A high efficiency rectifier thermal management method based on sic devices

Abstract

The application belongs to the technical field of high-efficiency rectifier thermal management, and provides a high-efficiency rectifier thermal management method based on SiC devices, which comprises the following steps: collecting the temperature distribution of SiC devices in the high-efficiency rectifier under full load conditions, and obtaining a transient temperature rise area and a steady temperature rise area by analyzing the range of temperature change; collecting the global voltage and the local voltage of the SiC devices, determining whether a global avalanche phenomenon occurs by comparing the global voltage change rate with a typical value, if yes, calculating a thermal-electric coupling coefficient by the local voltage and the temperature, extracting a candidate grid area of the avalanche breakdown source and positioning a local avalanche origin point, and determining the specific position of the avalanche breakdown origin point; outputting a spatial overlap degree according to the thermal-electric coupling coefficient and the spatial overlap proportion, judging whether the transient temperature rise is caused by the avalanche breakdown phenomenon, and triggering avalanche breakdown protection optimization if the avalanche breakdown causes the transient temperature rise.

Description

Technical Field

[0001] This invention belongs to the field of high-efficiency rectifier thermal management technology, specifically a high-efficiency rectifier thermal management method based on SiC devices. Background Technology

[0002] As power electronic systems develop towards higher frequencies, higher power densities, and higher efficiency, high-efficiency rectifiers based on silicon carbide (SiC) devices have become a core technology in fields such as new energy conversion, electric vehicle charging, and smart grids.

[0003] SiC devices, such as MOSFETs or Schottky diodes, have a much faster switching speed than Si devices. This is mainly because SiC has a higher carrier mobility and lower on-resistance, resulting in a larger rate of change of dv / dt and di / dt during the switching process. When the switching speed increases, the parasitic inductance in the circuit (such as lead inductance, PCB wiring inductance, internal module inductance, etc.) will generate larger voltage spikes. According to the basic formula of inductance V=L*(di / dt), when di / dt increases, even if L is the same, the voltage V will increase significantly.

[0004] If the voltage spike exceeds the rated withstand voltage of the device, it will cause the device to enter the avalanche breakdown state. During avalanche breakdown, the device will be subjected to high voltage and high current, generating a lot of heat and forming local hot spots. If this happens frequently, it will cause the device to overheat or even be damaged, which may lead to the failure of the high-efficiency rectifier.

[0005] Therefore, this invention provides a high-efficiency rectifier thermal management method based on SiC devices. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by this invention to solve its technical problem is: a high-efficiency rectifier thermal management method based on SiC devices, comprising the following steps:

[0008] The temperature distribution of SiC devices in a high-efficiency rectifier under full load conditions was collected, and the transient heating region and steady-state heating region were obtained by analyzing the range of temperature changes.

[0009] The global and local voltages of the SiC device are collected. The global voltage change rate is compared with the typical value to determine whether a global avalanche phenomenon has occurred. If so, the thermal-electric coupling coefficient is calculated by the local voltage and temperature. The candidate grid region of the avalanche breakdown source is extracted and the local avalanche origin point is located to clarify the specific location of the avalanche breakdown origin point.

[0010] Based on the thermal-electric coupling coefficient and the spatial overlap ratio, output the spatial overlap degree to determine whether the transient temperature rise is caused by avalanche breakdown. If the transient temperature rise is caused by avalanche breakdown, then trigger avalanche breakdown protection optimization.

[0011] After implementing avalanche breakdown protection optimization, the heat conduction path from the transient heating region to the steady-state heating region is predicted using a thermal coupling model. The steady-state heating region that is heated due to transient heat conduction in the transient heating region is marked as the affected region. The temperature changes of the transient heating region and the affected region before and after optimization are analyzed, and the comprehensive optimization coefficient is output to evaluate the optimization effect.

[0012] The beneficial effects of this invention are as follows:

[0013] This invention analyzes the spatial overlap and thermo-electric coupling relationship between avalanche breakdown and transient temperature rise to determine the causes of thermal failure and trigger targeted protection optimization. Then, it combines the thermal coupling model to evaluate the optimization effect and iteratively adjust the strategy. This system not only reduces ineffective optimization of non-critical factors, but also fundamentally suppresses the risk of thermal failure caused by avalanche breakdown, significantly improving the reliability and service life of SiC devices and rectifiers. Attached Figure Description

[0014] The invention will now be further described with reference to the accompanying drawings.

[0015] Figure 1 This is a flowchart of the steps of a high-efficiency rectifier thermal management method based on SiC devices according to the present invention;

[0016] Figure 2 This is a flowchart of step S2 of the high-efficiency rectifier thermal management method based on SiC devices according to the present invention;

[0017] Figure 3 This is an architecture diagram of a high-efficiency rectifier thermal management system based on SiC devices according to the present invention. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] Example 1

[0020] Please see Figure 1 and Figure 2 As shown in the embodiment of the present invention, a high-efficiency rectifier thermal management method based on SiC devices includes the following steps:

[0021] Step S1: Collect the temperature distribution of SiC devices in the high-efficiency rectifier under full load conditions, and obtain the transient heating region and steady-state heating region by analyzing the range of temperature changes;

[0022] In some embodiments, the full-load condition is defined as: setting the input voltage range, output current, and ambient temperature to make the test repeatable;

[0023] For example, an input voltage range of 600V±5%, an output current of 120A, and an ambient temperature of 25℃ are defined as a constant temperature chamber.

[0024] The surface of the SiC device is divided into several regions using a mesh pattern;

[0025] Optionally, SiC device surface meshing: Based on the SiC power module packaging structure, a two-dimensional coordinate system is established along the SiC device surface, and an equally spaced mesh is used with a fine mesh spacing of 2.4mm × 2.4mm; mesh refinement is implemented in known heat concentration areas such as the SiC device pin connection area, gate drive area, and power circuit connection point, which can be divided into 0.8mm × 0.8mm sections; the physical coordinates of each mesh node are defined, and a mapping relationship with the device's three-dimensional model is established;

[0026] In particular, the detection of transient temperature rise is more sensitive in the encrypted grid area, which can capture localized subtle thermal transients and reduce the missed detection of potential thermal hazards caused by the overall temperature averaging.

[0027] Set the sampling frequency, obtain the temperature value of each area at the sampling time, and calculate the temperature change rate of each area corresponding to adjacent sampling times.

[0028] During the data collection period, for each region, the data collection moments with a positive rate of temperature change are extracted as the heating moments.

[0029] The rate of temperature change at the moment of heating is compared with the limit of the rate of temperature change. If the rate of temperature change is greater than the limit, it is marked as transient heating; if the rate of temperature change is less than or equal to the limit, it is marked as steady-state heating.

[0030] Among them, by setting a limit on the rate of temperature change, two heating modes can be distinguished from a kinetic perspective. When the rate of temperature change exceeds the limit, it indicates that the heat accumulation rate exceeds the steady-state heat dissipation capacity, which is a transient thermal shock. Conversely, it is a steady-state heat accumulation. The limit on the rate of temperature change is determined by those skilled in the art based on the material properties, failure physical mechanisms and application scenarios of SiC devices, and needs to be calibrated through a combination of simulation and experiment.

[0031] The number of transient temperature rise moments is counted, and the ratio of the number of transient temperature rise moments to the total number of data collection moments is calculated as the proportion of transient temperature rise moments.

[0032] The proportion of transient heating moments is compared with the limit of transient heating moment proportion. If the proportion of transient heating moments is greater than the transient heating moment proportion, the region frequently experiences transient thermal shock and is marked as a transient high temperature region. If the proportion of transient heating moments is less than or equal to the transient heating moment proportion, the region is marked as a steady-state heating region.

[0033] The limit for the proportion of transient temperature rise moments is determined by those skilled in the art based on fatigue life models and system reliability targets, and is generally set at 20%-30%.

[0034] It should be explained that the percentage of transient heating moments represents the proportion of transient heating moments to the total number of data acquisition moments, and is used to assess the persistence of regional thermal characteristics.

[0035] By using a dual judgment logic based on the rate of temperature change and the proportion of transient moments, the thermal response of SiC devices is divided into transient and steady-state modes. Essentially, this allows for the precise location of potential thermal hazards from two dimensions: thermal shock intensity and thermal stress persistence.

[0036] Step S2: Collect the electrical parameters of the SiC device and identify whether avalanche breakdown occurs. If so, analyze the degree of overlap between the avalanche breakdown phenomenon and the transient heating region based on the spatial location.

[0037] In some embodiments, the electrical parameters of SiC devices are acquired at high speed and synchronously to detect avalanche phenomena.

[0038] Electrical parameters include voltage parameters, because avalanche breakdown is essentially a voltage-driven physical process;

[0039] A detection circuit is connected in parallel across the drain and source terminals of the SiC device to detect the global voltage, and a micro-voltage probe is set in a key area on the surface of the SiC device to detect the local voltage; the key area includes at least the terminal edge and the JFET region.

[0040] The overall and local voltages were filtered using a moving average to remove high-frequency noise and suppress the interference of switching noise on avalanche feature extraction.

[0041] Whether avalanche breakdown has triggered the avalanche breakdown phenomenon is determined by using both global and local voltage dimensions.

[0042] The global voltage determination process is as follows:

[0043] Calculate the global voltage change rate, which is the ratio of the difference in global voltage at adjacent acquisition times to the difference between adjacent acquisition times.

[0044] The global voltage change rate is compared with the typical value. If the voltage change rate is greater than the typical value, the global avalanche phenomenon is determined to be triggered; otherwise, the global avalanche phenomenon is determined not to be triggered.

[0045] The typical value is set by those skilled in the art based on experience and industry standards, and can be set as follows: ;

[0046] After determining that a global avalanche has been triggered, the local avalanche is located using local voltage. The process is as follows:

[0047] Calculate the voltage difference between adjacent micro-voltage probes and construct a voltage gradient vector;

[0048] If the magnitude of the voltage gradient vector exceeds the magnitude threshold and its direction points into the SiC device, it indicates that the electric field is concentrated.

[0049] Whether the direction points towards the SiC device is determined by the coordinate system orientation.

[0050] Map the transient heating region marked in step S1 above to the SiC device surface coordinate system;

[0051] Obtain the moment when the global avalanche phenomenon is triggered, and extract the local voltage of all micro-voltage probes and the temperature value of the corresponding grid region;

[0052] The thermal-electric coupling coefficient is calculated using the following formula: Where C represents the thermal-electric coupling coefficient, This represents the temperature of the i-th grid region. This represents the i-th local voltage change value, and N represents the total number of grid regions;

[0053] Mesh regions with thermal-electric coupling coefficients greater than the coupling coefficient threshold are identified as candidate mesh regions for avalanche breakdown sources.

[0054] Mesh regions with thermal-electric coupling coefficients greater than the coupling coefficient threshold are identified as candidate mesh regions for avalanche breakdown sources.

[0055] The voltage change values ​​of all micro-voltage probes are obtained and sorted, and the grid where the micro-voltage probe with the largest voltage change value is located is taken as the avalanche origin point;

[0056] The purpose of identifying the avalanche origin point is to provide a target location for targeted implementation of avalanche breakdown protection optimization, to focus on designing cooling solutions for the area where the avalanche origin point is located, to improve the accuracy of thermal management strategies, and to reduce resource waste caused by indiscriminate heat dissipation.

[0057] The thermal-electric coupling coefficient reflects the synergistic enhancement effect of temperature rise and voltage change in space. It captures the spatial colocation of temperature and voltage changes through the product term. If the two completely overlap in space, for example, an avalanche breakdown source simultaneously causes local electric field concentration and high temperature, the thermal-electric coupling coefficient is close to 1. If the two do not overlap in space, the thermal-electric coupling coefficient is close to 0.

[0058] The calculated thermal-electric coupling coefficient serves several purposes: First, it reflects the spatial system effect of temperature rise and voltage surge. Second, by comparing it with a threshold, it extracts candidate grid regions for avalanche breakdown sources, providing a basis for accurate location of the avalanche origin and helping to clarify the specific location of the avalanche breakdown origin. Third, in step S3 below, when determining whether transient temperature rise is caused by avalanche breakdown, it serves as one of the indicators, combined with the spatial overlap area, to comprehensively evaluate the correlation between transient temperature rise and avalanche breakdown in physical and control dimensions, providing a basis for subsequent avalanche breakdown protection optimization extraction.

[0059] Step S3: Based on the degree of spatial overlap, determine whether the transient temperature rise is caused by avalanche breakdown. If the transient temperature rise is caused by avalanche breakdown, then trigger avalanche breakdown protection optimization.

[0060] In some embodiments, the avalanche breakdown source and the grid region of the candidate avalanche breakdown source are obtained as the avalanche breakdown related region and spatially matched with the transient heating region marked in step S1 above.

[0061] Obtain the total area of ​​the overlapping grid region between the avalanche breakdown-related region and the transient heating region, and calculate the ratio of the total area of ​​the overlapping grid region to the total area of ​​the transient heating region to obtain the percentage of overlapping area.

[0062] The grid area is calculated according to the grid division rules in step S1 above;

[0063] The average value of the thermal-electric coupling coefficient corresponding to the total area of ​​the overlapping grid region is taken;

[0064] The spatial overlap is output by weighting and fusing the overlap area ratio with the mean thermal-electric coupling coefficient.

[0065] Among them, the weighting coefficients of the overlap area ratio and the mean thermal-electric coupling coefficient are back-calculated using statistical methods (such as least squares method and logistic regression) through a large amount of failure test data (such as the correlation samples of avalanche breakdown time and transient temperature rise recorded in accelerated aging tests) to make the weighted spatial overlap degree most correlated with the actual occurrence rate (true label) of "avalanche breakdown leading to transient temperature rise"; if the thermal-electric coupling coefficient contributes more in 80% of the true correlation samples in the experiment, its weight is increased.

[0066] Spatial overlap reflects the overall correlation strength between the avalanche breakdown-related region (avalanche source and candidate source) and the transient heating region on the surface of SiC devices, from spatial coincidence to thermo-electrophysical mechanism coupling.

[0067] By fusing the thermal-electric coupling coefficient with the overlap area ratio, the causal relationship between avalanche breakdown and transient temperature rise can be determined in several ways: First, it allows for comprehensive verification from both physical correlation and spatial distribution dimensions, leading to a more accurate assessment of the causal relationship. Second, by integrating these indicators, the contribution of avalanche breakdown to transient temperature rise can be more clearly understood, identifying key contributing factors and enabling subsequent thermal management strategies to address critical issues and improve the effectiveness of thermal management. Third, by accurately determining the causal relationship and implementing targeted optimization, the risk of localized hot spots and device overheating caused by avalanche breakdown can be reduced at its source, lowering the probability of SiC devices being damaged due to thermal failure, thereby improving the reliability and lifespan of high-efficiency rectifiers based on SiC devices.

[0068] If the spatial overlap is less than the spatial overlap threshold, it is determined that the transient temperature rise is not caused by avalanche breakdown, and other thermal management strategies are implemented, including but not limited to: optimizing the heat dissipation mechanism;

[0069] If the spatial overlap is greater than or equal to the spatial overlap threshold, the transient temperature rise is determined to be caused by the avalanche breakdown phenomenon, triggering the avalanche breakdown protection optimization process.

[0070] The avalanche breakdown protection optimization process includes the following optimization measures:

[0071] By dynamically adjusting the drive resistance through the gate drive circuit, the drive resistance is increased in the initial stage of conduction during the switching process to reduce di / d (the ratio of the change in current to the time taken for the change in current) t, and the drive resistance is decreased in the initial stage of turn-off to reduce dv / dt, thereby suppressing the voltage spike amplitude.

[0072] Targeted cooling enhancements can be implemented in the avalanche origin region, such as controlling and increasing the flow rate of the micro liquid cooling channels or triggering the activation of local thermoelectric cooling modules (TEC), so that the temperature in the avalanche origin region decreases at a faster rate, thereby reducing heat accumulation caused by continuous avalanches.

[0073] The reason for analyzing the causal relationship between avalanche breakdown and transient temperature rise in this step is that transient temperature rise can be caused by a variety of factors, and avalanche breakdown is the riskiest and most unique cause among them. If transient temperature rise is caused by avalanche breakdown, it is essentially a transient high power loss caused by voltage spikes, and it is necessary to specifically suppress avalanche breakdown itself, rather than simply enhancing heat dissipation. If transient temperature rise is caused by other factors, it is necessary to optimize the heat dissipation path, rather than adjusting circuit parameters.

[0074] Without making causal judgments, incorrect thermal management strategies may be adopted (such as using heat dissipation optimization to deal with transient temperature rise caused by avalanche breakdown), which will not only fail to solve the problem, but also waste resources.

[0075] Step S4: After implementing avalanche breakdown protection optimization, predict the heat conduction path from transient temperature rise to steady-state region using a thermal coupling model, mark the steady-state region that is heated due to transient heat conduction in the transient temperature rise region as the affected region, analyze the temperature changes of the transient temperature rise region and the affected region before and after optimization, and evaluate the optimization effect.

[0076] In some embodiments, a transient thermal coupling model is constructed based on the three-dimensional structural model of the SiC device. The optimized SiC device operating parameters and environmental parameters are input, and the transient temperature field, heat flux density and conduction path, and temperature change rate are output.

[0077] Operating parameters should include at least: gate drive resistor, switching frequency, and voltage and current waveforms (reflecting the electrical state after avalanche breakdown protection optimization).

[0078] Environmental parameters include at least: ambient temperature, cooling system parameters (such as liquid cooling flow rate), thermal conductivity, specific heat capacity, and density of each material;

[0079] As will be understood by those skilled in the art, the transient thermal coupling model is a dynamic simulation model that integrates the device's physical structure, thermal conductivity, and electro-thermal interaction.

[0080] The transient thermal coupling model serves to: predict how heat from the transient heating region diffuses to the steady-state region after avalanche breakdown protection optimization by dynamically simulating the transient heat conduction process, providing quantitative data support for extracting heat conduction paths and marking affected areas; and more realistically reflect the actual impact of avalanche breakdown protection optimization on the overall thermal management of the device.

[0081] The transient temperature field distribution at m (several) time points after optimization is obtained by thermal coupling model simulation; where m is set by those skilled in the art based on experience.

[0082] The temperature field data includes all grid regions on the surface of the SiC device; the temperature value, temperature change rate, and heat flux density of each grid region at different time points are recorded; the heat flux density reflects the intensity of heat transfer.

[0083] The process of extracting the diffusion path is as follows: starting from the transient heating region, the heat flow direction of each grid region is calculated. The heat flow direction is obtained based on the temperature gradient. The heat flow is conducted from the high temperature region to the low temperature region, and the direction is determined by the direction of the gradient vector.

[0084] Along the heat flow direction, select grid nodes with heat flux density greater than the heat flux density threshold (e.g., 0.5 W / mm², set according to the heat dissipation capacity of the device) to form a continuous heat conduction path;

[0085] The extracted heat flow is transferred from the transient heating region to the steady-state heating region marked in step S1 above;

[0086] Based on the heat conduction path and temperature change, the steady-state region that heats up due to transient heat conduction is marked as the affected region;

[0087] For the transient heating region and the affected region, calculate the temperature changes before and after optimization, and evaluate the optimization effect. The process is as follows:

[0088] For the transient heating region, obtain the highest temperature value in all transient heating regions before optimization and the highest temperature value in all transient heating regions after optimization, calculate the difference, and then calculate the ratio of the difference to the highest temperature value in all transient heating regions before optimization to obtain the highest temperature reduction ratio.

[0089] For the affected area, obtain the area of ​​the affected area before optimization and the area of ​​the affected area after optimization, calculate the difference, and then calculate the ratio of the difference to the area of ​​the affected area before optimization to obtain the reduction ratio of the affected area.

[0090] Among them, the affected area before optimization refers to the steady-state area where the temperature rise is caused by the transient temperature rise area when the avalanche breakdown protection optimization is not implemented;

[0091] The purpose of calculating the affected area reduction ratio is threefold: First, it reflects the degree of shrinkage of the heat conduction path; a higher area reduction ratio indicates that the optimization is more effective in suppressing heat diffusion. Second, the area of ​​the affected region is related to the failure probability of SiC. According to the failure physics model, long-term exposure to transient heat conduction in the steady-state region will accelerate material aging (such as gate oxide degradation and metallization migration). The area reduction ratio can be used as an input parameter to predict the remaining lifetime of the device: a higher reduction ratio indicates a slower aging rate and a more significant improvement in reliability, providing data support for the maintenance cycle and lifetime assessment of the rectifier. Third, if the affected area reduction ratio is low, it indicates that the existing heat dissipation structure (such as the layout of the liquid cooling channel and the location of the thermoelectric cooling module) may have design flaws (such as not covering the main heat conduction path).

[0092] The ratio of the highest temperature and the ratio of the reduction in affected area are weighted and fused to output a comprehensive optimization coefficient;

[0093] The weighting coefficients for the highest temperature ratio and the affected area reduction ratio are set by those skilled in the art based on the failure risk of SiC devices. If transient high temperature is the main cause of failure, the weighting coefficient for the highest temperature ratio is 0.6-0.7. If large-area overheating caused by thermal diffusion is the key cause, the weighting coefficient for the affected area reduction ratio is 0.6-0.7.

[0094] The purpose of evaluating the optimization effect by fusing the highest temperature ratio and the affected area reduction ratio is twofold: firstly, fusion allows for a more comprehensive assessment of the optimization strategy's effect on suppressing thermal failure; secondly, it clarifies the shortcomings of the optimization strategy, providing direction for subsequent iterative optimization and reducing trial and error.

[0095] If the overall optimization coefficient is greater than or equal to the overall optimization coefficient threshold, the optimization is deemed effective; if the overall optimization coefficient is less than the overall optimization coefficient threshold, the optimization is deemed invalid, and iterative optimization is performed, that is, returning to step S3 to adjust the avalanche breakdown protection optimization strategy until the overall optimization coefficient is greater than or equal to the overall optimization coefficient threshold.

[0096] Among them, the setting of the comprehensive optimization coefficient threshold is verified by those skilled in the art in combination with the characteristics of SiC devices, the reliability target of rectifiers, application scenario requirements and experimental data, so that the threshold can effectively avoid the risk of thermal failure and take into account the feasibility of optimization strategies.

[0097] For example, different application areas (such as new energy vehicle charging, smart grids, and aerospace) have different reliability requirements for rectifiers. The threshold must meet the definition of thermal failure risk level in industry standards. In the civilian field (such as new energy vehicle charging piles), the mean time between failures (MTBF) of the device is usually required to be ≥10. 5 For hours, the corresponding thermal failure probability is ≤0.1% / year. Through statistical experimental data, the minimum comprehensive optimization coefficient (e.g., 70%) to meet this MTBF is determined as the threshold. For industrial or aerospace applications requiring higher reliability (MTBF ≥ 10),... 6 (hours), thermal failure probability ≤0.01% / year, the threshold needs to be increased to above 80% to match more stringent risk control targets;

[0098] The effects of this step are as follows: First, by verifying the effectiveness of the protection optimization, it can be determined whether the avalanche breakdown protection optimization measures have actually reduced thermal shock and its impact on other mesh areas, reducing resource waste caused by ineffective optimization; Second, the evaluation process can quantify the suppression effect of avalanche breakdown protection optimization on transient thermal shock and thermal diffusion, ensuring that the thermal management strategy can effectively reduce the risk of thermal failure of SiC devices and improve the stability of the rectifier; Third, by predicting the heat conduction path, it is possible to understand the affected areas that still exist after optimization, providing directions for improvement in subsequent heat dissipation design.

[0099] This embodiment forms a closed-loop thermal management system by locating areas with potential thermal hazards, determining the causal relationship between transient temperature rise and avalanche breakdown, implementing targeted protection optimizations, and scientifically quantifying the optimization effects. This addresses the problem at its root, improves the thermal stability and reliability of high-efficiency rectifiers based on SiC devices, and promotes their widespread application in fields such as new energy vehicles and smart grids.

[0100] Example 2

[0101] Based on the same inventive concept as the high-efficiency rectifier thermal management method based on SiC devices in the foregoing embodiments, such as Figure 3 As shown, this application provides a high-efficiency rectifier thermal management system based on SiC devices, wherein the system specifically includes:

[0102] Temperature distribution analysis module: Collects the temperature distribution of SiC devices in a high-efficiency rectifier under full load conditions, and obtains the transient heating region and steady-state heating region by analyzing the range of temperature changes;

[0103] Execution process: Under full load conditions, the temperature distribution of the SiC device is collected, and its surface is divided into a grid (2.4mm×2.4mm for normal areas and 0.8mm×0.8mm for heat concentration areas such as pin connection areas). The temperature values ​​of each area are obtained by setting the acquisition frequency, and the temperature change rate at adjacent time points is calculated. Combining the temperature change rate limit and the transient heating time proportion limit, transient heating areas (temperature change rate exceeds the limit and transient time proportion exceeds the threshold) and steady-state heating areas are distinguished and marked, and the mapping relationship between temperature distribution and device three-dimensional model is established.

[0104] Avalanche breakdown analysis module: Collects electrical parameters of SiC devices, identifies whether avalanche breakdown occurs, and if so, analyzes the degree of overlap between the avalanche breakdown phenomenon and the transient heating region based on the spatial location.

[0105] Execution process: The electrical parameters of the SiC device (mainly voltage parameters) are collected. A detection circuit is connected in parallel across the drain and source terminals to obtain the overall voltage. Micro voltage probes are set in key areas of the surface (such as the terminal edge and JFET area) to detect the local voltage. After removing high-frequency noise by using a moving average filter on the collected overall and local voltages, the avalanche breakdown phenomenon is determined by the dual dimensions of global voltage and local voltage.

[0106] First, calculate the overall voltage change rate (the ratio of the overall voltage difference between adjacent moments to the time difference) and compare it with the typical value. If it is greater than the typical value, it is determined that a global avalanche phenomenon has been triggered. After determining the global avalanche, calculate the voltage difference between adjacent micro-voltage probes to construct a voltage gradient vector. If its amplitude exceeds the threshold and its direction points into the device, locate the local avalanche origin point and extract the grid area with a thermal-electric coupling coefficient greater than the coupling coefficient threshold as the candidate area for avalanche breakdown source. Map the transient heating area to the device surface coordinate system. Combine the local voltage at the moment of global avalanche occurrence with the corresponding grid area temperature value to calculate the thermal-electric coupling coefficient and analyze the spatial overlap between the avalanche breakdown origin point, the candidate area and the transient heating area.

[0107] Overlap detection module: Based on the degree of spatial overlap, determine whether the transient temperature rise is caused by avalanche breakdown. If the transient temperature rise is caused by avalanche breakdown, trigger avalanche breakdown protection optimization.

[0108] Execution process: The spatial overlap ratio (the ratio of the overlapping area to the total area of ​​the transient region) of the avalanche breakdown-related region and the transient temperature rise region is weighted and fused with the thermal-electric coupling coefficient. If the spatial overlap ratio is greater than or equal to the threshold, the transient temperature rise is determined to be caused by avalanche breakdown, and protection optimization is triggered (such as dynamically adjusting the gate drive resistor to suppress voltage spikes and starting directional cooling to enhance heat dissipation in the overlapping region). If the spatial overlap ratio is less than the threshold, it is determined to be caused by other factors, and other thermal management strategies such as optimizing the heat dissipation structure are executed.

[0109] Optimization effect evaluation module: After implementing avalanche breakdown protection optimization, the heat conduction path from transient temperature rise to steady state region is predicted through thermal coupling model. The steady state region that is heated due to transient heat conduction in the transient temperature rise region is marked as the affected region. The temperature changes of the transient temperature rise region and the affected region before and after optimization are analyzed to evaluate the optimization effect.

[0110] Execution process: A transient thermal coupling model is constructed based on the three-dimensional structure of the SiC device. Optimized operating parameters and environmental parameters are input, and the transient temperature field distribution at m time points is obtained through simulation. The heat conduction path from the transient heating region to the steady-state region is extracted, and the steady-state region heated by transient heat conduction is marked as the affected region. The maximum temperature reduction ratio (the ratio of the temperature difference before and after transient region optimization to the maximum temperature before optimization) and the affected area reduction ratio (the ratio of the difference in affected area before and after optimization to the area before optimization) are calculated and weighted to form a comprehensive optimization coefficient. If the coefficient is greater than or equal to the threshold, the optimization is deemed effective; otherwise, the iterative adjustment strategy is returned.

[0111] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency rectifier thermal management method based on SiC devices, characterized in that: Includes the following steps: The temperature distribution of SiC devices in a high-efficiency rectifier under full load conditions was collected, and the transient heating region and steady-state heating region were obtained by analyzing the range of temperature changes. The global and local voltages of the SiC device are collected. The global voltage change rate is compared with the typical value to determine whether a global avalanche phenomenon has occurred. If so, the thermal-electric coupling coefficient is calculated by the local voltage and temperature. The candidate grid region of the avalanche breakdown source is extracted and the local avalanche origin point is located to clarify the specific location of the avalanche breakdown origin point. The formula for calculating the thermal-electric coupling coefficient is: Where C represents the thermal-electric coupling coefficient, This represents the temperature of the i-th grid region. This represents the i-th local voltage change value, and N represents the total number of grid regions; Based on the thermal-electric coupling coefficient and the percentage of overlapping area, output spatial overlap to determine whether transient temperature rise is caused by avalanche breakdown. If transient temperature rise is caused by avalanche breakdown, then trigger avalanche breakdown protection optimization. The output spatial overlap is determined as follows: Obtain the total area of ​​the overlapping grid region between the avalanche breakdown-related region and the transient heating region, and calculate the ratio of the total area of ​​the overlapping grid region to the total area of ​​the transient heating region to obtain the percentage of overlapping area. The average value of the thermal-electric coupling coefficient corresponding to the total area of ​​the overlapping grid region is taken; The spatial overlap is output by fusing the overlap area ratio with the average thermal-electric coupling coefficient. After implementing avalanche breakdown protection optimization, the heat conduction path from the transient heating region to the steady-state heating region is predicted using a thermal coupling model. The steady-state heating region that is heated due to transient heat conduction in the transient heating region is marked as the affected region. The temperature changes of the transient heating region and the affected region before and after optimization are analyzed, and the comprehensive optimization coefficient is output to evaluate the optimization effect.

2. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process of obtaining the transient heating region and the steady-state heating region is as follows: The surface of the SiC device is divided into several regions using a mesh pattern; the temperature value of each region is acquired at the acquisition time, and the temperature change rate of each region corresponding to adjacent acquisition times is calculated; and the heating time is obtained based on the temperature change rate. The heating moments with a temperature change rate greater than the temperature change rate limit are marked as transient heating moments; the heating moments with a temperature change rate less than or equal to the temperature change rate limit are marked as steady-state heating moments. Calculate the ratio of the number of transient heating moments to the total number of data collection moments, and use this ratio as the transient heating moment percentage. Mark the region where the transient heating moment percentage is greater than the transient heating moment percentage limit as the transient high temperature region. Mark the region where the transient heating moment percentage is less than or equal to the transient heating moment percentage limit as the steady-state heating region.

3. The high-efficiency rectifier thermal management method based on SiC devices according to claim 2, characterized in that: The process of obtaining the heating time: During the data collection period, for each region, the data collection moments with a positive rate of temperature change are extracted as the heating moments.

4. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process for determining whether a global avalanche has occurred is as follows: A detection circuit is connected in parallel across the drain and source terminals of the SiC device to detect the global voltage and calculate the global voltage change rate, which is the ratio of the difference in global voltage at adjacent acquisition times to the difference between adjacent acquisition times. If the rate of change of voltage is greater than the typical value, then a global avalanche phenomenon is determined to be triggered.

5. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process of locating the local avalanche origin point is as follows: Micro-voltage probes are set on the surface region of SiC devices to detect local voltage, the voltage difference between adjacent micro-voltage probes is calculated, and a voltage gradient vector is constructed. Map the transient heating region to the SiC device surface coordinate system; Obtain the moment when the global avalanche phenomenon is triggered, and extract the local voltage of all micro-voltage probes and the temperature value of the corresponding grid region; Calculate the thermal-electric coupling coefficient, and extract the grid regions with thermal-electric coupling coefficients greater than the coupling coefficient threshold as candidate grid regions for avalanche breakdown sources; The voltage change values ​​of all micro-voltage probes are obtained and sorted, and the grid where the micro-voltage probe with the largest voltage change value is located is taken as the avalanche origin point.

6. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process for determining whether the transient temperature rise is caused by avalanche breakdown is as follows: If the spatial overlap is greater than or equal to the spatial overlap threshold, the transient temperature rise is determined to be caused by avalanche breakdown, triggering the avalanche breakdown protection optimization process.

7. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process of obtaining the affected area is as follows: Based on the three-dimensional structural model of SiC devices, a transient thermal coupling model is constructed. The optimized SiC device operating parameters and environmental parameters are input, and the transient temperature field, heat flux density and conduction path, and temperature change rate are output. The transient temperature field distribution at several time points after optimization was obtained through thermal coupling model simulation. Starting from the transient heating region, calculate the heat flow direction for each grid region; Along the heat flow direction, grid nodes with heat flux density greater than the heat flux density threshold are selected to form a continuous heat conduction path; heat flow is extracted from the transient heating region to the steady-state heating region. Based on the heat conduction path and temperature change, the steady-state region that heats up due to transient heat conduction is marked as the affected region.

8. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process for evaluating and optimizing the effect is as follows: If the overall optimization coefficient is greater than or equal to the overall optimization coefficient threshold, the optimization is deemed effective; if the overall optimization coefficient is less than the overall optimization coefficient threshold, the optimization is deemed invalid, and iterative optimization is performed, that is, the avalanche breakdown protection optimization strategy is adjusted until the overall optimization coefficient is greater than or equal to the overall optimization coefficient threshold.

9. The high-efficiency rectifier thermal management method based on SiC devices according to claim 1, characterized in that: The process for obtaining the comprehensive optimization coefficient is as follows: For the transient heating region, obtain the highest temperature value in all transient heating regions before optimization and the highest temperature value in all transient heating regions after optimization, calculate the difference, and then calculate the ratio of the difference to the highest temperature value in all transient heating regions before optimization to obtain the highest temperature reduction ratio. For the affected area, obtain the area of ​​the affected area before optimization and the area of ​​the affected area after optimization, calculate the difference, and then calculate the ratio of the difference to the area of ​​the affected area before optimization to obtain the reduction ratio of the affected area. The ratio of the highest temperature reduction to the ratio of the reduction in affected area are combined to output a comprehensive optimization coefficient.

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