实现模块间的均压均流是保证模块串并联系统正常运行的关键,针对现有均压控制策略大都模块化程度低的问题,将输出电压上翘控制引入输入串联输出串联-双有源桥变换器(Input Series Output Series-Dual Active Bridge,ISOS-DAB)系统.首先,...实现模块间的均压均流是保证模块串并联系统正常运行的关键,针对现有均压控制策略大都模块化程度低的问题,将输出电压上翘控制引入输入串联输出串联-双有源桥变换器(Input Series Output Series-Dual Active Bridge,ISOS-DAB)系统.首先,在DAB变换器小信号建模基础上,结合ISOS拓扑关系和上翘控制,对ISOS-DAB系统进行完整的小信号建模,分析了控制原理及系统稳定性.其次,通过PSIM软件分别对采用校正前后的上翘控制的ISOS-DAB系统进行了仿真分析.最后,设计了两模块ISOS-DAB系统样机,进行了输出电压上翘特性、输入电压突变和负载突变的实验验证.结果表明:仿真和实验结果均验证了本文理论和上翘控制在ISOS-DAB系统中的有效性与稳定性,上翘控制能够保证ISOS-DAB系统在无互联通信条件下实现模块均压,提高了该系统的模块化程度.展开更多
The decadal variations of the North Pacifi c Tropical Water (NPTW) at 137°E in the western North Pacific Ocean are investigated based on the repeated hydrographic observations along with two global gridded ocean ...The decadal variations of the North Pacifi c Tropical Water (NPTW) at 137°E in the western North Pacific Ocean are investigated based on the repeated hydrographic observations along with two global gridded ocean products. The results indicate that the maximum salinity of NPTW experiences signifi cant quasi-decadal variations, having maxima around 1979, 1987, 1995, 2004, and 2012, while minima around 1974, 1983, 1991, 1999, and 2008 during the period of interest. The NPTW area also shows similar quasidecadal variation, expanding/shrinking as its maximum salinity increases/decreases at the 137°E section. These variations are induced mainly by changes in the mixed layer salinity in the source region and largescale circulation in the northwestern tropical Pacific Ocean, both of which are related to the Pacific Decadal Oscillation. The underlying processes at work are further confi rmed through conducting the subsurface salinity budget analysis. Besides, short-term processes are also at work through nonlinear interactions, especially after 2000.展开更多
A method is presented for estimating fatigue reliability under variable loading, which isbased on load cycles-fatigue life interference theory as well as cumulative fatigue damageanalysis. The basic opinion is that fo...A method is presented for estimating fatigue reliability under variable loading, which isbased on load cycles-fatigue life interference theory as well as cumulative fatigue damageanalysis. The basic opinion is that for variable loading the increment of failure probability pro-duced by each load cycle is determined by the stress level as well as the damage state at whichthis load cycle applies Contrast to 'conditional reliability-equivalent life methodology'. this meth-od calculates the equivalent cycle numbers between different stress levels according to cumulativefatigue damage rule but not equivalent failure probability.展开更多
文摘实现模块间的均压均流是保证模块串并联系统正常运行的关键,针对现有均压控制策略大都模块化程度低的问题,将输出电压上翘控制引入输入串联输出串联-双有源桥变换器(Input Series Output Series-Dual Active Bridge,ISOS-DAB)系统.首先,在DAB变换器小信号建模基础上,结合ISOS拓扑关系和上翘控制,对ISOS-DAB系统进行完整的小信号建模,分析了控制原理及系统稳定性.其次,通过PSIM软件分别对采用校正前后的上翘控制的ISOS-DAB系统进行了仿真分析.最后,设计了两模块ISOS-DAB系统样机,进行了输出电压上翘特性、输入电压突变和负载突变的实验验证.结果表明:仿真和实验结果均验证了本文理论和上翘控制在ISOS-DAB系统中的有效性与稳定性,上翘控制能够保证ISOS-DAB系统在无互联通信条件下实现模块均压,提高了该系统的模块化程度.
基金Supported by the National Natural Science Foundation of China(Nos.41506008,41606107,41476002,41776012)ZHAI F.G.is also supported by the Shandong Provincial Natural Science Foundation(No.ZR2015DQ006)China Postdoctoral Science Foundation(No.2015M570609)
文摘The decadal variations of the North Pacifi c Tropical Water (NPTW) at 137°E in the western North Pacific Ocean are investigated based on the repeated hydrographic observations along with two global gridded ocean products. The results indicate that the maximum salinity of NPTW experiences signifi cant quasi-decadal variations, having maxima around 1979, 1987, 1995, 2004, and 2012, while minima around 1974, 1983, 1991, 1999, and 2008 during the period of interest. The NPTW area also shows similar quasidecadal variation, expanding/shrinking as its maximum salinity increases/decreases at the 137°E section. These variations are induced mainly by changes in the mixed layer salinity in the source region and largescale circulation in the northwestern tropical Pacific Ocean, both of which are related to the Pacific Decadal Oscillation. The underlying processes at work are further confi rmed through conducting the subsurface salinity budget analysis. Besides, short-term processes are also at work through nonlinear interactions, especially after 2000.
文摘A method is presented for estimating fatigue reliability under variable loading, which isbased on load cycles-fatigue life interference theory as well as cumulative fatigue damageanalysis. The basic opinion is that for variable loading the increment of failure probability pro-duced by each load cycle is determined by the stress level as well as the damage state at whichthis load cycle applies Contrast to 'conditional reliability-equivalent life methodology'. this meth-od calculates the equivalent cycle numbers between different stress levels according to cumulativefatigue damage rule but not equivalent failure probability.
