This paper deals with optimization of hard switching commutation mode for high-power, high-frequency consumer applications for selected power transistor. The experimental investigation of suitable settings is outgoing...This paper deals with optimization of hard switching commutation mode for high-power, high-frequency consumer applications for selected power transistor. The experimental investigation of suitable settings is outgoing from simulation analysis of hard switching for different transistor structures. For these purposes, the simulation models of power semiconductor switches with high level of validity have been used. After that, the experimental analysis for selected transistor was done with change of parameters that are influencing commutation process of transistor. Target of such kind of analysis was to reach as low switching losses as possible, achieving high power density and efficiency of power system, without utilization of improved switching techniques such as resonant switching. The results confirm that this task is realizable through use of progressive semiconductor devices such as SiC diodes and/or through latest families of MOSFET devices.展开更多
Morphological evolution of the solid-liquid interface near grain boundaries has been studied during directional solidification of succinonitrile-based transparent alloys (SCN-0.9wt%DCB). Experimental results show that...Morphological evolution of the solid-liquid interface near grain boundaries has been studied during directional solidification of succinonitrile-based transparent alloys (SCN-0.9wt%DCB). Experimental results show that the grain boundary provides the starting point of morphological instability of the solid-liquid interface. The initial perturbation near the grain boundary is significantly larger than other perturbations on the interface. The initial shape of the interface and the competition between the thermal direction and preferred crystalline orientations determine the subsequent growth pattern selections. The temporal variations of the curvature radius of cell/ridge tips near the grain boundary have also been studied when the instability occurs. This process is divided into three parts. As the pulling velocity increases, dendrites at the grain boundary grow in two different directions to form a bicrystal microstructure. Side branches on either side of the dendrite exhibit different growth patterns.展开更多
文摘This paper deals with optimization of hard switching commutation mode for high-power, high-frequency consumer applications for selected power transistor. The experimental investigation of suitable settings is outgoing from simulation analysis of hard switching for different transistor structures. For these purposes, the simulation models of power semiconductor switches with high level of validity have been used. After that, the experimental analysis for selected transistor was done with change of parameters that are influencing commutation process of transistor. Target of such kind of analysis was to reach as low switching losses as possible, achieving high power density and efficiency of power system, without utilization of improved switching techniques such as resonant switching. The results confirm that this task is realizable through use of progressive semiconductor devices such as SiC diodes and/or through latest families of MOSFET devices.
基金supported by the National Natural Science Foundation of China (Grant Nos.61078057 and 51172183)NPU Foundation for Fundamental Research (Grant Nos.NPU-FFR-JC201048 and JC201155)+1 种基金the Science & Technology Program of Shanghai Maritime University (Grant No.20110054)the Project of the Excellent Youth of Shanghai (WANG CaiFang)
文摘Morphological evolution of the solid-liquid interface near grain boundaries has been studied during directional solidification of succinonitrile-based transparent alloys (SCN-0.9wt%DCB). Experimental results show that the grain boundary provides the starting point of morphological instability of the solid-liquid interface. The initial perturbation near the grain boundary is significantly larger than other perturbations on the interface. The initial shape of the interface and the competition between the thermal direction and preferred crystalline orientations determine the subsequent growth pattern selections. The temporal variations of the curvature radius of cell/ridge tips near the grain boundary have also been studied when the instability occurs. This process is divided into three parts. As the pulling velocity increases, dendrites at the grain boundary grow in two different directions to form a bicrystal microstructure. Side branches on either side of the dendrite exhibit different growth patterns.
