A temperature calculation method for a driving motor of a temperature-fluid weak coupling technology

Abstract

The application discloses a temperature-fluid weak coupling technology driving motor temperature calculation method, and solves the motor thermal network calculation oscillation problem caused by the transient rapid heat exchange between the fluid and the motor winding and the iron core components. The method deeply analyzes the thermal network capacitance matrix characteristics, considers the influence of the ratio of the maximum and minimum values of the matrix elements on the convergence of the iterative calculation, and considers that the driving motor cooling fluid and the motor temperature change little in a certain short time period, and the internal heat transfer phenomenon is relatively stable. The method establishes a weak coupling calculation method for the fast changing fluid field and the slow changing motor internal temperature field. The method avoids the inherent defects of the ratio of the maximum and minimum values of the thermal capacity matrix elements being too large by adopting different calculation frequencies in the fluid field and the temperature field, and realizes the rapid and stable calculation of the driving motor temperature. The temperature calculation method has the advantages of clear idea, simple operation, easy implementation, rapid calculation, universality and the like, and has superior performance.

Description

TECHNICAL FIELD

[0001] The application relates to a temperature-fluid weak coupling technology driving motor temperature calculation method and belongs to the technical field of motor design. BACKGROUND

[0002] Temperature management of a driving motor is crucial for its safe and stable operation. During the operation of the motor, various forms of losses such as copper loss, iron loss, eddy current loss and mechanical loss stay in the motor in the form of heat, resulting in the accumulation of heat in the motor and the increase of the temperature of the motor. High temperature in the motor can not only cause damage to the winding and the core insulation, but also can cause the decrease of the operation efficiency of the motor and the deterioration of the performance of the motor.

[0003] At present, the temperature calculation method of the driving motor mainly depends on actual test, experience model or simple lumped parameter thermal network model. Although the existing method can reflect the temperature rise characteristics of the motor to a certain extent, since the temperature rise mechanism of the motor and the coupling effect between the motor and the cooling medium (such as cooling oil and water cooling medium) are not fully considered, the precision is difficult to meet the requirements of the thermal management of the driving motor, so that the temperature rise characteristics cannot be accurately considered in the design stage of the motor.

[0004] In recent years, with the continuous progress of computational fluid dynamics (CFD) technology, temperature-fluid coupling analysis has become possible. The CFD method realizes the coupling model of the temperature field and the fluid field by establishing an accurate geometric model of the motor, and can accurately simulate the temperature distribution and change process of the motor. However, the complexity of materials, working conditions and loads and the high calculation cost of computational fluid dynamics make the temperature-fluid coupling analysis technology face many challenges in actual application and product development.

[0005] Therefore, it is very important to develop a temperature-fluid weak coupling technology driving motor temperature calculation method which can fully consider the complex temperature-fluid coupling process in the motor and adapt to different types of motors, cooling conditions and application scenarios, so as to improve the temperature rise prediction characteristics of the motor. SUMMARY

[0006] The technical problem to be solved by the application is to provide a temperature-fluid weak coupling technology driving motor temperature calculation method which can provide a general, efficient and stable temperature rise characteristic calculation method for driving motor temperature rise calculation and accurately consider the fluid-temperature coupling characteristics of the motor in the design stage of the motor.

[0007] The application adopts the following technical solution to solve the above technical problem:

[0008] A temperature-fluid weak coupling technology driving motor temperature calculation method comprises the following steps:

[0009] Step 1, pre-design calculation time, and establish the thermal resistance and thermal capacity matrix of the driving motor according to the size parameters and material characteristics of the core parts and supporting parts of the driving motor;

[0010] Step 2: Based on the type of drive motor fluid and the fluid flow path, and considering the interaction mechanism between the fluid cooling path and the stator and rotor, a drive motor cooling flow path calculation model is established that takes into account the influence of flow rate and flow path, thereby obtaining the fluid dynamics parameters under flow;

[0011] Step 3: Calculate the heat transfer coefficient caused by the flow of the cooling medium according to the fluid mechanics formula, the heat transfer cross-sectional area of ​​the cooling medium in contact with the cooling medium, and calculate the heat transfer thermal resistance between the cooling medium and the drive motor based on the heat transfer coefficient and the heat transfer cross-sectional area.

[0012] Step 4: According to the thermal resistance and heat capacity matrix of the drive motor and the heat exchange resistance between the cooling medium and the drive motor, corresponding fluid nodes are set at the cooling medium circulation point, and the thermal resistance and heat capacity matrix of the drive motor is expanded;

[0013] Step 5: Set the thermal network calculation interval t1 and the fluid field calculation interval t2, respectively, where t2 is a positive integer multiple of t1. Starting from the initial moment of the preset calculation time, perform a thermal network calculation on the expanded thermal resistance and heat capacity matrices every t1 to obtain the cooling medium temperature and the motor component temperature.

[0014] Step 6: After performing a thermal network calculation, the time is stepped forward by t1 to determine whether the moment after step t1, i.e., the current moment, is a positive integer multiple of t2. If so, proceed to step 7; otherwise, perform the thermal network calculation again.

[0015] Step 7: Determine whether the average temperature rise of the cooling medium is stable at the current moment. If so, proceed to Step 8. Otherwise, update the current moment to the current moment minus t2, while keeping the current cooling medium temperature unchanged. Update the motor component temperature to the temperature at the moment corresponding to the current moment minus t2, and return to Step 5 to perform the thermal network calculation again.

[0016] Step 8: Determine whether the current moment is the end moment of the preset calculation time. If so, the calculation is completed and the drive motor temperature is output; otherwise, return to step 5 and perform the thermal network calculation again.

[0017] As a preferred embodiment of the present invention, in step 1, the core components include a stator, a rotor, and a winding, and the supporting components include a casing, an end cover, and a mechanical connection mechanism between the casing and the end cover;

[0018] Among them, the stator tooth thermal resistance and heat capacity are expressed as:

[0019]

[0020] C st =c psteel ρ steel(R slotbot -R si )W st l stk

[0021] where R st , C st represent the thermal resistance and thermal capacity of the stator tooth respectively, R slotbot , R si represent the slot bottom circle radius and the stator inner diameter respectively, k steel represents the thermal conductivity of the silicon steel sheet, W st represents the stator tooth width, l stk represents the stator stack length, c psteel represents the specific heat capacity of the silicon steel sheet, and p steel represents the thermal capacity of the silicon steel sheet.

[0022] As a preferred scheme of the present application, in step 2, the flow mechanics parameters under the flow rate include Reynolds number, Prandtl number and Nusselt number.

[0023] As a preferred scheme of the present application, in step 3, if the cooling is spray cooling, the heat exchange coefficient caused by the flow of the cooling medium is represented as:

[0024]

[0025] where h spray represents the heat exchange coefficient caused by the spray cooling, k represents the thermal conductivity of the cooling medium, l represents the motor core length, Pr represents the Prandtl number, Red represents the Reynolds number, d represents the spray opening diameter, A r represents the spray area, and L represents the characteristic length.

[0026] If the heat exchange is planar heat exchange, the heat exchange coefficient caused by the flow of the cooling medium is represented as:

[0027] h flat = Nu × k air / L

[0028] where h flat represents the heat exchange coefficient caused by the planar heat exchange, k air represents the thermal conductivity of the air, and the Nusselt number Nu is represented as:

[0029]

[0030] Re represents that, for the flow state between laminar flow and turbulent flow, the Nusselt number is obtained by interpolation from the functional relationship between the heat exchange coefficient and the flow rate;

[0031] The heat exchange thermal resistance of the cooling medium and the driving motor is represented as:

[0032]

[0033] wherein R fs represents the heat transfer resistance between the cooling medium and the motor components, A fs represents the contact area between the motor components and the cooling medium, h fs represents the heat transfer coefficient between the cooling medium and the motor components, h fs = h spray if the heat transfer is by spraying, and h fs = h flat if the heat transfer is by planar heat transfer.

[0034] As a preferred scheme of the present application, in step 4, corresponding fluid nodes are set at the crown end, the welding end, and the rotor surface, and the extended heat resistance and heat capacity matrices are as follows:

[0035]

[0036] wherein R ex and C ex represent the extended heat resistance and heat capacity matrices respectively, R and C represent the heat resistance and heat capacity matrices of the motor established in step 1, R crown represents the heat resistance of the crown end oil flow node, R weld represents the heat resistance of the welding end oil flow node, R rotor represents the heat resistance of the rotor side oil flow node, R crowns represents the heat transfer resistance between the crown end oil flow node and the motor components, R welds represents the heat transfer resistance between the welding end oil flow node and the motor components, R rotors represents the heat transfer resistance between the rotor side oil flow node and the motor components, C crown represents the heat capacity of the crown end oil flow node, C wled represents the heat capacity of the welding end oil flow node, C rotor represents the heat capacity of the rotor side oil flow node.

[0037] As a preferred scheme of the present application, in the heat network calculation, the fluid heat capacity is represented as ρt2QC p wherein ρ represents the fluid medium density, Q represents the flow of the fluid in t2 time, and C p represents the specific heat capacity of the fluid medium.

[0038] A computer device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor implements the steps of the temperature-fluid weak coupling technology-based motor temperature calculation method when executing the computer program.

[0039] A computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the temperature-fluid weak coupling technology driving motor temperature calculation method.

[0040] Compared with the prior art, the above technical solution has the following technical effects:

[0041] 1. In view of the problem of long calculation time and poor stability caused by the complex fluid-temperature coupling characteristics of the driving motor, the application proposes a fluid field-temperature field multi-time scale weak coupling analysis technology. This method effectively improves the thermal network thermal capacity matrix properties by using different calculation time intervals for the fluid field and the temperature field, thereby improving the characteristic time scale of the thermal network matrix and realizing fast and stable calculation of the driving motor fluid-temperature coupling analysis.

[0042] 2. The temperature calculation method proposed in the application has excellent and fast and stable temperature rise calculation model performance. Considering that the fluid field time scale is lower and changes less in a short time compared with the temperature field time scale, this method can effectively improve the fluid-temperature coupling analysis calculation speed and improve the motor temperature rise characteristic accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a flow chart of the temperature-fluid weak coupling technology driving motor temperature calculation method of the application;

[0044] Figure 2 is a driving motor rotor (one sixth section) related to an embodiment of the application;

[0045] Figure 3 is a driving motor stator (one sixteenth section) related to an embodiment of the application;

[0046] Figure 4 is a fluid temperature field weak coupling calculation flowchart, wherein 1 represents a thermal network calculation interval, 2 represents a thermal network calculation time point, 3 represents a fluid field calculation interval, and 4 represents a fluid field calculation time point;

[0047] Figure 5 is a comparison of the effective part temperature, the crown end temperature and the welding end temperature under the weak coupling calculation and the strong coupling calculation method;

[0048] Figure 6 is a comparison of the calculation time of the weak coupling calculation and the strong coupling calculation method. DETAILED DESCRIPTION

[0049] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein like reference numerals refer to like elements throughout. The embodiments described below are exemplary and are not intended to be limiting in terms of the scope of the application. Embodiments of the present application can be implemented in any type of system that includes a drive motor.

[0050] To solve the problem of long calculation time and poor stability caused by the complex fluid-temperature coupling characteristics of the drive motor, the present application proposes a fluid field-temperature field multi-time scale weak coupling analysis technology to calculate the temperature of the drive motor, as shown in Figure 1 The specific steps include the following:

[0051] S1, according to the size parameters of the stator and rotor of the drive motor, modeling the thermal resistance and thermal capacity of the core components of the motor such as the stator teeth, rotor, permanent magnet and winding, and the mechanical support components such as the casing, end cover and bearing;

[0052] Generally, the internal components of the motor can be equivalent to simple geometric shapes. For components such as stator teeth and rotor permanent magnets, cuboids can be used for equivalent; for the rotor core, the magnetic bridge part can be equivalent to a cuboid, and the remaining part can be equivalent to a cylinder. The casing, bearing and end cover can all be simplified as a cylinder. The lumped thermal resistance R lump can be represented as:

[0053]

[0054] Where L represents the length of the heat transfer path, and A represents the cross-sectional area of the heat transfer path.

[0055] The lumped thermal capacity C lump can be represented as:

[0056] C lump = mc p

[0057] Where m represents the mass of the component, and c p represents the specific heat capacity of the component.

[0058] S2, according to the type of fluid in the drive motor and its flow path, considering the interaction mechanism between the cooling path and the stator and rotor, establishing a drive motor cooling flow calculation model considering the influence of flow rate and flow path;

[0059] S3, according to the fluid mechanics formula to calculate the heat transfer coefficient caused by the flow of the cooling medium, according to the geometric modeling model to calculate the heat transfer cross-sectional area contacted by the cooling medium, and according to the heat transfer coefficient to calculate the heat transfer resistance between the cooling medium and the drive motor;

[0060] For spray cooling, the convective heat transfer coefficient can be represented as:

[0061]

[0062] Wherein, Pr represents Planck number, Red represents Reynolds number, A r represents spray area, k represents cooling medium thermal conductivity, and L represents characteristic length.

[0063] For plane heat exchange, the convective heat exchange coefficient formula can be expressed as:

[0064] h flat = Nu x k air / L

[0065] Wherein, the Nusselt number Nu can be expressed as:

[0066]

[0067] For the flow state between laminar flow and turbulent flow, it can be obtained by interpolation of the function relationship between heat exchange coefficient and flow velocity.

[0068] The heat exchange resistance between the cooling medium and the driving motor can be expressed as:

[0069]

[0070] Wherein, A fs represents the contact area of the motor component and the cooling medium, and h fs represents the heat exchange coefficient of the cooling medium and the driving motor.

[0071] S4, according to the driving motor thermal resistance and the heat capacity matrix, the heat exchange resistance of the driving motor cooling medium and the driving motor, the heat exchange resistance corresponding to the fluid node is set, and the heat network matrix is expanded;

[0072] Generally, the original thermal resistance and heat capacity matrix can be expressed as R and C, and the thermal resistance and heat capacity matrix R ex and C ex of the expanded fluid node can be expressed as:

[0073]

[0074] Wherein, R fs represents the thermal resistance of the fluid and the motor component, R f represents the self thermal resistance of the fluid node, and for the cooling mode with circulating heat dissipation, the fluid inlet temperature can be considered unchanged, so R f can not be considered. C f represents the heat capacity of the fluid.

[0075] S5, the heat network calculation interval is t1, the fluid field calculation interval is t2, generally t1 < t2, the larger fluid field calculation interval can improve the temperature field calculation stability, but at the same time, it will reduce the cooling medium temperature rise calculation precision, Figure 4The relationship between t1 and t2 is shown in the figure. In the thermal network matrix, the fluid heat capacity can be expressed as ρt2QC p , wherein Q represents the flow of the fluid at t2, ρ represents the density of the fluid medium, and C p represents the specific heat capacity of the fluid medium.

[0076] S6, according to the motor loss and the thermal network and the fluid field calculation interval, iteratively calculate the temperature rise distribution of the driving motor. Take the average temperature rise of the cooling medium as the stability criterion, and iterate until the average temperature rise of the cooling medium is stable.

[0077] Embodiment

[0078] In this embodiment, the fluid field and the temperature field calculation interval are different. All the flowing cooling medium is treated as a lumped parameter in the fluid field calculation interval, that is, it is considered that all the fluids participate in heat exchange together in the time interval. In order to ensure the rationality of temperature calculation, the calculation program only records the temperature distribution at the time of fluid field calculation. The specific steps of the embodiment are as follows:

[0079] S1, the motor stator of this embodiment is a 48-slot structure, and the stator structure is as shown in Figure 3 . The stator thermal resistance and heat capacity parameters are calculated according to the tooth width, stator outer diameter, and slot bottom circle diameter; the motor winding thermal resistance and heat capacity parameters are calculated according to the winding form and size parameters, combined with the properties of pure copper, insulation, and impregnated paint materials; the rotor thermal resistance and heat capacity parameters are calculated according to the size of the rotor magnetic bridge and the position of the permanent magnet, and the motor rotor structure is as shown in Figure 2 .

[0080] For the stator teeth, the thermal resistance R st can be expressed as:

[0081]

[0082] , wherein R slotbot , R si represent the slot bottom circle radius and the stator inner diameter, k steel represents the thermal conductivity of the silicon steel sheet, W st represents the stator tooth width, and l stk represents the stator stack length.

[0083] The remaining motor thermal resistance parameters can also be given according to the stator tooth thermal resistance calculation formula.

[0084] For the motor stator tooth heat capacity C st , it can be expressed as:

[0085] C st = c psteel ρ steel (R slotbot -R si )W st l stk

[0086] wherein, p steel represents the thermal capacity of silicon steel sheet.

[0087] The rest of the electric heating capacity parameters can also be given according to the formula for calculating the thermal capacity of the stator tooth.

[0088] S2, the driving motor fluid involved in the embodiment is cooling oil, the cooling form is winding spraying, oil channel cooling of the machine shell and rotor oil throwing cooling, the oil flow circulation path and the oil flow distribution of the stator and rotor are analyzed, and a simple oil flow model in the motor is established.

[0089] For the total oil flow of the motor, the stator oil flow and the rotor oil flow, the following requirements are met:

[0090] Q total = Q stator + Q rotor

[0091] wherein, Q total represents the total oil flow of the motor, Q stator represents the stator oil flow, and Q rotor represents the rotor oil flow.

[0092] S3, according to the heat exchange calculation formula of spraying cooling, the spraying convection heat transfer coefficient is calculated by combining the Bernoulli number, Reynolds number, Prandtl number and other core parameters of fluid mechanics under the flow rate, the cross-sectional area of the winding is calculated by the radial and axial projection area, the heat exchange thermal resistance of the end winding under the stator spraying and the rotor oil throwing is calculated; according to the oil channel flow rate in the stator shell, the corresponding heat exchange coefficient is calculated by combining the plane fluid heat exchange calculation formula, the heat transfer cross-sectional area is calculated by the actual area of the oil channel, and the heat exchange thermal resistance is calculated.

[0093] S4, according to the thermal resistance, thermal capacity matrix of the driving motor, the fluid flow path of the driving motor and the heat exchange thermal resistance of the driving motor, the corresponding crown end, welded end and rotor surface fluid nodes are set, and the thermal network matrix is expanded.

[0094] For this embodiment, the expanded thermal resistance and thermal capacity matrix can be represented as:

[0095]

[0096] wherein, R crown represents the heat exchange thermal resistance of the crown end oil flow node and the motor components, R weld represents the heat exchange thermal resistance of the welded end oil flow node and the motor components, R rotor represents the heat exchange thermal resistance of the rotor side oil flow node and the motor components. R crowns represents the heat exchange thermal resistance of the crown end oil flow node and the motor components, R welds represents the heat exchange thermal resistance of the welded end oil flow node and the motor components, R rotors represents the heat exchange thermal resistance of the rotor side oil flow node and the motor components. C crownRepresenting the thermal capacity of the oil flow node at the crown end, C wled Representing the thermal capacity of the oil flow node at the welding end, C rotor Representing the thermal capacity of the oil flow node at the rotor side.

[0097] S5, the thermal network calculation interval is 1ms, the fluid field calculation interval is 1s, the oil flow thermal capacity in 1s is calculated, and the crown end, the welding end, and the rotor surface fluid node are allocated in the ratio of 0.5:0.5:1.

[0098] S6, according to the motor loss and the thermal network and the fluid field calculation interval, the driving motor temperature rise distribution is iteratively calculated. The average temperature rise of the cooling medium is taken as the stability criterion, and the iteration is performed until the average temperature rise of the cooling medium is stable.

[0099] Figure 5 The winding effective part temperature, the crown end temperature, and the welding end temperature under the temperature-fluid weak coupling calculation method and the strong coupling calculation method are compared. The weak coupling calculation result and the strong coupling calculation result have certain difference, and it is worth noting that the fluid will stay in the motor for a certain time and will not complete heat transfer immediately after leaving the heating surface, so it is also reasonable to set a longer fluid calculation interval. The calculation time of the weak coupling calculation method and the strong coupling calculation method is as shown in Figure 6 It can be seen that the weak coupling calculation method can reduce the calculation time by more than 99%, greatly improving the temperature field calculation efficiency of the vehicle driving motor.

[0100] The method of the application is not only suitable for water cooling, but also suitable for direct oil cooling, spray oil cooling, and rotor oil throwing cooling. The technology involved is not only suitable for permanent magnet vehicle driving motors, but also suitable for permanent magnet flat wire motors, permanent magnet hub motors, and permanent magnet servo motors. The method of the application is not only suitable for new energy vehicle driving motors, but also suitable for servo motors, industrial motors, special motors and other application occasions.

[0101] Based on the same inventive concept, the embodiment of the application provides a computer device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the computer program to realize the steps of the temperature-fluid weak coupling technology driving motor temperature calculation method.

[0102] Based on the same inventive concept, the embodiment of the application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the temperature-fluid weak coupling technology driving motor temperature calculation method.

[0103] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computer to perform any of the methods. The software implementation can be initialized by loading and executing a set of instructions arranged to perform one of the methods into the computer's memory. Alternatively, hard-wired circuitry can be used in place of, or in combination with, software instructions. Thus, the

[0104] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing device or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams block or blocks. Figure 1 one or more functions specified in one or more of the flowchart illustrations and / or block diagrams. Figure 1 means for performing the functions specified in one or more of the flowchart illustrations and / or block diagrams.

[0105] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart illustrations and / or block diagrams block or blocks. Figure 1 one or more functions specified in one or more of the flowchart illustrations and / or block diagrams. Figure 1 means for performing the functions specified in one or more of the flowchart illustrations and / or block diagrams.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart illustrations and / or block diagrams block or blocks. Figure 1 one or more functions specified in one or more of the flowchart illustrations and / or block diagrams. Figure 1 means for performing the functions specified in one or more of the flowchart illustrations and / or block diagrams.

[0107] The above embodiments are merely illustrative of the technical idea of the present application and cannot limit the scope of protection of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the scope of protection of the present application.

Claims

1. A method for calculating the temperature of a drive motor using a temperature-fluid weak coupling technology, characterized in that: The steps include: Step 1: Preset the calculation time and establish the thermal resistance and thermal capacity matrix of the drive motor based on the size parameters and material properties of the core components and supporting components of the drive motor; Step 2: Based on the type of drive motor fluid and the fluid flow path, and considering the interaction mechanism between the fluid cooling path and the stator and rotor, a drive motor cooling flow path calculation model is established that takes into account the influence of flow rate and flow path, thereby obtaining the fluid dynamics parameters under flow; Step 3: Calculate the heat transfer coefficient caused by the flow of the cooling medium according to the fluid mechanics formula, the heat transfer cross-sectional area of ​​the cooling medium in contact with the cooling medium, and calculate the heat transfer thermal resistance between the cooling medium and the drive motor based on the heat transfer coefficient and the heat transfer cross-sectional area. Step 4: According to the thermal resistance and heat capacity matrix of the drive motor and the heat exchange resistance between the cooling medium and the drive motor, corresponding fluid nodes are set at the cooling medium circulation point, and the thermal resistance and heat capacity matrix of the drive motor is expanded; Step 5: Set the thermal network calculation interval t1 and the fluid field calculation interval t2, respectively, where t2 is a positive integer multiple of t1. Starting from the initial moment of the preset calculation time, perform a thermal network calculation on the expanded thermal resistance and heat capacity matrices every t1 to obtain the cooling medium temperature and the motor component temperature. Step 6: After performing a thermal network calculation, the time is stepped forward by t1 to determine whether the moment after step t1, i.e., the current moment, is a positive integer multiple of t2. If so, proceed to step 7; otherwise, perform the thermal network calculation again. Step 7: Determine whether the average temperature rise of the cooling medium is stable at the current moment. If so, proceed to Step 8. Otherwise, update the current moment to the current moment minus t2, while keeping the current cooling medium temperature unchanged. Update the motor component temperature to the temperature at the moment corresponding to the current moment minus t2, and return to Step 5 to perform the thermal network calculation again. Step 8: Determine whether the current moment is the end moment of the preset calculation time. If so, the calculation is completed and the drive motor temperature is output; Otherwise, return to step 5 and perform the thermal network calculation again.

2. The method for calculating the temperature of a driving motor using the temperature-fluid weak coupling technology according to claim 1, characterized in that: In step 1, the core components include a stator, a rotor, and windings, and the supporting components include a housing, an end cover, and a mechanical connection mechanism between the housing and the end cover; Among them, the stator tooth thermal resistance and heat capacity are expressed as: C st =c psteel ρ steel (R slotbot -R si )W st l stk Where R st 、C st Represent the stator tooth thermal resistance and heat capacity respectively, R slotbot 、R si Represent the slot bottom radius and stator inner diameter respectively, k steel Represents the thermal conductivity of silicon steel sheet, W st represents the stator tooth width, l stk Represents the stator stack length, C psteel Represents the specific heat capacity of silicon steel sheet, ρ steel Represents the heat capacity of silicon steel sheet.

3. The method for calculating the temperature of a driving motor using the temperature-fluid weak coupling technology according to claim 1, characterized in that: In step 2, the fluid mechanics parameters under flow rate include Reynolds number, Planck number and Nusselt number.

4. The method for calculating the temperature of a driving motor using the temperature-fluid weak coupling technology according to claim 1, characterized in that: In step 3, if spray cooling is used, the heat transfer coefficient caused by the flow of the cooling medium is expressed as: Where h spray represents the heat transfer coefficient caused by spray cooling, k represents the thermal conductivity of the cooling medium, l represents the length of the motor core, Pr represents the Planck number, Red represents the Reynolds number, d represents the diameter of the spray port, and A r represents the spraying area, and L represents the characteristic length; If the heat transfer is plane, the heat transfer coefficient caused by the flow of cooling medium is expressed as: h flat =Nu×k air / L Where h flat Represents the heat transfer coefficient caused by plane heat transfer, k air Represents the thermal conductivity of air, and the Nusselt number Nu is expressed as: Re represents the Nusselt number for the flow regime between laminar and turbulent, which is obtained by interpolation of the functional relationship between the heat transfer coefficient and the flow velocity; The heat transfer resistance between the cooling medium and the drive motor is expressed as: Where R fs Represents the heat transfer resistance between the cooling medium and the drive motor, A fs Represents the contact area between the motor components and the cooling medium, h fs Represents the heat transfer coefficient between the cooling medium and the drive motor. If spray cooling is used, h fs =h spray , if it is a plane heat transfer, h fs =h flat .

5. The method for calculating the temperature of a driving motor using the temperature-fluid weak coupling technology according to claim 1, characterized in that: In step 4, corresponding fluid nodes are set at the crown end, welding end, and rotor surface. The expanded thermal resistance and heat capacity matrices are as follows: Where R ex 、C ex Represent the expanded thermal resistance and thermal capacity matrices respectively, R and C represent the thermal resistance and thermal capacity matrices of the drive motor established in step 1 respectively, R crown Represents the self-thermal resistance of the oil flow node at the crown end, R weld represents the oil flow node at the welding end, R rotor represents the oil flow node on the rotor side, R crowns Represents the heat transfer resistance between the crown end oil flow node and the motor components, R welds Represents the heat transfer resistance between the oil flow node at the welding end and the motor components, R rotors Represents the heat transfer resistance between the rotor side oil flow node and the motor components, C crown represents the heat capacity of the oil flow node at the crown end, C wled Represents the heat capacity of the oil flow node at the welding end, C rotor Represents the heat capacity of the oil flow node on the rotor side.

6. The method for calculating the temperature of a driving motor using the temperature-fluid weak coupling technology according to claim 1, characterized in that: In the thermal network calculation, the fluid heat capacity is expressed as ρt2QC p , where ρ represents the density of the fluid medium, Q represents the flow rate of the fluid in time t2, and C p Represents the specific heat capacity of the fluid medium.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for calculating the temperature of a driving motor using the temperature-fluid weak coupling technology according to any one of claims 1 to 6 are implemented.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating the temperature of a drive motor using the temperature-fluid weak coupling technology according to any one of claims 1 to 6 are implemented.

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