Method and apparatus for evaluating temperature rise in a closed space of a cylinder-type linear motor

Abstract

The application discloses a kind of closed space temperature rise evaluation method and device of Stirling with cylindrical linear motor, method includes: building motor model;According to the fluid domain model of closed space obtained from motor model;According to the convection heat dissipation coefficient obtained by CFD simulation of fluid domain model;Obtain the loss and heat generation rate of heat source component;According to motor model, fluid domain model and loss and heat generation rate, obtain first model;Based on the first condition, steady-state thermal simulation is carried out according to first model, and steady-state temperature distribution is obtained;First condition includes eliminating the convection heat dissipation of cylindrical linear motor and fluid domain contact surface;The convection heat dissipation coefficient is introduced into first model, and second model is obtained;With steady-state temperature distribution as initial temperature distribution, according to second model, transient thermal simulation is carried out, and simulation result is used as initial temperature distribution of next time step transient thermal simulation, until the calculation of preset maximum time step is completed, and the motor operating temperature rise is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, in particular to a sealed space temperature rise evaluation method and device for a cylinder type linear motor for Stirling. BACKGROUND

[0002] As the core energy conversion component of the free piston Stirling generator, the thermal characteristics of the cylinder type linear motor directly determine the energy conversion efficiency and operation stability of the system. During the operation of the free piston Stirling generator, the continuous movement of the cylinder type linear motor will generate significant copper loss, iron loss and eddy current loss, resulting in temperature rise of each component of the motor. When the temperature of the winding rises, its resistivity increases, further aggravating the copper loss, and if the temperature exceeds the temperature resistance limit of the insulation material, the winding insulation will fail. At the same time, the excessive temperature of the permanent magnet will cause irreversible demagnetization, which seriously affects the electromagnetic performance of the motor. Therefore, the temperature field distribution characteristics of the cylinder type linear motor for Stirling have important engineering significance.

[0003] The overall sealed structure of the Stirling generator leads to differences in heat transfer inside the generator from conventional motors. The heat generated by the cylinder type linear motor inside the generator is directly transferred to the fluid in the sealed space, while the sealed structure hinders the effective dissipation of heat to the external environment, causing the fluid temperature to continue to rise, which in turn affects the heat dissipation of the cylinder type linear motor. The existing motor temperature rise calculation mainly adopts finite element analysis method and CFD (Computational Fluid Dynamics) method. Although the CFD method can accurately simulate the internal heat transfer process of the motor, it has a large amount of calculation, high hardware requirements, and it takes several days to obtain the results. The finite element analysis method has high calculation efficiency, but the boundary conditions need to be determined in advance. For the Stirling generator, the fluid temperature rise in the sealed space makes it difficult to accurately set the convective heat dissipation boundary conditions of the linear motor, thereby affecting the reliability of the calculation results.

[0004] Therefore, there is an urgent need for a new technical solution to solve the technical problem of how to evaluate the temperature rise of the sealed space of the cylinder type linear motor in the free piston Stirling generator. SUMMARY

[0005] The present application provides a sealed space temperature rise evaluation method and device for a cylinder type linear motor for Stirling, to solve the technical problem of how to evaluate the temperature rise of the sealed space of the cylinder type linear motor in the free piston Stirling generator.

[0006] To achieve the above-mentioned purpose, the present application provides a sealed space temperature rise evaluation method for a cylinder type linear motor for Stirling, comprising:

[0007] building a motor model; obtaining a fluid domain model of the closed space according to the motor model; obtaining a convection heat dissipation coefficient by performing CFD simulation according to the fluid domain model; obtaining a loss and a heat generation rate of the heat source component; and obtaining a first model according to the motor model, the fluid domain model, and the loss and the heat generation rate.

[0008] performing steady-state thermal simulation according to the first model based on a first condition to obtain a steady-state temperature distribution; the first condition including excluding the convection heat dissipation of the contact surface between the cylindrical linear motor and the fluid domain.

[0009] importing the convection heat dissipation coefficient into the first model to obtain a second model; performing transient thermal simulation according to the second model with the steady-state temperature distribution as an initial temperature distribution, and taking the simulation result as an initial temperature distribution of the next time step transient thermal simulation until a preset maximum time step is calculated to obtain a motor operating temperature rise.

[0010] Preferably, the building of the motor model comprises:

[0011] obtaining the structure of the Stirling generator and the cylindrical linear motor; building an initial model according to the structure of the Stirling generator and the cylindrical linear motor; and simplifying the initial model to obtain the motor model.

[0012] The simplification processing comprises: deleting threaded holes and screws; excluding the influence of the threaded holes and the screws on heat transfer; deleting gaps between components smaller than a preset value and regarding them as direct contact; excluding the gap heat transfer between components; deleting the fillets and chamfers of components; and processing the surfaces of components to be flat and without recesses.

[0013] Preferably, the obtaining of the fluid domain model of the closed space according to the motor model comprises:

[0014] modeling the fluid in the closed space inside the Stirling generator shell according to the motor model to obtain an overall fluid domain model; intercepting a local fluid domain model between the cylindrical linear motor and the Stirling generator shell according to the overall fluid domain model; and intercepting a quarter of the local fluid domain model longitudinally divided into four equal parts to obtain the fluid domain model.

[0015] Preferably, the obtaining of the convection heat dissipation coefficient by performing CFD simulation according to the fluid domain model comprises:

[0016] setting the motion speed of the fluid motion boundary according to the actual motion mode of the cylindrical linear motor; closing the energy equation for solving the fluid temperature rise in the CFD simulation; and splitting the fluid domain model into sub-fluid domains; the sub-fluid domains including concentric circular tube regions, stationary end surface regions, moving end surface regions, and linear motor shell regions.

[0017] The CFD simulation is performed according to the sub-fluid domains to obtain the flow velocity distribution of each sub-fluid domain; the convection heat dissipation coefficient is obtained according to the flow velocity distribution of each sub-fluid domain in combination with the Nusselt number empirical formula of each sub-fluid domain; the convection heat dissipation coefficient includes the convection heat dissipation coefficient between the cylindrical linear motor and the contact surface of each sub-fluid domain.

[0018] Preferably, the obtaining of the loss and heat generation rate of the heat source component includes:

[0019] The loss of the heat source component is obtained by simulation solution; the loss of the heat source component includes the copper loss, iron loss and eddy current loss of the motor winding, stator and permanent magnet; the heat generation rate is obtained according to the loss of the heat source component in combination with the volume of the heat source component.

[0020] Preferably, the obtaining of the first model according to the motor model, the fluid domain model and the loss and heat generation rate includes:

[0021] The fluid domain model is restored to the overall fluid domain model; the motor model and the overall fluid domain model are imported into the temperature field finite element simulation software to generate a model mesh; the loss is equivalent to a uniform loss and is applied to the mesh nodes corresponding to the heat source component; the heat generation rate is evenly applied to the mesh nodes corresponding to the heat source component; the first model is obtained.

[0022] Preferably, the steady-state temperature distribution is taken as the initial temperature distribution, the transient thermal simulation is performed according to the second model, and the simulation result is taken as the initial temperature distribution of the next time step transient thermal simulation until the calculation of the preset maximum time step is completed, and the motor operating temperature rise is obtained, including:

[0023] The average temperature of each sub-fluid domain and the contact surface of the cylindrical linear motor is obtained according to the steady-state temperature distribution to obtain a first data set; the first data set is taken as the environmental temperature, the transient thermal simulation is performed according to the steady-state temperature distribution and the second model to obtain the motor transient temperature distribution; the motor transient temperature distribution simulation result of each time step is taken as the initial temperature distribution of the next time step, the first data set is updated according to the initial temperature distribution, and the transient thermal simulation is performed according to the second model at each time step until the calculation of the preset maximum time step is completed; the motor transient temperature distribution simulation result of each time step is integrated to obtain the operating temperature rise of the motor within the preset maximum time step.

[0024] Preferably, the average temperature of each sub-fluid domain and the contact surface of the cylindrical linear motor is obtained according to the steady-state temperature distribution to obtain a first data set, including:

[0025] The temperature distribution of the sub-fluid domain is obtained according to the steady-state temperature distribution; the average temperature of the contact surface of the cylindrical linear motor and each sub-fluid domain is obtained according to the temperature distribution of the sub-fluid domain, and the first data set is integrated; the average temperature includes the average temperature of all mesh nodes in the sub-fluid domain.

[0026] Preferably, the average temperature of the contact surface between the cylindrical linear motor and each sub-fluid domain is obtained according to the temperature distribution of the sub-fluid domain, and the average temperature of the contact surface between the cylindrical linear motor and each sub-fluid domain comprises:

[0027] In the concentric circular tube region, the average temperature at the center position of the gap between the inner and outer walls is taken.

[0028] In the stationary end face region, the average temperature at the position of the preset distance above or below is taken.

[0029] In the moving end face region, the average temperature at the position of the preset distance above or below is taken.

[0030] In the linear motor shell region, the average temperature at the position of the preset distance radially outward of the shell is taken.

[0031] The application also provides a sealed space temperature rise evaluation device for a Stirling cylindrical linear motor, which is used for the method of the application, and the device comprises a first module, a second module, a third module and a fourth module.

[0032] The first module is used for building a motor model; a fluid domain model of the sealed space is obtained according to the motor model; and a convection heat dissipation coefficient is obtained by CFD simulation according to the fluid domain model.

[0033] The second module is used for obtaining the loss and heat generation rate of the heat source component; a first model is obtained according to the motor model, the fluid domain model and the loss and heat generation rate.

[0034] The third module is used for obtaining a steady-state temperature distribution by steady-state thermal simulation based on the first condition according to the first model; the first condition comprises eliminating the convection heat dissipation of the contact surface between the cylindrical linear motor and the fluid domain.

[0035] The fourth module is used for importing the convection heat dissipation coefficient into the first model to obtain a second model; transient thermal simulation is performed according to the second model with the steady-state temperature distribution as the initial temperature distribution, and the simulation result is taken as the initial temperature distribution of the next time step transient thermal simulation until the calculation of the preset maximum time step is completed to obtain the motor operating temperature rise.

[0036] The application has the following beneficial effects:

[0037] The closed space temperature rise evaluation method of the cylinder type linear motor for Stirling, combining the calculation accuracy of the CFD simulation method and the smaller calculation amount of the finite element method, considers the influence of the fluid temperature rise in the closed space of the Stirling generator on the heat dissipation of the linear motor, and simulates through the static temperature rise and the motion temperature rise in a two-step simulation superposition manner, so that the simulation calculation amount is reduced, and more accurate temperature rise evaluation of the Stirling generator and the internal fluid domain and the linear motor is realized.

[0038] The closed space temperature rise evaluation device of the cylinder type linear motor for Stirling of the present application is used for the method of the present application, and has the same beneficial effects as the method of the present application.

[0039] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the application, and are incorporated herein for explanation by reference. In the drawings:

[0041] Figure 1 is a cross-sectional structure schematic diagram of a moving magnet type free piston Stirling generator which is a preferred embodiment of the present application.

[0042] Figure 2 is a cross-sectional structure schematic diagram of a moving coil type free piston Stirling generator which is a preferred embodiment of the present application.

[0043] Figure 3 is a method flowchart of a preferred embodiment of the present application.

[0044] Figure 4 is a moving magnet type Stirling generator simplified model and a quarter fluid domain model schematic diagram of a preferred embodiment of the present application.

[0045] Figure 5 is a moving coil type Stirling generator simplified model and a quarter fluid domain model schematic diagram of a preferred embodiment of the present application.

[0046] Figure 6 is a moving magnet motor local fluid domain flow velocity distribution schematic diagram of a preferred embodiment of the present application.

[0047] Figure 7is a schematic of the velocity profile of the fluid domain of a moving coil motor of a preferred embodiment of the invention.

[0048] Figure 8 is a schematic of the steady state overall temperature of a moving magnet Stirling generator of a preferred embodiment of the invention.

[0049] Figure 9 is a schematic of the steady state overall fluid domain temperature of a moving magnet Stirling generator of a preferred embodiment of the invention.

[0050] Figure 10 is a schematic of the steady state overall temperature of a moving magnet linear motor of a preferred embodiment of the invention.

[0051] Figure 11 is a schematic of the steady state winding temperature of a moving magnet linear motor of a preferred embodiment of the invention.

[0052] Figure 12 is a schematic of the steady state mover temperature of a moving magnet linear motor of a preferred embodiment of the invention.

[0053] Figure 13 is a schematic of the steady state permanent magnet temperature of a moving magnet linear motor of a preferred embodiment of the invention.

[0054] Figure 14 is a schematic of the steady state inner stator temperature of a moving magnet linear motor of a preferred embodiment of the invention.

[0055] Figure 15 is a schematic of the steady state outer stator temperature of a moving magnet linear motor of a preferred embodiment of the invention.

[0056] Figure 16 is a schematic of the steady state overall temperature of a moving coil Stirling generator of a preferred embodiment of the invention.

[0057] Figure 17 is a schematic of the steady state overall fluid domain temperature of a moving coil Stirling generator of a preferred embodiment of the invention.

[0058] Figure 18 is a schematic of the steady state overall temperature of a moving coil linear motor of a preferred embodiment of the invention.

[0059] Figure 19 is a schematic of the steady state winding temperature of a moving coil linear motor of a preferred embodiment of the invention.

[0060] Figure 20 is a schematic of the steady state permanent magnet temperature of a moving coil linear motor of a preferred embodiment of the invention.

[0061] Figure 21 is a schematic of the steady state U-shaped stator temperature of a moving coil linear motor of a preferred embodiment of the invention.

[0062] Figure 22 is a schematic of the transient overall temperature of a moving magnet Stirling generator of a preferred embodiment of the present invention.

[0063] Figure 23 is a schematic of the transient overall fluid domain temperature of a moving magnet Stirling generator of a preferred embodiment of the present invention.

[0064] Figure 24 is a schematic of the transient overall temperature of a moving magnet linear motor of a preferred embodiment of the present invention.

[0065] Figure 25 is a schematic of the transient winding temperature of a moving magnet linear motor of a preferred embodiment of the present invention.

[0066] Figure 26 is a schematic of the transient mover temperature of a moving magnet linear motor of a preferred embodiment of the present invention.

[0067] Figure 27 is a schematic of the transient permanent magnet temperature of a moving magnet linear motor of a preferred embodiment of the present invention.

[0068] Figure 28 is a schematic of the transient inner stator temperature of a moving magnet linear motor of a preferred embodiment of the present invention.

[0069] Figure 29 is a schematic of the transient outer stator temperature of a moving magnet linear motor of a preferred embodiment of the present invention.

[0070] Figure 30 is a schematic of the transient overall temperature of a moving coil Stirling generator of a preferred embodiment of the present invention.

[0071] Figure 31 is a schematic of the transient overall fluid domain temperature of a moving coil Stirling generator of a preferred embodiment of the present invention.

[0072] Figure 32 is a schematic of the transient overall temperature of a moving coil linear motor of a preferred embodiment of the present invention.

[0073] Figure 33 is a schematic of the transient winding temperature of a moving coil linear motor of a preferred embodiment of the present invention.

[0074] Figure 34 is a schematic of the transient permanent magnet temperature of a moving coil linear motor of a preferred embodiment of the present invention.

[0075] Figure 35 is a schematic of the transient U-shaped stator temperature of a moving coil linear motor of a preferred embodiment of the present invention.

[0076] Figure 36 is a schematic of the transient cylinder connecting frame temperature of a moving coil Stirling generator of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0077] The embodiments of the present application will be described in detail with reference to the drawings, but the present application can be implemented in various different ways as defined and covered by the claims.

[0078] In the preferred embodiments of the present application, the moving-magnet free-piston Stirling generator and the moving-coil free-piston Stirling generator are analyzed as examples. The above-mentioned two types of free-piston Stirling generators and the cylindrical linear motor are only part of the preferred embodiments of the present application.

[0079] Referring to Figure 1 , the moving-magnet free-piston Stirling generator uses a single-phase double-stator moving-magnet cylindrical linear motor as a power generation component. In Figure 1 , A1 is the hot end of the Stirling generator, A2 is the cold end of the Stirling generator, A3 is a gas distribution piston, A4 is a regenerator, A5 is a cylinder, A6 is a wear-resistant lubricating ring, A7 is a cylinder fixing frame, A8 is a power piston, A9 is a moving-magnet cylindrical linear motor, A10 is a power piston connecting frame, A11 is a power piston plate spring, A12 is a gas distribution piston plate spring grommet, A13 is a gas distribution piston plate spring, A14 is a voice coil motor fixing ring, A15 is a gas distribution piston rod, A16 is a voice coil motor connecting frame, A17 is a voice coil motor, A18 is the Stirling generator housing, and A19 is the Stirling generator base. In the moving-magnet cylindrical linear motor, A91 is an inner and outer stator connecting frame, A92 is the motor outer stator, A93 is the motor winding, A94 is the motor housing, A95 is the motor inner stator, A96 is the motor permanent magnet, and A97 is the motor mover.

[0080] Referring to Figure 2 , the moving-coil free-piston Stirling generator uses a single-phase double-permanent magnet moving-coil cylindrical linear motor as a power generation component. In Figure 2 , B1 is the hot end of the Stirling generator, B2 is the cold end of the Stirling generator, B3 is a gas distribution piston, B4 is a regenerator, B5 is a cylinder, B6 is a 7-pin terminal, B7 is a power piston, B8 is a 1-pin terminal, B9 is a moving-coil cylindrical linear motor, B10 is a power piston connecting frame, B11 is a cylinder connecting frame, B12 is a counterweight copper ring, B13 is a power piston plate spring connecting frame, B14 is a power piston plate spring, B15 is a displacement sensor, B16 is a gas distribution piston plate spring grommet, B17 is a gas distribution piston plate spring, B18 is a gas distribution piston rod, B19 is the Stirling generator housing, and B20 is the Stirling generator base. In the moving-coil cylindrical linear motor, B91 is a moving-coil motor U-shaped stator, B92 is a permanent magnet connecting frame, B93 is a permanent magnet, B94 is the motor winding, and B95 is the motor mover.

[0081] Referring to Figure 3In the preferred embodiment of the present application, a sealed space temperature rise evaluation method for a Stirling cylindrical linear motor is provided, comprising:

[0082] S1, building a motor model; obtaining a fluid domain model of the sealed space according to the motor model; obtaining a convection heat dissipation coefficient by CFD simulation according to the fluid domain model; obtaining the loss and heat generation rate of the heat source component; obtaining a first model according to the motor model, the fluid domain model, and the loss and heat generation rate.

[0083] In the preferred embodiment of the present application, building a motor model comprises:

[0084] Obtaining the structure of the Stirling generator and the cylindrical linear motor; building an initial model according to the structure of the Stirling generator and the cylindrical linear motor; simplifying the initial model to obtain the motor model.

[0085] The simplification process includes: deleting threaded holes and screws; eliminating the influence of threaded holes and screws on heat transfer; deleting gaps between components smaller than a preset value and considering them as direct contact; eliminating gap heat transfer between components; deleting the fillets and chamfers of each component; and treating the surface of each component as flat and without recesses.

[0086] In the preferred embodiment of the present application, the motor model is built using the mechanical design software ANSYS SpaceClaim 2022 R1.

[0087] In the preferred embodiment of the present application, obtaining a fluid domain model of the sealed space according to the motor model comprises:

[0088] Modeling the fluid in the sealed space inside the Stirling generator housing according to the motor model to obtain an overall fluid domain model; considering that the overall fluid domain model is too large, directly importing it into the CFD software for analysis would consume a lot of time, therefore, a local fluid domain model between the cylindrical linear motor and the Stirling generator housing is cut from the overall fluid domain model; at the same time, since the Stirling generator and the linear motor are overall axially symmetrical structures, the fluid velocity is also symmetrically distributed, the local fluid domain model is longitudinally quartered to obtain a fluid domain model. The fluid domain model is shown in Figure 4 to Figure 5 , wherein Figure 4 is a simplified model of a moving magnet Stirling generator and a quarter of a fluid domain model, Figure 5 is a simplified model of a moving coil Stirling generator and a quarter of a fluid domain model. In the preferred embodiment of the present application, the internal fluid of the Stirling is 2Mpa helium.

[0089] In the preferred embodiment of the present application, obtaining a convection heat dissipation coefficient by CFD simulation according to the fluid domain model comprises:

[0090] The motion velocity of the fluid motion boundary is set according to the actual motion mode of the cylindrical linear motor; the energy equation for solving fluid temperature rise in the CFD simulation is closed to reduce the calculation cost, the temperature rise in the fluid motion process is ignored, and the fluid motion is regarded as constant-temperature flow, and the fluid flow velocity distribution at a constant temperature of 22 DEG C is obtained through simulation.

[0091] The fluid domain model is divided into sub-fluid domains; the sub-fluid domains include concentric circular pipe regions, stationary end face regions, moving end face regions and linear motor shell regions. The flow velocity distribution of each sub-fluid domain is obtained through CFD simulation according to the sub-fluid domains; the convective heat dissipation coefficient is obtained according to the flow velocity distribution of each sub-fluid domain combined with the Nusselt number empirical formula of each sub-fluid domain; the convective heat dissipation coefficient includes the convective heat dissipation coefficient between the cylindrical linear motor and the contact surface of each sub-fluid domain.

[0092] In the preferred embodiment of the application, the motion velocity of the fluid motion boundary includes:

[0093] ;

[0094] Wherein, is the velocity of the mover and the fluid domain motion boundary, is the time.

[0095] In the preferred embodiment of the application, the fluid domain model of one quarter of the whole fluid domain model is imported into ANSYS Fluent 2022 R1, the transient analysis is opened, and the energy equation solving function is closed to avoid solving the temperature rise in the fluid motion process, and the temperature rise of the fluid in the motion process is not considered, and only the flow velocity distribution after the stable flow of the fluid is solved. Subsequently, the motion boundary and the corresponding motion velocity of the fluid domain are set by using the dynamic mesh function of the software. In this embodiment, the velocity of the fluid domain motion boundary of the two types of Stirling generators is equivalent to the motion velocity of the mover of the two types of linear motors. After setting the velocity of the fluid domain motion boundary in the dynamic mesh, the flow velocity distribution of the fluid is calculated by running the simulation software. In order to obtain the velocity distribution after stable flow, the simulation time in the embodiment is set to 2 periods, i.e. Figure 6 to Figure 7 Wherein, Figure 6 is the local fluid domain flow velocity distribution of the moving magnet motor, Figure 7 is the local fluid domain flow velocity distribution of the moving coil motor.

[0096] In the preferred embodiment of the application, the convective heat dissipation coefficient includes:

[0097] ;

[0098] Wherein, is the Reynolds number; is the fluid density; is the average velocity of the fluid flow; is the characteristic length at the calculation position; is the dynamic viscosity of the fluid; is the Grashof number; is the Prandtl number; is the Nusselt number, which is derived from the Reynolds number , the Grashof number and the Prandtl number by solving the empirical formula; is the thermal conductivity of the fluid; is the convective heat transfer coefficient of the fluid.

[0099] For a Stirling generator, there are two convective heat dissipation modes, i.e., forced convective heat dissipation coefficient and natural convective heat dissipation coefficient. The type of convective heat dissipation is determined by the type of fluid, the flow velocity of the fluid, the shape and size of the contact surface between the motor and the fluid domain, and other factors. In the preferred embodiment of the present application, the sub-fluid domain includes a concentric circular tube region, a stationary end surface region, a moving end surface region and a linear motor housing region, and the convective heat dissipation coefficients of the above four types of sub-fluid domains are considered:

[0100] (1) The concentric circular tube region, the characteristic length is the difference between the inner and outer diameters:

[0101] ;

[0102] wherein, is the outer diameter of the concentric circular tube, is the inner diameter of the concentric circular tube.

[0103] (2) The stationary end surface region, the convective heat dissipation thereof is approximated as fluid sweeping a flat plate, the characteristic length is the length of the fluid sweeping flat plate, which is the radial length of the stationary end surface in the present application.

[0104] (3) The moving end surface region, the convective heat dissipation thereof is approximated as fluid passing through a special-shaped object, the characteristic length is the difference between the inner and outer diameters of the moving end surface.

[0105] (4) The linear motor housing region, the convective heat dissipation thereof is approximated as natural convective heat dissipation, the characteristic length is the axial length of the linear motor housing.

[0106] In the preferred embodiment of the present application, the dynamic viscosity of 2Mpa helium gas is 19.7μPa·s, is 3.2544kg / m 3 , the thermal conductivity is 0.15483W / m·℃, and the Prandtl number is 0.661. The convection heat dissipation calculation regions of the two types of Stirling generators and linear motors are shown in the following figures Figure 4 and Figure 5 For the moving magnet type Stirling generator, C1 and C2 are concentric circular tube regions, C3 and C4 are stationary end face regions, C5, C6 and C7 are moving end face regions, and C8 is the moving magnet linear motor housing region. For the moving coil type Stirling generator, D1 and D2 are concentric circular tube regions, D3 and D4 are stationary end face regions, D5, D6 and D7 are moving end face regions, and D8 is the moving coil linear motor housing region.

[0107] In the preferred embodiment of the present application, for the moving magnet type Stirling generator, in order to calculate the convection heat dissipation coefficients of the four types of sub-fluid domains, the Nusselt number empirical formula needs to be determined:

[0108] In the moving magnet type Stirling generator:

[0109] The Nusselt number empirical formula corresponding to the concentric circular tube region includes:

[0110] ;

[0111] wherein, and are the Nusselt numbers corresponding to the inner wall surface and the outer wall surface of the concentric circular tube, and are the Nusselt number influence coefficients of the inner wall surface and the outer wall surface, which are taken as 5.385 in the embodiment of the present application. and are also influence coefficients, which are taken as 0.346 in the embodiment of the present application. and are the heat flux densities of the inner wall surface and the outer wall surface, which can be positive or negative, and are considered equal in the embodiment of the present application.

[0112] The Nusselt number empirical formula corresponding to the stationary end face region includes:

[0113] ;

[0114] The Nusselt number empirical formula corresponding to the moving end face region includes:

[0115] ;

[0116] For the linear motor housing region, it is considered as natural convection heat dissipation, and the Nusselt number empirical formula corresponding thereto includes:

[0117] ;

[0118] wherein, is the Rayleigh number; is the acceleration of gravity, which is taken as 9.81 m / s2 ; is the thermal expansion coefficient of the fluid, which is 0.0033 / °C in this embodiment; is the wall temperature; is the ambient temperature. In the preferred embodiment of the present invention, is the linear motor casing temperature, is the Stirling generator casing temperature. is the thermal diffusivity of the fluid, which is 9.53×10 -6 .

[0119] In a moving-magnet Stirling generator:

[0120] The empirical formulas for the Nusselt number in the stationary end face region, the moving end face region, and the linear motor housing region are the same as those for the moving-magnet Stirling generator. However, the empirical formula for the Nusselt number in the concentric tube region is significantly different, including:

[0121] ;

[0122] in, is the friction factor for a smooth surface.

[0123] In a preferred embodiment of the present invention, the dynamic viscosity, thermal diffusivity, thermal conductivity and Prandtl number of the local fluid domain inside the Stirling can be obtained by looking up different types of fluids.

[0124] In the preferred embodiment of the present invention, the calculation results of the convection heat dissipation coefficients of the two types of Stirling generators and linear motors are shown in Table 1 and Table 2:

[0125] Table 1 Calculation results of convection heat dissipation coefficient of moving-magnet Stirling generator

[0126] ;

[0127] Table 2 Calculation results of convection heat dissipation coefficient of moving coil Stirling generator

[0128] ;

[0129] In a preferred embodiment of the present invention, obtaining the loss and heat generation rate of the heat source component includes:

[0130] A linear motor simulation model is built using electromagnetic field simulation software. Based on the actual motion of the linear motor rotor, a motion velocity is applied, and the losses of the heat source components are obtained through simulation. The losses of the heat source components include copper loss, iron loss, and eddy current loss in the motor windings, stator, and permanent magnets. The heat generation rate is calculated based on the losses of the heat source components and their volume, and used as the heat source for the motor. In a preferred embodiment of the present invention, the heat generation rate includes:

[0131] ;

[0132] wherein, is the heat generation rate, is the loss of the corresponding component, is the volume of the corresponding component.

[0133] In the preferred embodiment of the present application, ANSYS Electronics Desktop 2022 R1 is used to build the electromagnetic field simulation model of the moving-magnet cylindrical linear motor and the moving-coil cylindrical linear motor. Since the overall structure of these two types of motors is axisymmetric, the electromagnetic field model can be simplified to two dimensions to reduce the amount of calculation. The volumes of the key components of the two types of linear motors can be directly obtained through the modeling software ANSYS SpaceClaim 2022 R1, and then the heat generation rates of the windings, stators, and permanent magnets under the rated operating condition are solved. The calculation results are shown in Tables 3 and 4:

[0134] Table 3 Heat generation rates of key components of moving-magnet linear motor

[0135] ;

[0136] Table 4 Heat generation rates of key components of moving-coil linear motor

[0137] ;

[0138] In the preferred embodiment of the present application, the first model is obtained according to the motor model, the fluid domain model, and the losses and heat generation rates, and includes:

[0139] The fluid domain model is restored to the overall fluid domain model; the motor model and the overall fluid domain model are imported into the temperature field finite element simulation software to generate a model mesh; the losses are equivalent to uniform losses and applied to the mesh nodes of the corresponding heat source components; the heat generation rates are evenly applied to the mesh nodes of the corresponding heat source components; and the first model is obtained.

[0140] In the preferred embodiment of the present application, the steady-state heat calculation module in ANSYS Workbench 2022 R1 is used to import the motor model and the overall fluid domain model, and the model mesh is divided. The number of mesh nodes of the moving-magnet Stirling generator is 1405182, and the number of mesh nodes of the moving-coil Stirling generator is 2394717. The heat generation rates of the windings, stators, and permanent magnets have been given in Tables 3 and 4, and can be directly input into the software.

[0141] S2, based on the first condition, performing steady-state thermal simulation according to the first model to obtain a steady-state temperature distribution; the first condition includes removing the convection heat dissipation of the contact surface between the cylindrical linear motor and the fluid domain.

[0142] In the preferred embodiment of the present application, when performing steady-state thermal simulation, the convection heat dissipation of the contact surface between the cylindrical linear motor and the fluid domain is eliminated, and the cylindrical linear motor is regarded as being static in the Stirling generator, and only the copper loss, iron loss, eddy current loss of the key components, and the heat generated by the hot and cold end temperatures of the Stirling generator reach thermal equilibrium with the outside of the Stirling generator housing.

[0143] In the preferred embodiment of the present application, the linear motor moves continuously in the Stirling generator, and the losses of the key components and the Stirling hot and cold end temperatures are the fundamental reasons for the temperature rise in the Stirling generator, and the convection heat dissipation directly affects the temperature distribution. For the convection heat dissipation, the heat transfer process can be explained by Newton's heat transfer law, including the first calculation formula:

[0144] ;

[0145] Among them, is the heat transfer amount of the convection heat dissipation, is the convection heat dissipation coefficient, is the area of the convection heat dissipation wall surface, is the temperature of the convection heat dissipation wall surface, is the ambient temperature.

[0146] In the first calculation formula, the convection heat dissipation coefficient is known, and in order to obtain the heat transfer amount of the convection heat dissipation, the temperature difference between the heat dissipation wall surface and the ambient environment must be obtained. If this temperature difference cannot be obtained through actual experimental testing, and if the ambient temperature is arbitrarily set to the normal temperature of 22℃, the final temperature distribution obtained will inevitably be greatly different from the actual temperature distribution. Therefore, based on the first condition, the steady-state thermal simulation is performed according to the first model to obtain the steady-state temperature distribution, and the steady-state temperature distribution is used as the initial temperature distribution for subsequent transient thermal simulation, and the temperature of the convection heat dissipation wall surface and the ambient temperature are obtained from the steady-state temperature distribution, and the ambient temperature in the first calculation formula is replaced by .

[0147] For the Stirling generator, the closed space inside the Stirling generator is filled with fluid, and there is no direct contact with the outside environment and the cold end, which makes it difficult to dissipate heat inside the Stirling generator. The copper loss, iron loss, and eddy current loss generated during the movement of the linear motor continuously transfer heat to the fluid in the Stirling generator, and the fluid cannot timely transfer the heat to the outside, so the temperature continuously rises. For the linear motor, the way to transfer heat to the fluid is convection heat dissipation, and the transmission process can be explained by the first calculation formula. As can be seen from the first calculation formula, the ambient temperature is one of the key conditions to determine the heat transfer amount of convection heat dissipation, if the motor is directly placed in the external air, the ambient temperature can be directly regarded as the normal temperature 22 DEG C, but the linear motor in the application is in the closed space inside the Stirling generator, and the ambient temperature should be regarded as the temperature of the calculation area of the convection heat dissipation of each contact surface of the linear motor and the local fluid domain, and is recorded as the reference temperature Obviously, as the initial condition It is closer to the operating condition of the motor when it is static than directly taking the normal temperature 22 DEG C as the initial condition.

[0148] In the preferred embodiment of the application, the convection heat dissipation coefficients of the two types of linear motors are all set to 0W / m 2 ℃, and the convection heat dissipation between the Stirling generator shell and the outside world is set to 15W / m 2 ℃. The steady-state temperature distribution of the two types of Stirling generators and linear motors is shown in Figure 8 to Figure 21 .

[0149] S3, the convection heat dissipation coefficient is introduced into the first model to obtain a second model; the steady-state temperature distribution is taken as the initial temperature distribution, transient thermal simulation is carried out according to the second model, and the simulation result is taken as the initial temperature distribution of the next time step transient thermal simulation until the calculation of the preset maximum time step is completed, and the motor operating temperature rise is obtained.

[0150] In the preferred embodiment of the application, the convection heat dissipation coefficient is introduced into the first model, that is, the convection heat dissipation coefficients of the four types of sub-fluid domains are input into the corresponding sub-fluid domains in the first model.

[0151] In the preferred embodiment of the application, the steady-state temperature distribution is taken as the initial temperature distribution, transient thermal simulation is carried out according to the second model, and the simulation result is taken as the initial temperature distribution of the next time step transient thermal simulation until the calculation of the preset maximum time step is completed, and the motor operating temperature rise is obtained, which includes:

[0152] According to the steady-state temperature distribution, the average temperature of each sub-fluid domain and the contact surface of the cylindrical linear motor is obtained to obtain a first data set; the first data set is taken as the ambient temperature , transient thermal simulation is carried out according to the steady-state temperature distribution and the second model to obtain the motor transient temperature distribution; the motor transient temperature distribution simulation result of each time step is taken as the initial temperature distribution of the next time step, the first data set is updated according to the initial temperature distribution, and transient thermal simulation is carried out according to the second model at each time step until the calculation of the preset maximum time step is completed; the motor transient temperature distribution simulation result of each time step is integrated to obtain the operating temperature rise of the motor within the preset maximum time step.

[0153] In the preferred embodiment of the application, the motor transient temperature distribution specifically includes the transient temperature distribution of the Stirling generator, the overall fluid domain of the Stirling generator and the linear motor.

[0154] In the preferred embodiment of the present application, the temperature distribution of the transient thermal simulation of the two types of Stirling generators and linear motors is shown in Figure 22 to Figure 35 The temperature distribution of the steady-state thermal simulation of the Stirling generator is compared with the temperature distribution of the transient thermal simulation of the Stirling generator, and the temperature obtained by the transient thermal simulation is slightly higher than that obtained by the steady-state thermal simulation. The overall temperature fluctuation does not exceed 5℃. By comparing the linear motor, the stator, the permanent magnet and other structures, it can be found that the temperature distribution has changed. Without considering the influence of convective heat dissipation, the temperature values obtained by the steady-state thermal simulation and the transient thermal simulation are close, and the difference lies in the temperature distribution on each component. For example, the moving coil linear motor in Figure 8 to Figure 21 and the moving coil linear motor in Figure 22 to Figure 35 Compared with the steady-state thermal simulation without considering convective heat dissipation, the winding temperature obtained by the transient thermal simulation is more concentrated in the center, and as shown in Figure 32 , the winding surface temperature is more uniform, and the overall maximum temperature and minimum temperature decrease by 4.45℃ and 2.87℃ respectively, with a small decrease. This result further illustrates the influence of convective heat dissipation on the temperature distribution, and also illustrates that the steady-state thermal simulation result can provide an initial condition closer to the actual working condition for the transient thermal simulation. Figure 18 Figure 33 In the preferred embodiment of the present application, the average temperature of each sub-fluid domain and the contact surface of the cylindrical linear motor is obtained according to the steady-state temperature distribution, and the first data set includes:

[0155] The temperature distribution of the sub-fluid domain is obtained according to the steady-state temperature distribution, the average temperature of the contact surface of the cylindrical linear motor and each sub-fluid domain is obtained according to the temperature distribution of the sub-fluid domain, and the first data set is integrated. The average temperature includes the average temperature of all grid nodes in the sub-fluid domain.

[0156] In the preferred embodiment of the present application, the average temperature of the contact surface of the cylindrical linear motor and each sub-fluid domain is obtained according to the temperature distribution of the sub-fluid domain, which includes:

[0157] In the concentric circular tube area, the average temperature at the center position of the gap between the inner and outer walls is taken.

[0158] In the stationary end surface area, the average temperature at the upper or lower preset distance position is taken.

[0159] In the moving end surface area, the average temperature at the upper or lower preset distance position is taken.

[0160] In the linear motor shell area, the average temperature at the radial outer preset distance position of the shell is taken.

[0161] In the linear motor shell area, the average temperature at the radial outer preset distance position of the shell is taken.

[0162] ​In the preferred embodiment of the present application, in the ANSYS Workbench 2022 R1 transient heat calculation module, the time step is set to 1200s, the total simulation time is set to 7200s, wherein the automatic time sub-step method is used in each time step, and there are 1 to 10 sub-steps in the time step, which is automatically calculated by the software.

[0163] The closed space temperature rise evaluation method of the cylindrical linear motor for Stirling in the present application combines the calculation accuracy of the flow rate of the CFD simulation method and the smaller calculation amount of the finite element method, considers the influence of the fluid temperature rise in the closed space of the Stirling generator on the heat dissipation of the linear motor, and simulates through the static temperature rise and the motion temperature rise in a two-step simulation superposition manner, which reduces the simulation calculation amount and realizes more accurate temperature rise evaluation of the Stirling generator and the fluid domain and the linear motor inside the Stirling generator. Through repeated iteration, the update of the convection and radiation boundary conditions is realized, the calculation error caused by the constant boundary is avoided, and the calculation accuracy of the two-step simulation is improved. The method realizes the temperature rise evaluation of the closed space of the cylindrical linear motor for Stirling in the free piston Stirling generator.

[0164] In the preferred embodiment of the present application, a closed space temperature rise evaluation device of a cylindrical linear motor for Stirling is also provided, which is used for the method of the present application, and the device comprises a first module, a second module, a third module and a fourth module.

[0165] The first module is used for building a motor model; a fluid domain model of the closed space is obtained according to the motor model; and a convection and radiation coefficient is obtained by CFD simulation according to the fluid domain model.

[0166] The second module is used for obtaining the loss and heat generation rate of the heat source component; and a first model is obtained according to the motor model, the fluid domain model and the loss and heat generation rate.

[0167] The third module is used for obtaining a steady-state temperature distribution by steady-state thermal simulation based on the first condition according to the first model; and the first condition comprises eliminating the convection and radiation of the contact surface between the cylindrical linear motor and the fluid domain.

[0168] The fourth module is used for importing the convection and radiation coefficient into the first model to obtain a second model; and transient thermal simulation is performed according to the second model with the steady-state temperature distribution as the initial temperature distribution, and the simulation result is used as the initial temperature distribution of the next time step transient thermal simulation until the calculation of the preset maximum time step is completed to obtain the motor operating temperature rise.

[0169] The closed space temperature rise evaluation device of the cylindrical linear motor for Stirling in the present application is used for the method of the present application, and has the same beneficial effects as the method of the present application.

[0170] Verification part:

[0171] To further illustrate the advantages of the method of the present application, the temperature near the stator of a linear motor is compared with the conventional simulation results and experimental measurements. The conventional simulation results refer to the same model as the transient thermal simulation of the embodiment of the present application, the time step is set to be the same as the embodiment of the present application, but the convection heat dissipation reference temperature is set to be the normal temperature 22℃ at each time step , and then the transient thermal temperature distribution of the conventional simulation is obtained. The temperature of some nodes is compared with the results obtained by the method of the present application, i.e. Figure 4 C1, C2, C4 and C8 in the region of Figure 5 D1, D2, D3 and D8 in the region of , and the results are listed in Table 5 and Table 6. As can be seen from the tables, the temperature obtained by the conventional method with the convection heat dissipation reference temperature of 22℃ is significantly lower than the results obtained by the method of the present application, and the maximum temperature difference is 32.19℃. The results show that different reference temperatures will lead to a large difference in the temperature distribution obtained by convection heat dissipation. For the motor of the present application, it is difficult to obtain the temperature at each place inside the motor by direct measurement, which leads to the difficulty in determining the specific convection heat dissipation reference temperature , and the temperature obtained by the final simulation must have a significant error.

[0172] Table 5 Comparison of simulation results of a moving magnet Stirling generator

[0173] ;

[0174] Table 6 Comparison of simulation results of a moving coil Stirling generator

[0175] ;

[0176] The simulation results are compared with the experimental test results. The test results are for a moving coil Stirling generator, a temperature test paper is attached to the motor cylinder connecting frame, i.e. B11 in Figure 2 , and the motor is operated under the rated operating condition for a period of time, see Figure 36 , the temperature shown by the test paper is about 50℃. The test paper is attached to the position D8 in Figure 5 , and it can also be seen from the results in Table 6 that the simulation temperature is 48.06℃, and the temperature difference with the test paper is within 3℃. However, the simulation takes the copper loss, iron loss and permanent magnet eddy current generated by the linear motor as the heat source, and does not consider the heat generated by the mechanical loss of the Stirling generator, therefore, the simulation temperature obtained is less than the test result of the test paper. The results show that the method of the present application does not need to measure the temperature inside the motor in advance, provides an initial condition close to the static operating condition through the steady-state thermal simulation, and updates the reference temperature in real time during the transient thermal simulation The application considers the influence of fluid temperature rise in a closed space on convection heat dissipation, avoids errors caused by artificially setting convection heat dissipation conditions in a conventional method, and ensures calculation accuracy while reducing calculation amount.

[0177] The above merely provides the preferred embodiments of the application, and is not intended to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall fall within the protection scope of the application.

Claims

1. A method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling, characterized in that: include: Build a motor model; obtain a fluid domain model of the confined space based on the motor model; perform CFD simulation based on the fluid domain model to obtain a convection heat dissipation coefficient; and obtain the loss and heat generation rate of the heat source component; Obtaining a first model based on the motor model, the fluid domain model, and the loss and heat generation rate; Performing a steady-state thermal simulation according to the first model based on a first condition to obtain a steady-state temperature distribution; the first condition includes eliminating convection heat dissipation at a contact surface between the cylindrical linear motor and the fluid domain; The convection heat dissipation coefficient is imported into the first model to obtain a second model; the steady-state temperature distribution is used as the initial temperature distribution, and a transient thermal simulation is performed according to the second model, and the simulation results are used as the initial temperature distribution of the transient thermal simulation in the next time step until the calculation of the preset maximum time step is completed to obtain the motor operating temperature rise.

2. The method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling use according to claim 1, wherein: The motor model building includes: Obtaining the structures of the Stirling generator and the cylindrical linear motor; building an initial model based on the structures of the Stirling generator and the cylindrical linear motor; simplifying the initial model to obtain the motor model; The simplification process includes: deleting threaded holes and screws; eliminating the influence of threaded holes and screws on heat transfer; deleting gaps between components that are smaller than a preset value and treating them as direct contact; eliminating heat transfer in the gaps between components; deleting fillets and chamfers of each component; and processing the surface of each component to be flat and free of depressions.

3. The method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling use according to claim 2, wherein: Obtaining the fluid domain model of the enclosed space according to the motor model includes: The fluid in the enclosed space inside the Stirling generator casing is modeled according to the motor model to obtain an overall fluid domain model; a local fluid domain model between the cylindrical linear motor and the Stirling generator casing is intercepted according to the overall fluid domain model; and one fourth of the local fluid domain model is intercepted longitudinally to obtain the fluid domain model.

4. The method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling use according to claim 3, wherein: The convective heat dissipation coefficients obtained by CFD simulation based on the fluid domain model include: The motion velocity of the fluid motion boundary is set according to the actual motion mode of the cylindrical linear motor; the energy equation for solving the fluid temperature rise in the CFD simulation is closed; the fluid domain model is split into sub-fluid domains; the sub-fluid domains include a concentric tube area, a stationary end face area, a moving end face area, and a linear motor housing area; CFD simulation is performed on the sub-fluid domains to obtain the flow velocity distribution of each sub-fluid domain; the convective heat dissipation coefficient is obtained based on the flow velocity distribution of each sub-fluid domain combined with the empirical formula of the Nusselt number of each sub-fluid domain; the convective heat dissipation coefficient includes the convective heat dissipation coefficient between the cylindrical linear motor and the contact surface of each sub-fluid domain.

5. The method for evaluating the temperature rise in a closed space of a cylindrical linear motor for Stirling use according to claim 4, wherein: The obtaining of the loss and heat generation rate of the heat source component includes: The losses of the heat source components are obtained through simulation; the losses of the heat source components include copper loss, iron loss and eddy current loss of the motor windings, stator and permanent magnets; the heat generation rate is obtained based on the losses of the heat source components and the volume of the heat source components.

6. The method for evaluating the temperature rise in a closed space of a cylindrical linear motor for Stirling use according to claim 5, wherein: Obtaining a first model according to the motor model, the fluid domain model, and the loss and heat generation rate includes: The fluid domain model is restored to the overall fluid domain model; the motor model and the overall fluid domain model are imported into the temperature field finite element simulation software to generate a model grid; the loss is equivalent to a uniform loss and applied to the grid nodes of the corresponding heat source components; the heat generation rate is averaged and applied to the grid nodes of the corresponding heat source components; and the first model is obtained.

7. The method for evaluating the temperature rise in a closed space of a cylindrical linear motor for Stirling use according to claim 6, wherein: Taking the steady-state temperature distribution as the initial temperature distribution, performing transient thermal simulation according to the second model, and using the simulation results as the initial temperature distribution of the transient thermal simulation in the next time step until the calculation of the preset maximum time step is completed, the motor operating temperature rise is obtained, including: According to the steady-state temperature distribution, the average temperature of each sub-fluid domain and the contact surface of the cylindrical linear motor is obtained to obtain a first data set; taking the first data set as the ambient temperature, a transient thermal simulation is performed according to the steady-state temperature distribution and the second model to obtain the transient temperature distribution of the motor; the simulation result of the transient temperature distribution of the motor at each time step is used as the initial temperature distribution of the next time step, the first data set is updated according to the initial temperature distribution, and a transient thermal simulation is performed according to the second model at each time step until the calculation of the preset maximum time step is completed; the simulation results of the transient temperature distribution of the motor at each time step are integrated to obtain the operating temperature rise of the motor within the preset maximum time step.

8. The method for evaluating the temperature rise in a closed space of a cylindrical linear motor for Stirling use according to claim 7, wherein: The average temperature of the contact surface between each sub-fluid domain and the cylindrical linear motor is obtained according to the steady-state temperature distribution, and the first data set is obtained, including: The temperature distribution of the sub-fluid domain is obtained according to the steady-state temperature distribution; the average temperature of the contact surface between the cylindrical linear motor and each sub-fluid domain is obtained according to the temperature distribution of the sub-fluid domain, and the first data set is obtained by integration; the average temperature includes the average temperature of all grid nodes in the sub-fluid domain.

9. The method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling use according to claim 8, wherein: Obtaining the average temperature of the contact surface between the cylindrical linear motor and each sub-fluid domain according to the temperature distribution of the sub-fluid domain includes: In the concentric tube area, the average temperature at the center of the gap between the inner and outer walls is taken; In the static end face area, take the average temperature at the position with a preset distance above or below; In the moving end face area, take the average temperature at the upper or lower preset distance position; In the linear motor casing area, the average temperature at a preset distance radially outward from the casing is taken.

10. A device for evaluating temperature rise in a closed space of a cylindrical linear motor for Stirling use, used in the method according to any one of claims 1 to 9, characterized in that: The device includes a first module, a second module, a third module and a fourth module; The first module is used to build a motor model; obtain a fluid domain model of the enclosed space based on the motor model; and perform CFD simulation based on the fluid domain model to obtain a convection heat dissipation coefficient; The second module is used to obtain the loss and heat generation rate of the heat source component; the first model is obtained according to the motor model, the fluid domain model and the loss and heat generation rate; The third module is used to perform steady-state thermal simulation according to the first model based on a first condition to obtain a steady-state temperature distribution; the first condition includes eliminating convection heat dissipation at the contact surface between the cylindrical linear motor and the fluid domain; The fourth module is used to import the convection heat dissipation coefficient into the first model to obtain a second model; using the steady-state temperature distribution as the initial temperature distribution, a transient thermal simulation is performed according to the second model, and the simulation results are used as the initial temperature distribution of the transient thermal simulation in the next time step until the calculation of the preset maximum time step is completed to obtain the motor operating temperature rise.

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