Enclosed space temperature rise evaluation method and device for Stirling cylindrical linear motor

Abstract

The invention discloses a closed space temperature rise evaluation method and device for a Stirling cylindrical linear motor. The method comprises the following steps: building a motor model; obtaining a fluid domain model of the closed space according to the motor model; performing CFD simulation according to the fluid domain model to obtain a convective heat dissipation coefficient; acquiring loss and heat generation rate of the heat source part; obtaining a first model according to the motor model, the fluid domain model and the loss and heat generation rate; performing steady-state thermal simulation according to the first model based on a first condition to obtain steady-state temperature distribution; the first condition comprises removal of convection heat dissipation of a cylindrical linear motor and a fluid domain contact surface; importing the convective heat dissipation coefficient into the first model to obtain a second model; and taking the steady-state temperature distribution as initial temperature distribution, performing transient thermal simulation according to the second model, and taking a simulation result as initial temperature distribution of transient thermal simulation of a next time step until calculation of a preset maximum time step is completed, so as to obtain the running temperature rise of the motor.

Description

Technical Field

[0001] The present invention relates to the field of motor technology, and in particular to a method and device for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling use. Background Art

[0002] As the core energy conversion component of a free-piston Stirling generator, the thermal characteristics of a cylindrical linear motor directly determine the system's energy conversion efficiency and operational stability. During free-piston Stirling generator operation, the continuous motion of the cylindrical linear motor generates significant copper, iron, and eddy current losses, leading to elevated temperatures in various motor components. As the winding temperature rises, its resistivity increases, further exacerbating copper losses. If the temperature exceeds the insulation material's maximum temperature resistance, the winding insulation will fail. Furthermore, excessively high permanent magnet temperatures can cause irreversible demagnetization, severely impacting the motor's electromagnetic performance. Therefore, studying the temperature field distribution characteristics of cylindrical linear motors for Stirling applications is of great engineering significance.

[0003] The overall enclosed structure of a Stirling generator results in internal heat transfer that differs from that of conventional motors. The heat generated by the cylindrical linear motor inside is directly transferred to the fluid in the enclosed space. However, the enclosed 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 cylindrical linear motor. Existing motor temperature rise calculations mainly use finite element analysis and CFD (Computational Fluid Dynamics) methods. Although the CFD method can accurately simulate the internal heat transfer process of the motor, it is computationally intensive, has high hardware requirements, and can take several days to obtain results. The finite element analysis method has high computational efficiency, but it requires pre-determined boundary conditions. For Stirling generators, the temperature rise of the fluid in the enclosed space makes it difficult to accurately set the convective heat dissipation boundary conditions of the linear motor, thus affecting the reliability of the calculation results.

[0004] Therefore, a new technical solution is urgently needed to solve the technical problem of how to evaluate the temperature rise in the confined space of the cylindrical linear motor in the free piston Stirling generator. Summary of the Invention

[0005] The present invention provides a method and device for evaluating the temperature rise in the confined space of a cylindrical linear motor for a Stirling generator, so as to solve the technical problem of how to evaluate the temperature rise in the confined space of the cylindrical linear motor in a free piston Stirling generator.

[0006] To achieve the above objectives, the present invention provides a method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling motors, comprising: Build a motor model; obtain a fluid domain model of the enclosed space based on the motor model; perform CFD simulation based on the fluid domain model to obtain the convection heat dissipation coefficient; obtain the loss and heat generation rate of the heat source components; and obtain a first model based on the motor model, the fluid domain model, and the loss and heat generation rate.

[0007] Based on the first condition, a steady-state thermal simulation is performed according to the first model 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.

[0008] The convection heat dissipation coefficient is imported into the first model to obtain the 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. 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.

[0009] Preferably, building a motor model includes: The structures of the Stirling generator and the cylindrical linear motor are obtained; an initial model is constructed according to the structures of the Stirling generator and the cylindrical linear motor; and the initial model is simplified to obtain a motor model.

[0010] 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 the preset value and treating them as direct contact; eliminating heat transfer in the gaps between components; deleting the fillets and chamfers of each component; and processing the surface of each component to be flat and without depressions.

[0011] Preferably, obtaining a fluid domain model of a confined 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 the overall fluid domain model; the 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.

[0012] Preferably, the convective heat dissipation coefficient obtained by performing CFD simulation according to the fluid domain model includes: Set the velocity of the fluid motion boundary according to the actual motion mode of the cylindrical linear motor; disable the energy equation for solving the fluid temperature rise in the CFD simulation; split the fluid domain model into sub-fluid domains; the sub-fluid domains include the concentric tube area, the stationary end face area, the moving end face area, and the linear motor housing area.

[0013] 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 and 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.

[0014] Preferably, obtaining 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.

[0015] Preferably, obtaining the 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 mesh; the loss is equivalent to uniform loss and applied to the mesh nodes of the corresponding heat source components; the heat generation rate is applied on average to the mesh nodes of the corresponding heat source components; and the first model is obtained.

[0016] Preferably, 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, obtaining the motor operating temperature rise includes: 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; with the first data set as the ambient temperature, 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 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.

[0017] Preferably, 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 subfluid domain is obtained according to the steady-state temperature distribution; the average temperature of the contact surface between the cylindrical linear motor and each subfluid domain is obtained according to the temperature distribution of the subfluid domain, and the first data set is obtained by integration; the average temperature includes the average temperature of all grid nodes in the subfluid domain.

[0018] Preferably, 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.

[0019] In the static end face area, take the average temperature at the position above or below the preset distance.

[0020] In the moving end surface area, take the average temperature at the position above or below the preset distance.

[0021] In the linear motor casing area, the average temperature at a preset distance radially outward from the casing is taken.

[0022] The present invention also provides a closed space temperature rise assessment device for a cylindrical linear motor for Stirling, which is used in the method of the present invention. The device includes a first module, a second module, a third module and a fourth module.

[0023] The first module is used to build a motor model; based on the motor model, a fluid domain model of a confined space is obtained; and based on the fluid domain model, CFD simulation is performed to obtain the convection heat dissipation coefficient.

[0024] 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.

[0025] The third module is used to perform steady-state thermal simulation according to the first model based on the 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.

[0026] The fourth module is used to import the convection heat dissipation coefficient into the first model to obtain the second model; using the steady-state temperature distribution as the initial temperature distribution, 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.

[0027] The present invention has the following beneficial effects: The method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling of the present invention combines the calculation accuracy of the flow velocity of the CFD simulation method with the characteristic of the small amount of calculation of the finite element method. While considering the influence of the temperature rise of the fluid in the confined space of the Stirling generator on the heat dissipation of the linear motor, the method performs simulation by successively superimposing the static temperature rise and the dynamic temperature rise in two steps, which reduces the amount of simulation calculation and realizes a more accurate temperature rise evaluation of the Stirling generator and its internal fluid domain and the linear motor. The convection heat dissipation boundary conditions are updated through repeated iterations, the calculation errors caused by the constant boundary are avoided, and the calculation accuracy of the two-step simulation is improved. The method of the present invention realizes the temperature rise evaluation of the confined space of the cylindrical linear motor in the free piston Stirling generator.

[0028] The closed space temperature rise evaluation device of the cylindrical linear motor for Stirling of the present invention is used in the method of the present invention and has the same beneficial effects as the method of the present invention.

[0029] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic cross-sectional structural diagram of a moving-magnetic free-piston Stirling generator according to a preferred embodiment of the present invention.

[0031] Figure 2 It is a schematic cross-sectional structural diagram of a moving coil free piston Stirling generator according to a preferred embodiment of the present invention.

[0032] Figure 3 It is a schematic diagram of a method flow of a preferred embodiment of the present invention.

[0033] Figure 4 It is a simplified model of a moving-magnetic Stirling generator and a schematic diagram of a quarter of a fluid domain model according to a preferred embodiment of the present invention.

[0034] Figure 5 It is a simplified model of a moving coil Stirling generator and a schematic diagram of one quarter of a fluid domain model according to a preferred embodiment of the present invention.

[0035] Figure 6 It is a schematic diagram of the flow velocity distribution in the local fluid domain of the dynamic magnet motor according to the preferred embodiment of the present invention.

[0036] Figure 7 Schematic diagram of flow velocity distribution in a local fluid domain of a moving coil motor according to a preferred embodiment of the present invention.

[0037] Figure 8 1 is a schematic diagram of the overall steady-state temperature of a moving-magnet Stirling generator according to a preferred embodiment of the present invention.

[0038] Figure 9 1 is a schematic diagram of the steady-state overall fluid domain temperature of a moving-magnet Stirling generator according to a preferred embodiment of the present invention.

[0039] Figure 10 1 is a schematic diagram of the overall steady-state temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0040] Figure 11 1 is a schematic diagram of the steady-state winding temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0041] Figure 12 1 is a schematic diagram of the steady-state rotor temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0042] Figure 13 1 is a schematic diagram of the steady-state permanent magnet temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0043] Figure 14 1 is a schematic diagram of the steady-state internal stator temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0044] Figure 15 1 is a schematic diagram of the steady-state external stator temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0045] Figure 16 1 is a schematic diagram of the steady-state overall temperature of a moving-coil Stirling generator according to a preferred embodiment of the present invention.

[0046] Figure 17 1 is a schematic diagram of the steady-state overall fluid domain temperature of a moving-coil Stirling generator according to a preferred embodiment of the present invention.

[0047] Figure 18 1 is a schematic diagram of the overall steady-state temperature of a moving coil linear motor according to a preferred embodiment of the present invention.

[0048] Figure 19 1 is a schematic diagram of the steady-state winding temperature of a moving coil linear motor according to a preferred embodiment of the present invention.

[0049] Figure 20 1 is a schematic diagram of the steady-state permanent magnet temperature of a moving coil linear motor according to a preferred embodiment of the present invention.

[0050] Figure 21 1 is a schematic diagram of the steady-state U-shaped stator temperature of a moving coil linear motor according to a preferred embodiment of the present invention.

[0051] Figure 22 1 is a schematic diagram of the transient overall temperature of a moving-magnet Stirling generator according to a preferred embodiment of the present invention.

[0052] Figure 23 Schematic diagram of transient overall fluid domain temperature of a moving-magnet Stirling generator according to a preferred embodiment of the present invention.

[0053] Figure 24 3 is a schematic diagram of the transient overall temperature of the moving magnet linear motor according to the preferred embodiment of the present invention.

[0054] Figure 25 1 is a schematic diagram of transient winding temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0055] Figure 26 Schematic diagram of transient rotor temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0056] Figure 27 1 is a schematic diagram of the transient permanent magnet temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0057] Figure 28 Schematic diagram of transient internal stator temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0058] Figure 29 1 is a schematic diagram of the transient external stator temperature of a moving magnet linear motor according to a preferred embodiment of the present invention.

[0059] Figure 30 1 is a schematic diagram of the transient overall temperature of a moving coil Stirling generator according to a preferred embodiment of the present invention.

[0060] Figure 31 Schematic diagram of transient overall fluid domain temperature of a moving coil Stirling generator according to a preferred embodiment of the present invention.

[0061] Figure 32 1 is a schematic diagram of the transient overall temperature of the moving coil linear motor according to a preferred embodiment of the present invention.

[0062] Figure 33 1 is a schematic diagram of transient winding temperature of a moving coil linear motor according to a preferred embodiment of the present invention.

[0063] Figure 34 1 is a schematic diagram of the transient permanent magnet temperature of the moving coil linear motor according to the preferred embodiment of the present invention.

[0064] Figure 35 1 is a schematic diagram of the transient U-shaped stator temperature of a moving coil linear motor according to a preferred embodiment of the present invention.

[0065] Figure 36 1 is a schematic diagram of the temperature of the cylinder connecting frame of the moving coil Stirling generator according to the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0066] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0067] In the preferred embodiment of the present invention, a moving magnet free piston Stirling generator and a moving coil free piston Stirling generator are used as examples for analysis. The two types of free piston Stirling generators and cylindrical linear motors mentioned above are only some of the preferred embodiments of the present invention.

[0068] See also Figure 1 The moving magnet free piston Stirling generator uses a single-phase dual-stator moving magnet cylindrical linear motor as the power generation component. Figure 1Among them, A1 is the hot end of the Stirling generator, A2 is the cold end of the Stirling generator, A3 is the gas distribution piston, A4 is the regenerator, A5 is the cylinder, A6 is the wear-resistant lubrication ring, A7 is the cylinder fixing frame, A8 is the power piston, A9 is the moving magnet cylindrical linear motor, A10 is the power piston connecting frame, A11 is the power piston leaf spring, A12 is the gas distribution piston leaf spring gasket, A13 is the gas distribution piston leaf spring, A14 is the voice coil motor fixing ring, A15 is the gas distribution piston rod, A16 is the voice coil motor connecting frame, A17 is the voice coil motor, A18 is the Stirling generator casing, and A19 is the Stirling generator base. In the moving magnet cylindrical linear motor, A91 is the inner and outer stator connecting frame, A92 is the outer stator of the motor, A93 is the motor winding, A94 is the motor casing, A95 is the inner stator of the motor, A96 is the permanent magnet of the motor, and A97 is the motor mover.

[0069] See also Figure 2 The moving coil free piston Stirling generator uses a single-phase dual permanent magnet moving coil cylindrical linear motor as the power generation component. Figure 2 In the figure, B1 is the hot end of the Stirling generator, B2 is the cold end of the Stirling generator, B3 is the valve piston, B4 is the regenerator, B5 is the cylinder, B6 is the 7-pin terminal, B7 is the power piston, B8 is the 1-pin terminal, B9 is the moving coil cylindrical linear motor, B10 is the power piston connector, B11 is the cylinder connector, B12 is the counterweight copper ring, B13 is the power piston leaf spring connector, B14 is the power piston leaf spring, B15 is the displacement sensor, B16 is the valve piston leaf spring washer, B17 is the valve piston leaf spring, B18 is the valve piston rod, B19 is the Stirling generator housing, and B20 is the Stirling generator base. In the moving coil cylindrical linear motor, B91 is the moving coil motor U-shaped stator, B92 is the permanent magnet connector, B93 is the permanent magnet, B94 is the motor winding, and B95 is the motor mover.

[0070] See also Figure 3 In a preferred embodiment of the present invention, a method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling is provided, comprising: S1. Build a motor model; obtain a fluid domain model of the enclosed space based on the motor model; perform CFD simulation based on the fluid domain model to obtain the convection heat dissipation coefficient; obtain the loss and heat generation rate of the heat source components; and obtain a first model based on the motor model, the fluid domain model, and the loss and heat generation rate.

[0071] In a preferred embodiment of the present invention, building a motor model includes: The structures of the Stirling generator and the cylindrical linear motor are obtained; an initial model is constructed according to the structures of the Stirling generator and the cylindrical linear motor; and the initial model is simplified to obtain a motor model.

[0072] 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 the preset value and treating them as direct contact; eliminating heat transfer in the gaps between components; deleting the fillets and chamfers of each component; and processing the surface of each component to be flat and without depressions.

[0073] In a preferred embodiment of the present invention, the motor model is built using the mechanical design software ANSYS SpaceClaim 2022 R1.

[0074] In a preferred embodiment of the present invention, obtaining a fluid domain model of a confined space based on a motor model includes: Based on the motor model, the fluid in the enclosed space inside the Stirling generator casing is modeled to obtain the overall fluid domain model; considering that the overall fluid domain model is too large, it would take a lot of time to directly import it into CFD software for analysis. Therefore, based on the overall fluid domain model, a local fluid domain model between the cylindrical linear motor and the Stirling generator casing is intercepted; at the same time, since the Stirling generator and the linear motor are overall axisymmetric structures, the flow velocity of the fluid is also symmetrically distributed, and one-fourth of the local fluid domain model is intercepted longitudinally to obtain the fluid domain model. Fluid domain model can be found in Figures 4 and 5 ,in Figure 4 This is a simplified model of a moving-magnet Stirling generator and a quarter of the fluid domain model. Figure 5 The simplified model of the moving coil Stirling generator and the model of one quarter of the fluid domain are shown in FIG. In a preferred embodiment of the present invention, the internal fluid of the Stirling generator is 2 MPa helium.

[0075] In a preferred embodiment of the present invention, the convective heat dissipation coefficient obtained by performing CFD simulation based on the fluid domain model includes: The 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 disabled to reduce the computational cost. The temperature rise during the fluid motion is ignored, and the fluid motion is regarded as constant temperature flow. The simulation obtains the fluid velocity distribution at a normal temperature of 22°C.

[0076] The fluid domain model is divided into sub-domains; these sub-domains include the concentric tube region, the stationary end face region, the moving end face region, and the linear motor housing region. CFD simulations are performed on these sub-domains to determine the velocity distribution of each sub-domain. The convective heat dissipation coefficient is derived from the velocity distribution of each sub-domain, combined with the empirical formula for the Nusselt number of each sub-domain. This convective heat dissipation coefficient includes the convective heat dissipation coefficient between the cylindrical linear motor and the contact surface of each sub-domain.

[0077] In a preferred embodiment of the present invention, setting the movement speed of the fluid movement boundary includes: ; in, is the velocity of the boundary between the mover and the fluid domain, For time.

[0078] In a preferred embodiment of the present invention, a fluid domain model of one-quarter of the overall fluid domain model is imported into ANSYSFluent 2022 R1, transient analysis is turned on, and the energy equation solving function is turned off to avoid solving the temperature rise of the fluid motion process. The temperature rise of the fluid during the motion process is not considered, and only the flow velocity distribution after the fluid flows steadily is solved. Subsequently, the dynamic grid function of the software is used to set the motion boundary of the fluid domain and the corresponding motion speed. In this embodiment, the speed of the motion boundary of the fluid domain inside the two types of Stirling generators is equivalent to the motion speed of the two types of linear motor rotors. After setting the speed of the fluid domain motion boundary in the dynamic grid, run the simulation software to calculate the flow velocity distribution of the fluid. In order to obtain the velocity distribution after stable flow, the simulation time in the embodiment is set to 2 cycles, that is, 0.04s. After the simulation is completed, the flow velocity distribution of the 1 / 4 fluid domain model of the two types of Stirling generators is obtained. Figures 6 and 7 ,in, Figure 6 is the velocity distribution of the local fluid domain of the dynamic magnet motor, Figure 7 Velocity distribution of the local fluid domain of the moving coil motor.

[0079] In a preferred embodiment of the present invention, the convection heat dissipation coefficient includes: ; in, 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 fluid dynamic viscosity; is the Grashof number; is the Prandtl number; is the Nusselt number, and the Reynolds number , Grashov number and Prandtl number Combined with the empirical formula to solve the problem; is the thermal conductivity of the fluid; is the fluid convection heat dissipation coefficient.

[0080] Stirling generators have two internal convective heat dissipation modes: forced convection and natural convection. Factors such as the type of fluid, its flow rate, and the shape and size of the interface between the motor and the fluid domain determine the type of convective heat dissipation. In a preferred embodiment of the present invention, the sub-fluid domains include the concentric tube region, the stationary end face region, the moving end face region, and the linear motor housing region. Considering the convective heat dissipation coefficients of the above four sub-fluid domains: (1) Concentric tube area, characteristic length is the difference between the inner and outer diameters: ; in, is the outer diameter of the concentric tube, is the inner diameter of the concentric tube.

[0081] (2) In the static end face area, the convective heat dissipation is approximated as a fluid sweeping a flat plate, with a characteristic length It is the length of the fluid-swept flat plate, which is the radial length of the static end face in the present invention.

[0082] (3) Move the end face area and approximate its convective heat dissipation as a fluid passing through a special shaped object with a characteristic length It is the difference between the inner and outer diameters of the moving end face.

[0083] (4) The linear motor housing area, where the convection heat dissipation is approximately natural convection heat dissipation, and the characteristic length is the axial length of the linear motor housing.

[0084] In the preferred embodiment of the present invention, the dynamic viscosity of helium is 2Mpa is 19.7 μPa·s, 3.2544 kg / m 3 , thermal conductivity is 0.15483W / m·℃, Prandtl number is 0.661. The convection heat dissipation calculation areas of the two types of Stirling generators and linear motors are respectively Figure 4 and Figure 5 For a moving-magnet Stirling generator, C1 and C2 are the concentric tube regions, C3 and C4 are the stationary end-face regions, C5, C6, and C7 are the moving end-face regions, and C8 is the moving-magnet linear motor housing region. For a moving-coil Stirling generator, D1 and D2 are the concentric tube regions, D3 and D4 are the stationary end-face regions, D5, D6, and D7 are the moving end-face regions, and D8 is the moving-coil linear motor housing region.

[0085] In a preferred embodiment of the present invention, for a moving-magnet Stirling generator, in order to calculate the convection heat dissipation coefficients of its four sub-fluid domains, it is necessary to determine the empirical formula of its Nusselt number: In a moving-magnet Stirling generator: The empirical formulas for the Nusselt number corresponding to the concentric tube area include: ; in, and are the Nusselt numbers corresponding to the inner and outer walls of the concentric tube, and are the Nusselt number influence coefficients of the inner wall and the outer wall, respectively, and are 5.385 in the embodiment of the present invention. and The influence coefficient is also 0.346 in the embodiment of the present invention. and are the heat flux densities of the inner and outer walls, which can be positive or negative and are considered equal in the embodiment of the present invention.

[0086] The empirical formulas for the Nusselt number corresponding to the stationary end face area include: ; The empirical formulas for the Nusselt number corresponding to the moving end face area include: ; For the linear motor housing area, natural convection heat dissipation is considered, and the corresponding Nusselt number empirical formula includes: ; in, is the Rayleigh number; is the acceleration due to gravity, take the acceleration due to gravity as 9.81m / s 2 ; 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 .

[0087] In a moving-magnet Stirling generator: 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: ; in, is the friction factor for a smooth surface.

[0088] 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.

[0089] 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: Table 1 Calculation results of convection heat dissipation coefficient of moving-magnet Stirling generator ; Table 2 Calculation results of convection heat dissipation coefficient of moving coil Stirling generator ; In a preferred embodiment of the present invention, obtaining the loss and heat generation rate of the heat source component includes: 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 simulated and solved. 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, which serves as the heat source for the motor. In a preferred embodiment of the present invention, the heat generation rate includes: ; in, is the heat generation rate, is the loss of the corresponding component, is the volume of the corresponding component.

[0090] In a preferred embodiment of the present invention, ANSYS Electronics Desktop 2022 R1 was used to build electromagnetic field simulation models for a moving-magnet cylindrical linear motor and a moving-coil cylindrical linear motor. Because these two types of motors are axisymmetric, the electromagnetic field models can be simplified to two dimensions to reduce computational complexity. The volumes of the key components of these two linear motors can be directly determined using the modeling software ANSYS SpaceClaim 2022 R1. The heat generation rates of the windings, stator, and permanent magnets under rated operating conditions can then be calculated. The calculation results are shown in Tables 3 and 4: Table 3 Heat generation rate of key components of moving magnet linear motor ; Table 4 Heat generation rate of key components of moving coil linear motor ; In a preferred embodiment of the present invention, obtaining the first model based on 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 mesh; the loss is equivalent to uniform loss and applied to the mesh nodes of the corresponding heat source components; the heat generation rate is applied on average to the mesh nodes of the corresponding heat source components; and the first model is obtained.

[0091] In a preferred embodiment of the present invention, the steady-state thermal calculation module in ANSYS Workbench 2022 R1 was used to import the motor model and the overall fluid domain model, and the model mesh was partitioned. The number of mesh nodes for the moving-magnet Stirling generator was 1,405,182, and the number of mesh nodes for the moving-coil Stirling generator was 2,394,717. The heat generation rates of the windings, stator, and permanent magnets are given in Tables 3 and 4 and can be directly entered into the software.

[0092] S2. Perform a steady-state thermal simulation according to the first model based on the 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.

[0093] In a preferred embodiment of the present invention, when performing steady-state thermal simulation, the convective heat dissipation of the contact surface between the cylindrical linear motor and the fluid domain is eliminated, and it is regarded as stationary inside the Stirling generator. The heat is generated only by the copper loss, iron loss, eddy current loss of key components, and the temperature of the hot and cold ends of the Stirling generator to achieve thermal equilibrium with the outside of the Stirling generator casing.

[0094] In a preferred embodiment of the present invention, a linear motor continuously moves within a Stirling generator. Losses in key components and the temperatures at the hot and cold ends of the Stirling generator are the fundamental causes of internal temperature rise. Convection heat dissipation directly affects the temperature distribution. The heat transfer process for convection heat dissipation can be explained by Newton's law of heat transfer, including the first calculation formula: ; in, The heat transfer due to convection is is the convection heat dissipation coefficient, is the area of ​​the convection heat dissipation wall, is the temperature of the convection heat dissipation wall, is the external ambient temperature.

[0095] In the first calculation formula, the convection heat dissipation coefficient is known. If the heat transfer of convection heat dissipation is to be obtained, the temperature difference between the heat dissipation wall and the external environment must be obtained. If this temperature difference is not obtained through actual experimental testing, and if the ambient temperature is arbitrarily set to a normal temperature of 22°C, the final temperature distribution and the actual temperature distribution will inevitably be significantly different. Therefore, based on the first condition, a steady-state thermal simulation is performed according to the first model to obtain a steady-state temperature distribution; the steady-state temperature distribution is used as the initial temperature distribution for subsequent transient thermal simulations, and the temperature of the convection heat dissipation wall is obtained from the steady-state temperature distribution. and external ambient temperature , replace the external environment temperature in the first calculation formula with Replace with .

[0096] For Stirling generators, the enclosed space inside is filled with fluid and has no direct contact with the external environment or the cold end, which makes it difficult to dissipate heat inside the Stirling generator. The linear motor movement process generates copper loss, iron loss, and permanent magnet eddy currents that continuously transfer heat to the internal fluid of the Stirling. However, the fluid cannot transfer heat to the outside in time, so the temperature continues to rise. For linear motors, the way they transfer heat to the fluid is convection heat dissipation, and the transfer process can be explained by the first calculation formula. As can be seen from the first calculation formula, the ambient temperature It is one of the key conditions for determining the convective heat transfer. If the motor is directly placed in the outside air, the ambient temperature can be directly regarded as the normal temperature of 22°C. However, the linear motor in the present invention is in the closed space inside the Stirling generator. Its ambient temperature should be regarded as the temperature of the convection heat transfer calculation area on each contact surface between the linear motor and the local fluid domain, which is recorded as the reference temperature. Obviously As the initial condition, it is closer to the operating condition of the motor when it is stationary than directly using the normal temperature of 22℃ as the initial condition.

[0097] In the preferred embodiment of the present invention, the convection heat dissipation coefficient of the two types of linear motors is set to 0W / m 2 ℃, the heat dissipation between the Stirling generator casing and the outside world is set to 15W / m 2 ℃. For steady-state thermal simulation temperature distribution of two types of Stirling generators and linear motors, see Figures 8 to 21 .

[0098] S3. Import the convection heat dissipation coefficient into the first model to obtain the second model; use the steady-state temperature distribution as the initial temperature distribution, perform transient thermal simulation according to the second model, and use 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 to obtain the motor operating temperature rise.

[0099] In a preferred embodiment of the present invention, the convective heat dissipation coefficient is imported into the first model, that is, the convective heat dissipation coefficients of the four types of sub-fluid domains are input into the corresponding sub-fluid domains in the first model.

[0100] In a preferred embodiment of the present invention, a steady-state temperature distribution is used as the initial temperature distribution, a transient thermal simulation is performed according to the second model, and the simulation result is 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. 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 the first data set; the first data set is taken 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.

[0101] In a preferred embodiment of the present invention, the transient temperature distribution of the motor specifically includes the transient temperature distribution of the Stirling generator, the entire fluid domain of the Stirling generator, and the linear motor.

[0102] In the preferred embodiment of the present invention, the temperature distribution of the two types of Stirling generators and linear motors in transient thermal simulation is shown in FIG. Figures 22 to 35 .Will Figures 8 to 21 Transient thermal simulation temperature distribution and Figures 22 to 35 The temperature distribution of the transient thermal simulation is compared with that of the linear motor. The final temperature obtained by the transient thermal simulation is slightly higher than that of the linear motor, stator, permanent magnet, etc. The overall temperature fluctuation does not exceed 5°C. However, it is not difficult to find that the temperature distribution of the linear motor, stator, permanent magnet and other structures has changed. Without considering the influence of convection heat dissipation, the temperature values ​​obtained by the steady-state thermal simulation and the transient thermal simulation are close. The difference lies in the temperature distribution differences on each component. Figure 32 and Figure 18 Compared with the steady-state thermal simulation without considering convection heat dissipation, the winding temperature obtained by transient thermal simulation is more concentrated in the center of the moving coil linear motor. Figure 33 As shown, the winding surface temperature is more uniform, with the overall maximum and minimum temperatures decreasing by 4.45°C and 2.87°C, respectively, a relatively small decrease. This result further illustrates the impact of convection on temperature distribution and demonstrates that steady-state thermal simulation results can provide initial conditions for transient thermal simulations that are closer to actual operating conditions.

[0103] In a preferred embodiment of the present invention, 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 obtained includes: The temperature distribution of the subfluid domain is obtained according to the steady-state temperature distribution; the average temperature of the contact surface between the cylindrical linear motor and each subfluid domain is obtained according to the temperature distribution of the subfluid domain, and the first data set is obtained by integration; the average temperature includes the average temperature of all grid nodes in the subfluid domain.

[0104] In a preferred embodiment of the present invention, 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.

[0105] In the static end face area, take the average temperature at the position above or below the preset distance.

[0106] In the moving end surface area, take the average temperature at the position above or below the preset distance.

[0107] In the linear motor casing area, the average temperature at a preset distance radially outward from the casing is taken.

[0108] In a preferred embodiment of the present invention, in the transient thermal calculation module of ANSYS Workbench 2022 R1, the time step is set to 1200s and the total simulation time is set to 7200s, wherein an automatic time substepping method is adopted in each time step, and there are 1 to 10 substeps in the time step, which are automatically calculated by the software.

[0109] The method for evaluating the temperature rise in a confined space of a cylindrical linear motor for Stirling of the present invention combines the calculation accuracy of the flow velocity of the CFD simulation method with the characteristic of the small amount of calculation of the finite element method. While considering the influence of the temperature rise of the fluid in the confined space of the Stirling generator on the heat dissipation of the linear motor, the method performs simulation by successively superimposing the static temperature rise and the dynamic temperature rise in two steps, which reduces the amount of simulation calculation and realizes a more accurate temperature rise evaluation of the Stirling generator and its internal fluid domain and the linear motor. The convection heat dissipation boundary conditions are updated through repeated iterations, the calculation errors caused by the constant boundary are avoided, and the calculation accuracy of the two-step simulation is improved. The method of the present invention realizes the temperature rise evaluation of the confined space of the cylindrical linear motor in the free piston Stirling generator.

[0110] In a preferred embodiment of the present invention, a closed space temperature rise assessment device for a cylindrical linear motor for Stirling is provided, which is used in the method of the present invention. The device includes a first module, a second module, a third module and a fourth module.

[0111] The first module is used to build a motor model; based on the motor model, a fluid domain model of a confined space is obtained; and based on the fluid domain model, CFD simulation is performed to obtain the convection heat dissipation coefficient.

[0112] 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.

[0113] The third module is used to perform steady-state thermal simulation according to the first model based on the 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.

[0114] The fourth module is used to import the convection heat dissipation coefficient into the first model to obtain the second model; using the steady-state temperature distribution as the initial temperature distribution, 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.

[0115] The closed space temperature rise evaluation device of the cylindrical linear motor for Stirling of the present invention is used in the method of the present invention and has the same beneficial effects as the method of the present invention.

[0116] Verification part: To further illustrate the advantages of the method of the present invention, the following compares conventional simulation results with experimentally measured temperatures near the stator of a linear motor. Conventional simulation results refer to the use of the same model as the transient thermal simulation of the embodiment of the present invention, with the same time step settings as the embodiment of the present invention, but with room temperature of 22°C as the convection heat dissipation reference temperature in each time step. , and then the transient thermal temperature distribution of conventional simulation is obtained. The temperature of some nodes is compared with the results obtained by the method of the present invention, that is, Figure 4 The C1, C2, C4, and C8 areas in Figure 5 The results of D1, D2, D3 and D8 are listed in Table 5 and Table 6. As can be seen from the table, the conventional method uses 22℃ as the reference temperature for convection heat dissipation. The temperature obtained is significantly lower than that obtained by the method of the present invention, with the maximum temperature difference being 32.19°C. This result shows that different reference temperatures This will result in a large difference in the temperature distribution obtained by convection heat dissipation. For the motor of the present invention, it is difficult to obtain the temperature of various locations inside the motor by direct measurement, which makes it difficult to determine the specific convection heat dissipation reference temperature. , the final simulated temperature must have obvious errors.

[0117] Table 5 Comparison of simulation results of moving-magnet Stirling generator ; Table 6 Comparison of simulation results of moving coil Stirling generator ; The simulation results are compared with the experimental test results. The test results are for a moving coil Stirling generator with a motor cylinder connecting frame, i.e. Figure 2 Put a temperature test paper on B11 in the figure, and run it for a period of time under rated working conditions. Figure 36 , the temperature displayed by the test paper is about 50℃. Figure 5At position D8, it can be seen from the comparison results in Table 6 that the simulated temperature is 48.06°C, which is within 3°C of the temperature shown on the test paper. However, considering that the simulation uses the copper loss, iron loss and permanent magnet eddy current generated by the linear motor as heat sources, the heat generated by the mechanical loss of the Stirling generator is not considered. Therefore, the obtained simulation temperature is lower than the test paper test result. This result shows that the method of the present invention does not require the prior measurement of the internal temperature of the motor. It provides an initial condition close to the static working condition through steady-state thermal simulation, and updates the reference temperature in real time during the transient thermal simulation process. , taking into account the influence of fluid temperature rise in a confined space on convective heat dissipation, avoiding the errors caused by artificially setting convective heat dissipation conditions in conventional methods, and ensuring calculation accuracy while reducing the amount of calculation.

[0118] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

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 confined 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.

Images