The dynamic avalanche effect is a critical factor influencing the performance and reliability of the field-stop insulated gate bipolar transistors(FS-IGBT).Unclamped inductive switching(UIS)is the primary method for t...The dynamic avalanche effect is a critical factor influencing the performance and reliability of the field-stop insulated gate bipolar transistors(FS-IGBT).Unclamped inductive switching(UIS)is the primary method for testing the dynamic avalanche capability of FS-IGBTs.Numerous studies have demonstrated that factors such as device structure,avalanche-generating current filaments,and electrical parameters influence the dynamic avalanche effect of the FS-IGBT.However,few studies have focused on enhancing the avalanche reliability of the FS-IGBT by adjusting circuit parameters during operation.In this paper,the dynamic avalanche effect of the FS-IGBT under UIS conditions is comprehensively investigated through a series of comparative experiments with varying circuit parameters,including bus voltage V_(DC),gate voltage V_(G),gate resistance R_(g),load inductance L,and temperature TC.Furthermore,a method to enhance the dynamic avalanche reliability of the FS-IGBT under UIS by optimizing circuit parameters is proposed.In practical applications,reducing gate voltage,increasing load inductance,and lowering temperature can effectively improve the dynamic avalanche capability of the FS-IGBT.展开更多
An improved field charge extraction （FCE） diode with a deep p＋ adjusting region at the cathode side is studied. The reverse recovery mechanism and electric field gradient are thoroughly analyzed and validated using...An improved field charge extraction （FCE） diode with a deep p＋ adjusting region at the cathode side is studied. The reverse recovery mechanism and electric field gradient are thoroughly analyzed and validated using ISE simulation results. The results show that, based on the premise of ensuring the static characteristics, the improved FCE diode can clearly improve the softness and effectively suppress the peak electric field of the nnjunction at the cathode side during reverse recovery, and thus has a high dynamic avalanche capability compared with conventional FCE diodes.展开更多
Analyzing large prehistoric rock avalanches provides significant data for evaluating the disaster posed by these relatively infrequent but destructive geological events. This paper attempts to study the characteristic...Analyzing large prehistoric rock avalanches provides significant data for evaluating the disaster posed by these relatively infrequent but destructive geological events. This paper attempts to study the characteristics and dynamics of the Ganqiuchi granitic rock avalanche, in the middle of the northern margin of Qinling Mountains, 30 km to the south of Xi’an, Shaanxi Province, China. In plane view, this rock avalanche is characterized by source area, accumulation area and dammed lake area. Based on previous studies, historical records and regional geological data, the major trigger of the Ganqiuchi rock avalanche is considered to be a strong paleo-earthquake with tremendous energy. The in situ deposit block size distributions of the intact rock mass and the debris deposits are presented and analyzed by using a simple model for estimating the number of fragmentation cycles that the blocks underwent. The results show that the primary controlling factor of the fragmentation process is the pre-existing fractures, and there is a relationship between the potential energy and the fragmentation energy: the latter is approximately 20% of the former. Based on the dynamic discrete element technique, the study proposes a four-stage model for the dynamic course of the Ganqiuchi rock avalanche:(1) failing;(2) highspeed sliding;(3) collision with obstacles;(4) decelerated sliding, which has implication for hazard assessment of the potential rock avalanches in China and other countries with similar geological setting.展开更多
A novel trench insulated gate bipolar transistor(IGBT) with improved dynamic characteristics is proposed and investigated. The poly gate and poly emitter of the proposed IGBT are arranged alternately along the trench....A novel trench insulated gate bipolar transistor(IGBT) with improved dynamic characteristics is proposed and investigated. The poly gate and poly emitter of the proposed IGBT are arranged alternately along the trench. A self-biased p-MOSFET is formed on the emitter side. Owing to this unique three-dimensional(3D) trench architecture, both the turnoff characteristic and the turn-on characteristic can be greatly improved. At the turn-off moment, the maximum electric field and impact ionization rate of the proposed IGBT decrease and the dynamic avalanche(DA) is suppressed. Comparing with the carrier-stored trench gate bipolar transistor(CSTBT), the turn-off loss(E_(off)) of the proposed IGBT also decreases by 31% at the same ON-state voltage. At the turn-on moment, the built-in p-MOSFET reduces the reverse displacement current(I_(G_dis)), which is conducive to lowing dI_(C)/d_(t). As a result, compared with the CSTBT with the same turn-on loss(E_(on)), at I_(C) = 20 A/cm^(2), the proposed IGBT decreases by 35% of collector surge current(I_(surge)) and 52% of dI_(C)/d_(t).展开更多
We perform an experimental study of two-dimensional（2D） electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show...We perform an experimental study of two-dimensional（2D） electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show a feature of hollow core. To illustrate the feature, we present a theoretical investigation by using dynamics analysis. In the simulation, the propagation of laser pulse with the evolution of electron density is utilized to evaluate ionization of air target for the plasma-formation stage. In the plasma-expansion stage, a simple adiabatic fluid dynamics is used to calculate the evolution of plasma outward expansion. The simulations show good agreements with experimental results, and demonstrate an effective way of determining 2D density profiles of the laser-induced plasma plume in gas.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 62071073in part by the Fundamental Research Funds for Central Universities under Grant 2023CDJXY-041in part by the Foundation from Guangxi Key Laboratory of Optoelectronic Information Processing under Grant GD20201.
文摘The dynamic avalanche effect is a critical factor influencing the performance and reliability of the field-stop insulated gate bipolar transistors(FS-IGBT).Unclamped inductive switching(UIS)is the primary method for testing the dynamic avalanche capability of FS-IGBTs.Numerous studies have demonstrated that factors such as device structure,avalanche-generating current filaments,and electrical parameters influence the dynamic avalanche effect of the FS-IGBT.However,few studies have focused on enhancing the avalanche reliability of the FS-IGBT by adjusting circuit parameters during operation.In this paper,the dynamic avalanche effect of the FS-IGBT under UIS conditions is comprehensively investigated through a series of comparative experiments with varying circuit parameters,including bus voltage V_(DC),gate voltage V_(G),gate resistance R_(g),load inductance L,and temperature TC.Furthermore,a method to enhance the dynamic avalanche reliability of the FS-IGBT under UIS by optimizing circuit parameters is proposed.In practical applications,reducing gate voltage,increasing load inductance,and lowering temperature can effectively improve the dynamic avalanche capability of the FS-IGBT.
基金supported by the Doctoral Program of Higher Education of China(RFDP)(No.20136118110004)the National Natural Science Foundation of China(Nos.51077110,51477137)
文摘An improved field charge extraction （FCE） diode with a deep p＋ adjusting region at the cathode side is studied. The reverse recovery mechanism and electric field gradient are thoroughly analyzed and validated using ISE simulation results. The results show that, based on the premise of ensuring the static characteristics, the improved FCE diode can clearly improve the softness and effectively suppress the peak electric field of the nnjunction at the cathode side during reverse recovery, and thus has a high dynamic avalanche capability compared with conventional FCE diodes.
基金financially supported by the National Natural Science Foundation of China(grant numbers 4167020392)the State Key Laboratory Foundation of Geohazard Prevention and Geoenvironment Protection(SKLGP2018K015)the Geological Investigation Project fromChina Geological Survey(DD20160336)
文摘Analyzing large prehistoric rock avalanches provides significant data for evaluating the disaster posed by these relatively infrequent but destructive geological events. This paper attempts to study the characteristics and dynamics of the Ganqiuchi granitic rock avalanche, in the middle of the northern margin of Qinling Mountains, 30 km to the south of Xi’an, Shaanxi Province, China. In plane view, this rock avalanche is characterized by source area, accumulation area and dammed lake area. Based on previous studies, historical records and regional geological data, the major trigger of the Ganqiuchi rock avalanche is considered to be a strong paleo-earthquake with tremendous energy. The in situ deposit block size distributions of the intact rock mass and the debris deposits are presented and analyzed by using a simple model for estimating the number of fragmentation cycles that the blocks underwent. The results show that the primary controlling factor of the fragmentation process is the pre-existing fractures, and there is a relationship between the potential energy and the fragmentation energy: the latter is approximately 20% of the former. Based on the dynamic discrete element technique, the study proposes a four-stage model for the dynamic course of the Ganqiuchi rock avalanche:(1) failing;(2) highspeed sliding;(3) collision with obstacles;(4) decelerated sliding, which has implication for hazard assessment of the potential rock avalanches in China and other countries with similar geological setting.
基金Project supported by the Natural Science Foundation of Hunan Province, China (Grant No. 2023JJ40161)the Natural Science Foundation of Changsha, China (Grant No. kq2202163)+1 种基金the National Natural Science Foundation of China (Grant No. U21A20499)the Fundamental Research Funds for the Central Universities, China (Grant No. 531118010735)。
文摘A novel trench insulated gate bipolar transistor(IGBT) with improved dynamic characteristics is proposed and investigated. The poly gate and poly emitter of the proposed IGBT are arranged alternately along the trench. A self-biased p-MOSFET is formed on the emitter side. Owing to this unique three-dimensional(3D) trench architecture, both the turnoff characteristic and the turn-on characteristic can be greatly improved. At the turn-off moment, the maximum electric field and impact ionization rate of the proposed IGBT decrease and the dynamic avalanche(DA) is suppressed. Comparing with the carrier-stored trench gate bipolar transistor(CSTBT), the turn-off loss(E_(off)) of the proposed IGBT also decreases by 31% at the same ON-state voltage. At the turn-on moment, the built-in p-MOSFET reduces the reverse displacement current(I_(G_dis)), which is conducive to lowing dI_(C)/d_(t). As a result, compared with the CSTBT with the same turn-on loss(E_(on)), at I_(C) = 20 A/cm^(2), the proposed IGBT decreases by 35% of collector surge current(I_(surge)) and 52% of dI_(C)/d_(t).
基金supported by National Natural Science Foundation of China(Nos.11264036,11465016 and 11364038)
文摘We perform an experimental study of two-dimensional（2D） electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show a feature of hollow core. To illustrate the feature, we present a theoretical investigation by using dynamics analysis. In the simulation, the propagation of laser pulse with the evolution of electron density is utilized to evaluate ionization of air target for the plasma-formation stage. In the plasma-expansion stage, a simple adiabatic fluid dynamics is used to calculate the evolution of plasma outward expansion. The simulations show good agreements with experimental results, and demonstrate an effective way of determining 2D density profiles of the laser-induced plasma plume in gas.
