Construction method of MOSFET power device electric heating machine joint simulation model
By building a joint simulation model of MOSFET power devices and electric thermal engines in MATLAB and COMSOL, the problem of behavior prediction under multi-physics field coupling was solved, accurate characteristic analysis and safe operation were achieved, and operation and maintenance costs were reduced.
Patent Information
- Application Number
- CN202510802066.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-26
AI Technical Summary
Existing technologies make it difficult to accurately predict the behavior of MOSFET power devices and explain their failure mechanisms under multi-physics field coupling, and existing electrothermal coupling models cannot accurately reflect electrical characteristics, leading to limitations of thermal-mechanical coupling models.
An electrical model of a MOSFET power device was built in MATLAB, and a thermal-mechanical coupling model was built in COMSOL. The simulation data of temperature and power loss were transferred through scripts to achieve electric-thermal-mechanical joint simulation. An accurate multi-physics coupling model was established by combining SPICE first-level formulas and MOSFET physical dimensions.
It achieves accurate prediction and analysis of the behavior and characteristics of MOSFET power devices under multi-physical field conditions, ensuring the safe operation of the devices and reducing operation and maintenance costs.
Smart Images
Figure CN120706155A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of MOSFET power device state assessment, and in particular to a method for constructing a MOSFET power device and electric heating machine joint simulation model. Background Art
[0002] With the development of semiconductor technology, semiconductor devices have been widely used in fields such as renewable energy generation, transportation, aerospace, industrial automation, and transportation. MOSFET power devices are the most widely used, fully controlled semiconductor devices in power electronics systems. According to manufacturer surveys, semiconductor devices are considered the most critical and vulnerable components in industrial power electronics systems. The operating characteristics of MOSFET power devices dictate that they simultaneously experience electric, temperature, and mechanical stress fields during operation, with a strong coupling relationship between these three. Existing research indicates that most MOSFET power device package failures are the result of multi-physics coupling interactions. It is difficult to effectively predict the behavior of MOSFET power devices and explain their failure mechanisms from a single physics perspective. Therefore, establishing accurate and efficient multi-physics coupling models is crucial for optimizing the design, analyzing characteristics, and predicting failures under specific conditions of MOSFET power devices.
[0003] Extensive research has been conducted on multi-field coupled modeling of MOSFET power devices, but different modeling methods ultimately require implementation on specific simulation platforms. In recent years, circuit simulation platforms (such as SABER, PSPICE, and MATLAB) and finite element (FE) simulation platforms (such as ANSYS and COMSOL) have become widely used. However, mainstream circuit simulation platforms can only simulate electrical behavior at a fixed temperature. Existing electrothermal coupling models primarily use RC thermal networks to represent heat transfer through thermoelectric analogies, enabling electrothermal coupling simulation within circuit-based simulations. However, due to the limited number of nodes in the RC thermal network, the calculated temperature distribution is discontinuous, making it unsuitable for coupling with stress fields to resolve thermal stresses.
[0004] Finite element simulation platforms are numerical methods based on materials and structures. By solving the diffusion-convection-reaction partial differential equations, they can obtain high-resolution temperature and mechanical stress distributions in semiconductor devices, making them the primary choice for building thermomechanical coupling models. However, the input power consumption of existing thermomechanical coupling models is often replaced by a simplified power dissipation model. Due to the lack of an accurate electrical model, the electrical characteristics of semiconductor devices cannot be obtained in this way as input parameters for the thermal model, which leads to the limitations of these thermomechanical coupling models. Summary of the Invention
[0005] To solve the above technical problems, the present invention provides a method for constructing an electric-thermal-machine joint simulation model of a MOSFET power device. The method respectively constructs an electrical model of the MOSFET power device to be tested in MATLAB and a thermal-mechanical coupling model of the MOSFET power device to be tested in COMSOL. The simulation data of the temperature and power loss of the MOSFET power device to be tested are transmitted between MATLAB and COMSOL through a script to realize the construction of the electric-thermal-machine joint simulation model of the MOSFET power device to be tested. The model construction method described in the present invention not only solves the problem that the electrical characteristics, thermal characteristics, and mechanical characteristics of the existing multi-physics field model of semiconductor devices are difficult to observe and analyze simultaneously, but also solves the problem that the multi-physics field coupling status of semiconductor devices cannot be accurately represented by a single simulation software, and realizes the prediction and analysis of the behavior and characteristics of the MOSFET power device to be tested under multi-physics field conditions. The safe operation of semiconductor devices is guaranteed and the operation and maintenance costs are reduced.
[0006] The technical solution adopted by the present invention is: A method for constructing a MOSFET power device and an electric heat machine joint simulation model is provided. An electrical model of the MOSFET power device to be tested is constructed in MATLAB, and an initial temperature is set. The MOSFET power device electrical model calculates the power loss P of the MOSFET power device through simulation. Build a thermal-mechanical coupling model of the MOSFET power device to be tested in COMSOL. The thermal-mechanical coupling model simulation includes heat transfer simulation and mechanical simulation. Script to transfer MOSFET power device junction temperature T between MATLAB and COMSOL j Simulation data of power loss P; Realize the construction of MOSFET power device and electric heating machine joint simulation model.
[0007] The heat transfer simulation and mechanical simulation are strongly coupled and use the MOSFET power device thermal-mechanical coupling model for calculation. After the power loss P of the MOSFET power device is injected into the thermal-mechanical coupling model, the power loss P is used as the input of the heat transfer simulation. The heat transfer simulation calculates the junction temperature T of the MOSFET power device based on the power loss P. j , mechanical simulation receiving junction temperature T j Calculate the stress and deformation of each part of the MOSFET power device.
[0008] In the MOSFET power device electric heat machine joint simulation model: The MOSFET power device electrical model is based on the SPICE first-level formula and is used for simulating the electrical characteristics of the MOSFET power device; The MOSFET power device thermal-mechanical coupling model is based on the physical dimensions of the MOSFET power device and is used to simulate the thermal and mechanical properties of the MOSFET power device. The MATLAB script is used to transfer the MOSFET power device junction temperature T j Simulation data of power loss P.
[0009] In the electrical model of the MOSFET power device: Linearly fit the input and output characteristics curves from the MOSFET power device data sheet to determine the unknown parameter values in the SPICE primary formula, and write the formula into the MATLAB Function module in the core module of the MOSFET power device electrical model; In MATLAB, an equivalent electrical model of a MOSFET power device is constructed with the MATLAB Function module as the core. The equivalent model includes five ports: drain D, gate G, source S, temperature T, and mode M. The calculated power loss P of the MOSFET power device is transmitted to the MATLAB workspace through the To Workspace module within the model.
[0010] according to Figure 1 Build an equivalent electrical model of MOSFET power device in MATLAB. The built model ignores the internal parasitic inductance L d With L s , R d With R s Merged into on-resistance module.
[0011] The internal connection logic block diagram of the MOSFET power device electrical model is as follows: Figure 2 As shown; The internal connection diagram of the core module of the MOSFET power device electrical model is as follows: Figure 5 As shown; The internal connection diagram of the on-resistance module of the MOSFET power device electrical model is as follows: Figure 6 shown.
[0012] The MOSFET power device electrical model mainly includes an on-resistance module and a core module.
[0013] The on-resistance module mainly includes: MATLAB Function module, used to write the on-resistance voltage drop formula to calculate the voltage drop when the MOSFET is turned on; The controlled voltage source module (Controlled VoltageSource) is used to connect the MATLAB function module and the resistor R to represent the output on-resistance voltage drop of the MATLAB function module; The core modules mainly include: Voltage measurement module (Voltage Measurement), used to measure the drain-source voltage V of MOSFET power devices ds and the gate-source voltage V gs and transfer the data to the memory module; Meomory, used to delay, store, and transmit signals during simulation to avoid algebraic loops; MATLAB Function module, used to write SPICE first-level formulas to calculate the drain current I of the MOSFET power device electrical model d , output ideal switch control signal; Ideal Switch module: used to control the on and off of the electrical model of the MOSFET power device; The Controlled Current Source module is used to connect the ideal switch module and the current measurement module, and transmit the output drain current I of the MATLAB function module. d ; Current Measurement module, used to measure the drain current I of the MOSFET power device electrical model d , and I d The value is transmitted to the on-resistance module; Resistance (R g ): represents the internal parasitic resistance of MOSFET power device; Capacitance (C gs , C ds , C gd ): represents the internal parasitic capacitance of MOSFET power device; The on-resistance voltage drop calculation formula written into the MATLAB function module in the on-resistance module is: VR on =R on *I d ; R on Is affected by T and I d The function of common influence, R on The formula can be fitted from the data sheet.
[0014] The MATLAB function module in the MOSFET power device core module is written into the SPICE first-level formula, including: When V ds <0 or V gs <V th When I d =0; When V gs >V th or 0 <V ds <V gs -V th When I d =K p * (V gs -V th -V ds / 2)*V ds *(1+z*V ds ); When V gs >V th or V ds >=V gs -V th When I d =K p / 2*(V gs -V th )^2*(1+z*V ds ).
[0015] Among them, V gs and V ds represents a known quantity, z represents a fixed value, V th and K p Represents the function affected by temperature T, z, V th and K p The values of the resistor and capacitor can be obtained by fitting the input characteristic curve in the data sheet with the input characteristic curve; the values of the resistor and capacitor are filled in by looking up the data in the data sheet.
[0016] In the thermal-mechanical coupling model of the MOSFET power device: Based on the known physical dimensions of the MOSFET power device, a thermal-mechanical coupling model of the MOSFET power device is built in COMSOL, and the property values of parameters such as materials and physical fields are set; a global variable P is set. g Used to receive the power loss P generated by the electrical model of the MOSFET power device; set a domain probe to read the junction temperature T calculated by the heat transfer simulation of the thermal-mechanical coupling model of the MOSFET power device j .
[0017] The MOSFET power device thermal-mechanical coupling model includes: Geometric model establishment: used to establish the appearance of MOSFET power devices and the internal three-dimensional structure of the package; Material definition: used to write the material property values of MOSFET power device packaging and internal layers; Meshing: used to divide the MOSFET power device thermal-mechanical coupling model into small unit calculation nodes to improve the accuracy of simulation calculation results; Multi-physics field property definition: Set the property values of each physical field when the MOSFET power device is working; Global variable P g : Used to transfer the power loss P of the MOSFET power device electrical model read by the script to the silicon chip of the MOSFET power device thermal-mechanical coupling model, so that the power loss P is used as the input of the MOSFET power device thermal-mechanical coupling model; Domain probe: used to read the junction temperature T corresponding to each simulation step of the MOSFET power device j .
[0018] The MATLAB script transfers the MOSFET power device power loss P stored in the MATLAB workspace to the global variable P in the MOSFET power device thermal-mechanical coupling model. g middle; The junction temperature T read by the domain probe in the thermal-mechanical coupling model of the MOSFET power device is j Transmitted to the port temperature T of the MOSFET power device electrical model.
[0019] The MATLAB script writing method includes: mphload function: used to load the MOSFET power device thermal-mechanical coupling model into the MATLAB workspace; load_system function: used to load the MOSFET power device electrical model into memory so that it can be accessed and operated; set_param function: used to set the simulation time and step size of the MOSFET power device electrical model; sim function: used to control the simulation operation of the electrical model of MOSFET power device; model.param.set function: used to set the simulation time and step size of the thermal-mechanical coupling model of MOSFET power devices; model.sol.run function: used to control the simulation operation of the thermal-mechanical coupling model of MOSFET power devices; Save function: used to save the simulation data of MOSFET power device electrical model and MOSFET power device thermal-mechanical coupling model to the current folder; for function: used to control the number of simulation cycles of the electrothermal-mechanical coupling model of MOSFET power devices.
[0020] The present invention provides a method for constructing a MOSFET power device and electric heating machine joint simulation model, and the technical effects are as follows: 1) The electrical model of the MOSFET power device of the present invention is based on the SPICE first-level formula. By rationally connecting and applying the function module, controllable current source module, current measurement module, controllable voltage source module, memory module, resistor and capacitor modules, and finally creating a subsystem from the connected modules, a single module with only five ports: drain D, gate G, source S, temperature T, and mode M is obtained. This model can not only correctly represent the MOSFET at 25 ° C, and can represent the electrical characteristics of MOSFET under the influence of different temperatures.
[0021] 2) The MOSFET power device thermal-mechanical coupling model of the present invention is established by accurately setting the material properties, mesh division and other aspects of the 3D model of the MOSFET power device to be tested. By setting appropriate domain probes, the model can calculate and display the temperature characteristics and mechanical characteristics of each preset plane or domain, and can be used through the global variable P g Changing the input size of the thermal-mechanical coupling model simulation is of great significance for the optimal design, characteristic analysis and failure prediction of semiconductor devices under specific conditions.
[0022] 3) The script of the present invention can set the simulation time and step size of the electrical model and the thermal-mechanical coupling model at the same time, control the start and end of the simulation, and save the simulation results to the MATLAB workspace. The specific effect is that the electrical model can be controlled at an initial temperature of 25 ° C, and transfer the power loss P calculated by the electrical model to the global variable P of the thermal-mechanical coupling model. g In the simulation, the junction temperature T is obtained by controlling the thermal-mechanical coupling model. j , and finally T j The temperature T is transmitted to the port of the electrical model, and the number of simulation cycles of the MOSFET power device electric heat machine joint simulation model can be controlled by the for function. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is the equivalent circuit diagram of MOSFET power device.
[0024] Figure 2 It is the internal connection logic block diagram of the electrical model.
[0025] Figure 3 It is a flow chart of the method of the present invention.
[0026] Figure 4 It is a simulation process diagram of the electric heating machine joint simulation model.
[0027] Figure 5 This is the internal connection diagram of the core module of the electrical model.
[0028] Figure 6 This is the internal connection diagram of the on-resistance module of the electrical model.
[0029] Figure 7 It is the internal connection diagram of the electrical model.
[0030] Figure 8 It is the circuit connection diagram of the electrical model during short-circuit testing.
[0031] Figure 9 This is the internal structure diagram of the thermal-mechanical coupling model package; Among them, 1-bonding wire, 2-metal film layer (aluminum), 3-solder layer, 4-silicon grease, 5-chip (silicon), 6-copper layer, 7-heat sink.
[0032] Figure 10 This is a three-dimensional diagram of the thermal-mechanical coupling model after meshing. DETAILED DESCRIPTION
[0033] A method for constructing an electric-thermal-mechanical co-simulation model for MOSFET power devices can obtain data on the electrical, thermal, and mechanical properties of MOSFET power devices under different operating conditions. The basic idea of this method is to build an electrical model of the MOSFET power device to be tested in MATLAB and a thermal-mechanical coupling model of the MOSFET power device to be tested in COMSOL, and transfer the power loss P and junction temperature T of the MOSFET power device to be tested between MATLAB and COMSOL through a script. j The simulation data is used to build a joint electric-thermal-mechanical simulation model for the MOSFET power device to be tested. In the specific implementation of the method of the present invention, the electrical model of the MOSFET power device is based on the SPICE first-level formula. The unknown parameter values in the SPICE first-level formula are determined by linearly fitting the input characteristics and output characteristic curves of the MOSFET data sheet to be tested. The thermal-mechanical coupling model of the MOSFET power device is based on the physical dimensions of the MOSFET to be tested. The model is improved by setting material properties and physical field properties. By changing the external circuit connection method of the MOSFET electrical model to be tested, the model can predict and analyze the electrical, thermal, and mechanical properties of the device under different working conditions.
[0034] Example: IXFK80N60P3 is selected as the MOSFET power device to be tested. The present invention provides a method for constructing an electric-thermal-mechanical joint simulation model of a MOSFET power device. Based on this method, an electrical model of the MOSFET power device to be tested is constructed in MATLAB, a thermal-mechanical coupling model of the MOSFET power device to be tested is constructed in COMSOL, and a script is written in MATLAB to realize data interaction. The implementation method is as follows: Figure 3 shown.
[0035] First, an electrical model of the MOSFET power device to be tested is built in MATLAB, and the initial temperature is set. The electrical model calculates the power loss P of the device to be tested through simulation. Then, a thermal-mechanical coupling model of the MOSFET power device to be tested is built in COMSOL. The thermal-mechanical coupling model simulation includes heat transfer simulation and mechanical simulation. After the power loss P is transferred as the heat transfer simulation input to the thermal-mechanical coupling model through the MATLAB script, the heat transfer simulation calculates the junction temperature T of the MOSFET power device. j , the MATLAB script converts the junction temperature T j The temperature T is transmitted to the port of the MOSFET power device electrical model, thus completing the operation of one cycle of the MOSFET power device electric-heating machine joint simulation model. The for function in the MATLAB script can be used to control the number of cycles of the MOSFET power device electric-heating machine joint simulation model. j As the input of mechanical simulation, the deformation of the thermal-mechanical coupling model and the stress of each part can be calculated.
[0036] like Figure 5 The following figure shows the core module of the MOSFET power device electrical model built in MATLAB. The main modules used are: Voltage Measurement module, which is used to measure the MOSFET drain-source voltage V ds and the gate-source voltage V gs The data is transferred to the memory module; the memory module (Meomory) is used to delay, store and transfer the signal during simulation to avoid algebraic loops; the MATLAB function module (MATLAB Function) is used to write the SPICE first-level formula to calculate the output current drain I of the MOSFET power device electrical model d and ideal switch control signal; ideal switch module (IdealSwitch), used to control the on and off of the MOSFET power device electrical model; controlled current source module (ControlledCurrent Source), used to connect the ideal switch module and the voltage measurement module, and transmit the MATLAB function module output drain current I dCurrent measurement module (Current Measurement), used to measure the output drain current I of the MOSFET power device electrical model d , and I d The value of the resistance (R g ): Indicates the parasitic resistance of the input MOSFET power device itself; Capacitance (C gs , C ds , C gd ): Indicates the parasitic capacitance of the input MOSFET power device. Figure 5 Make the connections as shown.
[0037] like Figure 6 As shown in the figure, the on-resistance module of the MOSFET power device electrical model is built in MATLAB. The main modules used are: MATLAB Function module (MATLAB Function), which is used to write the on-resistance voltage drop calculation formula and calculate the voltage drop when the MOSFET power device is turned on; Controlled Voltage Source module (Controlled VoltageSource), which is used to connect the MATLAB function module and the resistor R to represent the on-resistance voltage drop output by the MATLAB function module. Figure 6 Make the connections as shown.
[0038] like Figure 7 As shown, Figure 5 Electrical model core module and Figure 6 All modules used in the electrical model on-resistance module are encapsulated into one module by creating a subsystem. The electrical model core module has two custom inputs, temperature T and mode M, three ports, drain D, gate G, and source S, and one output, drain current I. d The on-resistance module has a custom input temperature T, two ports + and -, and an input drain current I d .exist Figure 5 and Figure 6 The modules added on the basis of the Diode module are: Diode module, which is used to equal the body diode of the MOSFET power device under test; Power consumption module, which is used to calculate the power consumption of the electrical model, and the power consumption P is equal to V ds with I d The product of the workspace module (To workspace) is used to transmit the power consumption P data to the MATLAB workspace. Figure 7 Make the connections as shown.
[0039] like Figure 8 As shown, Figure 7After creating a subsystem, all modules used in the simulation are reduced to a single module with only five ports: drain D, gate G, source S, temperature T, and mode M. This module is recorded as module IXFK80N60P3, and the electrical model is now complete. This module can be directly connected to the simulation circuit through drain D, gate G, and source S. Temperature T and mode M are self-set inputs. Figure 8 Taking the short circuit condition of small current and small voltage as an example, the initial temperature of the electrical model port T in this circuit simulation is set to 25 ° C, port M is set to 0, then the bypass resistor R p1 Disconnect, R p2 Close. The workspace module transfers the power consumption P calculated by the power consumption module to the workspace, waiting for the script to read it.
[0040] like Figure 9 The internal structure of the MOSFET package under test is shown in Table 1. Table 1 Simulation component parameters
[0041] like Figure 10 As shown in the figure, by accurately setting the physical size, material properties, mesh division and other aspects of the MOSFET to be tested, an accurate three-dimensional model of the MOSFET to be tested is established in COMSOL. The power consumption P is transferred to the global variable P through the script g The input quantity of the thermo-mechanical coupling model simulation can be changed. By setting the domain probe, the junction temperature T calculated by the thermo-mechanical coupling model can be displayed. j .
[0042] The control functions of the script written are as follows Figure 4 As shown. The script is written by correctly using functions such as mphload, load_system, set_param, model.param.set, model.sol.run, save, and for. The electrical model is controlled to perform microsecond simulation, the thermal-mechanical coupling model to perform millisecond simulation, and the data exchange function is performed every 2ms. Click "Run" in MATLAB to realize the joint simulation operation of the MOSFET power device electrical model and the MOSFET power device thermal-mechanical coupling model. The script converts the power consumption P and the junction temperature T j The data is saved in the current folder as a text file.
Claims
1. A method for constructing a MOSFET power device and electric heating machine joint simulation model, characterized by: Build an electrical model of the MOSFET power device to be tested in MATLAB and set the initial temperature. The MOSFET power device electrical model calculates the power loss P of the MOSFET power device through simulation; Build a thermal-mechanical coupling model of the MOSFET power device to be tested in COMSOL. The thermal-mechanical coupling model simulation includes heat transfer simulation and mechanical simulation. Script to transfer MOSFET power device junction temperature T between MATLAB and COMSOL j Simulation data of power loss P; Realize the construction of MOSFET power device and electric heating machine joint simulation model.
2. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 1, characterized in that: The heat transfer simulation and mechanical simulation use a common MOSFET power device thermal-mechanical coupling model for calculation. After the power loss P of the MOSFET power device is injected into the thermal-mechanical coupling model, the power loss P is used as the input of the heat transfer simulation. The heat transfer simulation calculates the junction temperature T of the MOSFET power device based on the power loss P. j , mechanical simulation receiving junction temperature T j Calculate the stress and deformation of each part of the MOSFET power device.
3. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 1, characterized in that: The MOSFET power device electrical model is based on the SPICE first-level formula and is used for simulating the electrical characteristics of the MOSFET power device; The MOSFET power device thermal-mechanical coupling model is based on the physical dimensions of the MOSFET power device and is used to simulate the thermal and mechanical properties of the MOSFET power device. MATLAB script for transferring the junction temperature T of MOSFET power devices j Simulation data of power loss P.
4. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 1, characterized in that: The MOSFET power device electrical model includes an on-resistance module and a core module; The on-resistance module includes: MATLAB function module, used to write the on-resistance voltage drop formula to calculate the voltage drop when the MOSFET is turned on; The controllable voltage source module is used to connect the MATLAB function module and the resistor R to represent the output on-resistance voltage drop of the MATLAB function module; Core modules include: Voltage measurement module, used to measure the drain-source voltage V of MOSFET power devices ds and the gate-source voltage V gs and transfer the data to the memory module; Memory module, used to delay, store and transmit signals during simulation to avoid algebraic loops; MATLAB function module for writing SPICE first-level formulas to calculate the drain current I of the MOSFET power device electrical model d , output ideal switch control signal; Ideal switch module: used to control the on and off of the electrical model of MOSFET power devices; The controllable current source module is used to connect the ideal switch module and the current measurement module, and transmit the MATLAB function module output drain current I d ; Current measurement module, used to measure the drain current I of the MOSFET power device electrical model d , and I d The value is transmitted to the on-resistance module; Resistor R g : represents the internal parasitic resistance of MOSFET power device; Capacitor C gs , C ds , C gd : Represents the internal parasitic capacitance of MOSFET power device.
5. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 4, characterized in that: The on-resistance voltage drop calculation formula written into the MATLAB function module in the on-resistance module is: VR on =R on *I d ; R on Is affected by T and I d Common influence function.
6. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 4, characterized in that: The MATLAB function module in the MOSFET power device core module is written into the SPICE first-level formula, including: When V ds <0 or V gs <V th When I d =0; When V gs >V th or 0 <V ds <V gs -V th When I d =K p * (V gs -V th -V ds / 2)*V ds *(1+z*V ds ); When V gs >V th or V ds >=V gs -V th When I d =K p / 2*(V gs -V th )^2*(1+z*V ds ); Among them, V gs and V ds represents a known quantity, z represents a fixed value, V th and K p Represents a function affected by temperature T.
7. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 1, characterized in that: In the thermal-mechanical coupling model of the MOSFET power device: Based on the known physical dimensions of the MOSFET power device, a thermal-mechanical coupling model of the MOSFET power device was built in COMSOL, and the property values of parameters such as materials and physical fields were set. Set a global variable P g Used to receive the power loss P generated by the electrical model of the MOSFET power device; Set up a domain probe to read the junction temperature T after the heat transfer simulation calculation of the thermal-mechanical coupling model of the MOSFET power device j .
8. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 7, characterized in that: The MOSFET power device thermal-mechanical coupling model includes: Geometric model establishment: used to establish the appearance of MOSFET power devices and the internal three-dimensional structure of the package; Material definition: used to write the material property values of MOSFET power device packaging and internal layers; Meshing: used to divide the MOSFET power device thermal-mechanical coupling model into small unit calculation nodes; Multi-physics field property definition: Set the property values of each physical field when the MOSFET power device is working; Global variable P g : Used to transfer the power loss P of the MOSFET power device electrical model read by the script to the silicon chip of the MOSFET power device thermal-mechanical coupling model, so that the power loss P is used as the input of the MOSFET power device thermal-mechanical coupling model; Domain probe: used to read the junction temperature T corresponding to each simulation step of the MOSFET power device j .
9. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 3, characterized in that: The MATLAB script transfers the MOSFET power device power loss P stored in the MATLAB workspace to the global variable P in the MOSFET power device thermal-mechanical coupling model. g middle; The junction temperature T read by the domain probe in the thermal-mechanical coupling model of the MOSFET power device is j Transmitted to the port temperature T of the MOSFET power device electrical model.
10. The method for constructing a MOSFET power device and electric heat engine joint simulation model according to claim 9, characterized in that: The MATLAB script writing method includes: mphload function: used to load the MOSFET power device thermal-mechanical coupling model into the MATLAB workspace; load_system function: used to load the MOSFET power device electrical model into memory so that it can be accessed and operated; set_param function: used to set the simulation time and step size of the MOSFET power device electrical model; sim function: used to control the simulation operation of the electrical model of MOSFET power device; model.param.set function: used to set the simulation time and step size of the thermal-mechanical coupling model of MOSFET power devices; model.sol.run function: used to control the simulation operation of the thermal-mechanical coupling model of MOSFET power devices; Save function: used to save the simulation data of MOSFET power device electrical model and MOSFET power device thermal-mechanical coupling model to the current folder; for function: used to control the number of simulation cycles of the electrothermal-mechanical coupling model of MOSFET power devices.