Permanent magnet motor

Abstract

The invention relates to the technical field of motors, in particular to a permanent magnet motor. The stator assembly and the rotor assembly are accommodated in the housing. The stator assembly comprises a stator framework and a winding, and an iron core is abandoned. A cold water groove is formed in the stator framework. The windings are bound and fixed by non-magnetic fiber bundles, and the adjacent windings are physically isolated through non-magnetic materials. The winding and the stator framework are combined into a whole and assisted by a cold water tank to cooperatively form a cold water flow channel. Therefore, on one hand, the cold water groove is directly formed in the stator framework and is combined with the winding to form the cold water flow channel, so that cooling liquid is in direct contact with the winding, the heat conduction path is effectively shortened, the heat resistance is reduced, and the heat dissipation efficiency is greatly improved; and on the other hand, the stator assembly adopts a stator framework structure without tooth grooves, so that the tooth groove effect and the iron loss phenomenon are eliminated fundamentally. When the motor operates, the torque output is smoother and more stable.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a permanent magnet motor. Background Art

[0002] Permanent magnet motors (PMMs) have become a core component of drive systems due to their high power density, high efficiency, and excellent control performance. However, traditional PMMs generally utilize a toroidal iron core with slots in their stator design. While this core provides a magnetic path for the windings, it presents numerous technical bottlenecks. Firstly, the slot effect of the core generates cogging torque, leading to large torque fluctuations, high vibration and noise during motor operation, and affecting the accuracy and stability of the equipment. Secondly, the core, constructed from laminated silicon steel sheets, generates hysteresis and eddy current losses in an alternating magnetic field. This significantly increases iron losses, especially under high-frequency conditions, causing severe heating of the motor.

[0003] In terms of heat dissipation, traditional permanent magnet motors are primarily cooled by air or indirect water. Air cooling, limited by ambient temperature and heat dissipation area, has low heat dissipation efficiency and is unable to meet the heat dissipation requirements of high-power density motors. Indirect water cooling, while removing heat through cooling channels in the casing or core, is difficult due to the presence of multiple layers of dielectric material, such as insulation layers and the core, between the coolant and the windings. This creates a long heat conduction path and high thermal resistance, making it difficult to quickly and effectively dissipate heat generated by the windings.

[0004] As far as the industry is concerned, some manufacturers are attempting to address these issues by optimizing core materials and improving cooling structures. For example, using low-loss silicon steel sheets or amorphous alloys can reduce core losses, but they cannot completely eliminate cogging. Increasing the number of cooling channels in the core or optimizing the water channel layout can enhance heat dissipation to some extent, but due to the inherent flaws of the core structure, the improvement in heat dissipation is limited and increases the manufacturing complexity and cost of the motor. Therefore, technical personnel are urgently needed to address these issues. Summary of the Invention

[0005] The present invention discloses a permanent magnet motor, which can not only eliminate the traditional annular iron core to eliminate the cogging effect and reduce iron loss, but also significantly improve the heat dissipation performance of the motor through the design of an efficient heat dissipation structure.

[0006] To address the above-mentioned technical problems, the present invention relates to a permanent magnet motor comprising a housing, a stator assembly, and a rotor assembly. The stator assembly and the rotor assembly are housed within the housing. The stator assembly comprises a stator frame and windings, and does not include an iron core. A cold water trough is formed on the stator frame. The windings are secured by binding with non-magnetic fiber bundles, and adjacent windings are physically isolated by non-magnetic material. The windings are integrated with the stator frame and supplemented by a cold water trough to form a cold water flow channel.

[0007] As a further improvement of the technical solution disclosed in the present invention, the stator assembly and the rotor assembly form an integrated structure with the aid of a vacuum pressure potting process, and the potting material adopts an epoxy resin-based composite material.

[0008] As a further improvement of the technical solution disclosed in the present invention, non-magnetic materials include but are not limited to epoxy resin and carbon fiber composite materials.

[0009] As a further improvement of the technical solution disclosed in the present invention, the inner surface of the cold water flow channel is anodized to form a corrosion-resistant layer, and the water inlet and outlet are both provided with temperature sensors and / or flow regulating valves.

[0010] As a further improvement to the technical solution disclosed in this invention, the rotor assembly includes permanent magnets, a rotor core, and a rotating shaft. The permanent magnet structure adopts a Halbach array or an alternating pole array and is radially constrained by a carbon fiber sleeve. A layer of thermally conductive silicone grease is provided between the rotor core and the rotating shaft.

[0011] As a further improvement of the technical solution disclosed in the present invention, an air gap is formed between the stator assembly and the rotor assembly, and the gap value is controlled to be 0.5 to 2 mm.

[0012] As a further improvement of the technical solution disclosed in the present invention, when the rotor assembly adopts a permanent magnet structure, it is compatible with surface-mounted, tangential or radial magnetic circuit topologies, and the permanent magnet remanence Br ≥ 1.2T and the intrinsic coercive force Hci ≥ 800kA / m;

[0013] When the rotor assembly adopts a non-magnetic steel structure, the rotor core is made of laminated high-magnetic permeability silicon steel sheets, and the magnetic resistance torque accounts for ≥60%.

[0014] As a further improvement of the technical solution disclosed in the present invention, the winding is a six-phase winding or a multi-phase winding.

[0015] As a further improvement of the technical solution disclosed in the present invention, the permanent magnet motor is also suitable for hub motor or eVTOL motor application scenarios.

[0016] In practical applications, the permanent magnet motor disclosed in the present invention can achieve at least the following beneficial technical effects, specifically:

[0017] 1) A cold water tank is directly formed on the stator frame and integrated with the winding to form a cold water flow channel, allowing the coolant to directly contact the winding, effectively shortening the heat conduction path, reducing thermal resistance, and significantly improving heat dissipation efficiency. Even under high load and long-term operating conditions, the motor can maintain a low temperature range, avoiding problems such as permanent magnet demagnetization and winding insulation aging caused by high temperature, thereby improving the reliability and stability of the motor;

[0018] 2) The stator assembly adopts a slotless stator skeleton structure, eliminating the slot effect at its root. When the motor is running, the torque output is smoother and more stable, effectively reducing vibration and noise levels. It is particularly suitable for scenarios with extremely high requirements for operating accuracy and stability.

[0019] 3) Thanks to the elimination of the iron core in the stator assembly, iron losses are completely eliminated. Furthermore, the windings are physically isolated with non-magnetic materials, preventing magnetic coupling losses between the windings. During motor operation, energy losses are significantly reduced, significantly improving overall efficiency. For example, in new energy vehicle drive motors, this increased efficiency translates to extended vehicle range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a three-dimensional schematic diagram of the permanent magnet motor disclosed in the present invention.

[0022] Figure 2 yes Figure 1 Front view of .

[0023] Figure 3 yes Figure 2 AA cross-sectional view.

[0024] 1-housing; 2-stator assembly; 21-stator frame; 22-winding; 3-rotor assembly; 31-permanent magnet; 32-rotor core; 33-rotating shaft. DETAILED DESCRIPTION

[0025] In the description of the present invention, it should be understood that the terms "left", "right", "up", "down", "front", "back", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0026] A permanent magnet motor uses permanent magnets to provide excitation, generating a magnetic field in the rotor or stator. This replaces the field windings in traditional motors to generate a constant magnetic field. For example, in a permanent magnet synchronous motor, when multiphase alternating current flows through the stator windings, a rotating magnetic field is generated. This rotating magnetic field interacts with the constant magnetic field generated by the permanent magnets on the rotor, causing the rotor to rotate synchronously with the speed of the rotating magnetic field, thereby converting electrical energy into mechanical energy.

[0027] The following is a further detailed description of the present invention in conjunction with specific embodiments. Figure 1 As shown in the figure, the permanent magnet motor mainly consists of several parts, including the housing 1, stator assembly 2, and rotor assembly 3. The stator assembly 2 and rotor assembly 3 are housed within the housing 1, with an air gap formed between the stator assembly 2 and the rotor assembly 3, and the gap value is controlled to be 0.5 to 2mm. The housing 1, serving as the motor's external protective structure, is made of high-strength aluminum alloy or magnesium alloy and is precision die-cast. Its inner wall is equipped with positioning bosses and sealing grooves to ensure the precise positioning of the stator assembly 2 and the rotor assembly 3 and ensure waterproof and dustproof performance.

[0028] like Figure 2 、 Figure 3 As shown in , the stator assembly 2 includes a stator frame 21 and a winding 22. The rotor assembly 3 includes a permanent magnet 31, a rotor core 32 and a rotating shaft 33. It is particularly important to note that in this embodiment, the stator assembly 2 breaks through the traditional motor design concept, completely abandons the annular core structure formed by stacking silicon steel sheets, and instead adopts a lightweight, high-strength stator frame 21. The stator frame 21 is manufactured from high-strength engineering plastics (such as polyetheretherketone PEEK or modified nylon) through an injection molding process, or is made of aviation-grade aluminum alloy through milling by a CNC machining center, which significantly reduces the overall weight while ensuring mechanical strength. In addition, the circumferential surface of the stator frame 21 is precisely machined into a spiral or serpentine cold water groove 211 based on the results of thermal simulation optimization to ensure that the coolant forms a turbulent state in the groove to maximize the convective heat transfer efficiency. The windings 22 are secured with non-magnetic fiber bundles, and adjacent windings 22 are physically isolated by non-magnetic materials (including but not limited to epoxy resin and carbon fiber composite materials). The windings 22 are integrated with the stator frame 21 and supplemented with a cold water tank 211 to form a cold water flow channel.

[0029] In the manufacturing process, the winding 22 is first wound on a dedicated mold using a precision winding machine. The epoxy resin is fully infiltrated into the coil gap through a vacuum pressure impregnation (VPI) process, and after curing, a high-strength insulation is formed. Subsequently, the formed winding 22 is bonded to the stator frame 21 using hot melt adhesive or high-strength structural adhesive, and the bonding surface is roughened to enhance adhesion. When the winding 22 and the stator frame 21 are assembled, the cold water tank 211 and the outer surface of the winding 22 together form a closed cold water flow channel, and the coolant can directly contact the winding 22, significantly improving the heat dissipation efficiency.

[0030] By adopting the above technical solution, the heat conduction path is effectively shortened, thermal resistance is reduced, and heat dissipation efficiency is significantly improved. Even under high load and long-term operating conditions, the motor can maintain a low temperature range, improving its reliability and stability. Furthermore, the stator assembly 2 adopts a slotless stator skeleton structure 21, eliminating the cogging effect at its root. During motor operation, torque output is smoother and more stable, effectively reducing vibration and noise levels. This makes it particularly suitable for scenarios requiring extremely high operating precision and stability.

[0031] It should also be noted that the elimination of the iron core in the stator assembly 2 completely eliminates iron losses. Furthermore, the use of non-magnetic materials to physically isolate the windings 22 prevents magnetic coupling losses between the windings 22. This significantly reduces energy losses during motor operation, significantly improving overall efficiency.

[0032] As a further optimization of the above technical solution, the inner surface of the cold water flow channel is anodized to form a corrosion-resistant layer. In this way, through anodizing treatment, a dense ceramic-like corrosion-resistant layer is formed on the inner surface of the cold water flow channel, which can effectively resist the erosion of acidic or alkaline substances in the coolant and prevent problems such as rust and perforation on the inner wall of the flow channel.

[0033] To enhance the cooling system's precise temperature control, and as a further optimization of the aforementioned technical solution, temperature sensors are installed at both the inlet and outlet of the cold water channel, and a flow control valve is installed at the inlet to regulate the amount of coolant flowing through per unit time. In actual applications, the control system can accurately determine the heating status of the permanent magnet motor by collecting temperature data, combining it with preset temperature thresholds and the operating conditions of the permanent magnet motor. When the load and heat generation of the permanent magnet motor increase, the temperature sensor detects an increase in the outlet temperature. The system can then adjust the flow control valve in a timely manner based on the algorithm, increasing the coolant flow rate and accelerating the heat removal process, allowing the motor temperature to quickly return to a normal range. Conversely, when the permanent magnet motor is under light load or in standby mode, the coolant flow rate is appropriately reduced to avoid unnecessary energy consumption and achieve energy-saving operation.

[0034] As a further optimization of the above technical solution, the permanent magnet 31 structure adopts a Halbach array, which is conducive to improving the power density of the motor and outputting greater power and torque at the same volume and weight. It is especially suitable for application scenarios with strict requirements on space and weight.

[0035] Of course, as another modified design of the above technical solution, the permanent magnet 31 structure can also adopt a Halbach array. This helps optimize the air gap magnetic field waveform, reduce harmonic content, and reduce the cogging torque and torque ripple during motor operation, making the motor run more smoothly and quietly, making it suitable for equipment with high operating precision requirements.

[0036] It is known that when the permanent magnet motor is running at high speed, the permanent magnet 31 will be subjected to extremely strong centrifugal force. If the constraint is improper, the permanent magnet 31 may fall off. In view of this, as a further optimization of the above technical solution, the permanent magnet 31 is radially constrained by a carbon fiber sleeve (not shown in the figure). The carbon fiber sleeve has the characteristics of high strength, low density and high modulus. Its tensile strength is several times that of steel, while its density is only about one-quarter of that of steel. By adopting the above technical solution for setting, without adding too much weight, a strong binding force is provided for the permanent magnet 31 to ensure its structural stability when rotating at high speed. At the same time, the excellent fatigue resistance of the carbon fiber sleeve enables it to withstand the alternating stress during the long-term operation of the motor, reducing the risk of failure caused by fatigue damage.

[0037] Furthermore, during the operation of the permanent magnet motor, the rotor core 32 will generate a large amount of heat due to factors such as hysteresis loss, eddy current loss and mechanical friction. The shaft 33, as an important component of the rotor assembly 3, is one of the key paths for heat to be conducted outward. However, even after precision machining, there are still many tiny gaps between the rotor core 32 and the shaft 33 at the microscopic level. These gaps are filled with air with extremely low thermal conductivity, which greatly hinders heat transfer. In view of this, as a further optimization of the above technical solution, a thermal grease layer (not shown in the figure) is provided between the rotor core 32 and the shaft 33. In this way, thanks to the excellent thermal conductivity of the thermal grease and its ability to effectively fill tiny gaps, thereby facilitating the elimination of air thermal resistance, the heat generated by the rotor core 32 can be quickly and efficiently conducted to the shaft 33, and then transferred to the housing 1 or the cooling system through the shaft 33, thereby significantly reducing the temperature of the rotor core 32.

[0038] In the above embodiment, the rotor assembly 3 adopts a permanent magnet structure, which is compatible with surface-mounted, tangential or radial magnetic circuit topology structures, and the permanent magnet remanence Br≥1.2T and the intrinsic coercive force Hci≥800kA / m.

[0039] Of course, as another modified design of the above technical solution, the rotor assembly 3 can also adopt a non-magnetic steel structure, and the rotor core 32 is made of high-permeability silicon steel sheets stacked together, and the magnetic resistance torque accounts for ≥60%. In this way, in the manufacture of the rotor assembly 3, the traditional permanent magnet 31 can be shielded. At the same time, as a mature industrial material, high-permeability silicon steel sheets have mature production processes and controllable costs. In terms of maintenance, since there are no problems such as demagnetization and aging of the permanent magnet 31 in the traditional design, it is beneficial to reduce the risk of motor failure. In addition, the rotor assembly 3 with a non-magnetic steel structure is relatively simple in structure, easy to disassemble and repair, and further improves the maintainability of the motor.

[0040] It should also be noted here that the permanent magnet motor is also suitable for hub motor or eVTOL motor application scenarios. And the winding 22 is not limited to three phases. Depending on the different application scenarios of the permanent magnet motor, six phases or even multiple phases are selected as the best. In this way, compared with the traditional three-phase, the multi-phase winding 22 can effectively reduce torque pulsation and make the permanent magnet motor run more smoothly. During vehicle starting, acceleration and braking, the multi-phase winding 22 can provide smoother torque output, reduce vehicle frustration, and improve driving comfort. At the same time, the multi-phase winding 22 can also improve the fault tolerance of the permanent magnet, that is, when a phase winding 22 fails, the other phases can still maintain the normal operation of the motor.

[0041] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A permanent magnet motor comprising a housing, a stator assembly, and a rotor assembly; the stator assembly and the rotor assembly are accommodated in the housing, characterized in that: The stator assembly includes a stator frame and windings, and the iron core is discarded; a cold water trough is formed on the stator frame; the windings are fixed by binding with non-magnetic fiber bundles, and adjacent windings are physically isolated by non-magnetic materials; the windings are integrated with the stator frame, and supplemented by the cold water trough to collaboratively form a cold water flow channel.

2. The permanent magnet motor according to claim 1, characterized in that: The stator assembly and the rotor assembly are integrated into an integrated structure by means of a vacuum pressure potting process, and the potting material is an epoxy resin-based composite material.

3. The permanent magnet motor according to claim 1, characterized in that: The non-magnetic conductive material includes but is not limited to epoxy resin and carbon fiber composite material.

4. The permanent magnet motor according to claim 1, characterized in that: The inner surface of the cold water flow channel is anodized to form a corrosion-resistant layer, and the water inlet and outlet are both provided with a temperature sensor and / or a flow regulating valve.

5. The permanent magnet motor according to claim 1, characterized in that: The rotor assembly includes a permanent magnet, a rotor core and a rotating shaft; the permanent magnet frame adopts a Halbach array or an alternating pole array and is radially constrained by a carbon fiber sleeve; a thermal conductive silicone grease layer is provided between the rotor core and the rotating shaft.

6. The permanent magnet motor according to claim 5, characterized in that: An air gap is formed between the stator assembly and the rotor assembly, and the gap value is controlled to be 0.5 to 2 mm.

7. The permanent magnet motor according to claim 5, characterized in that: When the rotor assembly adopts a permanent magnet structure, it is compatible with surface-mount, tangential or radial magnetic circuit topology structures, and the permanent magnet remanence Br ≥ 1.2T, and the intrinsic coercive force Hci ≥ 800kA / m; When the rotor assembly adopts a non-magnetic steel structure, the rotor core is formed by stacking high-magnetic permeability silicon steel sheets, and the magnetic resistance torque accounts for ≥60%.

8. The permanent magnet motor according to any one of claims 1 to 7, characterized in that: The winding is a six-phase winding or a multi-phase winding.

9. The permanent magnet motor according to any one of claims 1 to 7, characterized in that: The permanent magnet motor is suitable for both hub motor and eVTOL motor application scenarios.

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