Driving motor temperature calculation method based on temperature-fluid weak coupling technology

Abstract

The invention discloses a driving motor temperature calculation method based on a temperature-fluid weak coupling technology. The problem of motor heat network calculation oscillation caused by transient rapid heat exchange between fluid and a motor winding and an iron core component is solved. According to the method, heat network capacitance matrix characteristics are deeply analyzed, the influence of the ratio of the maximum value and the minimum value of matrix elements on iterative calculation convergence is considered, and a certain short time period is considered, the motor cooling fluid is driven, the temperature change of the motor is small, and the internal heat transfer phenomenon is stable; according to the method, a weak coupling calculation method of a rapid change fluid field and a slow change motor internal temperature field is established, different calculation frequencies are adopted in the fluid field and the temperature field, the inherent defect that the ratio of the maximum value to the minimum value of a heat capacity matrix element is too large is overcome, and rapid and stable calculation of the temperature of the driving motor is achieved. The temperature calculation method is clear in thought and easy to operate, has the advantages of being easy to implement, rapid in calculation, universal and the like, and shows excellent performance.

Description

Technical Field

[0001] The invention relates to a temperature calculation method for a driving motor using a temperature-fluid weak coupling technology, and belongs to the technical field of motor design. Background Art

[0002] The temperature management of the drive motor is crucial to 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 are retained in the motor in the form of heat, causing the motor's heat accumulation temperature to rise. The high temperature inside the motor will not only cause damage to the winding and core insulation, but may also cause the motor's operating efficiency to decrease and performance to deteriorate.

[0003] At present, the temperature calculation method of the drive motor mainly relies on actual tests, empirical models or simple lumped parameter thermal network models. Although the existing methods can reflect the temperature rise characteristics of the motor to a certain extent, the accuracy is difficult to meet the thermal management requirements of the drive motor because the motor temperature rise mechanism and the coupling between the motor and the cooling medium (such as cooling oil and water cooling medium) are not fully considered, resulting in the inability to accurately consider the temperature rise characteristics of the motor during the design stage.

[0004] In recent years, with the continuous advancement of computational fluid dynamics (CFD) technology, temperature-fluid coupling analysis has become possible. The CFD method establishes an accurate geometric model inside the motor to realize the coupling model of the temperature field and the fluid field, which can accurately simulate the temperature distribution and change process of the motor. However, the complexity of materials, working conditions, and loads, as well as the high computational cost of computational fluid dynamics, make temperature-fluid coupling analysis technology face many challenges in practical applications and product development.

[0005] Therefore, it is crucial to develop a method that can fully consider the complex temperature rise-fluid coupling process inside the motor and adapt to different motor types, cooling conditions and application scenarios in order to improve the motor temperature rise prediction characteristics. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a temperature calculation method for a driving motor using a temperature-fluid weak coupling technology, which can provide a universal, efficient and stable temperature rise characteristic calculation method for the driving motor temperature rise calculation, and the motor fluid-temperature coupling characteristics can be accurately taken into account during the motor design stage.

[0007] The present invention adopts the following technical solutions to solve the above technical problems:

[0008] A method for calculating the temperature of a driving motor using a temperature-fluid weak coupling technology comprises the following steps:

[0009] Step 1, preset the calculation time, and establish the thermal resistance and thermal capacity matrix of the drive motor according to the size parameters and material properties of the core components and supporting components of the drive motor;

[0010] Step 2: According to the type of drive motor fluid and the fluid flow path, the interaction mechanism between the fluid cooling path and the stator and rotor is considered, and a drive motor cooling flow path calculation model taking into account the influence of flow velocity and flow path is established to obtain the fluid mechanics parameters under flow rate;

[0011] Step 3, combining the fluid mechanics parameters under the flow rate, calculating the heat transfer coefficient caused by the flow of the cooling medium according to the fluid mechanics formula, calculating the heat transfer cross-sectional area contacted by the cooling medium, and calculating the heat transfer thermal resistance between the cooling medium and the drive motor according to 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 thermal 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, respectively setting the thermal network calculation interval t1 and the fluid field calculation interval t2, t2 being a positive integer multiple of t1, starting from the initial moment of the preset calculation time, performing a thermal network calculation on the expanded thermal resistance and heat capacity matrix every t1 to obtain the cooling medium temperature and the motor component temperature;

[0014] Step 6, after performing a thermal network calculation, step the time forward by t1, and 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 at the current moment is stable, if so, proceed to step 8; otherwise, update the current moment to the current moment minus t2, while keeping the cooling medium temperature at the current moment 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 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 to perform the thermal network calculation again.

[0017] As a preferred solution 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] In the formula, R st , C st Represent the stator tooth thermal resistance and thermal 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.

[0022] As a preferred embodiment of the present invention, in step 2, the fluid mechanics parameters under flow rate include Reynolds number, Planck number and Nusselt number.

[0023] As a preferred embodiment of the present invention, in step 3, if spray cooling is used, the heat transfer coefficient caused by the flow of the cooling medium is expressed as:

[0024]

[0025] In the formula, 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 spray area, and L represents the characteristic length;

[0026] If it is a plane heat exchange, the heat transfer coefficient caused by the flow of cooling medium is expressed as:

[0027] h flat =Nu×k air / L

[0028] In the formula, 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:

[0029]

[0030] Re represents, for the flow regime between laminar and turbulent, the Nusselt number obtained by interpolation of the functional relationship between the heat transfer coefficient and the flow velocity;

[0031] The heat transfer resistance between the cooling medium and the drive motor is expressed as:

[0032]

[0033] In the formula, 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 exchange 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 .

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

[0035]

[0036] In the formula, 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.

[0037] As a preferred solution of the present invention, 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.

[0038] A computer device comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the computer program, the steps of the method for calculating the temperature of a drive motor using the temperature-fluid weak coupling technology are implemented.

[0039] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for calculating the temperature of a drive motor using the temperature-fluid weak coupling technology.

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

[0041] 1. In order to solve the problem of long calculation time and poor stability caused by the complex fluid-temperature rise coupling characteristics inside the drive motor, the present invention proposes a multi-time scale weak coupling analysis technology of fluid field-temperature field. This method effectively improves the properties of the thermal network heat capacity matrix by adopting different calculation time intervals in the fluid field and temperature field, thereby improving the characteristic time scale of the thermal network matrix and realizing fast and stable calculation of the fluid-temperature rise coupling analysis of the drive motor.

[0042] 2. The temperature calculation method proposed in the present invention has an excellent, fast and stable temperature rise calculation model. Considering that the fluid field time scale is lower and the short-term changes are smaller than the temperature field time scale, this method can effectively improve the fluid-temperature coupling analysis and calculation speed, while improving the accuracy of the motor temperature rise characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of a method for calculating the temperature of a driving motor using a temperature-fluid weak coupling technology of the present invention;

[0044] Figure 2 The driving motor rotor (one sixth section) involved in the embodiment of the present invention;

[0045] Figure 3 The stator of the driving motor involved in the embodiment of the present invention (one sixteenth section);

[0046] Figure 4 1 is a schematic diagram of a weak coupling calculation process of a fluid temperature field involved in an embodiment of the present invention, 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 It is the comparison of the effective part temperature of the winding, the crown end temperature, and the welding end temperature under the weak coupling calculation method and the strong coupling calculation method;

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

[0049] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0050] Aiming at the problem of long calculation time and poor stability caused by the complex coupling characteristics of fluid and temperature rise inside the drive motor, the present invention proposes a multi-time scale weak coupling analysis technology of fluid field and temperature field to calculate the temperature of the drive motor, such as Figure 1 As shown, the specific steps include:

[0051] S1. Based on the size parameters of the drive motor stator and rotor, model the thermal resistance and thermal capacity of the motor core components such as stator teeth, rotor, permanent magnet, winding, and mechanical support components such as housing, end cover, and bearing;

[0052] Generally speaking, the internal parts of the motor can be equivalent to simple geometric shapes. For parts such as stator teeth and permanent magnets, a rectangular parallelepiped can be used as the equivalent; for the rotor core, the magnetic isolation bridge part can be equivalent to a rectangular parallelepiped, and the rest can be equivalent to a cylinder. The housing, bearings, and end covers can all be simplified to cylinders. Its lumped thermal resistance R lump It can be expressed as:

[0053]

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

[0055] Lumped heat capacity C lump It can be expressed as:

[0056] C lump =mc p

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

[0058] S2. According to the type of drive motor fluid and its flow path, the interaction mechanism between its cooling path and the stator and rotor is considered, and a drive motor cooling flow path calculation model taking into account the influence of flow velocity and flow path is established;

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

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

[0061]

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

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

[0064] h flat = Nu × k air / L

[0065] Among them, 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 from the functional relationship between the heat transfer coefficient and the flow velocity.

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

[0069]

[0070] Among them, A fs represents the contact area between the motor component and the cooling medium, and h fs represents the heat transfer coefficient between the cooling medium and the drive motor.

[0071] S4. Set the fluid nodes corresponding to the heat transfer resistance and expand the thermal network matrix according to the thermal resistance and heat capacity matrix of the drive motor and the heat transfer resistance between the drive motor cooling medium and the drive motor;

[0072] Generally speaking, the original thermal resistance and heat capacity matrices can be expressed as R and C. For the thermal resistance and heat capacity matrices R ex and C ex of the expanded fluid nodes, they can be expressed as:

[0073]

[0074] Among them, R fs represents the thermal resistance between the fluid and the motor component, and R f represents the self-thermal resistance of the fluid node. For the cooling method with circulating heat dissipation, the fluid inlet temperature can be considered unchanged, so R f can be not considered. C f represents the heat capacity of the fluid.

[0075] S5. The thermal network calculation interval is denoted as t1, and the fluid field calculation interval is denoted as t2. Usually, t1 < t2. A larger fluid field calculation interval will improve the calculation stability of the temperature field, but it will also reduce the calculation accuracy of the temperature rise of the cooling medium. Figure 4is the relationship diagram between t1 and t2. In the thermal network matrix, the fluid heat capacity can be expressed as ρt2QC p , where Q represents the flow rate of the fluid in time t2, ρ represents the density of the fluid medium, and C p Represents the specific heat capacity of the fluid medium.

[0076] S6. Iteratively calculate the temperature rise distribution of the drive motor according to the motor loss and the thermal network and fluid field calculation intervals. 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] Example

[0078] In this embodiment, the calculation intervals of the fluid field and the temperature field are different. All cooling media flowing through the fluid field calculation interval will be processed as lumped parameters, that is, it is considered that all fluids in the time interval participate in heat exchange. To ensure the rationality of temperature calculation, the calculation program only records the temperature distribution during fluid field calculation. The specific steps of the embodiment are as follows:

[0079] S1. The motor stator of this embodiment has a 48-slot structure. The stator structure is as follows: Figure 3 As shown in the figure, the stator thermal resistance and heat capacity parameters are calculated according to its 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 impregnation paint materials; the rotor thermal resistance and heat capacity parameters are calculated according to the rotor magnetic isolation bridge size and permanent magnet position. The motor rotor structure is shown in the figure. Figure 2 As shown;

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

[0081]

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

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

[0084] For the heat capacity C of the motor stator teeth st , which can be expressed as:

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

[0086] Among them, ρ steel Represents the heat capacity of silicon steel sheet.

[0087] The remaining electrical thermal capacity parameters can also be given by referring to the stator tooth thermal capacity calculation formula.

[0088] S2. The driving motor fluid involved in the embodiment is cooling oil, and the cooling forms are winding spraying, casing oil channel cooling and rotor oil throwing cooling. The oil flow path and the stator and rotor oil flow distribution are analyzed, and a simple oil flow model inside the motor is established.

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

[0090] Q total =Q stator +Q rotor

[0091] Among them, Q total Represents the total oil flow of the motor, Q stator represents the stator oil flow, Q rotor Represents the rotor oil flow.

[0092] S3. According to the heat transfer calculation formula of spray cooling, the spray convection heat transfer coefficient is calculated in combination with the core parameters of computational fluid dynamics such as the Bernoulli number, Reynolds number, and Prandtl number under the flow rate. The winding cross-sectional area is calculated as the radial and axial projection area, and the heat transfer thermal resistance of the end winding under the stator spray and rotor oil throwing is calculated; according to the oil channel flow rate in the stator casing, the corresponding heat transfer coefficient is calculated in combination with the plane fluid heat transfer calculation formula, the heat transfer cross-sectional area is calculated as the actual area of ​​the oil channel, and the heat transfer thermal resistance is calculated.

[0093] S4. According to the thermal resistance of the drive motor, the heat capacity matrix, the fluid flow path of the drive motor and the heat transfer thermal resistance of the drive motor, the corresponding crown end, welding end, and rotor surface fluid nodes are set to expand the thermal network matrix.

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

[0095]

[0096] Among them, R crown Represents the crown end oil flow node, 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 crownrepresents 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.

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

[0098] S6. Iteratively calculate the temperature rise distribution of the drive motor according to the motor loss and the thermal network and fluid field calculation intervals. 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.

[0099] Figure 5 The temperature of the effective part of the winding, the crown end temperature, and the welding end temperature are compared under the temperature-fluid weak coupling calculation method and the strong coupling calculation method. There are certain differences between the weak coupling calculation results and the strong coupling calculation results. It is worth noting that the fluid will stay inside the motor for a certain period of time and will not immediately leave the heating surface after completing the heat transfer. Therefore, it is 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 follows Figure 6 As shown, it can be seen that the weak coupling calculation method can reduce the calculation time by more than 99%, greatly improving the calculation efficiency of the temperature field of the automotive drive motor.

[0100] The method of the present invention is not only applicable to water cooling, but also to direct oil cooling, spray oil cooling and rotor oil cooling. The technology involved is not only applicable to permanent magnet automotive drive motors, but also to permanent magnet flat wire motors, permanent magnet hub motors and permanent magnet servo motors. The method of the present invention is not only applicable to new energy vehicle drive motors, but also to servo motors, industrial motors, special motors and other application occasions.

[0101] Based on the same inventive concept, an embodiment of the present application provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the drive motor temperature calculation method of the aforementioned temperature-fluid weak coupling technology are implemented.

[0102] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the drive motor temperature calculation method of the aforementioned temperature-fluid weak coupling technology are implemented.

[0103] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0104] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0105] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0107] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

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 according to the size parameters and material properties of the core components and supporting components of the drive motor; Step 2: According to the type of drive motor fluid and the fluid flow path, the interaction mechanism between the fluid cooling path and the stator and rotor is considered, and a drive motor cooling flow path calculation model taking into account the influence of flow velocity and flow path is established to obtain the fluid mechanics parameters under flow rate; Step 3, combining the fluid mechanics parameters under the flow rate, calculating the heat transfer coefficient caused by the flow of the cooling medium according to the fluid mechanics formula, calculating the heat transfer cross-sectional area contacted by the cooling medium, and calculating the heat transfer thermal resistance between the cooling medium and the drive motor according to 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 thermal 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, respectively setting the thermal network calculation interval t1 and the fluid field calculation interval t2, t2 being a positive integer multiple of t1, starting from the initial moment of the preset calculation time, performing a thermal network calculation on the expanded thermal resistance and heat capacity matrix every t1 to obtain the cooling medium temperature and the motor component temperature; Step 6, after performing a thermal network calculation, step the time forward by t1, and 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 at the current moment is stable, if so, proceed to step 8; otherwise, update the current moment to the current moment minus t2, while keeping the cooling medium temperature at the current moment 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 thermal network calculation again; Step 8, determining 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 a winding, and the supporting components include a casing, an end cover and a mechanical connection mechanism between the casing 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 In the formula, R st , C st Represent the stator tooth thermal resistance and thermal 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: In the formula, 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 spray area, and L represents the characteristic length; If it is a plane heat exchange, the heat transfer coefficient caused by the flow of cooling medium is expressed as: h flat =Nu×k air / L In the formula, 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, for the flow regime between laminar and turbulent, the Nusselt number 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: In the formula, 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 exchange 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, and the expanded thermal resistance and heat capacity matrices are as follows: In the formula, 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 drive motor using the temperature-fluid weak coupling technology as described in 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 as described in any one of claims 1 to 6 are implemented.

Images