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Analysis of dynamic behavior in the digitally controlled single-phase full-bridge inverter
一种数字控制单相全桥逆变电路运动行为分析方法研究

雷博,肖国春,旋律
物理学报 , 2012,
Abstract: Considering the multiformity in the PWM modulation principle, the diversity in the structures of filter and load, and the limitation of the method based on state transition matrix in the analysis of digital controlled single-phase full-bridge inverter, we present a new method based on analytic expression of the elements in the state transition matrix. This method can analytically express the relationship between the parameters and the dynamic motion of a system named N-M digitally controlled single-phase full-bridge inverter, which has N state variables and structure changing M times within one switching cycle. As an example, the discriminant of Hopf bifurcation, the analytic expressions of the stability boundary and the oscillation frequency of a 3-3 digitally controlled single-phase full-bridge inverter are derived. Finally, the theoretical results are verified by simulations and circuit experiments.
Analysis of partial oscillation phenomenon in a digital-controlled three-phase inverter
一种数字控制三相逆变电路的局部振荡行为分析

Lei Bo,Xiao Guo-Chun,Wu Xuan-L&#,
雷博
,肖国春,旋律

物理学报 , 2013,
Abstract: A partial oscillation phenomenon in a digital-controlled three-phase inverter system, which is controlled by proportional controller in synchronous rotating reference frame, is analyzed in this paper. First, the discrete-time model of the system is derived. Then, a dynamics analysis scheme for this type of system is proposed. In addition, the underlying mechanism of the partial oscillation phenomenon occurring in this system is analyzed. The factors, which will cause the partial oscillation, are exactly predicted by analytical expressions. Finally, the theoretical results are verified by both simulations and experiments. These conclusions can provide an insight into the dynamics of the system.
Improved discrete-time model for a digital controlled single-phase full-bridge voltage inverter
数字控制单相全桥电压型逆变电路的改进离散迭代模型

Wu Xuan-Lü,Xiao Guo-Chun,Lei Bo,
旋律
,肖国春,雷博

物理学报 , 2013,
Abstract: An improved discrete-time model for a digital controlled single-phase full-bridge voltage inverter is proposed in this paper. Based on state-space averaging in every switching cycle, the improved discrete-time model combines the advantages of the average model and the traditional discrete-time model, which can accurately analyze the digital control delay and sample-and-hold process inherently in digital controlled system. Consequently, under the accuracy premise, the improved discrete-time model can effectively simplify the traditional discrete-time modeling. As an example, an LC filter capacitor-voltage and inductor-current feed-back plus voltage-reference feed-forward control algorithm is analyzed based on the improved discrete-time model. The stability boundary and oscillation frequency are accurately predicted. Finally, theoretical results are verified by simulations and experiments.
Analysis of oscillation phenomenon in digital controlled DC-AC H-bridge inverter
单相全桥DC-AC电压逆变电路数字控制中的振荡现象分析

Lei BoXiao Guo-Chun Wu Xuan-Lü Qi Yuan-Rui,
雷博
,肖国春,旋律,齐元瑞

物理学报 , 2011,
Abstract: The discrete-time iterative map of digitally controlled DC-AC H-bridge inverter with outer load-voltage loop and inter inductance-current loop plus voltage-reference feedforward loop is derived by considering the effect of the time delay problems inherent in digital control system. The type of the bifurcation point when the system loses stability is predicted in terms of the eigenvalues of the Jacobian matrix,and it is found that the type is of the Hopf bifurcation. The analytic expressions of the stability boundaries and the oscillation frequency are deduced, and the underlying mechanism of this nonlinear phenomenon is analyzed. Finally, the theoretical results are verified by simulations and circuit experiments.
基因治疗的现况和前景

遗传 , 1985,
Abstract: 早在人类开始种植谷物和驯养家畜起,就已经在自觉或不自觉地通过选择优良种子或种畜进行基因操作了。一百年以前英国博物学家高尔顿倡导的优生学则是一种将类似方法(控制生育)用于改善人类的理想。这种理想曾在本世纪的前四十年中风行一时,成为一种运动,引起了遗传学界的意见分歧。希特勒法西斯主义在三十年代的出现和以优生、种族卫生为“理
近50a来科尔沁地区沙漠化土地的动态监测结果与分析

中国沙漠 , 2003,
Abstract: 在明确了沙漠化土地的程度分级及其指标、监测方法的基础上,对科尔沁地区近50a来的沙漠化土地进行了遥感动态监测和分析。结果表明:科尔沁地区20世纪50年代未至70年代中期,是沙漠化土地扩展速度最快的一个时期,总面积增加了9084km2。从70年代中期到80年代后期,沙漠化土地继续呈快速增长之势,增加了9624km2;进入90年代,沙漠化过程呈现出逆转的趋势,沙漠化土地总面积由1987年的61008km2,减少到2000年的50142km2,减少了10866km2。就近50a来沙漠化土地变化的整体而言,经历了发展-再发展-逆转的过程。到2000年,科尔沁地区的沙漠化态势依然是严峻的。但从整个发展过程来看,沙漠化已呈现逆转的趋势。整个区域的生态环境在改善,环境容量在提高,继续发展下去,有望进入良性循环以保障生态环境与社会经济的可持续发展。
近50年来毛乌素沙地的沙漠化过程研究

中国沙漠 , 2001,
Abstract: 根据野外考察、应用遥感和地理信息系统技术对毛乌素沙地进行动态研究表明,50年代沙漠化土地面积约为12900km2,到了70年代中期达41110km2,80年代后期,减少为32590km2,至1993年又下降到了30650km2。50~70年代是沙漠化土地迅速发展的时期,而进入80年代以后,总体上是处于逆转过程中,已有近9460km2的沙漠化土地得到了治理,这主要得益于"三北"防护林工程的实施和当地政府与干部群众积极开展沙漠化防治的努力。也进一步证明了:沙漠化主要是人类造成的,也只有人类能够控制它。
我国内陆沙漠与海岸沙丘石英颗粒表面结构的对比研究

中国沙漠 , 1995,
Abstract: 本文通过扫描电镜分析,对我国内陆沙漠与海岸抄丘石英颗粒表面结构进行了对比研究。研究认为,无论是内陆沙漠砂或海岸沙丘砂,其石英颗粒都具有较好的磨圆度,表面有碟形坑、麻坑及SiO2沉淀物等代表风成环境的典型特征;此外,还叠加有代表原生沙物质来源于水下环境的V型撞击坑、撞击沟等痕迹。然而,受环境尤其是气候影响,其表面结构特征仍有差异,表现在内陆干旱区大陆性气候的沙漠砂的风成机械作用和化学沉淀作用,都要比沿海湿润季风性气候的海岸沙丘砂强烈;但海岸沙丘砂的化学溶蚀作用却比内陆沙漠砂要明显。同属海岸抄丘环境,其石英颗粒表面结构特征表现为北方温带海岸沙丘砂的机械作用痕迹强;而南方热带海岸沙丘砂的化学作用痕迹发育,但机械作用痕迹并非少见,仍然十分明显。
我校1993年招生计划创14年来最高记录

南京林业大学学报(自然科学版) , 1993, DOI: 10.3969/j.jssn.1000-2006.1993.02.015
Abstract: <正>经国家教委、林业部批准,我校1993年将在国内25个省、市、自治区招生,招生计划确定为950名。其中,国家任务613名,委托培养276名,自费生61名,计划总数比去年增长50%,比去年实际录取数增长32%,创14年来的最高记录。今年我校将继续深化招生改革,除了招收参加全国统考的考生外,继续试行单独录取,计划招收有实践经验的林区考生50人,定向生46人,中等林校保送生19人。招生的专业为:本科11个,即林学、森林保护、园林、森林采运工程、林业机械、木材加工、林产化工、家具设计与
网格技术及其应用分析

武汉理工大学学报 , 2008,
Abstract: ?构筑网格是为了提高计算机资源的共享能力,它以分布共享性、自相似性及整体性、动态多样性以及自治虚拟性等为特点。从介绍网格的核心概念入手,并深入分析了网格技术的关键要素及核心问题,在此基础上讨论网格的体系结构和开发平台。通过实例展示了网格技术目前的广泛应用,对其应用优势加以分析。
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