微逆变器交流侧泛Buck-boost功率解耦技术研究

针对微逆变器二倍频功率扰动问题,提出了一种交流侧泛Buck-boost功率解耦技术。设计的四种能实现能量双向流动的解耦电路均并联在逆变器交流侧,不同拓扑都可等效工作在Buck、Boost或Buck-boost的模式中。从拓扑结构、工作模式及解耦性能三方面分析了设计的四个解耦电路,以及每种拓扑抑制二次谐波的能力。讨论了脉冲能量缓冲的计算方法。仿真结果表明,三模态六开关Buck-boost功率解耦电路抑制电压二次谐波效果最优,单模态六开关Buck-boost功率解耦电路抑制电流二次谐波效果最优。泛Buck-boost功率解耦技术可以在不依赖母线大电压情况下,大幅降低解耦电容容值,实现无电解电容,提高微逆变器可靠性并延长其使用寿命。     

纳米CL-20/AP含能复合粒子的制备及性能表征

为了改善2,4,6,8,10,12?六硝基?2,4,6,8,10,12?六氮杂异伍兹烷(CL?20)的安全性能,采用一步球磨法制备出纳米CL?20/AP含能复合粒子,并通过扫描电子显微镜(SEM)、粉末X射线衍射(XRD)、差示扫描量热法(DSC)和撞击感度测试对其性能进行了研究。结果表明,纳米CL?20/AP含能复合粒子球形化效果明显,粒径约为300～500 nm;复合粒子的峰位置发生明显的偏移、新增和消失,推测其物相晶型可能发生变化,由于多晶样品的择优取向,复合粒子的X射线衍射峰强度明显降低;纳米CL?20/AP含能复合粒子的放热峰相比原料提前了,更容易发生热分解;撞击感度测试中,复合粒子的特性落高比CL?20增加了13.10 cm,安全性能更好。     

大容量柔性直流换流站阀厅联合建筑结构选型及优化

大容量柔性直流换流站工艺复杂,布置紧凑。由于阀厅联合建筑体量大且各区域使用功能不用,造成联合建筑不同区域的跨度、层高及荷载差别巨大。厦门柔性直流换流站阀厅联合建筑通过概念设计,合理设置结构缝,使整个建筑各单体结构明晰,受力合理,提高了结构的抗震性能,减小温度应力影响。同时,根据阀厅跨度大、高度高、荷载重的特点,联合建筑阀厅采用综合效益最优的全钢结构,满足规范对结构承载力和位移要求。此外,屋面采用以压型钢板为底模表面浇筑混凝土的组合屋面以利于抗风防水。     

竖向地震对柔性直流换流站大跨度阀厅结构影响分析

柔性直流换流站阀厅常常采用大跨度钢结构,由于阀厅结构的复杂性和重要性,应对其竖向地震响应进行分析。依托厦门柔性直流换流站工程,采用弹性时程分析法对大跨度阀厅结构的竖向地震响应进行计算分析。结果表明,不同于水平地震,竖向地震对阀厅屋盖弦杆及钢柱的轴力影响较大,其对重型屋盖阀厅结构的影响比轻型屋盖阀厅结构更为显著。此外,通过对不同跨度的重型屋盖阀厅钢结构在不同场地类别下的竖向地震响应的试算,推荐该类结构在7度0.15g时竖向地震影响系数可偏安全的取0.08。     

CAD/CAM实现对圆柱直齿轮的模拟数控加工

目前CAD/CAM在制造业中得当了广泛的应用,文章介绍了利用CAXA软件实现CAD/CAM的数控加工过程.选择了常用的圆柱直齿轮作为研究对象,建立模型、求出加工轨迹并实现仿真的具体方法.     

Adaptive Noise Cancellation Method Used for Wheel Speed Signal of Integrate ABS/ASR System

The anti-lock braking system (ABS) and anti-slip regulation system(ASR) are the very i mportantparts of active safety systems used for modern vehi-cles . This two systems make up of commonintegratesystem ABS/ASR[1 ,2]. At present ,the main controlmethodin ABS/ASRis the logic threshold method.When getting the wheel speed signal ,ECUcomputesand applies control after comparing current signalwith the threshold[3 -5].Because of many reasons ,the wheel speed sig-nals sampled in ABS/ASRalw…     

基于FIFO的高速A/D和DSP接口设计

在DSP高速数据采集系统中,DSP往往不能适应A/D芯片的工作速率.为了提高DSP的工作效率,避免数据的丢失和方便控制,用FIFO作为两者之间的接口可以产生很好的效果.介绍了用FIFO器件CY7C4261实现A/D芯片AD9283和DSP芯片TMS320VC5416之间接口的方法,详细分析了数据从A/D送至DSP的整个过程.实际设计及应用表明该接口提高了DSP的使用效率,具有广阔的应用前景.     

Impact of stray inductances of the power loop on false trigger‐on in the zero‐voltage‐switching full‐bridge converter

Here, we propose an exhaustive theoretical investigation and experimental verification of the false trigger‐on phenomenon, which would lead to the interaction between the upper and lower devices during the switching transient, in the zero‐voltage‐switching (ZVS) full‐bridge converter. An equivalent model of the converter, which takes not only the parasitic capacitors of the metal–oxide–semiconductor field‐effect transistors into account but also the stray inductances of the main circuit, is presented. Based on the model, a comprehensive study of the false trigger‐on phenomenon is carried out. According to the analysis results, the stray inductances of the metal–oxide–semiconductor field‐effect transistors have negligible influence on the false trigger‐on phenomena since the soft‐switching is realized. The false trigger‐on phenomenon is induced by the stray inductances of the main circuit. Moreover, the arrangement of the switching sequence would cause significant discriminations in the false trigger‐on phenomena because of the specific working mode of the ZVS full‐bridge converter. According to the investigation results, optimization methods are presented to suppress the induced voltage. At last, the theoretical investigations are verified by tests of a ZVS full‐bridge converter. Copyright © 2016 John Wiley & Sons, Ltd.     

Revisited generalized substitution theorem and its consequences for circuit analysis

The Substitution Theorem (ST) is generally perceived as a mere theoretical curiosity. In this paper, a formerly derived generalized ST (GST) is carefully revised, which leads to both a Weak Revisited GST (RGST) and a Strong RGST (characterized by noticeably relaxed hypotheses with respect to the GST). Then, despite the common opinion about the ST, such RGSTs are showed to be powerful analytical tools to generalize, make rigorous and rigorously prove several classic results of Circuit Theory, namely: the Substitution Theorem for Multiterminal Circuits, the Source‐Shift Theorem, the Thévenin–Norton Theorem, the Miller Theorem alongside its Dual, and the Augmentation Principle. More specifically, the Substitution Theorem for Multiterminal Circuits is extended to an arbitrary set of sources, possibly including nullors. The Source‐Shift Theorem is rigorously derived, and possible related ambiguities are removed. Also, all possible hybrid forms of the Thévenin–Norton Theorem for multiports are individuated, and a precise operative procedure for calculating the relevant entities is provided for all cases. Furthermore, the Miller Theorem and its Dual are extended to an arbitrary number of variables and to multiports. As to the Augmentation Principle, the constraint regarding the linearity of the augmenting resistors is removed. Finally, thoroughly worked examples are given in which the aforementioned noteworthy consequences of the RGSTs are proved to be efficient tools for analysis by inspection of linear and nonlinear circuits. Among the other things, systematic pencil‐and‐paper procedures for DC‐point and input‐output (or driving‐point) characteristic calculation in nonlinear networks are derived and applied to circuits with considerably complex topology. Copyright © 2016 John Wiley & Sons, Ltd.     

Corrosive effects of the electromagnetic induction caused by the high voltage power lines on buried X70 steel pipelines

This paper diagnoses the corrosive effects of the electromagnetic induction caused by double circuit high voltage power lines (HVPL) on the buried X70 steel pipelines. To achieve this objective, firstly the electromagnetic interference between the double circuit HVPL and the X70 steel pipeline (the distribution of the magnetic field and the induced AC current densities in the buried X70 steel pipeline) and the factors affecting this interference such as the vertical distance between the double circuit HVPL and the X70 steel pipeline, and the conductor phase sequence orientation were studied. Then, electrochemical measurements were used to characterize the corrosion polarization properties of X70 steel in simulated soil at various AC current densities. The results show that with an increase in the AC current density, the corrosion rate of the X70 steel increased, indicating that the induced AC current density has accelerated the corrosion degree of X70 steel, by comparison with that in the absence of the AC current density. We can conclude from these results that the electromagnetic induction caused by the double circuit high voltage power lines affects the electrochemical characteristic of the X70 steel pipeline and accelerates the corrosion of the pipeline.