Aviation converter SiC power module multi-time scale life evaluation method

Abstract

The invention discloses a multi-time-scale life evaluation method for a SiC power module of an aviation converter. The method comprises the following steps: establishing a semi-physical simulation platform; establishing a finite element model of the S < iC > power module to perform electric heating multi-physics field coupling simulation; constructing a thermal network model of the S C power module; obtaining junction temperature data of the SiC power module in a whole year; and calculating low-frequency damage consumption and fundamental frequency damage consumption for evaluating the service life of the SiC power module. According to the method, the preparation process of SiC power module packaging can be quantitatively simulated through mathematical modeling based on the finite element theory, the complex working condition environment can be analyzed and calculated, and the cost of products in the aspects of development and research, data acquisition, experimental verification and the like is greatly reduced. The internal packaging of the SiC power module is relatively complicated, so that the influence of the actual physical structure and the material attribute deviation of a research object on the accuracy of a simulation model can be better considered by adopting the multi-physics-field coupled three-dimensional modeling, and the deviation of a thermal parameter result in an actual operation environment is reduced to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of reliability assessment of aviation converter devices, and in particular relates to a multi-time scale life assessment method for a SiC power module of an aviation converter. Background Art

[0002] Since the industrialization of society, energy reserves have always been an important symbol of a country's comprehensive strength. Traditional energy represented by coal and oil is becoming increasingly depleted and increasingly unable to meet the needs of today's rapidly developing society. Therefore, investing in the construction of large-capacity, high-efficiency new wind power and promoting the grid-connected operation of photovoltaic power generation, advocating the use of new energy equipment such as electric vehicles and solar panels to meet the needs of production and life are of great significance to the creation of a green and sustainable development society. As power electronic devices that play a core role in high-power system converters such as rail traction, mine hoisting, wind power generation, and aerospace, their safe and reliable operation is a strong backing to ensure national production safety and improve the quality of life.

[0003] In recent years, with the rapid development of electric aircraft, its power supply system is required to have higher reliability. However, according to the statistical results of system failure rate, the aviation inverter in the electrical system, as the core component of the electric aircraft power system, is also one of the main failure components. The reliability of the aviation inverter is related to the reliability of each component, and its failure is largely attributed to the failure of the SiC power module used. Therefore, it is necessary to evaluate the reliability of the SiC power module in the aviation inverter, and then study the measures and methods to extend the reliability of the aviation inverter and reduce the maintenance and repair costs required for the aviation inverter due to unscheduled failures.

[0004] The failure of SiC power modules is largely affected by the impact of thermal cycles during the working process. The internal material structure of SiC power modules is generally divided from top to bottom into bonding wires (Al), chips (SiC), chip solder layers (96.5Sn3.5Ag), DBC upper copper layers (Cu), ceramic layers (Al2O3), DBC lower copper layers (Cu), DBC solder layers (96.5Sn3.5Ag) and copper substrates. Because the thermal expansion coefficients of the various layers of materials in SiC power modules are different, they will be subjected to different degrees of thermal stress, which will lead to thermal fatigue failure of the device after long-term accumulation. There are many forms of failure in SiC power modules, mainly including the shedding of bonding wires and the aging of solder layers. The thermal cycle of SiC power modules in aviation inverters is related to the flight stage. The input power and device loss change with the flight stage, causing the device junction temperature to fluctuate randomly, thus affecting the device life. Summary of the invention

[0005] In order to solve the above problems, the object of the present invention is to provide a multi-time scale life assessment method for SiC power modules of aviation converters.

[0006] In order to achieve the above object, the multi-time scale life assessment method of SiC power module of aviation converter provided by the present invention comprises the following steps performed in sequence:

[0007] 1) Establish a semi-physical simulation platform based on the circuit structure of the actual aviation converter, and use the semi-physical simulation platform to obtain the power loss of the SiC power module under different flight conditions;

[0008] 2) Establishing a finite element model of the SiC power module based on the SiC power module object and data sheet, and then inputting the power loss obtained in step 1) into the finite element model to perform electrothermal multi-physics field coupling simulation, and obtaining the thermal resistance and thermal capacity values ​​between the layers of the SiC power module under different flight conditions;

[0009] 3) constructing a thermal network model of the SiC power module based on the thermal resistance and thermal capacitance values ​​obtained in step 2), and setting different flight conditions including power and temperature as boundary conditions in the thermal network model;

[0010] 4) Taking the flight conditions including different flight altitudes, flight times, flight powers, and ambient temperatures for a whole year as boundary conditions, and inputting them together with the power loss value into the thermal network model obtained in step 3) for simulation, and obtaining the junction temperature data of the SiC power module for a whole year;

[0011] 5) The junction temperature data obtained in step 4) above is processed using the rain flow algorithm, and then the failure cycle number of the SiC power module is calculated using the Bayerer model. The low-frequency damage consumption and fundamental frequency damage consumption of the SiC power module are calculated using the linear cumulative damage model to evaluate the life of the SiC power module.

[0012] In step 1), the semi-physical simulation platform includes a controller, a SiC power module driver, an NPC three-level circuit and a motor; wherein the controller is installed with an RT-LAB semi-physical simulation platform, the RT-LAB semi-physical simulation platform contains electrical parameter sensors including current and voltage, the controller is connected to a computer, and remote control is performed by the computer; the NPC three-level circuit includes a SiC power module; the controller is used to output a control signal to the SiC power module driver, and then the SiC power module driver drives the SiC power module in the NPC three-level circuit according to the control strategy, and finally the motor as a load is successfully operated according to the operation requirements, thereby quickly obtaining and solving the actual current and voltage values ​​inside the NPC three-level circuit under different flight conditions, and then calculating the power loss of the SiC power module:

[0013] The power loss is the sum of conduction loss and switching loss. The conduction loss of the SiC power module is composed of the conduction loss of each chip inside the SiC power module. The calculation formula for the instantaneous conduction loss of a SiC power module with N parallel chips is as follows:

[0014]

[0015] Where P condT / D_chip (t) is the conduction loss of each chip; v chip The on-state voltage of each chip is calculated by the on-state voltage v in the chip data sheet. cond and current i cond The data fitting curve is obtained; i chip (t) is the current flowing through each chip, through the load current i load (t) and the number of parallel chips N are calculated; D T / D (t) is the duty cycle of the chip / diode;

[0016] The switching loss is calculated as follows:

[0017]

[0018] In the formula, p sw-chip (t) is the switching loss of each chip in the SiC power module; E sw_chip is the switching energy of a single chip, which is calculated using the corresponding load current in the chip data sheet; f s is the switching frequency of the SiC power module in the NPC three-level circuit.

[0019] In step 2), the finite element model of the SiC power module is established based on the SiC power module object and the data manual, and then the power loss obtained in step 1) is input into the finite element model to perform electrothermal multi-physics field coupling simulation, and the method for obtaining the thermal resistance and thermal capacity values ​​between each layer of the SiC power module under different flight conditions is:

[0020] A three-dimensional model of the SiC power module is drawn based on the actual SiC power module and the data sheet, and then various data in the SiC power module are set according to the information in the data sheet. The three-dimensional model is then imported into the finite element simulation software, and boundary conditions including ambient temperature and humidity are set to form a finite element model. The power loss obtained in step 1) is then input into the finite element model for electrothermal multi-physics field coupling simulation, and the thermal resistance and heat capacity values ​​between the layers on the SiC power module under different boundary conditions are measured from the simulation results.

[0021] In step 4), the voltage value of each node in the thermal network model is the corresponding junction temperature data.

[0022] In step 5), the junction temperature data obtained in step 4) is processed by the rain flow algorithm, and then the failure cycle number of the SiC power module is calculated by the Bayerer model, and then the low-frequency damage consumption and fundamental frequency damage consumption of the SiC power module are calculated by the linear cumulative damage model. The method for evaluating the life of the SiC power module is:

[0023] The Bayerer model considers the same factors affecting life as other models, and also considers the heating time t on 、Maximum junction temperature T jmax , minimum junction temperature T jmin , the effective value of the current I passing through each aluminum bonding wire and the diameter D of the aluminum bonding wire, the number of failure cycles N f The expression is:

[0024]

[0025] Where, T jmax and T jmin are the maximum and minimum junction temperatures of the device within a fundamental frequency cycle; the heating time t on is 1 / (2f o ), f o is the output frequency of the NPC three-level circuit; the effective value I of the current passing through each aluminum bonding wire is 1 / 32 of the converter line current, and the number of bonding wires in the SiC power module is related to the type of SiC power module; U = 22V is the voltage of the SiC power module; the diameter of the aluminum bonding wire D = 200μm, k = 9.3×10 14 , β1=-3.581, β2=1537, β3=-0.463, β4=-0.716, β5=-0.761,

[0026] β6 = -0.5;

[0027] The failure cycle number N of SiC power module is calculated using the Bayerer model f Finally, the linear cumulative damage model is used to predict the damage consumption under variable working conditions. The calculation formula is:

[0028]

[0029] Where N f,n N is the number of cycles to failure corresponding to the nth thermal cycle; n is the corresponding number of thermal cycles;

[0030] The damage consumption is divided into baseband damage consumption and low-frequency damage consumption; the baseband damage consumption C caused by baseband junction temperature fluctuation L_FIt can be directly calculated using the above formulas (3) and (4) by extracting the maximum junction temperature T from the fundamental frequency junction temperature fluctuation data during each thermal cycle. jmax and the minimum junction temperature T jmin , and then substitute it into formula (3). Since other parameters are known, the number of failure cycles N for each thermal cycle is further calculated. f ; Then use formula (4) to calculate the number of thermal cycles N n The number of cycles to failure corresponding to the nth thermal cycle is N f,n The fundamental frequency damage consumption C can be calculated by summing the ratio of L_F ; The low-frequency damage caused by low-frequency junction temperature fluctuation consumes C L_L The calculation requires first obtaining the low-frequency junction temperature data, and then processing it through the rain flow algorithm to calculate the device life C using equations (3) and (4). L_L The method is that in each operating state of the aviation inverter, the SiC power module has a steady-state average junction temperature, a maximum junction temperature and a minimum junction temperature in a fundamental frequency cycle; in a year, the aviation inverter has less than 10,000 operating states, so the 10,000 sets of average junction temperature data corresponding to these 10,000 operating states are pole extracted to obtain the low-frequency junction temperature data of the SiC power module, from which the maximum junction temperature T is extracted. jmax and the minimum junction temperature T jmin , and then substitute it into formula (3). Since other parameters are known, the number of failure cycles N for each thermal cycle is further calculated. f ; Then use formula (4) to calculate the number of thermal cycles N n The number of cycles to failure corresponding to the nth thermal cycle is N f,n The low-frequency damage consumption C can be calculated by summing the ratio of L_L Finally, the fundamental frequency damage caused by the fundamental frequency junction temperature fluctuation is used to consume C L_F and the low-frequency damage consumption C caused by low-frequency junction temperature fluctuations L_L Multi-time scale lifetime assessment of SiC power modules for aviation inverters.

[0031] The multi-time scale life assessment method for SiC power module of aviation converter provided by the present invention has the following characteristics:

[0032] Beneficial effects:

[0033] 1. The mathematical modeling based on finite element theory of the present invention can quantitatively simulate the preparation process of SiC power module packaging, and can analyze and calculate complex working conditions, greatly reducing the cost of product development research, data collection, experimental verification, etc. Since the internal packaging of SiC power modules is relatively complex, the three-dimensional modeling using multi-physical field coupling can better consider the actual physical structure of the research object and the influence of material property deviation on the accuracy of the simulation model, and to a certain extent reduce the deviation from the thermal parameter results in the actual operating environment.

[0034] 2. The thermal network model constructed by the present invention solves the problem of how to accurately measure the junction temperature during the operation of the converter based on the power loss obtained by the semi-physical platform and the thermal resistance parameters obtained by multi-physical field coupling simulation. The present invention only needs to perform a small amount of electrothermal simulation to calculate the multi-time scale life assessment results. Compared with the method of running the circuit simulation for each switching cycle, this method obtains two sets of information, power loss and thermal resistance, and constructs a new thermal network model to obtain information such as power loss, junction temperature and damage prediction, which significantly saves calculation time, while maintaining accurate calculation of short-term time scales, improving the accuracy and efficiency of life assessment.

[0035] 3. The present invention proposes to extract thermal cycles based on long-time-scale mission profiles and evaluate the life of SiC power modules in aviation inverters at multiple time scales, which can achieve more realistic life evaluation at a specified confidence level. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of the multi-time scale life assessment method for SiC power modules of aviation converters provided by the present invention.

[0037] Figure 2 It is a schematic diagram of the semi-physical simulation platform in the present invention.

[0038] Figure 3 Schematic diagram of the thermal network model of the SiC power module in the present invention. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1 As shown, the multi-time scale life assessment method for SiC power module of aviation converter provided by the present invention comprises the following steps performed in sequence:

[0041] 1) Establish a semi-physical simulation platform based on the circuit structure of the actual aviation converter, and use the semi-physical simulation platform to obtain the power loss of the SiC power module under different flight conditions;

[0042] like Figure 2As shown, the semi-physical simulation platform includes a controller, a SiC power module driver, an NPC three-level circuit and a motor; wherein the controller is installed with an RT-LAB semi-physical simulation platform, the RT-LAB semi-physical simulation platform contains electrical parameter sensors including current and voltage, the controller is connected to a computer, and the computer is used for remote control; the NPC three-level circuit includes a SiC power module; the controller is used to output a control signal to the SiC power module driver, and then the SiC power module driver drives the SiC power module in the NPC three-level circuit according to the control strategy, and finally the motor as a load is successfully operated according to the operation requirements, thereby quickly obtaining and solving the actual current and voltage values ​​inside the NPC three-level circuit under different flight conditions, and then calculating the power loss of the SiC power module:

[0043] The power loss is the sum of conduction loss and switching loss. The conduction loss of the SiC power module is composed of the conduction loss of each chip inside the SiC power module. The calculation formula for the instantaneous conduction loss of a SiC power module with N parallel chips is as follows:

[0044]

[0045] Where P condT / D_chip (t) is the conduction loss of each chip; v chip The on-state voltage of each chip is calculated by the on-state voltage v in the chip data sheet. cond and current i cond The data fitting curve is obtained; i chip (t) is the current flowing through each chip, through the load current i load (t) and the number of parallel chips N are calculated; D T / D (t) is the duty cycle of the chip / diode;

[0046] The switching loss is calculated as follows:

[0047]

[0048] In the formula, p sw-chip (t) is the switching loss of each chip in the SiC power module; E sw_chip is the switching energy of a single chip, which is calculated using the corresponding load current in the chip data sheet; f s is the switching frequency of the SiC power module in the NPC three-level circuit.

[0049] 2) Establishing a finite element model of the SiC power module based on the SiC power module object and data sheet, and then inputting the power loss obtained in step 1) into the finite element model to perform electrothermal multi-physics field coupling simulation, and obtaining the thermal resistance and thermal capacity values ​​between the layers of the SiC power module under different flight conditions;

[0050] A three-dimensional model of the SiC power module is drawn based on the actual SiC power module and the data sheet, and then various data in the SiC power module are set according to the information in the data sheet. The three-dimensional model is then imported into the finite element simulation software, and boundary conditions including ambient temperature and humidity are set to form a finite element model. The power loss obtained in step 1) is then input into the finite element model for electrothermal multi-physics field coupling simulation, and the thermal resistance and heat capacity values ​​between the layers on the SiC power module under different boundary conditions are measured from the simulation results.

[0051] 3) constructing a thermal network model of the SiC power module based on the thermal resistance and thermal capacitance values ​​obtained in step 2), and setting different flight conditions including power and temperature as boundary conditions in the thermal network model;

[0052] The thermal network model is as follows Figure 3 As shown, Pt(n) is the power loss, the dotted box is the thermal resistance and thermal capacitance between the layers of the SiC power module obtained in step 2), and Ta is the ambient temperature. Different flight conditions including power and temperature are set as boundary conditions in the thermal network model, so that the thermal network model can simulate the junction temperature under different flight conditions in a short time, which can greatly reduce the time consumption on the basis of accurate data;

[0053] 4) Taking the flight conditions including different flight altitudes, flight times, flight powers, and ambient temperatures for a whole year as boundary conditions, and inputting them together with the power loss value into the thermal network model obtained in step 3) for simulation, and obtaining the junction temperature data of the SiC power module for a whole year;

[0054] The voltage value of each node in the thermal network model is the corresponding junction temperature data.

[0055] 5) The junction temperature data obtained in step 4) above is processed using the rain flow algorithm, and then the failure cycle number of the SiC power module is calculated using the Bayerer model. The low-frequency damage consumption and fundamental frequency damage consumption of the SiC power module are calculated using the linear cumulative damage model to evaluate the life of the SiC power module.

[0056] At present, the life assessment models of SiC power modules are mainly divided into two types: analytical life assessment models and physics-based life assessment models. The analytical life assessment model is derived from the aging test results and a large amount of data collected from different power module packaging technologies, and is usually expressed in terms of the number of failure cycles N. f Because the analytical life assessment model does not consider the physical failure mechanism inside the SiC power module during the modeling process, and the parameters are easy to obtain, it is widely used. The present invention uses an analytical life assessment model to perform life assessment on the SiC power module.

[0057] There are many forms of analytical life assessment models, such as the Manson-Coffin model, the Arrhenius-Manson-Coffin model, the Norriss-Landzberg model and the Bayerer model. The present invention adopts the Bayerer model, which, in addition to considering the same life influencing factors as other models, also considers the heating time t on 、Maximum junction temperature T jmax , minimum junction temperature T jmin , the effective value of the current I passing through each aluminum bonding wire and the diameter D of the aluminum bonding wire, the number of failure cycles N f The expression is:

[0058]

[0059] Where, T jmax and T jmin are the maximum and minimum junction temperatures of the device within a fundamental frequency cycle; the heating time t on is 1 / (2f o ), f o is the output frequency of the NPC three-level circuit; the effective value I of the current passing through each aluminum bonding wire is 1 / 32 of the converter line current, and the number of bonding wires in the SiC power module is related to the type of SiC power module; U = 22V is the voltage of the SiC power module; the diameter of the aluminum bonding wire D = 200μm, k = 9.3×10 14 , β1=-3.581, β2=1537, β3=-0.463, β4=-0.716, β5=-0.761, β6=-0.5;

[0060] The failure cycle number N of SiC power module is calculated using the Bayerer model f Finally, the linear cumulative damage model is used to predict the damage consumption under variable working conditions. The calculation formula is:

[0061]

[0062] Where N f,n N is the number of cycles to failure corresponding to the nth thermal cycle; n is the corresponding number of thermal cycles; when the damage accumulates to a certain extent, the damage consumption C L_SiC =1, indicating that the SiC power module will fail.

[0063] The damage consumption is divided into baseband damage consumption and low-frequency damage consumption; the baseband damage consumption C caused by baseband junction temperature fluctuation L_FIt can be directly calculated using the above formulas (3) and (4) by extracting the maximum junction temperature T from the fundamental frequency junction temperature fluctuation data during each thermal cycle. jmax and the minimum junction temperature T jmin , and then substitute it into formula (3). Since other parameters are known, the number of failure cycles N for each thermal cycle is further calculated. f ; Then use formula (4) to calculate the number of thermal cycles N n The number of cycles to failure corresponding to the nth thermal cycle is N f,n The fundamental frequency damage consumption C can be calculated by summing the ratio of L_F ; The low-frequency damage caused by low-frequency junction temperature fluctuation consumes C L_L The calculation requires first obtaining the low-frequency junction temperature data, and then processing it through the rain flow algorithm to calculate the device life C using equations (3) and (4). L_L The method is that in each operating state of the aviation inverter, the SiC power module has a steady-state average junction temperature, a maximum junction temperature and a minimum junction temperature in a fundamental frequency cycle; in a year, the aviation inverter has less than 10,000 operating states, so the 10,000 sets of average junction temperature data corresponding to these 10,000 operating states are pole extracted to obtain the low-frequency junction temperature data of the SiC power module, from which the maximum junction temperature T is extracted. jmax and the minimum junction temperature T jmin , and then substitute it into formula (3). Since other parameters are known, the number of failure cycles N for each thermal cycle is further calculated. f ; Then use formula (4) to calculate the number of thermal cycles N n The number of cycles to failure corresponding to the nth thermal cycle is N f,n The low-frequency damage consumption C can be calculated by summing the ratio of L_L Finally, the fundamental frequency damage caused by the fundamental frequency junction temperature fluctuation is used to consume C L_F and the low-frequency damage consumption C caused by low-frequency junction temperature fluctuations L_L Multi-time scale lifetime assessment of SiC power modules for aviation inverters.

Claims

1. A multi-time scale life assessment method for SiC power modules of aviation converters, characterized by: The multi-time scale life assessment method for SiC power module of aviation converter comprises the following steps performed in sequence: 1) Establish a semi-physical simulation platform based on the circuit structure of the actual aviation converter, and use the semi-physical simulation platform to obtain the power loss of the SiC power module under different flight conditions; 2) Establishing a finite element model of the SiC power module based on the SiC power module object and data sheet, and then inputting the power loss obtained in step 1) into the finite element model to perform electrothermal multi-physics field coupling simulation, and obtaining the thermal resistance and thermal capacity values ​​between the layers of the SiC power module under different flight conditions; 3) constructing a thermal network model of the SiC power module based on the thermal resistance and thermal capacitance values ​​obtained in step 2), and setting different flight conditions including power and temperature as boundary conditions in the thermal network model; 4) Taking the flight conditions including different flight altitudes, flight times, flight powers, and ambient temperatures for a whole year as boundary conditions, and inputting them together with the power loss value into the thermal network model obtained in step 3) for simulation, and obtaining the junction temperature data of the SiC power module for a whole year; 5) The junction temperature data obtained in step 4) above is processed using the rain flow algorithm, and then the failure cycle number of the SiC power module is calculated using the Bayerer model. The low-frequency damage consumption and fundamental frequency damage consumption of the SiC power module are calculated using the linear cumulative damage model to evaluate the life of the SiC power module.

2. The multi-time scale life assessment method for SiC power module of aviation converter according to claim 1 is characterized in that: In step 1), the semi-physical simulation platform includes a controller, a SiC power module driver, an NPC three-level circuit and a motor; wherein the controller is installed with an RT-LAB semi-physical simulation platform, the RT-LAB semi-physical simulation platform contains electrical parameter sensors including current and voltage, the controller is connected to a computer, and remote control is performed by the computer; the NPC three-level circuit includes a SiC power module; the controller is used to output a control signal to the SiC power module driver, and then the SiC power module driver drives the SiC power module in the NPC three-level circuit according to the control strategy, and finally the motor as a load is successfully operated according to the operation requirements, thereby quickly obtaining and solving the actual current and voltage values ​​inside the NPC three-level circuit under different flight conditions, and then calculating the power loss of the SiC power module: The power loss is the sum of conduction loss and switching loss. The conduction loss of the SiC power module is composed of the conduction loss of each chip inside the SiC power module. The calculation formula for the instantaneous conduction loss of a SiC power module with N parallel chips is as follows: Where P condT / D_chip (t) is the conduction loss of each chip; v chip The on-state voltage of each chip is calculated by the on-state voltage v in the chip data sheet. cond and current i cond The data fitting curve is obtained; i chip (t) is the current flowing through each chip, through the load current i load (t) and the number of parallel chips N are calculated; D T / D (t) is the duty cycle of the chip / diode; The switching loss is calculated as follows: In the formula, p sw-chip (t) is the switching loss of each chip in the SiC power module; E sw_chip is the switching energy of a single chip, which is calculated using the corresponding load current in the chip data sheet; f s is the switching frequency of the SiC power module in the NPC three-level circuit.

3. The multi-time scale life assessment method for SiC power module of aviation converter according to claim 1, characterized in that: In step 2), the finite element model of the SiC power module is established based on the SiC power module object and the data manual, and then the power loss obtained in step 1) is input into the finite element model for electrothermal multi-physics field coupling simulation to obtain the thermal resistance and thermal capacity values ​​between the layers of the SiC power module under different flight conditions. The method is as follows: A three-dimensional model of the SiC power module is drawn based on the actual SiC power module and the data manual, and then the data in the SiC power module are set according to the information in the data manual. The three-dimensional model is then imported into the finite element simulation software, and boundary conditions including ambient temperature and humidity are set to form a finite element model. The power loss obtained in step 1) is then input into the finite element model for electrothermal multi-physics field coupling simulation, and the thermal resistance and thermal capacity values ​​between the layers on the SiC power module under different boundary conditions are measured from the simulation results.

4. The multi-time scale life assessment method for SiC power module of aviation converter according to claim 1, characterized in that: In step 4), the voltage value of each node in the thermal network model is the corresponding junction temperature data.

5. The multi-time scale life assessment method for SiC power module of aviation converter according to claim 1, characterized in that: In step 5), the junction temperature data obtained in step 4) is processed by the rain flow algorithm, and then the failure cycle number of the SiC power module is calculated by the Bayerer model, and then the low-frequency damage consumption and fundamental frequency damage consumption of the SiC power module are calculated by the linear cumulative damage model. The method for evaluating the life of the SiC power module is: The Bayerer model considers the same factors affecting life as other models, and also considers the heating time t on , Maximum junction temperature T jmax , minimum junction temperature T jmin , the effective value of the current I passing through each aluminum bonding wire and the diameter D of the aluminum bonding wire, the number of failure cycles N f The expression is: Where, T jmax and T jmin are the maximum and minimum junction temperatures of the device within a fundamental frequency cycle; the heating time t on is 1 / (2f o ), f o is the output frequency of the NPC three-level circuit; the effective value I of the current passing through each aluminum bonding wire is 1 / 32 of the converter line current, and the number of bonding wires in the SiC power module is related to the type of SiC power module; U = 22V is the voltage of the SiC power module; the diameter of the aluminum bonding wire D = 200μm, k = 9.3×10 14 , β1=-3.581, β2=1537, β3=-0.463, β4=-0.716, β5=-0.761, β6=-0.5; The failure cycle number N of SiC power module is calculated using the Bayerer model f Finally, the linear cumulative damage model is used to predict the damage consumption under variable working conditions. The calculation formula is: Where N f,n N is the number of cycles to failure corresponding to the nth thermal cycle; n is the corresponding number of thermal cycles; The damage consumption is divided into baseband damage consumption and low-frequency damage consumption; the baseband damage consumption C caused by baseband junction temperature fluctuation L_F It can be directly calculated using the above formulas (3) and (4) by extracting the maximum junction temperature T from the fundamental frequency junction temperature fluctuation data during each thermal cycle. jmax and the minimum junction temperature T jmin , and then substitute it into formula (3). Since other parameters are known, the number of failure cycles N for each thermal cycle is further calculated. f ; Then use formula (4) to calculate the number of thermal cycles N n The number of cycles to failure corresponding to the nth thermal cycle is N f,n The fundamental frequency damage consumption C can be calculated by summing the ratio of L_F ; The low-frequency damage caused by low-frequency junction temperature fluctuation consumes C L_L The calculation requires first obtaining the low-frequency junction temperature data, and then processing it through the rain flow algorithm to calculate the device life C using equations (3) and (4). L_L The method is that in each operating state of the aviation inverter, the SiC power module has a steady-state average junction temperature, a maximum junction temperature and a minimum junction temperature in a fundamental frequency cycle; in a year, the aviation inverter has less than 10,000 operating states, so the 10,000 sets of average junction temperature data corresponding to these 10,000 operating states are pole extracted to obtain the low-frequency junction temperature data of the SiC power module, from which the maximum junction temperature T is extracted. jmax and the minimum junction temperature T jmin , and then substitute it into formula (3). Since other parameters are known, the number of failure cycles N for each thermal cycle is further calculated. f ; Then use formula (4) to calculate the number of thermal cycles N n The number of cycles to failure corresponding to the nth thermal cycle is N f,n The low-frequency damage consumption C can be calculated by summing the ratio of L_L Finally, the fundamental frequency damage caused by the fundamental frequency junction temperature fluctuation is used to consume C L_F and the low-frequency damage consumption C caused by low-frequency junction temperature fluctuations L_L Multi-time scale lifetime assessment of SiC power modules for aviation inverters.

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