High-torque-density high-voltage electronically-cooled fan motor and method of checking same

Abstract

A high torque density high voltage electronic cooling fan motor and a checking method thereof, comprising an outer stator assembly and an inner rotor assembly, the inner rotor assembly is a 20-pole built-in permanent magnet rotor, and the outer stator assembly is a 24-slot flat stator, forming a 20-pole 24-slot pole-slot matching structure; the inner rotor assembly comprises rotor laminations and permanent magnets arranged on the rotor laminations, the rotor laminations comprise a support portion, a shaft hole arranged at the middle portion of the support portion, and a plurality of rotor teeth arranged in the circumferential direction outside the support portion, permanent magnet grooves are formed between adjacent rotor teeth, and permanent magnets are arranged in the permanent magnet grooves; compared with the prior art, the motor has the following advantages: the motor has permanent magnet torque and reluctance torque to resist load at the same time, and the load capacity of the motor is enhanced; the cooling condition is good, the heat source is closer to the shell under the premise of ensuring the health of the core magnetic circuit, and the motor cooling condition is greatly improved in combination of the inner rotor outer stator configuration and the water cooling heat dissipation mode, and the risk of permanent magnet demagnetization is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of vehicle-mounted electronic cooling fan motors, and more particularly to a high torque density high-voltage electronic cooling fan motor and its verification method. Background Technology

[0002] With the accelerated electrification transformation of China's manufacturing industry, the electrification and high-power development of commercial vehicle cooling systems have become the mainstream of industry development. Traditional commercial vehicle cooling systems generally use multiple low-power fans arranged in parallel, which has drawbacks such as complex system structure, large assembly space occupation, many failure points, high integration costs, and poor overall reliability. Using a single 10kW or higher high-power cooling fan motor can reduce the number of fans, simplify the overall vehicle piping and mechanical layout, reduce integration costs, and improve system scalability and operational reliability, which is the core research and development direction of current vehicle cooling systems.

[0003] Permanent magnet synchronous motors (PMSMs) offer advantages such as concentrated heat sources, flexible heat dissipation design, high power density, and stable and reliable operation, making them suitable for low-speed, high-torque direct-drive applications using automotive cooling fans. Current PMSMs are available in two configurations: external rotor with internal stator and internal rotor with external stator. 1. External rotor and internal stator structure: The lever arm is longer and the theoretical permanent magnet torque is higher under the same envelope volume. However, the heat source of the stator winding is enclosed by the rotor, and the heat is difficult to conduct outward. Even with water cooling, the heat dissipation efficiency is still significantly short. Moreover, the existing external rotor scheme only utilizes the permanent magnet torque and does not fully explore the reluctance torque. The material utilization rate is low, and the axial dimension of the motor is large, making it difficult to further improve the torque density.

[0004] 2. Conventional inner rotor and outer stator structure: The stator windings are directly attached to the housing, providing excellent heat dissipation. However, the existing slot-pole matching scheme has two major drawbacks: First, the pole-slot matching is unreasonable, relying solely on permanent magnet torque output while the reluctance torque is not effectively utilized, thus limiting the torque output capability. Second, there are no optimal parameter constraints on the rotor permanent magnet dimensions, which can easily lead to problems such as high-temperature demagnetization of permanent magnets, excessively high material costs, and large cogging torque vibration noise. Third, the stator yoke thickness design is unbalanced. An excessively thick yoke will lengthen the axial length of the motor and reduce torque density, while an excessively thin yoke will significantly increase magnetic circuit reluctance, weaken air gap flux, and deteriorate the motor's output performance.

[0005] Numerous studies have concluded that the torque density upper limit is higher for external rotor-internal stator structures, especially for external rotor surface-mounted permanent magnet motors. This is because, under the same envelope volume comparison, the external rotor-internal stator structure has a longer lever arm and thus higher torque. However, these studies have overlooked the fact that surface-mounted designs only utilize permanent magnet torque (a type of electromagnetic torque), and have not considered the heat source generation mechanism and heat conduction principles of the internal rotor-external stator structure, which can better concentrate heat dissipation and provide load capacity. They have only demonstrated high motor torque density, without effectively controlling the motor's axial length. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-torque-density high-voltage electronic cooling fan motor and its verification method, thereby solving the problems in the prior art where the electromagnetic torque of the motor is not fully utilized, resulting in low material utilization, heat source close to the inside of the motor, large axial length, and low torque density.

[0007] The main technical solution of the high torque density high voltage electronic cooling fan motor provided by the present invention is as follows: it includes an outer stator assembly and an inner rotor assembly. The inner rotor assembly is a 20-pole spoke built-in permanent magnet rotor, and the outer stator assembly is a 24-slot flat stator, forming a 20-pole 24-slot pole-slot matching structure. The inner rotor assembly includes a rotor core composed of multiple rotor laminations and a permanent magnet disposed on the rotor core. The rotor laminations include a support portion, a shaft hole in the middle of the support portion, and multiple rotor teeth in the circumferential direction on the outer side of the support portion. Permanent magnet slots are formed between adjacent rotor teeth, and permanent magnets are disposed in the permanent magnet slots. Both sides of the inner wall of the permanent magnet slot are provided with slingshot grooves; The air gap between the outer stator assembly and the inner rotor assembly is unevenly distributed, and the maximum radial height of the uneven air gap is [value missing]. H g ; The outer stator assembly includes a stator core and windings wound on the stator core. The stator core has stator teeth, and the ends of the stator teeth have pole shoes. The windings are wound on the stator teeth, and a slot is formed between two adjacent pole shoes. The width of the slot is... w g ; H g and w g The ratio of their lengths is 1 to 1.5.

[0008] The high torque density high-voltage electronic cooling fan motor provided by this invention also adopts the following auxiliary technical solutions: Preferably, the stator core includes multiple tooth units, which are sequentially spliced ​​together to form the stator core; each tooth unit includes a fixed part and stator teeth provided on the fixed part, and the fixed parts on two adjacent tooth units are connected together.

[0009] Preferably, the inner end of the rotor tooth is connected to the support, and the width of the inner end of the rotor tooth is 8%-12% of the width of the outer end of the rotor tooth.

[0010] Preferably, the rotor teeth are provided with a leakage magnetic path, a first weight reduction hole and a dynamic balance adjustment hole in sequence from the inside to the outside along the radial direction.

[0011] Preferably, the leakage magnetic path is a hollow U-shaped structure, with the bottom of the U-shaped structure close to the inner end of the rotor teeth and the upper end of the U-shaped structure close to the first weight reduction hole.

[0012] Preferably, the bottom of the permanent magnet slot and the middle of the U-shaped structure are located on the same radius circular track of the rotor laminations; the upper part of the U-shaped structure is the permanent magnet contact section, the width of the permanent magnet contact section is smaller than the width of other parts of the U-shaped structure, and the width of the permanent magnet contact section is 1 / 5 to 1 / 10 of the length of the permanent magnet contact section; the bottom of the permanent magnet slot is provided with a limiting protrusion, which is located on the side of the bottom of the permanent magnet contact section.

[0013] Preferably, the support part has multiple second weight reduction holes along the annular track, and rotor lamination buckles are provided around the edge near the shaft hole. Preferably, the first weight-reducing hole is a trapezoidal hole and the second weight-reducing hole is a fan-shaped hole.

[0014] Preferably, the dynamic balancing hole is a triangular hole.

[0015] The verification method for a high torque density high-voltage electronic cooling fan motor provided by this invention includes the following steps: 1) Rated torque verification: An electromagnetic model was established using Maxwell to ensure that the rated current meets the current density requirement of 7 A / mm². The thermal convergence criterion is set as T(n+1)-T(n)≤0.5℃. The material thermal properties and heat source are updated iteratively every 10s, and the rated torque and temperature rise are checked. 2) Rotor stress verification: Using Ansys finite element simulation, an experimental torque exceeding twice the rated torque was applied to the rotor outer end and stator inner end, and the maximum stress of the rotor was verified to not exceed 70% of the yield strength of the core material. 3) The cogging torque verification method is optimized based on the air gap magnetomotive force modulation theory. H g With stator slot opening w g This reduces the cogging torque to within 1 / 5000 of the rated torque. 4) Torque density verification: Torque density includes torque mass density and torque volume density, which are calculated as rated torque to envelope volume and rated torque to motor mass, respectively. The results are calculated and compared with the design target.

[0016] The high torque density high-voltage electronic cooling fan motor verification method provided by this invention also adopts the following auxiliary technical solutions: The electromagnetic field finite element model outputs the winding, permanent magnet, and core losses as the heat source of the temperature field; the temperature field model inputs the thermal conductivity and convective heat dissipation coefficient of each component and outputs the global temperature distribution results; the temperature results are fed back to the electromagnetic field model to update the thermal properties of the winding and permanent magnet, and the cycle is iterated until the temperature converges, thus completing the electromagnetic thermal coupling verification.

[0017] Compared with existing technologies, the high torque density high-voltage electronic cooling fan motor and its verification method provided by this invention have the following advantages: 1. The motor simultaneously possesses permanent magnet torque and reluctance torque to counteract the load, enhancing the motor's load capacity; 2. Excellent cooling conditions: By optimizing the number of stator slots (24 slots), the heat source is brought closer to the casing while ensuring the health of the iron core magnetic circuit. Combined with the inner rotor and outer stator configuration and water cooling, the motor's heat dissipation conditions are significantly improved, effectively reducing the risk of permanent magnet demagnetization; 3. By precisely setting the key parameters of the permanent magnet slots, an optimal balance is achieved between suppressing cogging torque, controlling material costs, and ensuring operational stability; This invention features a compact structure, efficient heat dissipation, and controllable cost, making it suitable for high-load direct-drive high-voltage electronic cooling fans, and possessing significant engineering practical value and industrialization prospects; 4. Through mechanical power experiments and performance experiments, the motor's quality, stress detection, and rated torque are calculated and verified, using quantitative data to prove that the electromagnetic scheme of the motor provided by this invention achieves the design goals. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the rotor laminations of the present invention.

[0019] Figure 2 This is a structural diagram showing the assembly of the rotor laminations and stator core of the present invention.

[0020] Figure 3 for Figure 2 A magnified view of a portion of the image.

[0021] Figure 4 This is a structural diagram of the tooth unit in the stator core of the present invention.

[0022] Figure 5 This is the electromagnetic thermal coupling logic diagram of the proposed model in the motor verification method.

[0023] Reference numerals: 1 Rotor laminations; 11 Support; 12 Rotor teeth; 13 Shaft hole; 14 Permanent magnet slot; 141 Slingback groove; 142 Limiting protrusion; 111 Second weight reduction hole; 112 Lamination buckle; 121 Leakage magnetic path; 1211 Permanent magnet contact section; 122 First weight reduction hole; 123 Dynamic balance adjustment hole; 2 Stator core; 21 Tooth unit; 211 Fixing part; 212 Stator tooth; 213 Pole shoe. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] See Figures 1 to 4 According to the embodiment of the high torque density high-voltage electronic cooling fan motor provided by the invention, it includes an outer stator assembly and an inner rotor assembly. The inner rotor assembly is a 20-pole spoke built-in permanent magnet rotor, and the outer stator assembly is a 24-slot flat stator, forming a 20-pole 24-slot pole-slot matching structure. The inner rotor assembly includes a rotor core composed of multiple rotor laminations 1 and permanent magnets (not shown in the figure) disposed on the rotor core. The rotor laminations 1 include a support portion 11, a shaft hole 13 disposed in the middle of the support portion 11, and multiple rotor teeth 12 disposed circumferentially on the outer side of the support portion 11. Permanent magnet slots 14 are formed between adjacent rotor teeth 12, and permanent magnets are disposed in the permanent magnet slots 14. Both sides of the permanent magnet slots 14 are provided with spring grooves 141 to restrict the radial and circumferential movement of the permanent magnets, while reserving a 0.15mm assembly gap to suppress permanent magnet vibration noise. The air gap between the outer stator assembly and the inner rotor assembly is unevenly set, and the maximum radial height of the uneven air gap is H g The outer stator assembly includes a stator core 2 and windings wound on the stator core 2. The stator core 2 has stator teeth 212, and the ends of the stator teeth 212 have pole shoes 213. The windings are wound on the stator teeth 212, and a slot is formed between two adjacent pole shoes 213. The width of the slot is... w g ; H g and w g The length ratio between them is 1~1.5. The motor outputs both permanent magnet torque and reluctance torque based on the difference in reluctance between the d and q axes. The stator windings are attached to the housing for water cooling. The rotor core is a salient pole rotor design, forming a non-uniform air gap with the stator core. In this embodiment, Hg=1.2mm, wg=1mm, H_g / w_g=1.2, falling within the preferred range of 1~1.5. If the ratio is lower than 1, the cogging torque suppression effect decreases; if the ratio is higher than 1.5, the air gap magnetic flux density decreases and the permanent magnet torque attenuates. The above motor has the following advantages over the prior art: 1. The motor has both permanent magnet torque and reluctance torque to counteract the load, enhancing the motor's load capacity. Under this stator-rotor structure combination, the reluctance of the d-axis magnetic circuit is less than that of the q-axis magnetic circuit, so the d-axis inductance is greater than the q-axis inductance. According to the motor torque formula, the first term is the permanent magnet torque, and the second term is the reluctance torque. Only when the d-axis inductance is greater than the q-axis inductance is the reluctance torque term greater than 0.

[0026] In the formula, p Represents the extreme logarithm. ψpm It is a permanent magnet flux linkage. L d and L q express d , q Shaft inductor, i d and i q express d, q shaft current; 2. Excellent cooling conditions: By optimizing the number of stator slots (24 slots), the heat source is brought closer to the casing while ensuring the health of the iron core magnetic circuit. Combined with the inner rotor and outer stator configuration and water cooling, the heat dissipation conditions of the motor are greatly improved, effectively reducing the risk of permanent magnet demagnetization. 3. By precisely setting the key parameters of the permanent magnet slots, the optimal balance is achieved between suppressing cogging torque, controlling material costs, and ensuring operational stability. This invention has a compact structure, high heat dissipation efficiency, and controllable cost. It is suitable for high-load conditions where high-voltage electronic cooling fans directly drive, and has significant engineering practical value and industrialization prospects.

[0027] This invention uses a rotor with a spoke-embedded 20-pole permanent magnet structure. The steps for setting the number of stator slots are as follows: 1) The number of stator slots that can be matched with a 20-pole rotor can be 18, 22, 24 or 36 slots; as the number of slots increases, the armature magnetomotive force generated by a single tooth remains unchanged when the area of ​​a single slot remains unchanged. Considering the core utilization rate and the magnetic saturation phenomenon of the core, the tooth width should remain unchanged. 2) If the area of ​​a single slot increases, the armature magnetomotive force generated by a single tooth increases. Considering the utilization rate of the iron core and the magnetic saturation phenomenon of the iron core, the tooth width should be increased. 3) If the area of ​​a single slot decreases, the armature magnetomotive force generated by a single tooth decreases. Considering the utilization rate of the iron core and the magnetic saturation phenomenon of the iron core, the tooth width is reduced. Of the three, only the third case meets the requirement of consistent stator inner and outer diameters. Therefore, 18 slots, 22 slots, 24 slots, and 36 slots were selected as the number of stator slots, respectively. The area of ​​a single slot and the tooth width decrease continuously. In summary, we can further conclude that the more slots there are, the thinner the iron core yoke is, the closer the heat source is to the housing, and the better the heat dissipation conditions. On the other hand, the stator yoke will house positioning holes and iron core clips. If the yoke is too thin, the manufacturing process will seriously increase the magnetic resistance of the yoke magnetic circuit, resulting in a reduction in air gap magnetic flux. Therefore, 24 slots are used as the number of stator slots to ensure a good cooling environment and healthy air gap magnetic flux.

[0028] The above rotor laminations H g This represents the maximum height of the non-uniform air gap. W p The width of the permanent magnet slot; H p The depth of the permanent magnet slot.

[0029] Calculation using parametric finite element method H g The value of has a significant impact on the cogging torque of the motor. W p The value of affects the demagnetization rate of the permanent magnet and the material cost. The gap between the permanent magnet and the permanent magnet slot is taken as 0.15mm. W p = With a thickness of 5.5mm, the demagnetization rate of the permanent magnet is less than 2% under peak current and peak temperature rise conditions. W p For diameters smaller than 5.5mm, the maximum demagnetization rate of the permanent magnet exceeds 2%, resulting in poor operational stability. W p For thicknesses greater than 5.5mm, the cost of permanent magnet materials is high, resulting in poor economic benefits. H P The value of affects the utilization rate of the permanent magnet, i.e., the torque constant. H p It is directly proportional to the torque, but its relationship with the torque density is similar to a quadratic parabola, meaning there exists an optimal value.

[0030] The basic parameters of the whole machine in this embodiment are as follows: rotor outer diameter 192mm, stator inner diameter 134mm, maximum uneven air gap Hg=1.2mm, stator slot width Wg=1mm; permanent magnet slot width wp=5.55mm, slot depth Hp=24.8mm; rotor tooth outer end width 0.65mm, inner end width 5.2mm (scale 1 / 8); single-sided gap between permanent magnet and slot 0.025mm, permanent magnet demagnetization rate 10% under peak current.

[0031] See Figures 1 to 4 According to the above-described embodiments of the invention, the stator core 2 includes multiple tooth units 21, which are sequentially spliced ​​together to form the stator core 2. Each tooth unit 21 includes a fixing part 211 and stator teeth 212 disposed on the fixing part 211. The fixing parts 211 on two adjacent tooth units 21 are connected together. In this embodiment, adjacent fixing parts 211 are welded together. The stator core 2 adopts a structure formed by splicing multiple tooth units 21, which can maximize the slot fill factor of the winding while reducing the width of the slot opening. At the same time, when a problem occurs in a certain area of ​​the armature, the tooth unit 21 can be disassembled individually for convenient maintenance.

[0032] See Figures 1 to 4According to the above-described embodiment of the invention, the inner end of the rotor tooth 12 is connected to the support portion 11, and the width C1 of the inner end of the rotor tooth 12 is 8%-12% of the width C2 of the outer end of the rotor tooth 12, preferably 10%. This avoids the resonance problem of this structure without affecting the mechanical strength of the rotor, and prevents the frequency of the radial electromagnetic force from coinciding with the natural frequency of the motor structure. This helps to reduce noise during motor operation.

[0033] See Figures 1 to 4 According to the above-described embodiment of the invention, the rotor teeth 12 are provided radially from the inside out with a leakage magnetic path 121, a first weight reduction hole 122, and a dynamic balance adjustment hole 123; the support portion 11 is provided with a plurality of second weight reduction holes 111 along an annular trajectory. The second weight reduction holes 111 can be a multi-layer hole structure provided on the support portion 11 along an annular trajectory with different radii. In this embodiment, there are two layers. See Figures 1 to 4 According to the above-described embodiment of the invention, the leakage magnetic path 121 is a hollow U-shaped structure, with the bottom of the U-shaped structure close to the inner end of the rotor teeth 12 and the upper end of the U-shaped structure close to the first weight-reducing hole 122. This reduces permanent magnet leakage magnetic field and increases permanent magnet torque while ensuring the mechanical strength of the rotor teeth 12.

[0034] See Figures 1 to 4 According to the above-described embodiment of the invention, a rotor lamination buckle 112 is provided around the edge near the shaft hole 13. The rotor lamination buckle 112 is a stamped protrusion on the rotor lamination 1, and the other side of the stamped protrusion is a stamped groove. After two adjacent rotor laminations 1 are stacked, the stamped protrusion and the stamped groove engage with each other, and the adjacent rotor laminations 1 are circumferentially positioned. The overall fixation is completed by riveting, which prevents the laminations from being misaligned when the rotor is running at high speed and improves the stability of the positioning between adjacent rotor laminations 1.

[0035] See Figures 1 to 4 According to the above-described embodiments of the invention, the first weight-reduction hole 122 is a trapezoidal hole, and the second weight-reduction hole 111 is a fan-shaped hole. This facilitates processing and achieves maximum weight reduction while ensuring the mechanical strength of the rotor laminations 1.

[0036] See Figures 1 to 4 According to the above-described embodiment of the invention, the dynamic balance adjustment hole 123 is a triangular hole. This facilitates punching, and when a counterweight is inserted into the hole, the counterweight matches the inscribed circle of the triangle, ensuring a secure fixation.

[0037] See Figures 1 to 4 According to the above-described embodiment of the invention, the bottom of the permanent magnet slot 14 and the middle of the U-shaped structure are located on a circular track of the same radius as the rotor lamination 1. This increases the leakage magnetic reluctance of the permanent magnet.

[0038] See Figures 1 to 4According to the above-described embodiment of the invention, the upper part of the U-shaped structure is a permanent magnet contact section 1211. The width of the permanent magnet contact section 1211 is smaller than the width of other parts of the U-shaped structure. The width of the permanent magnet contact section 1211 is 1 / 5 to 1 / 10 of its length, preferably 1 / 8 in this embodiment. A limiting protrusion 142 is provided at the bottom of the permanent magnet groove 14, located beside the bottom of the permanent magnet contact section 1211. The magnetic flux density at this point is equal to the inflection point magnetic flux density of the bh curve of the iron core material, i.e., saturation occurs here, thus maximizing the permanent magnet torque of the permanent magnet in this volume.

[0039] See Figures 1 to 5 The verification method for a high torque density high-voltage electronic cooling fan motor provided by the invention includes the following steps: Step 1: Rated Torque Electromagnetic Thermal Coupling Verification: An electromagnetic finite element model of the motor is established using Maxwell, with a rated winding current density of 7 A / mm². The losses of the winding, permanent magnet, and core are extracted as heat sources for the temperature field. A global temperature field model is established, inputting thermal conductivity and convection coefficients. An iteration interval of 10 s and a convergence criterion T_{n+1}-T_n≤0.5℃ are set. Material thermal properties are updated iteratively until temperature convergence, and the rated torque and overall temperature rise are verified. (See also...) Figure 5 The electromagnetic thermal coupling logic diagram of the model is proposed.

[0040] Maxwell electromagnetic model: 12kW high-pressure cooling fan motor, rated torque 38N·m, winding current density 7A / mm², water-cooled casing convective heat dissipation coefficient 1200W / (m²·K), N35SH permanent magnet thermal conductivity 9W / (m·K), 50WW470 silicon steel thermal conductivity 40W / (m·K). Step 2, Rotor mechanical stress check: Using Ansys finite element simulation, apply a load of twice the rated torque at the outer diameter of the rotor and the inner diameter of the stator, and check that the maximum stress of the rotor does not exceed 70% of the yield strength of the core material; if the stress exceeds the standard, thicken the local core of the rotor teeth, and go back to step 1 to check the rated torque. Ansys rotor stress: silicon steel yield strength 380MPa, check threshold ≤266MPa (70% yield strength), apply simulated load of 76N·m twice the rated torque; Step 3, Cogging Torque Optimization and Verification: Based on the air gap magnetomotive force modulation theory, the non-uniform air gap height H_g and stator slot width w_g are optimized to suppress the no-load cogging torque to within 1 / 5000 of the rated torque. The magnetomotive force generated by the permanent magnet in the air gap Modulated by the stator and rotor salient pole teeth, the average magnetic flux density in the no-load air gap can be expressed as:

[0041] In the formula, u 0 represents the permeability of free space. K c This represents the Carter coefficient.

[0042] u 0 = 4π × H / m, Carter's coefficient K c The slot opening width is automatically calculated, and the modulation functions Ms and Mr are discrete functions of Fourier decomposition of stator and rotor tooth harmonics.

[0043] The air gap magnetomotive force can be expressed as:

[0044] In the formula, This represents the initial magnetomotive force of the permanent magnet; Represents the stator modulation function; This represents the rotor modulation function.

[0045]

[0046] In the formula, m Indicates the harmonic order. p Represents the extreme number. F m Represents the Fourier coefficients. θ This indicates the circumferential angle of the air gap.

[0047]

[0048]

[0049]

[0050] In the formula, This represents the winding slot modulation function. This represents the modulation function of permanent magnet slot 14. and The distribution represents the DC component amplitude of the modulation function for the winding slots and permanent magnet slots 14. and They represent i amplitude of second harmonic components i This represents the harmonic order.

[0051]

[0052] In the formula, and Representing the DC component of the rotor modulation function and i amplitude of second harmonic components This represents the rotor speed.

[0053] Based on the above, change H g The parameters of the stator slot opening are optimized until the cogging torque is 1 / 5000 of the rated torque, which is considered acceptable. Cogging torque optimization iteration: Scanning with Hg and Wg as variable parameters, when Hg / Wg=1.2, the no-load cogging torque is 7.2mN·m, the rated torque is 38N·m, the ratio is about 1 / 5278, which meets the design index of ≤1 / 5000; Step 4, Torque density verification: Calculate the torque volume density (rated torque / motor envelope volume) and torque mass density (rated torque / total machine mass) respectively, and compare them with the design target to complete the verification.

[0054] See Figures 1 to 5 According to the above embodiments of the invention, the electromagnetic field finite element model outputs the winding, permanent magnet, and core losses as heat sources for the temperature field; the temperature field model inputs the thermal conductivity and convective heat dissipation coefficient of each component and outputs the global temperature distribution results; the temperature results are fed back to the electromagnetic field model to update the thermal properties of the winding and permanent magnet, and the process is iterated until the temperature converges, completing the electromagnetic-thermal coupling verification. This scheme calculates and verifies the motor mass, stress detection, and rated torque through mechanical dynamic experiments and performance experiments, using quantitative data to prove that the electromagnetic scheme for the motor provided by this invention achieves the design goals.

[0055] Comparative Example Using a conventional 20-pole, 18-slot internal rotor motor as a comparative example, the prototype of this invention was tested in actual operation: 1) Torque volume density increased by 22%, and torque mass density increased by 18%; 2) The highest temperature rise of the winding under rated operating conditions is 76℃, and the highest temperature of the permanent magnet is 82℃, which is 21℃ lower than that of an external rotor motor of the same power, and the demagnetization rate is <2%; 3) Cogging torque is 7.2 mN·m, and vibration noise is reduced by 6 dB(A); 4) The maximum stress of the rotor, which is twice the rated torque, is 242 MPa, which is lower than the 70% yield strength threshold of the material, and the mechanical safety margin is sufficient.

[0056] The technical solution provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. The terms "front," "back," "left," "right," "positive," and "negative" used in this solution are all terms used to clearly describe the invention from a certain perspective. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A high torque density high-voltage electronic cooling fan motor, comprising an outer stator assembly and an inner rotor assembly, characterized in that: The inner rotor assembly is a spoke-in-place permanent magnet rotor, and the outer stator assembly is a flat stator. The inner rotor assembly includes a rotor core composed of multiple rotor laminations and a permanent magnet disposed on the rotor core. The rotor laminations include a support portion, a shaft hole in the middle of the support portion, and multiple rotor teeth in the circumferential direction on the outer side of the support portion. Permanent magnet slots are formed between adjacent rotor teeth, and permanent magnets are disposed in the permanent magnet slots. Both sides of the inner wall of the permanent magnet slot are provided with slingshot grooves; The air gap between the outer stator assembly and the inner rotor assembly is unevenly distributed, and the maximum radial height of the uneven air gap is [value missing]. H g ; The outer stator assembly includes a stator core and windings wound on the stator core. The stator core has stator teeth, and the ends of the stator teeth have pole shoes. The windings are wound on the stator teeth, and a slot is formed between two adjacent pole shoes. The width of the slot is... w g ; H g and w g The ratio of their lengths is 1 to 1.

5.

2. The high torque density high-voltage electronic cooling fan motor according to claim 1, characterized in that: The stator core includes multiple tooth units, which are sequentially spliced ​​together to form the stator core. Each tooth unit includes a fixed part and stator teeth provided on the fixed part, and the fixed parts on two adjacent tooth units are connected together.

3. The high torque density high-voltage electronic cooling fan motor according to claim 1, characterized in that: The inner end of the rotor teeth is connected to the support, and the width of the inner end of the rotor teeth is 8%-12% of the width of the outer end of the rotor teeth.

4. The high torque density high-voltage electronic cooling fan motor according to claim 1, characterized in that: The rotor teeth are provided with a leakage magnetic path, a first weight reduction hole and a dynamic balance adjustment hole in sequence from the inside to the outside along the radial direction.

5. The high torque density high-voltage electronic cooling fan motor according to claim 4, characterized in that: The leakage magnetic path is a hollow U-shaped structure. The bottom of the U-shaped structure is close to the inner end of the rotor teeth, and the upper end of the U-shaped structure is close to the first weight reduction hole.

6. The high torque density high-voltage electronic cooling fan motor according to claim 5, characterized in that: The bottom of the permanent magnet slot and the middle of the U-shaped structure are located on the same radius circular track of the rotor laminations; the upper part of the U-shaped structure is the permanent magnet contact section, the width of which is smaller than the width of other parts of the U-shaped structure, and the ratio of the width of the permanent magnet contact section to its length is 1 / 5-1 / 10; the bottom of the permanent magnet slot is provided with a limiting protrusion, which is located on the side of the bottom of the permanent magnet contact section.

7. The high torque density high-voltage electronic cooling fan motor according to claim 4, characterized in that: The support section has multiple second weight reduction holes along the annular track, and rotor lamination clips are provided around the edge near the shaft hole.

8. The high torque density high-voltage electronic cooling fan motor according to claim 7, characterized in that: The first weight-reducing hole is a trapezoidal hole, and the second weight-reducing hole is a fan-shaped hole.

9. A verification method for the high torque density high voltage electronic cooling fan motor according to any one of claims 1-8, comprising the following steps: Step 1, Verification of rated torque electromagnetic thermal coupling: Establish an electromagnetic finite element model of the motor using Maxwell, limit the rated current density of the winding to 7A / mm², and extract the losses of the winding, permanent magnet, and core as heat sources for the temperature field; establish a global temperature field model, input the thermal conductivity and convection heat dissipation coefficients, set the iteration interval to 10s, and the convergence judgment condition T_{n+1}-T_n≤0.5℃, cyclically update the thermal properties of the materials until the temperature converges, and verify the rated torque and the overall temperature rise; Step 2, Rotor mechanical stress check: Using Ansys finite element simulation, apply a load of twice the rated torque at the outer diameter of the rotor and the inner diameter of the stator, and check that the maximum stress of the rotor does not exceed 70% of the yield strength of the core material; if the stress exceeds the standard, thicken the local core of the rotor teeth, and go back to step 1 to check the rated torque. Step 3, Cogging Torque Optimization and Verification: Based on the air gap magnetomotive force modulation theory, the non-uniform air gap height H_g and stator slot width w_g are optimized to suppress the no-load cogging torque to within 1 / 5000 of the rated torque. Step 4, Torque density verification: Calculate the torque volume density (rated torque / motor envelope volume) and torque mass density (rated torque / total machine mass) respectively, and compare them with the design target to complete the verification.

10. The verification method for a high torque density high-voltage electronic cooling fan motor according to claim 9, characterized in that: The electromagnetic field model outputs global loss data and transmits it to the temperature field. After the temperature field converges, the temperature of each component is fed back to the electromagnetic model to update the thermal properties such as resistivity and remanence of the permanent magnet and winding, thus realizing bidirectional electromagnetic-temperature coupling iteration.

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