Method for constructing magnetic part thermal simulation model of DCDC converter

Abstract

The invention relates to a method for constructing a thermal simulation model of a magnetic part of a DCDC converter, which comprises the following steps of: S1, establishing a magnetic core framework three-dimensional model, a magnetic core side three-dimensional model and a coil three-dimensional model aiming at loss areas of the magnetic part, and dividing a heat conduction area between the loss areas into a plurality of virtual areas according to different heat conduction surfaces, in contact with the loss areas, of the heat conduction area, establishing a virtual area three-dimensional model; s2, performing grid division on the three-dimensional model, and setting temperature monitoring points; s3, defining a material attribute for the three-dimensional model of the loss area, and calculating an equivalent heat conductivity coefficient of each virtual area according to the thickness and the heat conductivity coefficient of the pouring sealant layer, the insulating layer or the hole in each virtual area; and S4, setting boundary conditions, and setting and calculating a solver to obtain the simulation temperature of the temperature monitoring point. According to the method, partition modeling is carried out on different loss areas and heat conduction areas between the loss areas, loss is given according to the power consumption distribution condition, and the accurate thermal simulation model can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal simulation, and particularly to a method for constructing a thermal simulation model of magnetic components of a DCDC converter. Background Art

[0002] The DCDC converter is an important device in the power system of new energy vehicles. Its function is to convert the high-voltage direct current in the power battery into low-voltage direct current for the operation of low-voltage electrical equipment. In the DCDC converter, the power losses of magnetic components such as transformers and inductors are large and the heat generation is serious. If the temperature is too high, it will affect the output efficiency and even cause the device to explode. Therefore, during the development of DCDC products, it is necessary to focus on monitoring and controlling the working temperature of magnetic components. The CAE software can handle complex heat conduction problems and predict the actual effect at the design stage. Through thermal simulation, the temperature change of the product under working conditions can be simulated, and the accuracy of the simulation depends to a large extent on the fineness of the model and the accuracy of the boundary conditions. In the current thermal simulation of DCDC products, the traditional method treats the magnetic core skeleton, the side of the magnetic core, and the coil in the transformer and inductor as an integrated structure and assigns losses to the whole. However, the actual loss distribution should be concentrated on the magnetic core skeleton, and there is basically no loss on the side of the magnetic core. In addition, the influence of the holes inside the magnetic core and the insulating film between the magnetic core and the coil is ignored, and potting glue is directly filled between the coil and the magnetic core to simplify the model and facilitate calculation. However, the simulation results obtained by this treatment method often deviate greatly from the measured values. Because in the actual state, the thermal resistance of the internal holes and insulating tapes is relatively large, which has a significant impact on the heat dissipation of the internal magnetic core and coil. If factors such as holes and insulating tapes are ignored in the simulation, the measured result will be higher in temperature than the simulation result, which will cause the actual product to fail to meet the established power requirements, and at the same time, there will be a risk of losing efficiency due to excessive temperature and even damaging the product. Summary of the Invention

[0003] An embodiment of the present invention provides a method for constructing a thermal simulation model of magnetic components of a DCDC converter to solve the problem in the prior art that the simulation result deviates greatly from the measured value because the transformer and inductor are given losses as a whole and the surrounding area is set as potting glue as a whole, ignoring the internal holes and insulating film.

[0004] To achieve the above object, the embodiment of the present invention provides the following technical solutions:

[0005] A method for constructing a thermal simulation model of magnetic components of a DCDC converter includes:

[0006] S1. For the loss regions of each magnetic component, establish a core skeleton solid model, a core side solid model, and a coil solid model respectively. Divide the heat conduction regions between the loss regions into multiple virtual regions according to the different heat conduction surfaces in contact with the loss regions, establish a virtual region solid model for each virtual region, and import them into a thermal simulation software.

[0007] S2. Perform mesh division on the solid models and set temperature monitoring points in the loss regions.

[0008] S3. Define the material properties of the solid models in the loss regions, and calculate the equivalent thermal conductivity of each virtual region according to the thickness and thermal conductivity of the potting glue layer, insulation layer, or holes in each virtual region.

[0009] S4. Set the boundary conditions, solver settings and calculations to obtain the simulated temperatures of the temperature monitoring points.

[0010] Further, in S1, the heat conduction regions between the loss regions are divided into a first virtual region between the core and the coil, a second virtual region between the coils, a third virtual region on the surface of the magnetic component, and a fourth virtual region outside the surface of the magnetic component.

[0011] Further, the calculation method of the equivalent thermal conductivity of the virtual regions in S3 includes:

[0012] The total thermal resistance Rt of the virtual region = (ha / Ka + hb / Kb + hc / Kc) / A;

[0013] The equivalent thermal conductivity Kt of the virtual region = (ha + hb + hc) / (Rt·A);

[0014] In the formula, A is the heat transfer area (which can take a unit area of 1㎡);

[0015] ha is the thickness of the potting glue layer, in mm;

[0016] hb is the thickness of the insulation layer, in mm;

[0017] hc is the thickness of the holes, in mm;

[0018] Ka is the thermal conductivity of the potting glue layer, in W / (m·K);

[0019] Kb is the thermal conductivity of the insulation layer, in W / (m·K);

[0020] Kc is the thermal conductivity of the holes, in W / (m·K);

[0021] Rt is the total thermal resistance of the virtual region, in K / W;

[0022] $K_t$ is the equivalent thermal conductivity of the virtual region, with the unit of W / (m·K).

[0023] Further, the boundary conditions in S4 include ambient temperature, coolant medium, coolant temperature, coolant flow rate, and power consumption of each loss region.

[0024] Further, model calibration is performed on the simulated temperatures of the temperature monitoring points obtained in S4. The method of model calibration includes: comparing the simulated temperature of the temperature monitoring point in step S4 with the measured temperature of the temperature monitoring point. If the simulated temperature is lower than the measured temperature by more than the set threshold, then reduce the thermal conductivity of the virtual region associated with this temperature monitoring point; conversely, if the simulated temperature is higher than the measured temperature by more than the set threshold, then increase the thermal conductivity of the virtual region associated with this temperature monitoring point.

[0025] Further, the method for specifically adjusting the virtual region parameters in the model calibration includes: comparing the absolute value of the difference between the simulated temperature and the measured temperature of all temperature monitoring points, and for the virtual region associated with the temperature monitoring point with the largest absolute value of the difference and exceeding the error judgment threshold; if the difference is negative, then reduce the thermal conductivity of the virtual region corresponding to this temperature monitoring point; if the difference is positive, then increase the thermal conductivity of the virtual region corresponding to this temperature monitoring point.

[0026] The embodiments of the present invention have the following advantages:

[0027] A method for constructing a magnetic component thermal simulation model of a DCDC converter according to the present invention performs partitioned modeling on different loss regions during the modeling process, assigns losses respectively according to the power consumption distribution, and divides the heat conduction regions between the loss regions into multiple virtual regions according to the different heat conduction surfaces in contact with the loss regions, and fills them with multi-layer virtual materials, and defines the thermal conductivity of the virtual material layers respectively to equivalently simulate the combined effect of holes, insulating tapes, and potting layers. Moreover, this modeling method does not increase the number of grids and the amount of calculation, but can greatly improve the simulation accuracy.

[0028] A method for constructing a magnetic component thermal simulation model of a DCDC converter according to the present invention performs model calibration on the obtained thermal simulation results based on the comparison between the measured results, and continuously iteratively optimizes the input parameters of the thermal simulation, and finally can obtain an accurate thermal simulation model. Description of the Drawings

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained according to the provided drawings.

[0030] The structures, proportions, sizes, etc. illustrated in this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the implementation conditions of the present invention. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention.

[0031] Figure 1 It is a method flow chart of a method for constructing a magnetic component thermal simulation model of a DCDC converter provided by an embodiment of the present invention;

[0032] Figure 2 It is a structural diagram of the magnetic components of a DCDC converter in a method for constructing a magnetic component thermal simulation model of a DCDC converter provided by an embodiment of the present invention;

[0033] Figure 3 It is a simulation contour map obtained with conventional thermal simulation parameters;

[0034] Figure 4 It is a simulation contour map obtained by a method for constructing a magnetic component thermal simulation model of a DCDC converter provided by an embodiment of the present invention;

[0035] Figure 5 It is a simulation contour map after model calibration of a method for constructing a magnetic component thermal simulation model of a DCDC converter provided by an embodiment of the present invention;

[0036] Figure 6 It is a simulation contour map after re - simulation by modifying the boundary conditions of a method for constructing a magnetic component thermal simulation model of a DCDC converter provided by an embodiment of the present invention.

[0037] In the figure:

[0038] 1. First virtual area of the transformer; 2. Second virtual area of the transformer; 3. First virtual area of the inductor; 4. Second virtual area of the inductor; 5. Third virtual area; 6. Fourth virtual area; 7. Transformer magnetic core skeleton; 8. Transformer magnetic core side; 9. Primary coil of the transformer; 10. Secondary coil of the transformer; 11. Inductor magnetic core skeleton; 12. Inductor magnetic core side; 13. Inductor coil. Specific embodiments

[0039] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] As Figure 1 shown, a method for constructing a thermal simulation model of a magnetic component of a DCDC converter includes the following steps:

[0041] S1. For each loss region of the magnetic component, respectively establish a three-dimensional model of the magnetic core skeleton, a three-dimensional model of the side of the magnetic core, and a three-dimensional model of the coil, and divide the heat conduction regions between the loss regions into multiple virtual regions according to the different heat conduction surfaces in contact with the loss regions, and establish a three-dimensional model of each virtual region and import it into the thermal simulation software.

[0042] The loss regions of the magnetic component include the magnetic core and the coil. Since the actual loss distribution is concentrated on the magnetic core skeleton and there is basically no loss on the side of the magnetic core, the loss region of each magnetic component is split into a three-dimensional model of the magnetic core skeleton, a three-dimensional model of the side of the magnetic core, and a three-dimensional model of the coil. Also, since the porosity inside the magnetic component is relatively high and the surfaces of the magnetic core and the coil are both coated with insulating films, which will result in a large difference in thermal resistance inside and outside the potting region. Accordingly, the heat conduction regions outside the loss regions such as the magnetic core and the coil are divided into multiple virtual regions, a three-dimensional model of each virtual region is established, and it is imported into the thermal simulation software.

[0043] The division criteria for the virtual regions: different heat conduction surfaces in contact with the loss regions, that is, different numbers and / or positions of the heat conduction surfaces, can be divided into a first virtual region between the magnetic core and the coil, a second virtual region between the coils, a third virtual region on the surface layer of the magnetic component, and a fourth virtual region outside the surface layer of the magnetic component.

[0044] Specifically, both sides of the first virtual region are in contact with the coil and the magnetic core respectively. It can be the region between the magnetic core and the coil of the same magnet, or the region between the coil and the magnetic core between adjacent magnets.

[0045] Both sides of the second virtual region are in contact with the coils respectively. It can be the region between the coils of the same magnet, or the region between the coils between adjacent magnets.

[0046] The third virtual region is the outer shell of the magnetic core and the coil, that is, the third virtual region is the region in contact with the magnetic core or the coil on one side.

[0047] The fourth virtual region is the potting glue region outside the surface layer of the magnetic component, and the potting glue region is only in contact with the third virtual region.

[0048] As shown Figure 2 in the figure, the transformer is on the left side and the inductor is on the right side in this figure. Since there are two magnets, namely the transformer and the inductor, in this structure, they need to be divided separately. Specifically, for the transformer, the regions between the transformer core and the primary coil of the transformer, and between the transformer core and the secondary coil of the transformer are both the first virtual regions of the transformer, and the region between the primary coil and the secondary coil of the transformer is the second virtual region of the transformer. For the inductor, the region between the inductor core and the inductor coil is the first virtual region of the inductor, and the region between the inductor coils is the second virtual region of the inductor. The outer shell of the transformer and the inductor is the third virtual region, and the conventional potting glue region outside the outer shell is the fourth virtual region. After such division, the material parameters of each virtual region can be dynamically adjusted to custom parameters, so as to characterize the comprehensive thermal performance of the potting glue under the combined influence of the insulating film and the holes in the actual product. The above three-dimensional module can be modeled by three-dimensional modeling software (such as Creo, SolidWorks, CATIA, etc.) and small features (such as chamfers, bolt holes) can be removed to reduce the calculation amount.

[0049] S2. Perform mesh division on the three-dimensional model and set temperature monitoring points for the loss regions.

[0050] The mesh division includes: setting the mesh unit length of both the loss region and the virtual region to 1 mm, the mesh length of the remaining regions is adaptive, and temperature monitoring points are selected to monitor the key positions of the loss regions such as the core and the coil. Since the number of model regions increases in this technology, but the set mesh unit length remains unchanged, the number of meshes will not increase significantly. And the calculation amount of thermal simulation is mainly related to the number of meshes. Therefore, this technology will not increase the number of meshes on the basis of refining the model.

[0051] S3. Define the material properties for the three-dimensional model of each loss region, and calculate the equivalent thermal conductivity of the virtual region according to the thickness and thermal conductivity of the potting glue layer, insulating layer or holes in each virtual region.

[0052] The material properties include thermal conductivity, thickness, heat transfer area. If the material properties change significantly with temperature (such as semiconductor materials), multiple sets of data points or fitting formulas need to be input.

[0053] The materials in the virtual regions are different, that is, different materials have different thermal conductivities. If the materials in the same virtual region are different, the virtual region needs to be divided into different regions according to the material changes, and a three-dimensional model needs to be established for each region. In practice, there are holes in the inner layers of the transformer and the inductor. The thermal resistance of the holes is extremely large, and there is an insulating film attached to the surface of the coil and the magnetic component. The insulating film will increase the thermal resistance. Therefore, if there is a potting glue layer, insulating layer or hole in the same virtual region, the influence of the potting glue layer, insulating layer and hole on heat conduction needs to be discussed.

[0054] As the insulating film in the prior art is getting thinner and thinner, it is difficult to establish an accurate model for the insulating film and to perform mesh division, and the porosity is not easy to predict, so it is impossible to establish an accurate model for the holes. Therefore, in this technology, it is not necessary to establish a three-dimensional model for different material layers separately. Instead, the equivalent parameters of the region after the superposition of each material layer in this region are obtained through theoretical calculation, which are used to replace the comprehensive effect of each material layer. According to the thickness of the potting glue layer, insulating layer or holes in each virtual region and their respective thermal conductivities, the theoretical calculation formula for calculating the equivalent thermal conductivity of this virtual region is as follows:

[0055] The total thermal resistance Rt of the virtual region = (ha / Ka + hb / Kb + hc / Kc) / A;

[0056] The equivalent thermal conductivity Kt of the virtual region = (ha + hb + hc) / (Rt·A);

[0057] In the formula, A is the heat transfer area (the unit area of 1㎡ can be taken);

[0058] ha is the thickness of the potting glue layer, with the unit of mm;

[0059] hb is the thickness of the insulating layer, with the unit of mm;

[0060] hc is the thickness of the holes, with the unit of mm;

[0061] Ka is the thermal conductivity of the potting glue layer, with the unit of W / (m·K);

[0062] Kb is the thermal conductivity of the insulating layer, with the unit of W / (m·K);

[0063] Kc is the thermal conductivity of the holes, with the unit of W / (m·K);

[0064] Rt is the total thermal resistance of the virtual region, with the unit of K / W;

[0065] Kt is the equivalent thermal conductivity of the virtual region, with the unit of W / (m·K).

[0066] As Figure 2 shown in the example, there are a potting glue layer, an insulating layer, and holes in both the first virtual region and the second virtual region of the transformer (left side) and the inductor (right side). There are a potting glue layer and an insulating layer in both the third virtual region and the fourth virtual region. In this embodiment, through the theoretical calculation of the potting glue layer, insulating layer, and holes in different regions, the equivalent parameters of the first virtual region and the second virtual region are obtained respectively, and through the theoretical calculation of the potting glue layer and the insulating layer in different regions, the equivalent parameters of the third virtual region and the fourth virtual region are obtained respectively.

[0067] S4. Set boundary conditions, and then the solver is set and calculated to obtain the simulated temperature of the monitoring points in the loss area.

[0068] In this technology, the boundary conditions include: ambient temperature, coolant medium, coolant temperature, coolant flow rate, and power consumption of each loss area.

[0069] In this technology, the thermal analysis module of Flotherm XT software is used to solve the problem according to the default program to control the solver, and the simulated temperature of the monitoring points in the loss area is obtained. The temperature distribution cloud map can be displayed to intuitively know the temperature of the monitoring points.

[0070] Due to the complex internal structure of the magnetic component and the non-simple radial linear conduction of the heat transfer path, theoretical calculation cannot fully reflect the actual situation. Therefore, in this technology, the simulated temperature of the temperature monitoring points obtained in S4 is calibrated for the model, and the virtual material parameters are corrected according to the temperature trend and difference.

[0071] The method of the model calibration includes:

[0072] Compare the simulated temperature of the temperature monitoring points in step S4 with the measured temperature of the temperature monitoring points. If the simulated temperature is lower than the measured temperature by more than the set threshold, it means that the simulated thermal resistance in the virtual area corresponding to this temperature monitoring point is less than the actual thermal resistance, then reduce the thermal conductivity of the virtual area associated with this temperature monitoring point; on the contrary, if the simulated temperature is higher than the measured temperature by more than the set threshold, it means that the simulated thermal resistance in the virtual area corresponding to this temperature monitoring point is greater than the actual thermal resistance, then increase the thermal conductivity of the virtual area associated with this temperature monitoring point.

[0073] In the model calibration, by comparing the difference between the simulated temperature and the measured temperature of all temperature monitoring points, the simulation error of the local virtual area associated with this temperature monitoring point can be detected, and then the parameters of this local virtual area are adjusted. The specific adjustment method is as follows:

[0074] Compare the absolute value of the difference between the simulated temperature and the measured temperature of all temperature monitoring points. For the virtual area associated with the temperature detection point with the largest absolute value of the difference and exceeding the error judgment threshold; if the difference is negative, reduce the thermal conductivity of the virtual area corresponding to this temperature monitoring point; if the difference is positive, increase the thermal conductivity of the virtual area corresponding to this temperature monitoring point.

[0075] Specifically as follows:

[0076] The first virtual area: If the absolute value of the temperature difference between the simulated temperature and the measured temperature of the magnetic core skeleton or the side of the magnetic core is the largest among the absolute values of the differences of all temperature monitoring points and this absolute value of the difference exceeds the error judgment threshold, if the difference is negative, reduce the thermal conductivity of the first virtual area; on the contrary, if the difference is positive, increase the thermal conductivity of the first virtual area.

[0077] Second virtual region: If the absolute value of the temperature difference between the simulated temperature and the measured temperature of the coil is the largest among the absolute values of the differences at all temperature monitoring points and exceeds the error judgment threshold, if the difference is negative, then reduce the thermal conductivity of the second virtual region; conversely, if the difference is positive, then increase the thermal conductivity of the second virtual region.

[0078] Third virtual region: If the difference average value is obtained after accumulating the differences at all temperature detection points, if the difference average value exceeds the error judgment threshold and is negative, then reduce the thermal conductivity of the third virtual region; conversely, if the difference average value exceeds the error judgment threshold and is positive, then reduce the thermal conductivity of the third virtual region.

[0079] Fourth virtual region: The thermal conductivity of the fourth region is the actual material parameter and is not adjusted.

[0080] A method for constructing a magnetic component thermal simulation model of a DCDC converter provided by the present technology is compared with the existing thermal simulation methods, and the specific steps are as follows:

[0081] Adopt the DCDC converter structure as shown in Figure 2 , where the transformer is on the left and the inductor is on the right.

[0082] Boundary conditions: The ambient temperature is 25°C;

[0083] The coolant is a 50% ethylene glycol aqueous solution with a flow rate of 8 L / min;

[0084] The coolant temperature is 65°C;

[0085] The DCDC power is 3.5 kW, the input voltage is 380 V, and the output voltage is 14 V.

[0086] Components Power consumption / W Components Power consumption / W Transformer core skeleton 6.1 Transformer primary coil 7.7 Transformer core side 0.6 Transformer secondary coil 5.0 Inductor core skeleton 0.02 Inductor winding 22.26 Inductor core side 0.01

[0087] Table 1 Power consumption of each component under these boundary conditions

[0088] Conventional method: Set the external regions of the transformer and the inductor as potting glue, and the thermal conductivity is 2 W / (m·K) for both, and the obtained simulation cloud diagram is as shown in Figure 3 , and the results are recorded in Table 2. The obtained simulation temperature is generally lower than the actual situation, and the error exceeds 10% in all cases, with the highest reaching 24.1%.

[0089]

[0090]

[0091] Table 2 Simulation situations of each component obtained with conventional parameters

[0092] Method of the present technology:

[0093] Combined with the previous example, the material properties of the potting adhesive layer, insulation layer, and holes in the first virtual region of the transformer, the second virtual region of the transformer, the first virtual region of the inductor, the second virtual region of the inductor, the third virtual region, and the fourth virtual region are shown in Table 3.

[0094]

[0095] Table 3 Material properties of the potting adhesive layer, insulation layer, and holes in each virtual region

[0096] According to the above table, calculate the equivalent thermal conductivity of the first virtual region of the transformer, the second virtual region of the transformer, the first virtual region of the inductor, the second virtual region of the inductor, the third virtual region, and the fourth virtual region respectively, and obtain:

[0097] The thermal conductivity A2 of the first virtual region of the transformer is 0.02 W / (m·K);

[0098] The thermal conductivity B2 of the second virtual region of the transformer is 0.46 W / (m·K);

[0099] The thermal conductivity C2 of the first virtual region of the inductor is 0.27 W / (m·K);

[0100] The thermal conductivity D2 of the second virtual region of the inductor is 0.32 W / (m·K);

[0101] The thermal conductivity E2 of the third virtual region is 0.92 W / (m·K);

[0102] The thermal conductivity F2 of the fourth virtual region is 2 W / (m·K).

[0103] The obtained simulation cloud map is as Figure 4 shown, and the thermal simulation results are entered into Table 4.

[0104] Components Simulated temperature / °C Measured temperature / °C Difference / °C Error Transformer core 112.02 118.4 -6.38 5.39％ Transformer primary 102.71 111.1 -8.39 7.55％ Transformer secondary 96.198 97.2 -1.002 1.03％ Inductor core 106.45 110.2 -3.75 3.40％ Inductor winding 111.33 111.5 -0.17 0.15％

[0105] Table 4 Simulation conditions of each component obtained by the technical method of the present invention

[0106] As shown in Table 4, when the present technology takes into account the potting adhesive layer, insulation layer, and holes, the simulation temperature increases significantly, and at the same time, the accuracy is also greatly improved, and the error is less than 10%. It can be seen that the insulating film and holes have a significant impact on the heat dissipation of the magnetic component and cannot be ignored.

[0107] Due to the complex internal structure of the magnetic component and the non-simple radial linear conduction of the heat transfer path, theoretical calculations cannot fully reflect the actual situation, and it is still necessary to perform multiple simulation feedbacks and correct the virtual material parameters according to the temperature trend and difference. Therefore, based on the above data, model calibration can be carried out to increase the accuracy of thermal simulation.

[0108] Correction parameters for model calibration:

[0109] The thermal conductivity of the first virtual region of the transformer An = 0.01 W / (m·K),

[0110] The thermal conductivity of the second virtual region of the transformer Bn = 0.2 W / (m·K),

[0111] The thermal conductivity of the first virtual region of the inductor Cn = 0.5 W / (m·K),

[0112] The thermal conductivity of the second virtual region of the inductor Dn = 0.5 W / (m·K),

[0113] The thermal conductivity of the third virtual region En = 0.8 W / (m·K),

[0114] The thermal conductivity of the fourth virtual region F2 = 2 W / (m·K).

[0115] The obtained simulation cloud diagram is as Figure 5 shown, and the thermal simulation results are entered in Table 5.

[0116]

[0117]

[0118] Table 5 Simulation conditions of each component obtained after model calibration of this technology

[0119] As shown in Table 5, the error between the simulation data and the measured data is less than 5% at this time, and the thermal simulation model at this time is the optimal model.

[0120] The thermal simulation model obtained by using this method is verified again, as follows:

[0121] Modify the boundary conditions: The DCDC structure remains unchanged, the operating condition of DCDC becomes 2.5 kW, the input voltage is 380 V, the output voltage is 14 V, the ambient temperature is 25 °C, and the coolant temperature is 25 °C. The thermal simulation is carried out using the method of this technology, and its input loss becomes as shown in Table 6 below.

[0122] Components Power consumption / W Components Power consumption / W Transformer core middle column 6.1 Transformer primary 7.7 Transformer core side column 0.6 Transformer secondary 3.4 Inductor core middle column 0.02 Inductor winding 11.44 Inductor core side column 0.01

[0123] Table 6 Input losses of each component after modifying the boundary conditions

[0124] Adopt the equivalent thermal conductivity of each virtual region as follows:

[0125] The thermal conductivity of the first virtual region of the transformer An = 0.01 W / (m·K);

[0126] The thermal conductivity of the second virtual region of the transformer Bn = 0.2 W / (m·K);

[0127] The thermal conductivity coefficient Cn of the first virtual region of the inductor is 0.5 W / (m·K);

[0128] The thermal conductivity coefficient Dn of the second virtual region of the inductor is 0.5 W / (m·K);

[0129] The thermal conductivity coefficient En of the third virtual region is 0.8 W / (m·K);

[0130] The thermal conductivity coefficient F2 of the fourth virtual region is 2 W / (m·K).

[0131] The obtained simulation nephogram is as Figure 6 shown, and the thermal simulation results are entered into Table 7.

[0132]

[0133]

[0134] Table 7 Simulation conditions of each component obtained by the technical model

[0135] According to Table 7, the simulated temperature will be obtained and compared with the new round of working condition tests, and the error can still be kept less than 5%, indicating that the model is reliable.

[0136] Although the present invention has been described in detail above with general descriptions and specific embodiments, on the basis of the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A method for constructing a thermal simulation model of magnetic components of a DC-DC converter, characterized in that: S1. For each loss area of the magnetic component, respectively establish a three-dimensional model of the magnetic core skeleton, a three-dimensional model of the side of the magnetic core, and a three-dimensional model of the coil, and divide the heat conduction area between the loss areas into multiple virtual areas according to the different heat conduction surfaces in contact with the loss areas, and establish a three-dimensional model of each virtual area, and import it into the thermal simulation software; S2. Perform mesh division on the three-dimensional model, and set temperature monitoring points for the loss areas; S3. Define the material properties of the three-dimensional model of the loss area, and calculate the equivalent thermal conductivity of the virtual area according to the thickness and thermal conductivity of the potting glue layer, insulation layer or hole in each virtual area; S4. After setting the boundary conditions, set and calculate the solver to obtain the simulated temperature of the temperature monitoring points.

2. The method for constructing a magnetic component thermal simulation model of a DCDC converter according to claim 1, wherein: In the above S1, the heat conduction area between the loss areas is divided into a first virtual area between the magnetic core and the coil, a second virtual area between the coils, a third virtual area on the surface of the magnetic component, and a fourth virtual area outside the surface of the magnetic component.

3. The method for constructing a magnetic component thermal simulation model of a DCDC converter according to claim 1, wherein, The calculation method of the equivalent thermal conductivity of the virtual area in the above S3 includes: The total thermal resistance Rt of the virtual area = (ha / Ka + hb / Kb + hc / Kc) / A; The equivalent thermal conductivity Kt of the virtual area = (ha + hb + hc) / (Rt·A); In the formula, A is the heat transfer area (which can take a unit area of 1㎡); ha is the thickness of the potting glue layer, in mm; hb is the thickness of the insulation layer, in mm; hc is the thickness of the hole, in mm; Ka is the thermal conductivity of the potting glue layer, in W / (m·K); Kb is the thermal conductivity of the insulation layer, in W / (m·K); Kc is the thermal conductivity of the hole, in W / (m·K); Rt is the total thermal resistance of the virtual area, in K / W; Kt is the equivalent thermal conductivity of the virtual area, in W / (m·K).

4. A method for constructing a thermal simulation model of a magnetic component of a DCDC converter according to claim 1, characterized in that: The boundary conditions in the above S4 include the ambient temperature, the coolant medium, the coolant temperature, the coolant flow rate, and the power consumption of each loss area.

5. A method for constructing a thermal simulation model of a magnetic component of a DCDC converter according to claim 1, characterized in that, Perform model calibration on the simulated temperature of the temperature monitoring points obtained in S4. The method of the model calibration includes: Compare the simulated temperature of the temperature monitoring points in step S4 with the measured temperature of the temperature monitoring points. If the simulated temperature is lower than the measured temperature by more than the set threshold, then reduce the thermal conductivity of the virtual area associated with this temperature monitoring point; On the contrary, if the simulated temperature is higher than the measured temperature by more than the set threshold, then increase the thermal conductivity of the virtual area associated with this temperature monitoring point.

6. The method for constructing a magnetic component thermal simulation model of a DCDC converter according to claim 5, characterized in that, The method for adjusting the specific virtual area parameters in the above model calibration includes: comparing the absolute value of the difference between the simulated temperature and the measured temperature of all temperature monitoring points, and for the virtual area associated with the temperature detection point with the largest absolute value of the difference and exceeding the error judgment threshold; If the difference is negative, then reduce the thermal conductivity of the virtual area corresponding to this temperature monitoring point; If the difference is positive, then increase the thermal conductivity of the virtual area corresponding to this temperature monitoring point.

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