CN-120915110-B - Efficient rectifier thermal management method based on SiC device

CN120915110BCN 120915110 BCN120915110 BCN 120915110BCN-120915110-B

Abstract

The invention belongs to the technical field of high-efficiency rectifier thermal management, and provides a high-efficiency rectifier thermal management method based on a SiC device, which comprises the following steps of collecting temperature distribution of the SiC device in the high-efficiency rectifier under a full load condition, and obtaining a transient heating area and a steady heating area by analyzing the range of temperature change; the method comprises the steps of collecting global voltage and local voltage of an SiC device, judging whether a global avalanche phenomenon occurs through comparison of a global voltage change rate and a typical value, if so, calculating a thermal-electric coupling coefficient through the local voltage and temperature, extracting an avalanche breakdown source candidate grid region, positioning local avalanche starting points, determining specific positions of avalanche breakdown starting points, judging whether transient heating is caused by the avalanche breakdown phenomenon according to the thermal-electric coupling coefficient and the spatial overlapping duty ratio output spatial overlapping degree, and triggering avalanche breakdown protection optimization if the transient heating is caused by the avalanche breakdown.

Inventors

WU YONGZHAO
WANG JINLU
BI FUCHUN

Assignees

深圳市凌康技术有限公司

Dates

Publication Date: 20260508
Application Date: 20250814

Claims (9)

1. A high-efficiency rectifier thermal management method based on a SiC device is characterized by comprising the following steps: Acquiring the temperature distribution of the SiC device in the high-efficiency rectifier under the full load condition, and acquiring a transient heating area and a steady heating area by analyzing the range of temperature change; Collecting global voltage and local voltage of the SiC device, judging whether a global avalanche phenomenon occurs through comparison of a global voltage change rate and a typical value, if so, calculating a thermal-electric coupling coefficient through the local voltage and temperature, extracting an avalanche breakdown source candidate grid area, positioning a local avalanche starting point, and determining the specific position of the avalanche breakdown starting point; the thermal-electric coupling coefficient calculation formula is: Wherein C represents a thermo-electric coupling coefficient, Indicating the temperature of the i-th grid region, Represents the i-th local voltage variation value, and N represents the total number of grid areas; judging whether the transient temperature rise is caused by the avalanche breakdown phenomenon or not according to the thermal-electric coupling coefficient and the overlapping area occupation ratio output space overlapping degree, and triggering avalanche breakdown protection optimization if the transient temperature rise is caused by the avalanche breakdown; The output space overlapping degree comprises the following steps: Acquiring the total area of an overlapped grid region of the avalanche breakdown related region and the transient heating region, and calculating the ratio of the total area of the overlapped grid region to the total area of the transient heating region to obtain the overlapping area occupation ratio; Averaging the thermal-electric coupling coefficients corresponding to the total area of the overlapped grid areas; fusing the overlapping area occupation ratio with the thermal-electric coupling coefficient mean value to output the space overlapping degree; After avalanche breakdown protection optimization is implemented, a heat conduction path from a transient heating area to a steady heating area is predicted through a heat coupling model, the steady heating area heated up due to transient heat conduction of the transient heating area is marked as an affected area, temperature changes of the transient heating area and the affected area before and after optimization are analyzed, a comprehensive optimization coefficient is output, and an optimization effect is evaluated.
2. The method for thermal management of a high efficiency rectifier based on a SiC device according to claim 1, wherein the step of obtaining a transient heating region and a steady heating region comprises the following steps: Dividing the surface of the SiC device into a plurality of areas according to a grid type, acquiring a temperature value of each area at the acquisition time, calculating a temperature change rate corresponding to adjacent acquisition time of each area, and acquiring a temperature rise time based on the temperature change rate; Marking the temperature rise time with the temperature change rate smaller than or equal to the temperature change rate limit value as steady temperature rise time; the method comprises the steps of calculating the ratio of the number of transient heating moments to the total number of collecting moments as the transient heating moment duty ratio, marking the area with the transient heating moment duty ratio larger than the transient heating moment duty ratio limit value as a transient high-temperature area, and marking the area with the transient heating moment duty ratio smaller than or equal to the transient heating moment duty ratio limit value as a steady-state heating area.
3. The method for thermal management of a high-efficiency rectifier based on a SiC device according to claim 2, wherein the temperature rise time acquisition process comprises the following steps: And in the acquisition period, corresponding to each region, extracting the acquisition time with positive temperature change rate as the temperature rise time.
4. The method for thermal management of a high efficiency rectifier based on a SiC device according to claim 1, wherein said determining whether a global avalanche phenomenon occurs comprises the steps of: Detecting global voltages at two ends of a drain and a source of the SiC device in parallel by using a detection circuit, and calculating the global voltage change rate, namely the ratio of the difference value of the global voltages at adjacent acquisition moments to the difference value at adjacent acquisition moments; if the voltage change rate is greater than the typical value, it is determined that the global avalanche phenomenon is triggered.
5. The method for thermal management of a high efficiency rectifier based on a SiC device according to claim 1, wherein the locating of the localized avalanche origin comprises the following steps: Arranging micro-voltage probes on the surface area of the SiC device to detect local voltage, calculating the voltage difference of adjacent micro-voltage probes, and constructing a voltage gradient vector; Mapping the transient heating area to a SiC device surface coordinate system; acquiring the occurrence time of triggering the global avalanche phenomenon, and extracting the local voltages of all the micro-voltage probes and the temperature values of the corresponding grid areas; Calculating a thermal-electric coupling coefficient, and extracting a grid region with the thermal-electric coupling coefficient larger than a coupling coefficient threshold value to judge the grid region as an avalanche breakdown source candidate grid region; and acquiring voltage variation values of all the micro-voltage probes, sequencing, and taking the grid where the micro-voltage probe with the largest voltage variation value is positioned as an avalanche origin.
6. The method for thermal management of a high efficiency rectifier based on a SiC device according to claim 1, wherein the judging whether the transient temperature rise is caused by an avalanche breakdown phenomenon comprises the following steps: If the spatial overlapping degree is larger than or equal to the spatial overlapping degree threshold value, judging that the transient heating is caused by avalanche breakdown phenomenon, and triggering an avalanche breakdown protection optimization flow.
7. A method for efficient rectifier thermal management based on SiC devices as defined in claim 1, wherein the affected area is obtained by the following steps: Based on a three-dimensional structure model of the SiC device, a transient thermal coupling model is built, optimized running parameters and environment parameters of the SiC device are input, and a transient temperature field, a heat flux density, a conduction path and a temperature change rate are output; Obtaining transient temperature field distribution in a plurality of optimized time points through thermal coupling model simulation; Calculating the heat flow direction of each grid area by taking the transient heating area as a starting point; screening grid nodes with heat flux density larger than a heat flux density threshold value along the heat flux direction to form a continuous heat conduction path; based on the heat conduction path and the temperature change, a steady-state region where the temperature rises due to transient heat conduction is marked as an affected region.
8. The method for thermal management of a high-efficiency rectifier based on a SiC device according to claim 1, wherein the evaluation optimization effect process is as follows: If the comprehensive optimization coefficient is smaller than the comprehensive optimization coefficient threshold, the optimization is invalid, and iterative optimization is executed, namely, the avalanche breakdown protection optimization strategy is returned to be adjusted until the comprehensive optimization coefficient is larger than or equal to the comprehensive optimization coefficient threshold.
9. The method for efficiently managing the rectifier based on the SiC device according to claim 1, wherein the comprehensive optimization coefficient is obtained by the following steps: For the transient heating areas, obtaining the maximum temperature values in all the transient heating areas before optimization and the maximum temperature values in all the transient heating areas after optimization, carrying out differential value calculation, and carrying out ratio calculation on the differential value and the maximum temperature values in all the transient heating areas before optimization to obtain the maximum temperature amplitude reduction ratio; for the affected area, acquiring the area of the affected area before optimization and the area of the affected area after optimization, performing difference value calculation, and performing ratio calculation on the difference value and the area of the affected area before optimization to obtain an affected area reduction ratio; And fusing the highest temperature amplitude reduction ratio with the affected area reduction ratio, and outputting the comprehensive optimization coefficient.

Description

Efficient rectifier thermal management method based on SiC device Technical Field The invention belongs to the technical field of high-efficiency rectifier thermal management, and particularly relates to a high-efficiency rectifier thermal management method based on a SiC device. Background With the development of power electronic systems to high frequency, high power density and high efficiency, high-efficiency rectifiers based on silicon carbide (SiC) devices have become core technologies in the fields of new energy conversion, electric vehicle charging, smart grids and the like; SiC devices, such as MOSFETs or schottky diodes, switch much faster than Si devices, mainly because SiC has higher carrier mobility and lower on-resistance, so that the rates of change of dv/dt and di/dt during switching are greater, and when the switching speed is increased, parasitic inductances in the circuit (such as lead inductance, PCB wiring inductance, module internal inductance, etc.) can generate larger voltage spikes, and when di/dt increases, even if L is the same, the voltage V can increase significantly according to the basic formula v=l (di/dt) of inductance; When the voltage peak exceeds the rated withstand voltage value of the device, the device is caused to enter an avalanche breakdown state, the device can bear high voltage and high current during avalanche breakdown, a large amount of heat is generated, local hot spots are formed, if the situation happens frequently, the device is overheated or even damaged, and the high-efficiency rectifier is possibly disabled; To this end, the invention provides a high efficiency rectifier thermal management method based on SiC devices. Disclosure of Invention In order to overcome the deficiencies of the prior art, at least one technical problem presented in the background art is solved. The technical scheme adopted by the invention for solving the technical problems is that the high-efficiency rectifier thermal management method based on the SiC device comprises the following steps: Acquiring the temperature distribution of the SiC device in the high-efficiency rectifier under the full load condition, and acquiring a transient heating area and a steady heating area by analyzing the range of temperature change; Collecting global voltage and local voltage of the SiC device, judging whether a global avalanche phenomenon occurs through comparison of a global voltage change rate and a typical value, if so, calculating a thermal-electric coupling coefficient through the local voltage and temperature, extracting an avalanche breakdown source candidate grid area, positioning a local avalanche starting point, and determining the specific position of the avalanche breakdown starting point; judging whether the transient temperature rise is caused by the avalanche breakdown phenomenon or not according to the thermal-electric coupling coefficient and the spatial overlapping duty ratio output spatial overlapping degree, and triggering avalanche breakdown protection optimization if the transient temperature rise is caused by the avalanche breakdown; After avalanche breakdown protection optimization is implemented, a heat conduction path from a transient heating area to a steady heating area is predicted through a heat coupling model, the steady heating area heated up due to transient heat conduction of the transient heating area is marked as an affected area, temperature changes of the transient heating area and the affected area before and after optimization are analyzed, a comprehensive optimization coefficient is output, and an optimization effect is evaluated. The beneficial effects of the invention are as follows: According to the invention, through analyzing the spatial overlapping degree and the thermal-electric coupling relation between avalanche breakdown and transient temperature rise, the thermal failure cause is judged, the targeted protection optimization is triggered, and the optimization effect is evaluated by combining a thermal coupling model, so that the system reduces the ineffective optimization on non-key factors, suppresses the thermal failure risk caused by avalanche breakdown from the root, and remarkably improves the reliability and the service life of SiC devices and rectifiers. Drawings The invention is further described below with reference to the accompanying drawings. FIG. 1 is a flow chart of the steps of a method for efficient rectifier thermal management based on SiC devices of the invention; FIG. 2 is a flow chart of a method step S2 of thermal management of a high efficiency rectifier based on a SiC device of the invention; fig. 3 is an architecture diagram of a high efficiency rectifier thermal management system based on SiC devices of the present invention. Detailed Description The invention is further described in connection with the following detailed description in order to make the technical means, the creation characteristics, the achievement of