A multi-parameter collaborative design optimization method of an induction coil transverse magnetic heating system

Abstract

The application discloses a kind of multi-parameter collaborative design optimization methods of induction coil transverse magnetic heating system, belong to metal material induction heating technical field.The method first defines induction coil safety, system power consumption and so on check index and workpiece temperature related optimization goal, based on electromagnetic-thermal coupling finite element analysis method constructs finite element simulation model, the parameters of three aspects of electricity, coil, heat dissipation are integrated, through multiple rounds of iterative optimization, each parameter is adjusted to meet the requirements of workpiece average temperature and temperature uniformity, while checking induction coil current density, voltage, temperature and system power density.The application overcomes the limitations of traditional design parameters isolation, realizes heating process visualization, reduces design failure and cost, considers system reliability and low operating cost, strong universality, can be adapted to different workpieces and production needs.

Description

Technical Field

[0001] This invention belongs to the field of metal material induction heating technology, and relates to a multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system. Background Technology

[0002] Transverse magnetic induction heating is a highly efficient induction heating method widely used in precision industrial processes such as heat treatment of metal sheets and semiconductor crystal growth. Its basic principle is to generate a transverse magnetic field in an induction coil using alternating current, which forms eddy currents on the surface of the workpiece, thereby generating heat. During transverse magnetic induction heating, the magnitude of the input current and frequency directly determines the heating efficiency of the workpiece. Too low a current or frequency may result in insufficient heating efficiency to meet production cycle requirements, while too high a frequency may exceed the system's power consumption constraints, leading to coil overheating or even damage to the entire induction heating system. The shape, size, and positional distribution of the induction coil significantly affect the distribution of the electromagnetic field, which is fundamental to ensuring heating uniformity and preventing localized overheating of the workpiece.

[0003] Currently, the design of induction heating systems mainly involves the design of electrical parameters and the design of coil parameters. The former, based on existing induction heating coils, designs and controls electrical parameters such as current, frequency, and total power. The latter, given known electrical parameters, designs the shape, size, or location distribution of the induction coil, typically using segmented coils or altering the coil profile to compensate for temperature unevenness caused by sharp corner effects, and adjusting the local magnetic field strength by changing the coil turns density. However, the overall performance of an induction heating system is the result of the combined effects of coil parameters, electrical parameters, and heat dissipation parameters. Existing design methods often consider these factors in isolation, neglecting their coupling relationships. Induction heating systems designed based on a single objective lack adaptability for different materials, specifications, or production cycle requirements, necessitating complex redesign and trial-and-error processes.

[0004] Chinese patent application CN114861504A discloses an induction heating magnetic circuit design method and apparatus. The method includes: confirming the design parameters of the induction heating coil for the target heating object; establishing an induction heating model based on the design parameters; setting the appearance, size, structural parameters, electrical parameters, and material properties of the induction heating model; and performing 3D calculations based on the induction heating model to obtain a 3D design cloud map. Using this embodiment of the invention, a 3D design cloud map of the induction heater is obtained. This cloud map can be used to accurately design an induction heating coil that conforms to the target heating object, meeting the requirements of efficiency, accuracy, and versatility in induction heating coil design.

[0005] The parameters included in this patent application are coil parameters (number of turns, wire diameter, coil diameter, coil spacing), electrical parameters (power supply, operating current, operating frequency), and material properties. Its design requirements only include "meeting the efficiency, accuracy, and versatility requirements of induction heating coil design." The patent application does not constrain or optimize the safety of the induction coil or the system power consumption.

[0006] Therefore, there is an urgent need in this field for a systematic design method that can comprehensively coordinate various parameters of the induction heating system, while meeting production cycle requirements, taking into account the temperature uniformity of the workpiece, the safety of the long-term operation of the induction heating system, and the system power consumption requirements. Summary of the Invention

[0007] This invention aims to address the shortcomings of existing induction coil transverse magnetic heating system design methods, such as systematic deficiencies, singular objectives, and poor adaptability. It provides a design method that can synergistically optimize multiple parameters, thereby significantly improving system safety and reducing power consumption while ensuring highly uniform temperature of the heated workpiece.

[0008] This invention provides a multi-parameter collaborative design optimization method for an induction coil transverse magnetic heating system, comprising: Step 1: determining verification indicators and optimization target parameters, wherein the verification indicators include safety constraints and system power consumption constraints during the induction coil heating process, and the optimization target parameters include the target temperature and target temperature difference of the heated workpiece; Step 2: constructing a finite element simulation model composed of a geometric model and a theoretical model based on the electromagnetic-thermal coupling finite element analysis method; establishing the geometric model: establishing a geometric structure composed of an induction coil, cooling water, workpiece, and air, assigning material properties to the geometric structure and dividing it into meshes; establishing the theoretical model: for the... The geometric model introduces physical fields including magnetic field, temperature field and electromagnetic thermal field, sets boundary conditions, and inputs initial parameters. The initial parameters include electrical parameters including initial excitation current I0 and initial frequency f0, coil parameters including initial coil outer diameter D0, initial coil length L0, initial total number of turns N0, initial turn spacing S0 between adjacent coils and initial air gap distance G0 between the coil and the outer surface of the workpiece, and heat dissipation parameters including initial cooling water flow velocity v0. Step 3: Determine the synergistic relationship and iterative optimization logic between the electrical parameters, coil parameters and heat dissipation parameters, perform simulation calculations and adjustments, and determine the final design scheme.

[0009] In one specific implementation, the safety constraints in step 1 consider parameters including the allowable current density, allowable voltage, and allowable temperature of the induction coil, and the system power consumption constraints consider parameters including the allowable power density of the system.

[0010] In one specific implementation, step 2 includes the following steps: Step 2.1: Establish a geometric structure composed of an induction coil, cooling water, workpiece, and air; input coil parameters; initially construct an initial finite element simulation model; require the air portion to completely cover the induction coil and workpiece; and set an infinite element domain of appropriate thickness at the outermost edge of the air. Step 2.2: Set corresponding material properties for the induction coil, cooling water, workpiece, and air in the initial finite element simulation model, including density, relative permittivity, relative permeability, thermal conductivity, constant pressure heat capacity, reference resistivity, resistivity temperature coefficient, linear resistivity, and reference temperature. Step 2.3: Introduce a magnetic field into the initial finite element simulation model; apply an initial excitation current I0 to the induction coil; set the initial frequency f0 of the excitation current; and set boundary conditions for the initial finite element simulation model: set the magnetic potential of the outer edge of the infinite element domain to zero. Step 2.4: Set the initial finite element simulation... The model introduces a temperature field, setting both air and the infinite element domain as empty elements. Only the temperature fields of the workpiece, induction coil, and cooling water are calculated. Boundary conditions are set for the initial finite element simulation model: the initial temperature of the initial finite element simulation model is set to room temperature. Radiation and convection heat exchange are set between the workpiece and the air in contact with the surface of the induction coil. The heat exchange of the cooling water flow in the induction coil is equivalently treated as heat exchange from a fixed heat source. A heat source is directly set inside the induction coil. The initial cooling water flow velocity v0 is input, and the heat flux density of the inner wall of the induction coil is calculated. Step 2.5: The magnetic field and temperature field are coupled into an electromagnetic thermal field. Step 2.6: The geometry in the initial finite element simulation model is meshed. The outermost layer of the induction coil and the boundary layer on the workpiece near the induction coil are meshed. The mesh on the side of the workpiece near the induction coil is divided into boundary layers. The thickness of the boundary layer is taken as the skin depth of induction heating. The construction of the finite element simulation model is completed.

[0011] In one specific implementation, the heat flux density q of the inner wall of the induction coil in step 2.4 is calculated by the following formula: (1) (2) (3)

[0012] In the formula, D is the outer diameter of the coil, δ is the coil wall thickness, L is the coil length, Q is the cooling water heat dissipation, and p m C is the mass flow rate of the cooling water. p ρ is the specific heat capacity of the cooling water, Δt is the temperature change of the cooling water, ρ is the density of the cooling water, and v is the flow rate of the cooling water; the heat flux density q on the inner wall of the induction coil is adjusted by changing the flow rate v of the cooling water.

[0013] In one specific implementation, the skin depth δ in step 2.6 i Calculated using the following formula: (4)

[0014] In the formula, Let f be the resistivity of the workpiece, f be the frequency of the excitation current, and μ0 be the vacuum permeability. -7 H / m, μ r Let be the relative permeability of the workpiece.

[0015] In one specific implementation, step 3 includes the following steps: Step 3.1: Solve the finite element simulation model of the workpiece induction heating established in step 2 to obtain the average temperature of the workpiece after induction heating; Step 3.2: When the finite element simulation results show that the difference between the average temperature of the workpiece and the target temperature exceeds a certain value, adjust the excitation current I or the frequency f to change the average temperature of the workpiece after heating; specifically, if the average temperature of the workpiece is lower than the target temperature by a certain value, increase the excitation current I or the frequency f; conversely, decrease the excitation current I or the frequency f; when the finite element simulation results show that the difference between the average temperature of the workpiece and the target temperature does not exceed a certain value, adjust the excitation current I or the frequency f to change the average temperature of the workpiece after heating; When the value exceeds a certain threshold, no parameters need to be changed, proceed directly to the next step; Step 3.3: Extract and verify the current density and voltage of the induction coil to ensure the safety of the entire system; Specifically, if the current density exceeds the allowable current density, increase the outer diameter D of the coil; if the voltage of the induction coil exceeds the allowable voltage, increase the frequency f or decrease the total number of turns N; if neither the current density nor the voltage of the induction coil exceeds the allowable value, no parameters need to be adjusted; Perform simulation calculations on the finite element simulation model to obtain the workpiece temperature distribution curve; Step 3.4: Observe the workpiece temperature distribution curve calculated in Step 3.3, when the workpiece temperature... When the temperature distribution curve shows that the maximum temperature difference of the workpiece is greater than the target temperature difference, adjust the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece to reduce the maximum temperature difference of the workpiece. Specifically, increase the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece for the heat collection point, and decrease the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece for the cold point. When the temperature distribution curve of the workpiece shows that the maximum temperature difference of the workpiece is less than or equal to the target temperature difference, no parameters need to be changed, and proceed directly to the next step. Step 3.5: Check the coil temperature. Specifically, check the temperature distribution curve of the induction coil. Extraction and verification are performed. If the temperature of the induction coil at any point exceeds the allowable temperature, increase the cooling water flow rate v or the coil outer diameter D, or decrease the total number of turns N to ensure that the temperature of the induction coil is below the allowable temperature. If the temperature of the induction coil at any point does not exceed the allowable temperature, no parameters need to be changed, and proceed directly to the next step. Step 3.6: Calculate the system power density based on the simulation data. If it exceeds the allowable power density, reduce the excitation current I, coil length L, total number of turns N, or coil outer diameter D to reduce the system power density. If the system power density does not exceed the allowable power density, output the final system design parameters and end the iteration.

[0016] The certain values ​​in steps 3.2 to 3.6 of this invention are generally determined by the user, for example, ±10℃ or ±5℃.

[0017] In one specific implementation, if any coil parameter is adjusted in steps 3.2 to 3.6, the geometric model needs to be updated before calculating the finite element simulation model; if the coil parameter is not adjusted, the geometric model does not need to be updated, and the finite element simulation model can be calculated directly.

[0018] In one specific implementation, in step 3.4, if the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece changes, the finite element simulation model is simulated and calculated to obtain the workpiece temperature distribution curve; if the average workpiece temperature extracted from the workpiece temperature distribution curve obtained in step 3.4 deviates from the target temperature by a certain value, then return to step 3.2, otherwise proceed directly to the next step.

[0019] In one specific implementation, in step 3.5, if the cooling water flow rate v, the coil outer diameter D, or the total number of turns N changes, the finite element simulation model is used for simulation calculation to obtain the workpiece temperature distribution curve again. If the workpiece temperature distribution curve obtained in step 3.5 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, it is necessary to return to step 3.2 for adjustment and recalculation. If the workpiece temperature distribution curve obtained in step 3.5 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, the next step is directly performed. In step 3.6, if the excitation current I, the coil length L, the total number of turns N, or the coil outer diameter D changes, the finite element simulation model is used for simulation calculation to obtain the workpiece temperature distribution curve again. If the workpiece temperature distribution curve obtained in step 3.6 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, it is necessary to return to step 3.2 for adjustment and recalculation. If the workpiece temperature distribution curve obtained in step 3.6 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, the final design parameters of the system are directly output.

[0020] In one specific implementation, the system power density q in step 3.6 w Calculated using the following formula: (5)

[0021] In the formula, P is the power of the induction coil, and A is the surface area of ​​the part of the workpiece being heated.

[0022] Compared with the prior art, the present invention has the following advantages: (1) It integrates three aspects: electrical, coil geometry and layout, and heat dissipation. It incorporates eight key parameters, namely excitation current I, frequency f, coil outer diameter D, coil length L, total number of turns N, spacing between adjacent coil turns S, air gap distance G between the coil and the outer surface of the workpiece, and cooling water flow rate v, into a unified framework for collaborative design, overcoming the limitations of the traditional method of viewing parameters in isolation. (2) Through finite element simulation, it is possible to predict the comprehensive performance under different parameter combinations before manufacturing the physical object, realizing the visualization of the temperature distribution in the induction heating process, which helps to reduce design errors of such induction coils and reduce design costs. (3) By introducing safety constraints and system power consumption constraints as verification indicators, it ensures that the final design not only meets the performance standards, but also has high reliability and low operating costs in engineering practice, realizing the leap from "optimal single performance" to "optimal comprehensive efficiency". (4) It can quickly adjust the input conditions for iterative solution according to different workpieces and production requirements, and has good universality and promotion value.

[0023] In summary, this invention achieves comprehensive optimization of the temperature uniformity of the heated workpiece, the safety of the induction coil, and the power consumption of the system by synergistically optimizing multiple physical parameters, while meeting the production cycle requirements. Attached Figure Description

[0024] Figure 1 This is an iterative logic diagram of the multi-parameter collaborative design optimization method for the induction coil transverse magnetic heating system with a steel plate workpiece in the embodiment.

[0025] Figure 2 This is a two-dimensional finite element simulation model diagram of the steel plate-planar helical coil in the embodiment.

[0026] Figure 3 This is a finite element simulation model diagram of the steel plate under three iterations in the embodiment.

[0027] Figure 4 This example shows the workpiece temperature distribution before and after optimization of the steel plate heating system.

[0028] Explanation of reference numerals in the attached diagram: 1. Air; 2. Infinite elemental domain; 3. Induction coil; 4. Cooling water; 5. Steel plate. Detailed Implementation

[0029] To facilitate those skilled in the art in accurately grasping the technical solutions disclosed in this specification, the technical solutions in each embodiment will be clearly and comprehensively described below in conjunction with the accompanying drawings. It should be noted that the embodiments presented herein are only some embodiments of this application and not all of its technical implementations.

[0030] In this invention, the induction coil transverse magnetic heating system is usually referred to as the system, the induction coil is usually referred to as the coil, and the workpiece being heated is usually referred to as the workpiece.

[0031] A large-diameter 45# steel plate is used as the workpiece in this embodiment of the invention. Figure 1 The figure shows the iterative logic of the multi-parameter collaborative design optimization method for the transverse magnetic heating system of steel plate induction coil.

[0032] Reference Figure 1 Step 1 is to determine the verification index and the optimization target parameters.

[0033] Step 2 is to establish a finite element model of the workpiece for induction heating, and input the initial parameters I0, f0, D0, L0, N0, S0, G0 and v0.

[0034] Step 3.1 is to solve the finite element model of the workpiece induction heating to obtain the average temperature of the workpiece.

[0035] Step 3.2 involves comparing the average temperature of the workpiece with the target temperature, and adjusting the excitation current I or frequency f based on the comparison results.

[0036] Step 3.3 is to check the current density and voltage of the induction coil. First, determine whether the current density is greater than the allowable current density: if yes, increase the outer diameter D of the coil and then return to step 3.1; if no, continue to determine whether the voltage of the induction coil is greater than the allowable voltage: if yes, increase the frequency f or decrease the total number of turns N and then return to step 3.1; if no, output the workpiece temperature distribution curve and proceed to the next step.

[0037] Step 3.4 compares the maximum temperature difference of the workpiece with the target temperature difference, and adjusts the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece based on the comparison result. If the comparison result shows a change in the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece, the finite element simulation model is calculated to determine whether the average temperature of the workpiece deviates from the target temperature by a certain value: if yes, return to step 3.2; if no, proceed to the next step. If the comparison result shows no change in either the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece, proceed directly to the next step.

[0038] Step 3.5 compares the temperature at any point on the coil with the allowable temperature, and adjusts the coil outer diameter D, cooling water flow rate v, or total number of turns N based on the comparison result. If the comparison result shows a change in the coil outer diameter D, cooling water flow rate v, or total number of turns N, the finite element simulation model is calculated to determine whether the average temperature of the workpiece deviates from the target temperature by a certain value: if yes, return to step 3.2; if no, proceed to the next step. If the comparison result shows no change in the coil outer diameter D, cooling water flow rate v, and total number of turns N, proceed directly to the next step.

[0039] Step 3.6 compares the system power density with the allowable power density, and adjusts the excitation current I, coil length L, total number of turns N, or coil outer diameter D based on the comparison result. If the comparison result shows changes in the excitation current I, coil length L, total number of turns N, or coil outer diameter D, the finite element simulation model is calculated to determine whether the average workpiece temperature deviates from the target temperature by a certain value: if yes, return to step 3.2; if no, output the final system design parameters and end the iteration. If the comparison result shows no changes in the excitation current I, coil length L, total number of turns N, and coil outer diameter D, directly output the final system design parameters and end the iteration.

[0040] Figure 2 The figure shown is a two-dimensional finite element simulation model of a steel plate-planar helical coil in the embodiment. 1 represents air, 2 represents an infinite element domain, 3 represents the induction coil, 4 represents cooling water, and 5 represents the steel plate.

[0041] Figure 3 The figure shows the evolution of the finite element simulation model of the steel plate under three iterations in the embodiment.

[0042] Figure 4 The diagram shows the workpiece temperature distribution before and after optimization of the steel plate heating system in this embodiment. The effective temperature zone refers to the area of ​​the workpiece that needs to be heated. (Refer to...) Figure 4 As can be seen, the temperature difference of the optimized workpiece is significantly reduced compared to that before optimization, proving the feasibility of the present invention.

[0043] To better understand the technical solution provided by the present invention, taking the design of an induction coil transverse magnetic heating system for a circular No. 45 steel plate with a diameter of 1.2 m and a thickness of 1.6 mm as an example, this embodiment requires heating the circular No. 45 steel plate to 750°C and holding it at that temperature.

[0044] The design of a circular 45# steel plate induction coil according to an embodiment of the present invention includes the following steps.

[0045] Step 1: Determine the verification indicators and optimization target parameters. The verification indicators include: the current density of the induction coil is lower than the allowable current density of 20 A / mm². 2 The temperature at any point on the induction coil is below the allowable temperature of 85℃, the coil voltage is below the allowable voltage of 2000V, and the system power density is below the allowable power density of 1000kW / m². 2 The optimized target parameters include that the absolute value of the difference between the average temperature of the No. 45 steel plate and the target temperature of 750℃ is less than 5℃, and the maximum temperature difference of the No. 45 steel plate meets the requirement of the target temperature difference (i.e. ±10℃).

[0046] Step 2: Based on the electromagnetic-thermal coupling finite element analysis method, establish a finite element simulation model, including the following steps.

[0047] Step 2.1: Based on the axisymmetry of the circular No. 45 steel plate and the planar helical coil, a two-dimensional axisymmetric finite element simulation model is established using the finite element analysis software COMSOL Multiphysics. The finite element simulation model includes 1 air, 2 infinite element domain, 3 induction coil, 4 cooling water, and 5 steel plate. The air part is required to completely cover the induction coil and the steel plate. An infinite element domain of appropriate thickness is set at the outermost edge of the air. Input the coil parameters, including the initial coil outer diameter D0, the initial coil length L0, the initial total number of turns N0, the initial turn spacing between adjacent coils S0, and the initial air gap distance G0 between the coil and the outer surface of the workpiece. The specific values ​​are D0=10 mm, L0=29.32 m, N0=30, S0=20 mm, and G0=5 mm.

[0048] Step 2.2: Assign material properties to each part of the finite element simulation model (induction coil, cooling water, workpiece, air), defining the density, relative permittivity, relative permeability, thermal conductivity, constant pressure heat capacity, reference resistivity, resistivity temperature coefficient, linear resistivity, and reference temperature of a circular No. 45 steel plate within the temperature range of 20℃-750℃. The material properties of the induction coil, cooling water, and air are read from the built-in materials of COMSOL, namely Copper, H2O, and Air, respectively.

[0049] Step 2.3: Introduce a magnetic field into the finite element simulation model. Input an initial excitation current I0 to the cross-section of the induction coil. Set the outer edge of the infinite element domain to be magnetically insulated, i.e., set the magnetomotive force to zero; set the magnetomotive force to zero on the axis of symmetry. Apply an initial excitation current I0 = 280A to the induction coil and set the initial frequency of the excitation current f0 = 1 kHz.

[0050] Step 2.4: Introduce a temperature field into the finite element simulation model. Set both the air and the infinite element domain as empty elements. Only calculate the temperature fields of the circular 45# steel plate, the induction coil region, and the cooling water. Set the initial temperature of the finite element simulation model to room temperature. Set the circular 45# steel plate and the air in contact with the surface of the induction coil to perform radiation and convection heat exchange. Treat the heat exchange of the cooling water flow in the induction coil as equivalent to the heat exchange of a fixed heat source. Set the heat source directly inside the induction coil. Input the initial cooling water flow velocity v0, specifically v0=2 m / s, and calculate the heat flux density of the inner wall of the induction coil.

[0051] Step 2.5: Couple the magnetic field and temperature field into an electromagnetic thermal field.

[0052] Step 2.6: Mesh the established finite element simulation model, refine the mesh of the induction coil and the boundary layer near the induction coil on the circular 45# steel plate, and divide the boundary layer on the side of the 45# steel plate near the induction coil. The thickness of the boundary layer is taken as the skin depth of induction heating.

[0053] Step 3: Perform simulation calculations and iterative analysis on the induction heating process of a circular No. 45 steel plate, including the following steps.

[0054] Step 3.1: Solve the finite element simulation model established in Step 2 to obtain the average temperature of the workpiece after induction heating.

[0055] Step 3.2: Compare the average temperature of the workpiece with the target temperature, and adjust the excitation current I or frequency f based on the comparison results. Simulation calculations show that the average temperature of the circular No. 45 steel plate after induction heating under initial conditions is 734℃, which is 16℃ lower than the target temperature of 750℃. Therefore, the excitation current I should be appropriately increased while keeping other conditions unchanged, and the calculation should be recalculated. When the excitation current I is adjusted to 290 A, the absolute value of the difference between the average temperature of the circular No. 45 steel plate and the target temperature is less than 5℃, at which point the next step can be performed.

[0056] Step 3.3: Extract and verify the current density and voltage on the induction coil. The extracted induction coil current density is 7.2 A / mm². 2 Less than the allowable current density of 20 A / mm 2 The voltage meets safety requirements, but it is 3310V, which is greater than the allowable voltage of 2000V, posing a risk of circuit breakdown. Therefore, it is adjusted by reducing the total number of turns N. After reducing the total number of turns N to 16 turns, the geometric model is updated and the process returns to step 3.1 for the second round of iteration.

[0057] In the second iteration, at step 3.1, the average temperature of the circular No. 45 steel plate was found to be 478℃. In step 3.2, it was discovered that the average temperature of the steel plate (478℃) deviated from the target temperature of 750℃ by more than 5℃. Therefore, the excitation current I on the induction coil was adjusted to 550 A, ensuring that the absolute value of the difference between the average temperature of the circular No. 45 steel plate and the target temperature was less than 5℃. In step 3.3, the current density on the induction coil was extracted to be 13.7 A / mm². 2 Less than the allowable current density of 20 A / mm 2 The voltage is 1780 V, which is less than the allowable voltage of 2000 V, both of which meet the safety requirements, and the next step can be carried out.

[0058] Step 3.4: Based on the average temperature of the circular No. 45 steel plate, divide it into high-temperature and low-temperature regions. Increase the spacing S between adjacent coil turns of the induction coil in the high-temperature region or the air gap distance G between the coil and the outer surface of the workpiece. Take the opposite measures for the induction coil in the low-temperature region. Keep other conditions unchanged, reconstruct the finite element simulation model and calculate. Output the adjusted temperature distribution map of the circular No. 45 steel plate and the induction coil. It is observed that the maximum temperature difference of the circular No. 45 steel plate is within the target temperature difference (i.e., ±10℃). However, due to the change in the temperature field of the new finite element simulation model, the average temperature of the circular No. 45 steel plate deviates from the target temperature by more than 5℃. Therefore, it is necessary to return to step 3.2 and perform the third round of iteration.

[0059] In the third iteration, at step 3.2, the excitation current I on the induction coil is adjusted to 620A, and the absolute value of the temperature difference between the average temperature of the circular No. 45 steel plate and the target temperature is less than 5℃; in the next iteration, at step 3.3, the current density of the induction coil is extracted to be 15.5 A / mm². 2 Less than the allowable current density of 20 A / mm 2 The voltage is 1560 V, which is less than the allowable voltage of 2000 V, thus meeting the safety requirements. Iterating to step 3.4, the spacing between adjacent coil turns S and the air gap distance G between the coil and the outer surface of the workpiece are adjusted according to the method in step 3.4, resulting in the following data: The spacing between adjacent coil turns from the outermost to the innermost coil of the induction coil is S1=28.8mm, S2=38.8mm, S3=43.8mm, S4=47.7mm, S5=S6=S7=S8=S9=S 10 = S 11 =S 12 =42.7mm, S 13 =S 14 =28.8mm, S 15 =23.8mm, the air gap distances between the induction coil and the steel plate from the outermost to the innermost turn are G1=5mm, G2=13mm, G3=17mm, G4=20mm, G5=25mm, G6=G7=30mm, G8=27mm, G9=25mm, G 10 =20mm, G 11 =15 mm, G 12 =5 mm, G 13 =G 14 =G 15 =2 mm. The maximum temperature difference of the workpiece is within the target temperature difference (±10℃), and the next operation can be carried out.

[0060] Step 3.5: Extract the temperature distribution on the induction coil. At this point, the temperature at any point on the induction coil is less than the allowable temperature of 85°C, and you can proceed directly to the next step.

[0061] Step 3.6: The heating surface area of ​​the steel plate is known to be 1.13 m². 2 Based on the simulation results above, the power required by the induction coil is 484 kW. Using equation (5), the heating power density under this scheme is calculated to be 428 kW / m². 2 This is far below the system's allowable power density of 1000 kW / m³. 2 The iteration can be ended directly.

[0062] The coil optimization design process involved three iterations, resulting in the following parameters for the optimized induction coil: I = 620 A, f = 1 kHz, D = 10 mm, L = 29.32 m, N = 16, v = 2 m / s. The spacing between adjacent coil turns from the outermost to the innermost coil is as follows: S1 = 28.8 mm, S2 = 38.8 mm, S3 = 43.8 mm, S4 = 47.7 mm, S5 = S6 = S7 = S8 = S9 = S 10 =S 11 =S 12 =42.7 mm, S 13 =S 14 =28.8 mm, S 15 =23.8 mm, the air gap distances between the induction coil and the steel plate from the outermost to the innermost turn are G1=5 mm, G2=13 mm, G3=17 mm, G4=20 mm, G5=25 mm, G6=G7=30 mm, G8=27 mm, G9=25 mm, G 10 =20 mm, G 11 =15 mm, G 12 =5 mm, G 13 =G 14 =G 15 =2 mm.

[0063] In summary, this invention discloses a multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system. This method first clarifies verification indicators such as induction coil safety and system power consumption, as well as optimization objectives related to workpiece temperature. Based on the electromagnetic-thermal coupled finite element analysis method, a finite element simulation model is constructed, integrating parameters from electrical, coil, and heat dissipation aspects. Through multiple rounds of iterative optimization, the parameters are collaboratively adjusted to meet the requirements of workpiece average temperature and temperature uniformity. Simultaneously, the induction coil current density, voltage, temperature, and system power density are verified. This invention overcomes the limitations of isolated design parameters in traditional methods, enabling visualization of the heating process, reducing design errors and costs, balancing system reliability and low operating costs, and possessing strong versatility, adaptable to different workpieces and production needs.

[0064] Although embodiments of the present invention have been shown and described in detail above, those skilled in the art should understand that the foregoing embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention. Within the technical concept and protection scope set forth in the present invention, those skilled in the art have the right to make reasonable changes, modifications, substitutions, and variations to the above embodiments.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system, characterized in that, include: Step 1: Determine the verification indicators and optimization target parameters. The verification indicators include safety constraints and system power consumption constraints during the induction coil heating process. The optimization target parameters include the target temperature and target temperature difference of the heated workpiece. The safety constraints consider parameters including the allowable current density, allowable voltage and allowable temperature of the induction coil. The system power consumption constraints consider parameters including the allowable power density of the system. Step 2: Based on the electromagnetic-thermal coupling finite element analysis method, construct a finite element simulation model consisting of a geometric model and a theoretical model; establish the geometric model: establish a geometric structure consisting of an induction coil, cooling water, workpiece, and air, assign material properties to the geometric structure and mesh it; establish the theoretical model: introduce physical fields including magnetic field, temperature field and electromagnetic thermal field into the geometric model, set boundary conditions, and input initial parameters. The initial parameters include electrical parameters including the initial excitation current I0 and the initial frequency f0, coil parameters including the initial coil outer diameter D0, the initial coil length L0, the initial total number of turns N0, the initial turn spacing S0 between adjacent coils and the initial air gap distance G0 between the coil and the outer surface of the workpiece, and heat dissipation parameters including the initial cooling water flow rate v0; Step 3: Determine the synergistic relationship and iterative optimization logic among the electrical parameters, coil parameters, and heat dissipation parameters; perform simulation calculations and adjustments to determine the final design scheme; Step 3 includes the following steps: Step 3.1: Solve the finite element simulation model of the workpiece induction heating established in Step 2 to obtain the average temperature of the workpiece after induction heating; Step 3.2: When the finite element simulation results show that the difference between the average temperature of the workpiece and the target temperature exceeds a certain value, adjust the excitation current I or the frequency f to change the average temperature of the workpiece after heating; specifically, if the average temperature of the workpiece is lower than the target temperature by a certain value, increase the excitation current I or the frequency f; conversely, decrease the excitation current I or the frequency f; when the finite element simulation results show that the difference between the average temperature of the workpiece and the target temperature does not exceed a certain value, no parameters need to be changed, and proceed directly to the next step. Step 3.3: Extract and verify the current density and voltage of the induction coil to ensure the safety of the entire system; specifically, if the current density exceeds the allowable current density, increase the outer diameter D of the coil; if the voltage of the induction coil exceeds the allowable voltage, increase the frequency f or decrease the total number of turns N; if neither the current density nor the voltage of the induction coil exceeds the allowable value, no parameter adjustment is required; perform simulation calculations on the finite element simulation model to obtain the workpiece temperature distribution curve; Step 3.4: Observe the workpiece temperature distribution curve calculated in Step 3.

3. When the workpiece temperature distribution curve shows that the maximum temperature difference of the workpiece is greater than the target temperature difference, adjust the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece to reduce the maximum temperature difference of the workpiece. Specifically, increase the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece for the heat collection point, and decrease the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece for the cold point. When the workpiece temperature distribution curve shows that the maximum temperature difference of the workpiece is less than or equal to the target temperature difference, no parameters need to be changed, and proceed directly to the next step. Step 3.5: Check the coil temperature. Specifically, extract and check the temperature distribution curve of the induction coil. When the temperature of the induction coil at any point exceeds the allowable temperature, increase the cooling water flow rate v or the outer diameter of the coil D, or reduce the total number of turns N to ensure that the temperature of the induction coil is below the allowable temperature. When the temperature of the induction coil at any point does not exceed the allowable temperature, there is no need to change any parameters, and proceed directly to the next step. Step 3.6: Calculate the system power density based on the simulation data. If it exceeds the allowable power density, reduce the excitation current I, coil length L, total number of turns N, or coil outer diameter D to reduce the system power density. If the system power density does not exceed the allowable power density, output the final system design parameters and end the iteration.

2. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 1, characterized in that, Step 2 includes the following steps: Step 2.1: Establish a geometric structure consisting of an induction coil, cooling water, workpiece, and air. Input the coil parameters and initially construct the initial finite element simulation model. The air part should completely cover the induction coil and workpiece. Set an infinite element domain of appropriate thickness at the outermost edge of the air. Step 2.2: Set the corresponding material properties for the induction coil, cooling water, workpiece, and air in the initial finite element simulation model, including density, relative permittivity, relative permeability, thermal conductivity, constant pressure heat capacity, reference resistivity, resistivity temperature coefficient, linear resistivity, and reference temperature. Step 2.3: Introduce a magnetic field into the initial finite element simulation model, apply an initial excitation current I0 to the induction coil, set the initial frequency f0 of the excitation current, and set boundary conditions for the initial finite element simulation model: set the magnetopotential of the outer edge of the infinite element domain to zero. Step 2.4: Introduce a temperature field into the initial finite element simulation model. Set both the air and the infinite element domain as empty elements. Only calculate the temperature fields of the workpiece, the induction coil, and the cooling water. Set boundary conditions for the initial finite element simulation model: Set the initial temperature of the initial finite element simulation model to room temperature. Set the workpiece and the air in contact with the surface of the induction coil to perform radiation and convection heat exchange. Treat the heat exchange of the cooling water flow in the induction coil as equivalent to the heat exchange of a fixed heat source. Set the heat source directly inside the induction coil. Input the initial cooling water flow velocity v0 and calculate the heat flux density of the inner wall of the induction coil. Step 2.5: Couple the magnetic field and temperature field into an electromagnetic thermal field; Step 2.6: Mesh the geometry in the initial finite element simulation model, refine the mesh of the outermost layer of the induction coil and the boundary layer on the workpiece near the induction coil, and divide the mesh of the side of the workpiece near the induction coil into a boundary layer. The thickness of the boundary layer is taken as the skin depth of induction heating, thus completing the construction of the finite element simulation model.

3. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 2, characterized in that, The heat flux density q on the inner wall of the induction coil in step 2.4 is calculated using the following formula: (1) (2) (3) In the formula, D is the outer diameter of the coil, δ is the coil wall thickness, L is the coil length, Q is the cooling water heat dissipation, and p m C is the mass flow rate of the cooling water. p ρ is the specific heat capacity of the cooling water, Δt is the temperature change of the cooling water, ρ is the density of the cooling water, and v is the flow rate of the cooling water; the heat flux density q on the inner wall of the induction coil is adjusted by changing the flow rate v of the cooling water.

4. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 2, characterized in that, The skin depth δ in step 2.6 i Calculated using the following formula: (4) In the formula, Let f be the resistivity of the workpiece, f be the frequency of the excitation current, and μ0 be the vacuum permeability. -7 H / m, μ r Let be the relative permeability of the workpiece.

5. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 1, characterized in that, In steps 3.2 to 3.6, if any coil parameter is adjusted, the geometric model needs to be updated before calculating the finite element simulation model; if the coil parameter is not adjusted, the geometric model does not need to be updated, and the finite element simulation model can be calculated directly.

6. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 1, characterized in that, In step 3.4, if the spacing S between adjacent coil turns or the air gap distance G between the coil and the outer surface of the workpiece changes, the finite element simulation model is simulated and calculated to obtain the workpiece temperature distribution curve. If the average workpiece temperature extracted from the workpiece temperature distribution curve obtained in step 3.4 deviates from the target temperature by a certain value, the process returns to step 3.2; otherwise, the process proceeds directly to the next step.

7. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 1, characterized in that, In step 3.5, if the cooling water flow rate v, the coil outer diameter D, or the total number of turns N changes, the finite element simulation model is used for simulation calculation to obtain the workpiece temperature distribution curve again. If the workpiece temperature distribution curve obtained in step 3.5 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, it is necessary to return to step 3.2 for adjustment and recalculation. If the workpiece temperature distribution curve obtained in step 3.5 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, then proceed directly to the next step. In step 3.6, if the excitation current I, coil length L, total number of turns N, or coil outer diameter D changes, the finite element simulation model is used for simulation calculation, and the workpiece temperature distribution curve is obtained again. If the workpiece temperature distribution curve obtained again in step 3.6 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, it is necessary to return to step 3.2 for adjustment and recalculation. If the workpiece temperature distribution curve obtained again in step 3.6 shows that the average temperature of the workpiece deviates from the target temperature by a certain value, the final design parameters of the system are directly output.

8. The multi-parameter collaborative design and optimization method for an induction coil transverse magnetic heating system according to claim 1, characterized in that, In step 3.6, the system's power density q w Calculated using the following formula: (5) In the formula, P is the power of the induction coil, and A is the surface area of ​​the part of the workpiece being heated.

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