Motor heat dissipation working point prediction method and system based on numerical calculation

Abstract

The invention discloses a motor heat dissipation working point prediction method and system based on numerical calculation, and belongs to the technical field of motor heat dissipation. In the prior art, a motor heat dissipation working point cannot be quickly and accurately obtained, so that the design of a motor heat dissipation system is influenced. According to the method, a motor simulation object is subjected to numerical splitting by constructing a motor object generation model, a motor decomposition model, a motor flow field simulation model, an impedance curve fitting model and a heat dissipation simulation prediction model, so that a fan twinborn part and a motor twinborn part are obtained; numerical calculation is carried out on the flow field characteristics of the fan twinborn part and the motor twinborn part, impedance characteristic fitting is carried out, and therefore a characteristic relation curve of fan pressure and air volume and a system impedance curve can be rapidly and accurately obtained; finally, according to the characteristic relation curve and the system impedance curve, accurate prediction of the motor heat dissipation working point is achieved, and then heat dissipation evaluation can be conducted on a motor heat dissipation system design scheme by applying the method.

Description

Technical Field

[0001] The present invention relates to a method and system for predicting the operating point of motor heat dissipation based on numerical calculation, belonging to the technical field of motor heat dissipation. Background Art

[0002] As motors develop towards miniaturization and lightweight, the heat generation inside the motors increases sharply, while the effective heat dissipation space is severely insufficient. The heat dissipation problem has become a bottleneck for the further development of motor systems towards higher power density. Excessive temperature rise inside the motor will not only reduce the lifespan of insulating materials and the thermal demagnetization of permanent magnet components, but also reduce the operating efficiency, increase heat generation, and cause the temperature to rise further, forming a vicious cycle, seriously affecting the motor lifespan and operating safety. Therefore, adopting an efficient heat dissipation system to suppress temperature rise is the key to the development of motors towards high efficiency, high stability, and high reliability.

[0003] In the heat dissipation system of an internal flow channel air-cooled motor, the performance of the fan and the flow channel structure inside the motor are the key factors determining the heat dissipation efficiency. When designing an air-cooled motor, generally, by analyzing the actual operating point of the motor system under specific working conditions, the actual flow rate that the fan can provide under the current system resistance is determined. If the flow rate at the intersection point can meet the heat dissipation requirements of the motor under specific working conditions, then it can be considered that the heat dissipation system design is appropriate. Conversely, if the flow rate is insufficient, it may be necessary to reconsider the selection of the fan or the design of the internal flow channel of the motor to improve the heat dissipation performance.

[0004] Currently, it is difficult to obtain an accurate motor heat dissipation operating point. Usually, before calculating the motor heat dissipation operating point, it is necessary to obtain the characteristic relationship curve between the fan pressure and air volume and the system impedance curve accurately.

[0005] Regarding the characteristic relationship curve between the fan pressure and air volume, it is closely related to the design of the centrifugal fan. However, currently, there is a lack of an effective method to obtain the actual change relationship between the pressure and air volume of the centrifugal fan installed inside the motor, which limits the accurate evaluation of the fan performance and the optimization of the heat dissipation system design.

[0006] There are mainly two methods to obtain the system impedance curve: theoretical calculation and wind tunnel test. The theoretical calculation method involves calculating the wind resistance of each component inside the motor, including the air hood, fan, stator core, winding, rotor core, permanent magnet, shaft, and heat dissipation fins of the electronic control system, and then adding these wind resistances to obtain the total wind resistance of the entire system. Although this method is easy to operate, due to large calculation errors, it usually cannot accurately evaluate the actual resistance of the system. On the other hand, the wind tunnel test can provide more accurate measurement results and can measure the system impedance, but this method is both time-consuming and costly, and is not suitable for rapid iteration and large-scale applications.

[0007] Therefore, the prior art cannot quickly and accurately obtain the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve, resulting in the inability to obtain an accurate motor heat dissipation operating point, thereby affecting the design of the motor heat dissipation system.

[0008] The information disclosed in this background art is only used to understand the background of the inventive concept, so it may include information that does not constitute the prior art. Summary of the Invention

[0009] In view of the above problems or one of the above problems, the first object of the present invention is to provide a method and system for predicting the motor heat dissipation operating point based on numerical calculation. By constructing a motor object generation model, a motor decomposition model, a motor flow field simulation model, an impedance curve fitting model, and a heat dissipation simulation prediction model, the motor simulation object is numerically split to obtain a fan twin part and a motor twin part; then the flow field characteristics of the fan twin part and the motor twin part are numerically calculated respectively to obtain the fan total pressure difference data and the motor total pressure difference data; then the impedance characteristics of the motor simulation object are fitted, so that the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve can be quickly and accurately obtained; finally, the characteristic relationship curve and the system impedance curve are coupled to realize the accurate prediction of the motor heat dissipation operating point.

[0010] In view of the above problems or one of the above problems, the second object of the present invention is to provide a method and system for predicting the motor heat dissipation operating point based on numerical calculation. The impedance of the overall internal flow path of the motor is calculated by numerical methods; and the overall structure of the motor is split into a fan part and a motor part with the output end cover plate as the boundary; then polynomial and parabolic functions are used for numerical fitting, so that an accurate motor heat dissipation operating point can be obtained, and further the heat dissipation evaluation of the motor heat dissipation system design scheme can be carried out.

[0011] To achieve the above object, the first technical solution of the present invention is: A method for predicting the motor heat dissipation operating point based on numerical calculation, comprising the following steps: Step 1, through the previously established motor object generation model, obtain the structural parameters of an internal flow path air-cooled motor, and simplify the structural parameters to obtain a motor simulation object; Step 2, using the previously established motor decomposition model, numerically split the motor simulation object according to the air flow direction and flow characteristics to obtain a fan twin part and a motor twin part; Step 3, using the previously established motor flow field simulation model, numerically calculate the flow field characteristics of the fan twin part and the motor twin part respectively to obtain the fan total pressure difference data and the motor total pressure difference data; Step 4: Using the impedance curve fitting model established in advance, based on the fan total pressure difference data and the motor total pressure difference data, perform impedance characteristic fitting on the motor simulation object to obtain the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve; Step 5: Based on the heat dissipation simulation prediction model established in advance, perform coupling processing on the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve to obtain the motor heat dissipation operating point of a certain internal flow path air-cooled motor.

[0012] In the present invention, by constructing a motor object generation model, a motor decomposition model, a motor flow field simulation model, an impedance curve fitting model, and a heat dissipation simulation prediction model, the motor simulation object is numerically split to obtain a fan twin part and a motor twin part; then, numerical calculations are respectively performed on the flow field characteristics of the fan twin part and the motor twin part to obtain the fan total pressure difference data and the motor total pressure difference data; then, impedance characteristic fitting is performed on the motor simulation object, so that the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve can be quickly and accurately obtained; finally, coupling processing is performed on the characteristic relationship curve and the system impedance curve to accurately predict the motor heat dissipation operating point. The solution is scientific, reasonable, and practical.

[0013] Furthermore, the present invention uses a numerical method to calculate the impedance of the overall internal flow path of the motor; and the overall structure of the motor is split into a fan part and a motor part with the output end cover plate as the boundary; then, numerical fitting is performed using polynomial and parabolic functions, so that an accurate motor heat dissipation operating point can be obtained, and furthermore, the present invention can be applied to evaluate the heat dissipation of the motor heat dissipation system design scheme.

[0014] As a preferred technical measure: Step 1: The method for obtaining the structural parameters of a certain internal flow path air-cooled motor through the motor object generation model established in advance and performing simplification processing on the structural parameters to obtain the motor simulation object is as follows: S1: Obtain the structural parameters of the motor according to the structural design information of the motor product; S2: Construct the initial three-dimensional simulation object of the motor according to the structural parameters; S3: Based on a preset simplification mechanism, simplify the initial three-dimensional simulation object to obtain a motor simulation object with core component parts; the core component parts include a wind cover, a motor housing, a stator core, a stator winding, a rotor core, a magnet, a rotating shaft, an output end cover plate, a fan, and an output end fixing bracket.

[0015] As a preferred technical measure: Step 2: The method for numerically splitting the motor simulation object into a fan twin part and a motor twin part using the motor decomposition model established in advance according to the air flow direction and flow characteristics is as follows: Obtain the motor simulation object, and based on the motor simulation object, search for the information of the output end cover plate of the motor, which includes the geometric data and structural data of the end cover plate; the output end cover plate is located between the fan part and the motor part, and is both the air outlet of the motor and the air inlet of the fan volute. According to the preset splitting mechanism, split the motor simulation object with the output end cover plate as the boundary surface to obtain the fan part and the motor part. In the fan part and the motor part, couple the geometric data and structural data of the end cover plate respectively, so that the cover plate geometric data and structural data exist in the fan part and the motor part respectively, so that the two parts can be independent of each other, and at the same time can be docked consistently at the interface. Based on the fan part, search for the air inlet end information of the fan part. Based on the motor part, search for the air outlet end information of the motor part. Modify the air inlet end information and the air outlet end information to form the fan twin part and the motor twin part, so that after splitting, the air inlet end of the fan part and the air outlet end of the motor part are kept consistent, ensuring that the air flow direction and flow characteristics remain unchanged. The fan twin part is used to simulate the air acceleration situation and the outlet flow field in the fan volute structure starting from the output end cover plate; the motor twin part is used to simulate the air flow and heat transfer situation from the internal air flow channel to the output end cover plate.

[0016] As a preferred technical measure: The preset simplification mechanism includes the following content: For the bearing, simplify it into a circular ring sleeve with the same diameter size and merge it with the bearing groove. Ignore the feature structures that are difficult to capture and have little impact on the simulation, including chamfers, rounded corners, through holes, threaded holes, and terminal posts. Set the gap between the rotating shaft and the end cover to a fitting state. Fill the gaps between the stator windings to make them combined into a whole. Remove the insulating paper in the winding slots of each stator core. Or / and, the preset splitting mechanism includes the following content: During the splitting process, keep the original structural characteristics of the motor unchanged; the output end cover plate, as the key component of the boundary surface, keeps its position and structure consistent in the two parts of the motor and the fan. The volute structure of the fan twin part should be kept intact to ensure that the air inlet and acceleration processes of the fan are not affected by the splitting; it can reflect the true working characteristics of the fan and present the air-cooling effect in the simulation. The air flow channels of the motor twin parts should maintain the same flow direction after passing through the output end cover plate; the interface should be set to allow the air flow to smoothly enter the inlet of the fan volute, ensuring a continuous air flow direction and a natural transition of the air flow during the simulation process, and avoiding turbulence or direction deviation caused by splitting.

[0017] As a preferred technical measure: Step 3: Use the previously established motor flow field simulation model to perform numerical calculations on the flow field characteristics of the fan twin parts to obtain the fan total pressure difference data as follows: Obtain the cross-sectional shape of the fan inlet end and the cross-sectional shape of the fan outlet end; Based on the cross-sectional shape, determine the extended distance of the fan inlet end and the extended distance of the fan outlet end; Based on the extended distance, correct the fan twin parts to obtain a corrected fan model; fill the interior of the fan model to obtain the internal flow channel fluid domain; Divide the internal flow channel fluid domain into the rotating region and the non-rotating region of the centrifugal fan; Use the polyhedral mesh algorithm to perform mesh generation on the rotating region and the non-rotating region respectively to obtain a number of fan calculation meshes, and the basic size of the fan calculation meshes is X times the minimum length of the fan model; further, the value of X is 5 - 20.

[0018] Based on the incompressible Newtonian fluid algorithm, perform data simulation on the calculation meshes to obtain the fan total pressure difference data.

[0019] As a preferred technical measure: The method of dividing the internal flow channel fluid domain into the rotating region and the non-rotating region of the centrifugal fan is as follows: Obtain the centroid information, outer diameter information, and thickness information of the centrifugal fan; Based on the centroid information, outer diameter information, and thickness information, construct a cylindrical simulation object, and make the centroid of the cylindrical simulation object coincide with the centroid of the centrifugal fan. The outer diameter of the cylindrical simulation object is determined according to the outer diameter of the centrifugal fan, and the height of the cylindrical simulation object is determined according to the thickness of the centrifugal fan; Use the cylindrical simulation object as the rotating region; Based on the Boolean operation mechanism, use the entire internal flow channel fluid domain as the minuend and the rotating region as the subtrahend; Finally, subtract the rotating region from the internal flow channel fluid domain to obtain the non-rotating region.

[0020] As a preferred technical measure: The method of performing data simulation on the calculation meshes to obtain the fan total pressure difference data is as follows: Step 31: According to the working condition information, set the fan speed and the initial simulation conditions; The initial simulation conditions include the inlet type, outlet type, and pressure value; set both the inlet type and outlet type to pressure inlets / outlets and the pressure to zero; Step 32: According to the incompressible Newtonian fluid algorithm, perform a simulation calculation on the fan speed and the initial simulation conditions to obtain the maximum volume flow rate of the fan at this fan speed; Step 33: Keep the inlet type unchanged and change the outlet type to a volume flow rate outlet; Step 34: Generate a number of flow rate values based on the volume flow rate outlet, the maximum volume flow rate, and a preset increasing percentage; Step 35: Use the number of flow rate values as corresponding working conditions and perform numerical calculations respectively to obtain a number of fan total pressure difference values.

[0021] As a preferred technical measure: Step three: Use the previously established motor flow field simulation model to perform a numerical calculation on the flow field characteristics of the motor twin part to obtain the motor total pressure difference data as follows: Obtain the cross-sectional shape of the motor inlet end and the cross-sectional shape of the motor outlet end; Based on the cross-sectional shape, determine the extension distance of the motor inlet end and the extension distance of the motor outlet end; Based on the extension distance, correct the motor twin part to obtain a corrected motor model; Fill the inside of the motor model to obtain an internal flow channel fluid domain; Use the polyhedral mesh algorithm to perform mesh division on the internal flow channel fluid domain to obtain a number of motor calculation meshes, and the basic size of the motor calculation meshes is X times the minimum length of the motor model; Set the inlet type to a pressure inlet and the outlet type to a mass flow rate outlet; Based on the mass flow rate outlet, set a number of mass flow rates as corresponding simulation working conditions, and at the same time, based on the incompressible Newtonian fluid algorithm, perform data simulation on the calculation meshes to obtain the motor total pressure difference data.

[0022] As a preferred technical measure: Step four: Use the previously established impedance curve fitting model to perform impedance characteristic fitting on the motor simulation object based on the fan total pressure difference data and the motor total pressure difference data to obtain the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve as follows: Obtain a number of flow rate values and the corresponding fan total pressure difference values; Perform curve fitting on the flow rate values and the fan total pressure difference values using a polynomial function to obtain a fitting formula; According to the fitting formula, select an appropriate polynomial order and optimize the fitting error to obtain the PQ curve equation of the fan, that is, the characteristic relationship curve between the fan pressure and the air volume, which is used to characterize the variation relationship between the air volume and the fan pressure; Obtain a number of mass flow rates and corresponding total differential pressures of the motor; Perform curve fitting on the mass flow rate and the total differential pressure data of the motor using a parabola function passing through the origin to obtain the motor fitting formula; Generate a system impedance curve according to the motor fitting formula, which is used to characterize the relationship between the pressure loss and the air flow rate; And / or, step five, based on the previously established heat dissipation simulation prediction model, the method for coupling the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve to obtain the motor heat dissipation operating point of a certain internal flow channel air-cooled motor is as follows: Obtain the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve; Find the intersection point of the two curves according to the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve; Take the intersection point of the two curves as the fan operating point, that is, the motor heat dissipation operating point.

[0023] To achieve one of the above purposes, the second technical solution of the present invention is: A motor heat dissipation operating point prediction system based on numerical calculation, which includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned method for predicting the motor heat dissipation operating point based on numerical calculation.

[0024] Compared with the prior art solutions, the present invention has the following beneficial effects: The present invention constructs a motor object generation model, a motor decomposition model, a motor flow field simulation model, an impedance curve fitting model, and a heat dissipation simulation prediction model, numerically splits the motor simulation object to obtain a fan twin part and a motor twin part; then numerically calculates the flow field characteristics of the fan twin part and the motor twin part respectively to obtain the total differential pressure data of the fan and the total differential pressure data of the motor; and then fits the impedance characteristics of the motor simulation object, so that the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve can be obtained quickly and accurately; finally, the characteristic relationship curve and the system impedance curve are coupled to realize the accurate prediction of the motor heat dissipation operating point. The solution is scientific, reasonable, and feasible.

[0025] Furthermore, the present invention uses numerical methods to calculate the impedance of the overall internal flow path of the motor; the overall motor structure is split into a fan part and a motor part with the output end cover plate as the boundary; then polynomial and parabolic functions are used for numerical fitting, so that the accurate heat dissipation operating point of the motor can be obtained, and further, the present invention can be applied to evaluate the heat dissipation of the motor heat dissipation system design scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flowchart of a method of the present invention; Figure 2 is a structural schematic diagram of an initial three-dimensional simulation object of the present invention; Figure 3 is a schematic diagram of a simplified motor simulation object of the present invention; Figure 4 is a structural schematic diagram of the motor part after splitting of the present invention; Figure 5 is a structural schematic diagram of the fan part after splitting of the present invention; Figure 6 is a schematic diagram of extending the inlet of the fan part of the present invention; Figure 7 is a structural schematic diagram of a rotating area of the present invention; Figure 8 is a structural schematic diagram of a non-rotating area of the present invention; Figure 9 is a schematic diagram of extending the inlet of the motor part of the present invention; Figure 10 is a schematic diagram of the fluid domain of the motor part of the present invention; Figure 11 is a schematic diagram of predicting the actual heat dissipation operating point of the motor of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0028] On the contrary, the present invention covers any alternatives, modifications, equivalent methods and solutions made within the spirit and scope of the present invention as defined by the claims. Further, in order to enable the public to better understand the present invention, some specific details are described in detail in the following detailed description of the present invention. Those skilled in the art can fully understand the present invention without the description of these details.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the related listed items.

[0030] As Figure 1 shown, the first specific embodiment of the method for predicting the motor heat dissipation operating point based on numerical calculation of the present invention: A method for predicting the motor heat dissipation operating point based on numerical calculation, comprising the following steps: Step 1, through a pre-established motor object generation model, obtain the structural parameters of an internal flow path air-cooled motor, and perform a simplification process on the structural parameters to obtain a motor simulation object; Step 2, using a pre-established motor decomposition model, according to the air flow direction and flow characteristics, numerically split the motor simulation object to obtain a fan twin part and a motor twin part; Step 3, adopt a pre-established motor flow field simulation model, numerically calculate the flow field characteristics of the fan twin part and the motor twin part respectively to obtain fan total pressure difference data and motor total pressure difference data; Step 4, use a pre-established impedance curve fitting model, based on the fan total pressure difference data and the motor total pressure difference data, perform impedance characteristic fitting on the motor simulation object to obtain the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve; Step 5, based on a pre-established heat dissipation simulation prediction model, perform coupling processing on the characteristic relationship curve between the fan pressure and the air volume and the system impedance curve to obtain the motor heat dissipation operating point of an internal flow path air-cooled motor.

[0031] The second specific embodiment of the method for predicting the motor heat dissipation operating point based on numerical calculation of the present invention: A method for predicting the motor heat dissipation operating point based on numerical calculation, comprising the following steps: S1: According to the design requirements of the motor product, obtain the structural parameters of the motor.

[0032] S2: According to the structural parameters, use a motor object generation model to construct an initial three-dimensional simulation object of the motor, which can be referred to Figure 2 .

[0033] S3: For the convenience of simulation analysis and to improve the calculation efficiency, based on a preset simplification mechanism, simplify the initial three-dimensional simulation object to obtain a motor simulation object. The preset simplification mechanism is as follows: 1. The bearing is simplified to a ring sleeve of the same diameter and merged with the bearing groove; 2. Features and structures that are difficult to capture and have little impact on the overall simulation, such as chamfers, fillets, through holes, threaded holes, and terminal posts, are ignored; 3. The small gaps between the rotating shaft and the end cover will affect the overall mesh quality and quantity, and these gaps are set to a fitting state; 4. The small gaps between the stator windings are also filled to make them combined into a whole; 5. The insulating paper in the winding slots of each stator core is removed.

[0034] S4: After the above simplification, the simplified motor simulation object is obtained, as shown in Figure 3 , and finally 10 core components are retained, including: the wind cover, the motor housing, the stator core, the stator winding, the rotor core, the permanent magnet, the rotating shaft, the output end air guide cover plate, the fan, and the output end fixing bracket.

[0035] S5: When predicting the heat dissipation operating point of the air-cooled motor, it is necessary to perform numerical calculations on the fan characteristics and the impedance characteristics of the motor system respectively.

[0036] The fan characteristics describe the ability of the air flow driven by the fan to overcome the system resistance, including parameters such as flow rate, pressure, efficiency, and power consumption. The relationship curve between the flow rate and the pressure is called the pressure-flow characteristic relationship curve (Pressure-Flow curve), which is used to show the relationship between the pressure (Pressure, P) and the air flow rate (Flow rate, Q) of the fan under different operating conditions.

[0037] At different operating points of the fan, the pressure-flow characteristic relationship curve shows how the pressure generated by the fan changes with the change of the air flow rate. This curve is usually non-linear. Specifically: in the region of small air flow rate, the fan can provide a large pressure; as the air flow rate increases, the pressure gradually decreases and finally approaches the maximum output air flow rate of the fan.

[0038] The impedance characteristics of the motor system mainly refer to the resistance characteristics of the internal ventilation system of the motor to the air flow, including the hindering effects of components such as the stator winding, the rotor, and the internal air ducts of the motor housing on the air flow. This characteristic is usually expressed as the characteristic relationship curve between the pressure loss (resistance) and the air flow rate, that is, the system impedance curve. The operating point of the heat dissipation of the air-cooled motor is the intersection point of the impedance characteristic relationship curve of the motor system (system impedance curve) and the characteristic relationship curve of the fan pressure and air flow rate.

[0039] The air flow rate is usually directly input as a boundary condition to the numerical calculation, while the pressure can be obtained through the numerical calculation.

[0040] In the numerical calculation, the pressure usually refers to the total pressure difference of the air flow at the inlet and outlet , and its calculation formula is:

[0041] Among them, is the air pressure at the air outlet, is the air pressure at the air inlet.

[0042] S6: To achieve this goal, the simplified motor simulation object in S3 is split into two parts: the fan part and the motor part. Refer to Figure 4 and Figure 5 . The splitting method is as follows: Split with the output end cover plate of the motor as the interface. The end cover plate is located between the fan part and the motor part. It is both the air outlet of the motor and the air inlet of the fan volute. In the motor simulation object, the geometry and structure of the end cover plate are copied so that it exists in both the motor part and the fan part, enabling the two parts to be independent while being able to dock consistently at the interface. After splitting, the air outflow end of the motor part is consistent with the air inflow end of the fan part, ensuring that the air flow direction and flow characteristics remain unchanged. The motor part is responsible for simulating the air flow and heat transfer from the internal air flow path to the outlet end cover plate, and the fan part starts from the end cover plate to simulate the air acceleration and outlet flow field within the fan volute structure. Through this structure, the two subsystems can be independently simulated and effectively docked.

[0043] The splitting mechanism is as follows: (1) Structure remains unchanged: During the splitting process, the original structural characteristics of the motor are maintained. The end cover plate, as a key component of the interface, keeps its position and structure consistent in both the motor and fan parts.

[0044] (2) Air flow direction is continuous: The air flow path in the motor should maintain the same flow direction after passing through the end cover plate. The interface is set to enable the air flow to smoothly enter the fan volute inlet, ensuring the natural transition of the air flow during the simulation and avoiding turbulence or direction deviation caused by splitting.

[0045] (3) Volute structure is complete: In the model of the fan part, the volute structure should be kept complete to ensure that the air inflow and acceleration process of the fan are not affected by splitting. This can not only reflect the true working characteristics of the fan but also present the air-cooling effect in the simulation.

[0046] S7: Before calculating the characteristic relationship curve between the pressure and air volume of the fan part, the model of the fan part should be pre-processed, specifically including the extension of the inlet and outlet ends. Refer to Figure 6 . This extension treatment helps ensure that there is sufficient space for the air flow to fully develop before entering the fan and after leaving the fan, thereby reducing turbulence and instability and improving the accuracy of the simulation results.

[0047] The method for extending the inlet end is as follows: Obtain the cross-sectional shape of the inlet end; then calculate the hydraulic diameter according to the cross-sectional shape. If the cross-sectional shape of the inlet end is circular and the diameter of the circle is then the hydraulic diameter ; If the cross-sectional shape of the inlet end is rectangular, with length A and width B, then the hydraulic diameter The calculation formula is as follows:

[0048] Calculate the extended distance L of the inlet end according to the hydraulic diameter and the Reynolds number. The calculation formula is as follows:

[0049] Among them, is the Reynolds number, and its calculation formula is as follows:

[0050] Among them, is the fluid density, is the characteristic velocity, is the characteristic length, is the dynamic viscosity of the fluid. Under typical engineering conditions, generally take .

[0051] The method for extending the outlet end is as follows: Obtain the cross-sectional shape of the outlet end; then calculate the hydraulic diameter according to the cross-sectional shape. If the cross-sectional shape of the outlet end is circular and the diameter of the circle is then the hydraulic diameter ; If the cross-sectional shape of the outlet end is rectangular, with length A and width B, then the hydraulic diameter The calculation formula is as follows:

[0052] Calculate the extended distance L of the outlet end according to the hydraulic diameter and the Reynolds number. The calculation formula is as follows:

[0053] If the cross-sectional shapes of the inlet and outlet are irregular, then select the maximum edge length on the surface where the inlet (orifice) or outlet is located as the extended distance of the inlet end and the outlet end.

[0054] S8: Extract the fluid domain of the processed fan model, select the cross-sections of the inlet and outlet, and fill their interiors to obtain the internal flow field.

[0055] S9: The multiple reference frame (MRF) model is used for the calculation of the fan. Therefore, the fluid domain extracted in S8 needs to be divided into two parts. The first part is the rotating region of the centrifugal fan, which can be seen in Figure 7 . The rotating region is generally built as a cylinder, and its structural characteristics and dimensions are as follows: The centroid of the rotating region coincides with the centroid of the centrifugal fan. The outer diameter of the rotating region (unit: mm) is:

[0056] Among them, is the outer diameter of the centrifugal fan.

[0057] The height of the rotating region (unit: mm) is:

[0058] Among them, is the thickness of the centrifugal fan.

[0059] The second part is the non-rotating region, which can be seen in Figure 8 . In the 3D modeling software, using the Boolean operation, taking the whole fluid domain as the minuend and the rotating region as the subtrahend, the non-rotating region can be obtained.

[0060] S10: Mesh generation is performed on the obtained non-rotating region and rotating region respectively. The cell type for mesh generation can adopt polyhedral meshes, and the basic size of the mesh can be set to about 10 times the minimum length of the model.

[0061] S11: Read the computational mesh and set the solver to steady, incompressible Newtonian fluid. The fan speed can be input according to the actual working conditions. In the first simulation calculation, both the inlet and outlet types can be set to pressure inlets and outlets with a pressure of 0 Pa.

[0062] S12: After calculation according to the conditions in S10, the maximum volume flow rate of the fan at the input speed can be obtained . In order to obtain the characteristic curve of the non-linear pressure and air volume of the fan, more data points are needed to fit this function.

[0063] S13: Keep the inlet type unchanged, change the outlet type to volume flow rate outlet, and set the value of the volume flow rate to:

[0064] Among them is an increasing percentage, gradually increasing from 0% to 95% in steps of 5%, for a total of 20 working conditions. By performing numerical calculations on the 20 cases using the above method respectively, the fan total pressure difference values at 20 inlet volume flows can be obtained, denoted as:

[0065] where, is the volume flow value at the th working condition, is the static pressure difference of the fan at the th working condition.

[0066] S14: Calculate the internal system impedance of the motor part.

[0067] S15: Before calculating the characteristic relationship curve of the pressure and air volume of the motor part, the model of the motor part also needs to be pre-processed, specifically including the extension of the inlet and outlet ends, which can be referred to Figure 9 . The specific extension method is as follows: Obtain the cross-sectional shapes of the inlet and outlet ends of the motor part; Then, calculate the hydraulic diameter according to the cross-sectional shape; If the cross-sectional shapes of the inlet and outlet ends of the motor part are circular, and the diameter of the circle is , then the hydraulic diameter ; If the cross-sectional shapes of the inlet and outlet ends of the motor part are rectangular, with the length of the rectangle being A and the width being B, then the calculation formula for the hydraulic diameter is as follows:

[0068] According to the hydraulic diameter and the Reynolds number, calculate the extension distances L of the inlet and outlet ends, and its calculation formula is as follows:

[0069] where, is the Reynolds number, and its calculation formula is as follows:

[0070] where, is the fluid density, is the characteristic velocity, is the characteristic length, is the dynamic viscosity of the fluid. Under typical engineering conditions, generally take .

[0071] If the cross-sectional shapes of the inlet and outlet of the motor part are irregular shapes, then select the maximum side length on the surface where the inlet or outlet is located as the corresponding extension distance.

[0072] S16: Extract the fluid domain of the processed motor model, select the cross-sections of the inlet and outlet of the motor part, and fill its interior to obtain the fluid domain of the motor part. For details, see Figure 10 。

[0073] S17: Mesh the fluid domain of the internal flow path of the motor part. The cell type for meshing can be polyhedral mesh, and the base size of the mesh can be set to about 10 times the minimum length of the model.

[0074] S18: Read the computational mesh and set the solver to steady, incompressible Newtonian fluid. Set the inlet type to pressure inlet and change the outlet type to mass flow outlet. The magnitude of the mass flow is kept consistent with that set in S13, with a total of 20 working conditions. After the simulation is completed, the numerical values of the total pressure difference at the inlet and outlet of the motor part under 20 volume flow rates can be obtained, denoted as:

[0075] where, is the volume flow rate value under the th working condition, is the static pressure difference of the motor part under the th working condition.

[0076] S19: Fit the fan characteristic curve. Fit the 20 sets of fan part flow rates, i.e., the motor part flow rate Q - pressure data , collected from the simulation calculation using a polynomial function. The fitting formula is:

[0077] where, is the predicted static pressure difference of the fan part, is the polynomial coefficient (fitting parameter) of the jth term, and n is the order of the polynomial, with common values between 2 and 5.

[0078] Select an appropriate polynomial order and optimize the fitting error to obtain the characteristic relationship curve between the fan pressure and the air volume, i.e., the air volume (Q) - static pressure (P) characteristic curve of the fan.

[0079] S20: Fit the system impedance curve. Fit the 20 sets of motor part flow rates - pressure data collected from the simulation calculation using a parabola function passing through the origin. The fitting formula is as follows:

[0080] where, is the predicted static pressure difference of the motor part, and b is the system impedance coefficient.

[0081] S21: Find the intersection point of the two curves according to g(Q) = f(Q), and output the operating point ( ), to achieve the prediction of the actual heat dissipation operating point of the motor, which can be referred to Figure 11 .

[0082] An equipment embodiment applying the method of the present invention: An electronic device, which includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the above-mentioned method for predicting the heat dissipation operating point of a motor based on numerical calculation.

[0083] A computer medium embodiment applying the method of the present invention: A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the above-mentioned method for predicting the heat dissipation operating point of a motor based on numerical calculation is implemented.

[0084] The model in this application is an object that constitutes an objective description of the morphological structure by means of an entity or a virtual representation. The object is not equal to an object, and is not limited to an entity and a virtual one. It can be a data processing function, a software program, a processing mode, a usage method, an operation mode, a work flow, an application process, an electronic hardware, a circuit module, a processing system, a system imitation or a simulation object.

[0085] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention. Any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for predicting the motor heat dissipation working point based on numerical calculation, characterized in that: The following steps are involved: Step 1: obtain the structural parameters of a certain inner flow channel air-cooled motor through the motor object generation model established in advance, and simplify the structural parameters to obtain the motor simulation object; Step 2: Using the motor decomposition model established in advance, the motor simulation object is numerically split according to the airflow direction and flow characteristics to obtain the fan twin part and the motor twin part; Step 3, using the motor flow field simulation model established in advance, numerically calculate the flow field characteristics of the fan twin part and the motor twin part respectively, and obtain the fan full pressure difference data and the motor full pressure difference data; Step 4: Using the impedance curve fitting model established in advance, based on the fan full pressure difference data and the motor full pressure difference data, the motor simulation object is fitted with impedance characteristics to obtain the characteristic relationship curve between fan pressure and air volume and the system impedance curve; Step five, based on the heat dissipation simulation prediction model established in advance, the characteristic relationship curve between fan pressure and air volume and the system impedance curve are coupled to obtain the motor heat dissipation operating point of a certain internal flow channel air-cooled motor.

2. A method for predicting a motor heat dissipation operating point based on numerical calculation as claimed in claim 1, characterized in that: Step 1: The motor object generation model established in advance is used to obtain the structural parameters of a certain inner flow channel air-cooled motor, and the structural parameters are simplified to obtain the motor simulation object as follows: S1: Obtain the structural parameters of the motor according to the structural design information of the motor product; S2: constructing an initial three-dimensional simulation object of the motor according to the structural parameters; S3: Based on the preset simplification mechanism, the initial three-dimensional simulation object is simplified to obtain a motor simulation object with core components; the core components include a fan cover, a motor housing, a stator core, a stator winding, a rotor core, a magnet, a shaft, an output end cover, a fan and an output end fixing bracket.

3. A method for predicting a motor heat dissipation operating point based on numerical calculation as claimed in claim 2, characterized in that: Step 2: Using the motor decomposition model established in advance, the motor simulation object is numerically decomposed according to the airflow direction and flow characteristics. The method for obtaining the fan twin part and the motor twin part is as follows: Acquire a motor simulation object, and based on the motor simulation object, search for output end cover information of the motor, which includes geometric data and structural data of the end cover; According to the preset splitting mechanism, the motor simulation object is split with the output end cover as the interface to obtain the fan part and the motor part; In the fan part and the motor part, the end cover plate geometric data and the structural data are coupled respectively; Based on the fan part, searching for air inflow end information of the fan part; Based on the motor part, find the air outlet end information of the motor part; Correcting the air inlet end information and the air outlet end information to form a fan twin part and a motor twin part; The fan twin part is used to simulate the air acceleration and outlet flow field inside the fan volute structure starting from the output end cover; the motor twin part is used to simulate the air flow and heat transfer from the internal air flow channel to the output end cover.

4. A method for predicting the motor heat dissipation operating point based on numerical calculation as claimed in claim 3, characterized in that: The preset simplification mechanism includes the following: For the bearing, it is simplified into a ring sleeve of the same diameter and merged with the bearing groove; Ignore the feature structures that are difficult to capture and have little impact on the simulation, including chamfers, fillets, through holes, threaded holes, and terminals; Set the gap between the shaft and the end cover to fit; Fill the gaps between the stator windings to combine them into a whole; Remove the insulating paper from the winding slots of each stator core; or / and, preset splitting mechanism, including the following: During the splitting process, the original structural characteristics of the motor are kept unchanged; the output end cover is the key component of the interface; The volute structure of the twin parts of the fan should remain intact to ensure that the air inflow and acceleration process of the fan are not affected by the split; The air flow path of the twin parts of the motor should maintain the same flow direction after passing through the output end cover.

5. The method for predicting the motor heat dissipation operating point based on numerical calculation according to claim 1, characterized in that: Step 3: Use the motor flow field simulation model established in advance to numerically calculate the flow field characteristics of the fan twin part, and the method for obtaining the fan total pressure difference data is as follows: Obtaining a cross-sectional shape of a fan inlet end and a cross-sectional shape of a fan outlet end; Determine the extension distance of the fan inlet end and the extension distance of the fan outlet end according to the cross-sectional shape; Based on the extended distance, the twin part of the fan is corrected to obtain a corrected fan model; Fill the interior of the fan model to obtain the inner flow channel fluid domain; The inner flow channel fluid domain is divided into a rotating area and a non-rotating area of ​​the centrifugal fan; The polyhedron mesh algorithm is used to mesh the rotating area and the non-rotating area respectively to obtain several fan calculation meshes. The basic size of the fan calculation mesh is X times the minimum length of the fan model. Based on the incompressible Newtonian fluid algorithm, data simulation is performed on the computational grid to obtain the fan total pressure difference data.

6. A method for predicting the motor heat dissipation operating point based on numerical calculation as claimed in claim 5, characterized in that: The method of dividing the inner channel fluid domain into the rotating area and non-rotating area of ​​the centrifugal fan is as follows: Obtaining the centroid information, outer diameter information and thickness information of the centrifugal fan; Based on the centroid information, outer diameter information and thickness information, a cylindrical simulation object is constructed, and the centroid of the cylindrical simulation object is made to coincide with the centroid of the centrifugal fan. The outer diameter of the cylindrical simulation object is determined according to the outer diameter of the centrifugal fan, and the height of the cylindrical simulation object is determined according to the thickness of the centrifugal fan. Use the cylindrical simulation object as the rotation area; Based on the Boolean operation mechanism, the entire inner channel fluid domain is taken as the minuend and the rotation area as the subtrahend; Finally, the inner channel fluid domain is subtracted from the rotating region to obtain the non-rotating region.

7. A method for predicting a motor heat dissipation operating point based on numerical calculation as claimed in claim 6, characterized in that: The method of performing data simulation on the computational grid to obtain the fan full pressure difference data is as follows: Step 31, setting the fan speed and initial simulation conditions according to the working condition information; The initial simulation conditions include inlet type, outlet type and pressure value; the inlet type and outlet type are both set to pressure inlet and outlet and the pressure is zero; Step 32, performing simulation calculation on the fan speed and initial simulation conditions according to an incompressible Newtonian fluid algorithm to obtain the maximum volume flow of the fan at the fan speed; Step 33, keep the inlet type unchanged and change the outlet type to volume flow outlet; Step 34, generating a plurality of flow values ​​according to the volume flow outlet, the maximum volume flow and the preset increment percentage; Step 35, taking a plurality of flow values ​​as corresponding working conditions, respectively perform numerical calculations to obtain a plurality of fan total pressure difference values.

8. The method for predicting the motor heat dissipation operating point based on numerical calculation according to claim 1, characterized in that: Step 3: Use the motor flow field simulation model established in advance to perform numerical calculations on the flow field characteristics of the motor twin part, and obtain the motor full pressure difference data as follows: Obtaining the cross-sectional shape of the motor inlet end and the cross-sectional shape of the motor outlet end; Determine the extension distance of the motor inlet end and the extension distance of the motor outlet end according to the cross-sectional shape; Based on the extended distance, the twin part of the motor is modified to obtain a modified motor model; Fill the interior of the motor model to obtain the inner flow channel fluid domain; The polyhedron mesh algorithm is used to mesh the inner flow channel fluid domain to obtain a number of motor calculation grids. The basic size of the motor calculation grid is X times the minimum length of the motor model. Set the inlet type to pressure inlet and the outlet type to mass flow outlet; According to the mass flow outlet, several mass flow rates are set as the corresponding simulation conditions. At the same time, based on the incompressible Newtonian fluid algorithm, the calculation grid is simulated to obtain the total pressure difference data of the motor.

9. The method for predicting the motor heat dissipation working point based on numerical calculation according to claim 1, characterized in that: The method for obtaining the characteristic relationship curve between fan pressure and air volume and the system impedance curve is as follows: Obtain several flow values ​​and corresponding fan total pressure difference values; For the flow value and the fan total pressure difference value, a polynomial function is used to perform curve fitting to obtain a fitting formula; According to the fitting formula, the appropriate polynomial order is selected and the fitting error is optimized to obtain the characteristic relationship curve between the fan pressure and the air volume; Obtain several mass flow rates and corresponding motor total pressure difference data; For the mass flow rate and the total pressure difference data of the motor, a parabolic function passing through the origin is used for curve fitting to obtain the motor fitting formula; According to the motor fitting formula, a system impedance curve is generated to characterize the relationship between pressure loss and air flow; And / or, the method for obtaining the motor heat dissipation working point of a certain inner flow channel air-cooled motor is as follows: Obtain the characteristic relationship curve between fan pressure and air volume and the system impedance curve; According to the characteristic relationship curve between fan pressure and air volume and the system impedance curve, find the intersection of the two curves; The intersection of the two curves is taken as the fan operating point, that is, the motor heat dissipation operating point.

10. A motor heat dissipation working point prediction system based on numerical calculation, characterized in that: It includes: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement a motor heat dissipation operating point prediction method based on numerical calculation as described in any one of claims 1-9.

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