensions and performance.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is an exploded view of a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to the present invention. Figure 2 This is a schematic diagram of the DCB stator structure of a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to the present invention. Figure 3 This is a cooling pipe layout diagram of a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to the present invention. Figure 4 This is a schematic diagram of the stator core structure of a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to the present invention. Figure 5 The air gap magnetic field waveforms and harmonic decomposition diagrams of the experimental group and control group described in the experimental example are shown, where (a) is the air gap magnetic field waveform diagram and (b) is the harmonic decomposition diagram. Figure 6 The diagrams show the no-load back EMF waveforms and harmonic decomposition diagrams of the experimental group and control group described in the experimental example. (a) is the no-load back EMF waveform diagram, and (b) is the harmonic decomposition diagram.

[0016] Figure Labels 1. Central shaft; 2. Front end cover; 3. Inner bearing; 4. Rotor assembly; 41. Rotor back iron; 42. Permanent magnet; 5. DCB stator assembly; 51. DCB stator; 511. DCB base plate; 512. Winding coil; 5121. Outer end; 5122. Inner end; 5123. Effective conductor; 52. Stator core; 6. Outer bearing; 7. Rear end cover; 8. Cooling pipe; 81. Water inlet; 82. Water outlet. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0018] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0019] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] like Figures 1-4As shown, a water-cooled single-stator single-rotor DCB axial flux permanent magnet motor includes a front end cover 2, an inner bearing 3, a rotor assembly 4, a DCB stator assembly 5, an outer bearing 6, and a rear end cover 7, which are coaxially and parallelly sleeved on a central shaft 1. The DCB stator assembly 5 includes a DCB stator 51 and a stator core 52, with insulating material filling the space between them. The DCB stator 51 includes a DCB substrate 511 and winding coils 512 arranged on the upper and lower surfaces of the DCB substrate 511. The winding coils 512 adopt a concentrated winding, with the inner end 5122 and the outer end of the concentrated winding... The effective conductors 5123 are connected by a chain between the parts 5121. The effective conductors 5123 are led out through the motor leads embedded in the DCB substrate 511, and the motor leads are located inside the ring formed by the inner end 5122 of the concentrated winding. The stator core 52 is a flat ring structure. Its inner and outer diameters are adapted to the DCB stator 51 and are embedded in the rear end cover 7. Cooling pipes 8 are arranged coaxially in the axial idle space formed by the inner diameter of the flat ring stator core 52 inside the rear end cover 7, and the cooling pipes 8 are aligned with the inner end 5122 of the DCB stator 51.

[0021] The cooling pipe 8 is a circular or arc-shaped structure that coincides with the central axis of the permanent magnet motor. The cooling pipe 8 has an inlet 81 and an outlet 82 at both ends, and is sealed by a water channel cover.

[0022] The DCB substrate 511 adopts a copper-ceramic-copper sandwich eutectic bonding structure, and the ceramic material of the DCB substrate 511 is selected from any one of alumina, aluminum nitride, silicon nitride or silicon carbide; the copper foils on both sides of the DCB substrate 511 are masked and etched to obtain the winding coils 512, and the winding coils 512 on both sides of the ceramic are connected by holes.

[0023] The stator core 52 is a hollow cylindrical structure adapted to the DCB stator 51, made of silicon steel sheets of 0.10–0.35 mm. The structure is shaped by laser welding or epoxy resin impregnation and curing after the silicon steel sheets are wound.

[0024] The DCB stator 51 is formed by axially stacking one or more DCB plates, and the winding coils 512 on adjacent DCB plates are connected in series or in parallel.

[0025] The rotor assembly 4 includes a rotor back iron 41 and a permanent magnet 42. The permanent magnet 42 is bonded to the side of the rotor back iron 41 facing the DCB stator 51 by epoxy structural adhesive or acrylic adhesive, and the magnetic poles of the permanent magnet 42 are arranged alternately.

[0026] An air gap is left between the DCB stator assembly 5 and the rotor assembly 4, forming a single-sided air gap structure.

[0027] The insulating material filling the space between the DCB stator 51 and the stator core 52 is epoxy resin or ceramic plate.

[0028] Cooling Principle: First, the heat from the DCB stator 51 is rapidly conducted to its outer surface through its highly thermally conductive copper foil and ceramic substrate. Because the motor leads are concentrated at the inner end 5122 of the DCB stator 51, this inner end 5122 becomes a high-heat-load area. This high-heat-load area is precisely aligned with the cooling pipe 8 inside the rear end cover 7, allowing heat to be rapidly conducted to the rear end cover 7. Simultaneously, the iron loss heat generated by the stator core 52 is directly transferred to the metal body of the rear end cover 7 through its tight fit with the rear end cover 7. Second, cooling water continuously enters from the inlet 81 of the cooling pipe 8 into the circular / arc-shaped cooling pipe 8, which is coaxial with the motor's central axis, forming a continuous cooling system. In the water-cooled flow loop, the heat on the metal body of the rear cover 7 is transferred to the flowing cooling water through solid-liquid heat conduction, realizing forced convection heat exchange. Finally, the cooling water that has absorbed heat flows out quickly from the outlet 82, carrying away the heat generated by the motor from the body and completing the heat dissipation cycle. The sealing effect of the water channel cover on the cooling pipe 8 ensures that the cooling water only flows inside the pipe without leakage, ensuring continuous and efficient heat exchange. At the same time, the cooling pipe 8 is arranged using the axial unused space of the inner diameter of the stator core 52, without occupying the axial space of the motor, and without interfering with the normal operation of the motor magnetic circuit and windings. This achieves synergistic heat dissipation of material properties and structural design, greatly improving the motor's heat dissipation capacity within a limited space.

[0029] Test case To verify the air gap magnetic field and no-load back EMF performance of the water-cooled single-stator single-rotor DCB axial flux permanent magnet motor of the present invention, and to prove the effectiveness of the technical solution of the present invention, a comparative test under no-load conditions was designed. The traditional stator coreless PCB axial flux permanent magnet motor was used as the control group, and the water-cooled single-stator single-rotor DCB axial flux permanent magnet motor of the present invention was used as the test group for comparative testing.

[0030] This experiment adopted a single-variable principle. The control group was a PCB-based axial flux permanent magnet motor with no stator core, while the experimental group was the water-cooled single-stator, single-rotor DCB axial flux permanent magnet motor described in this invention. The only difference was that the experimental group had an added stator core and used a DCB board for the stator base plate, while the control group had no stator core and used a PCB board for the stator base plate. All other structural and performance parameters, such as rotor inner and outer diameters, permanent magnet thickness, and number of winding turns, were kept completely identical between the two groups of motors. Finite element analysis was used to simulate the no-load conditions of both motors, setting identical boundary conditions for both groups. The results were obtained as follows: Figure 5 and Figure 6 The two sets of motors are shown with air gap magnetic field waveforms and harmonic decomposition results at the average radius, and no-load back EMF waveforms and harmonic decomposition results.

[0031] It can be seen that the fundamental amplitude of the air gap magnetic field of the experimental group motor is 0.608T, which is 37.25% higher than that of the traditional PCB motor in the control group; at a speed of 1000r / min, the fundamental amplitude of the no-load back EMF of the experimental group motor is 1.751V, which is 47.85% higher than that of the traditional PCB motor in the control group.

[0032] The above test results show that the structural design of the water-cooled single-stator single-rotor DCB axial flux permanent magnet motor of the present invention can effectively reduce the magnetic reluctance of the motor magnetic circuit, significantly improve the fundamental wave amplitude of the air gap magnetic flux density and the amplitude of the no-load back EMF, and thus effectively improve the output power of the motor, fully demonstrating the effectiveness and superiority of the technical solution of the present invention.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A water-cooled single-stator single-rotor DCB axial flux permanent magnet motor, characterized in that: It includes a front end cover, an inner bearing, a rotor assembly, a DCB stator assembly, an outer bearing, and a rear end cover, which are coaxially and parallelly sleeved on the central shaft. The DCB stator assembly includes a DCB stator and a stator core, with insulating material filling the space between them. The DCB stator includes a DCB substrate and winding coils arranged on the upper and lower sides of the DCB substrate. The winding coils adopt a concentrated winding. The inner and outer ends of the concentrated winding are connected by a chain-like effective conductor. The effective conductor is led out through motor leads embedded in the DCB substrate, and the motor leads are located inside the ring formed by the inner ends of the concentrated winding. The stator core is a flat circular ring structure. Its inner and outer diameters are adapted to the DCB stator and are embedded in the rear end cover. Cooling pipes are arranged coaxially in the axial unused space enclosed by the inner diameter of the flat circular ring stator core inside the rear end cover, and the cooling pipes are aligned with the inner end of the DCB stator.

2. The water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: The cooling pipe is a circular or arc-shaped structure that coincides with the central axis of the permanent magnet motor. The cooling pipe has an inlet and an outlet at both ends, and is sealed by a water channel cover.

3. The water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: The DCB substrate adopts a copper-ceramic-copper sandwich eutectic bonding structure, and the ceramic material of the DCB substrate is selected from any one of alumina, aluminum nitride, silicon nitride or silicon carbide. The copper foils on both sides of the DCB substrate are masked and etched to obtain the winding coils, and the winding coils on both sides of the ceramic are connected by holes.

4. A water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: The stator core is a hollow cylindrical structure adapted to the DCB stator, made of silicon steel sheets of 0.10–0.35 mm. The structure is shaped by laser welding or epoxy resin impregnation and curing after the silicon steel sheets are wound.

5. A water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: The DCB stator is formed by axially stacking one or more DCB plates, and the winding coils on adjacent DCB plates are connected in series or in parallel.

6. A water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: The rotor assembly includes a rotor back iron and permanent magnets. The permanent magnets are bonded to the side of the rotor back iron facing the DCB stator by epoxy structural adhesive or acrylic adhesive, and the magnetic poles of the permanent magnets are arranged alternately.

7. A water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: An air gap is left between the DCB stator assembly and the rotor assembly, forming a single-sided air gap structure.

8. A water-cooled single-stator single-rotor DCB axial flux permanent magnet motor according to claim 1, characterized in that: The insulating material filling the space between the DCB stator and the stator core is epoxy resin or ceramic plate.

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