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| 1 | Exploiting buck-boost duality in dual active bridge modular multilevel converters to achieve high DC step ratios显示文摘A previously unidentified duality between buck and boost configured dc‐ac modular multilevel converters(MMCs)is firstly revealed.Armed with this insight,a new dual‐active‐bridge(DAB)‐MMC is proposed for high‐voltage dc(HVDC)‐to‐medium‐voltage dc(MVDC)power conversion that utilizes cascaded buck and boost dc-ac stages to obtain high dc step ratios.Single‐phase and three‐phase variants are presented.When compared with the conventional DAB‐MMC solution for the same dc step ratio,both the single‐phase and three‐phase topologies offer reduced MVDC side transformer winding current stresses,while the three‐phase topology also yields reduced MVDC side MMC submodule current stresses.The former is achieved by having the freedom to design the transformer with a lower turns ratio,and the latter is achieved due to the inherent par-alleling of submodules on the MVDC side of the converter.Analysis of the three‐phase topology reveals its low‐voltage side transformer winding current stresses can be reduced by a factor of 3.27.A generalized mathematical model of the proposed buck-boost DAB‐MMC is derived and used to propose a dynamic controller for both the single‐phase and three‐phase topologies.Real‐time simulations obtained from a real‐time digital simulator system that incorporates an FPGA‐based controller for the valve firing controls validate the proposed buck-boost DAB‐MMC operation and dynamic controls. | Sunny Kung Dalu Liu Chatumal Perera Moosa Moghimi Haji John Salmon Gregory Kish | 2021 | High Voltage2021，6，3： | 1 |
| 2 | Technology Development Analysis on Low Carbon for Power of Heavy-Duty Commercial Vehicle显示文摘Commercial vehicle industry worldwide is facing challenges from environmental pressures,stringent limits of CO_(2) emission,governmental regulations as well as ever-increased customer demands.This paper analyzes the above-mentioned challenges,especially in China,including the potential improvement to increase the brake thermal efficiency(BTE),with five levels of BTE proposed,ranging from current 45 to 60%in future,corresponding to China fuel consumption regulation(CFCR)in different phases.The authors also proposed the technology roadmaps to meet the upcoming CFCR3 and CFCR4;finally,the authors draw the conclusions to conform with ever-stringent regulation in China. | Jiangwei Liu Jun Li Yongjun Wang Dalu Dong Yansheng Yin Huayu Jin Shijie Sun Huili Dou Yanbo Shi Lei Fu Fei Ge | 2019 | Automotive Innovation2019，2，1： | 1 |
| 3 | Preliminary Report on Species and Occurrence Regularity of Diseases,Pests and Weeds of Corn in Angola显示文摘[Objective]The paper was to understand species of diseases,pests and weeds and their occurrence periods and dynamic changes of quantity during corn growing period in rainy and dry seasons in Angola.[Method]Using systematic investigation method,the species and occurrence regularity of diseases,pests and weeds of corn in Pedras Negras farm(Malanje),Sanza Pombo farm(Uige)and Catete farm(Luanda)in the African continent,the Republic of Angola,were studied in two dry seasons and a rainy season from 2011 to 2012.[Result]The occurrence status of pests and diseases of corn during dry and rainy seasons were basically similar,and only individual diseases and pests had different incidence degrees.The corn varieties from the United States and Brazil had prominent advantages in resistance to diseases and barren.Due to different climate environments in dry and rainy seasons,the unearthed rate of weeds in fields was also different.Soil moisture had great impact on weed population and density.Soil layer depth greatly influenced unearthed speed and unearthed rate of weeds.[Conclusion]The study cleared species,occurrence period and harmful levels of pests,diseases and weeds of corn in three provinces of Angola. | Xue Gensheng Liu Bin Wang Lusheng Liu Jianhua Liu Dalu Yang Hui | 2013 | Plant Diseases and Pests2013，4，5： | 0 |
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