Zero-current Switching Series Resonant High-voltage DC-DC Converter with Series-connected Primary Windings of Center-tapped Transformer

Abstract—This article proposes a novel zero-current switching series resonant inverter-fed voltage multiplier based high-voltage DC-DC converter. The series resonant inverter in the proposed topology has two power switches (insulated-gate bipolar transistors), two resonant capacitors, and only one high-voltage transformer with center-tapped primary windings. The power switches are connected in the form of a half-bridge network. The leakage inductances of the transformer's primary windings together with resonant capacitors form two series resonant circuits. The series resonant circuits are fed alternately by operating power switches with an interleaved half-switching cycle. The secondary winding of the high-voltage transformer is connected to a voltage multiplier circuit to rectify and boost the voltage. The converter operates in discontinuous conduction mode, and its output voltage is regulated by pulse-frequency modulation. Therefore, all the power switches turn ON and OFF at the zero-current switching condition. The main features of the proposed converter are lower power loss, less cost, and smaller size compared to previously proposed series resonant high-voltage DC-DC converters. The experimental results of a 130-W prototype of the proposed converter are presented both for dynamic and steady-state operation. The results confirm the excellent operation and performance of the converter.     

基于BIM的碰撞检查在协同设计中的研究

碰撞检查是针对整个建筑设计周期中的多专业协同设计,将不同专业的信息模型进行协调审查和碰撞分析。通过碰撞检查有助于建筑设计、结构设计、MEP(Mechanical,Electrical,Plumbing,即电气、暖通、给排水)专业的设计团队及时发现问题和解决矛盾,优化工程设计,减少在项目实施过程中错误和返工可能性。本文将介绍利用Revit系列软件碰撞检查工具,探究其在多专业协同设计中的作用。     

按许用传动角综合单曲柄双摇杆式翻板机驱动机构

单曲柄双摇杆式翻板机驱动机构,实为两套共驱动轴的正置式曲柄摇杆机构,但两曲柄具有一相位差.在分析驱动机构工作原理的基础上,给出了其综合问题的准确表述,即:已知机架长度和摇杆摆角,按许用传动角综合正置式曲柄摇杆机构.推导出这类机构最小传动角与杆长及摇杆摆角之间的解析关系,分析最小传动角接近其上确界时的杆长及最大杆长比变化趋势,进而建立了按许用传动角综合正置式曲柄摇杆机构的解析法.给出了翻板机驱动机构综合实例,性能参数分析结果验证了综合方法的正确性和可行性.     

基于涡扇螺旋磁电机的新能源汽车节能技术研究

针对能源危机的日趋严重化的现状,优化能源结构、发展清洁环保的可再生能源迫在眉睫,设计了一款可用于新能源汽车的涡扇螺旋磁电机.该装置电机可将风能转化为电能,在传统小型风力发电机的结构基础上加以改进,对新能源汽车的结构进行改进安装,并利用新能源汽车行驶中的风能为工作介质,带动扇叶转动,扇叶通过传动系统带动发电机启动发电,从而实现风能向电能的转换.实验结果证明,采用此改进方法,在汽车行驶过程中,将风能转变成电能,可提升汽车行驶里程数,进一步增加新能源汽车续航能力,最终起到节省能源的作用.     

Preparation and Characterization of Silver‐Doped Cu(In,Ga)Se2 Films via Nonvacuum Solution Process

Cu(In,Ga)Se₂ films doped with different contents of silver ions (Ag⁺) were successfully prepared using nonvacuum spin coating followed by selenization at elevated temperatures. Increasing the Ag⁺ ion content increased the lattice parameters of the chalcopyrite structure, and shifted the A1 mode in the Raman signals to low frequencies. The band gaps of the prepared (Ag,Cu)(In,Ga)Se₂ (ACIGS) films were considerably increased, thereby increasing the open‐circuit voltage (V_oc) of the solar cells. As Ag⁺ ion content increased, the microstructures of ACIGS films became densified because the formed (Cu,Ag)₂In alloy phase with a low melting point facilitated liquid‐phase sintering. The evaporation of selenium species was correspondingly suppressed in the films during selenization, thereby reducing the selenium vacancies. The improvement in the microstructures and the defects of ACIGS films increased short‐circuit current (J_sc) and fill factor of the solar cells. The spectral response of the solar cells was also enhanced remarkably. This study demonstrated that incorporation of Ag⁺ ions into Cu(In,Ga)Se₂ films substantially improved the efficiency of the solar cells.     

A comparative study of the dependency of colour measurement on surface temperature

In this paper, we evaluated in depth how the spectrophotometric colour measurement of an object will respond to surface temperature change. The colorimetric variations of eight coloured ceramic tiles against temperature changes were studied. Colorimetric data measured at specific temperature were compared with data measured at about 20 °C. For each coloured ceramic tile, reflectance curves and colorimetric differences resulting from temperature differences were examined to demonstrate the exact dependency of colorimetric properties across the temperature range studied. Experimental data showed that peaks and slopes on a reflectance curve are the major impact resulting from temperature variation. Colours with lower lightness and lower chroma showed smaller colorimetric changes with change in temperature, while colour with higher lightness and chroma exhibited a distinct thermochromism and linearity changes across the temperature range. A conspicuous correlation potential between surface temperature and CIE colorimetric coordinates was observed.     

微乳法制备Pd-Cu双金属催化剂

选择Cu为助剂,采用微乳法分别优选具有较好稳定性的Cu和Pd微乳液体系,并将Cu和Pd依次负载于Al_2O_3载体上,经干燥、活化和还原制备了Pd-Cu/Al_2O_3催化剂。采用原位IR、CO化学吸附和HRTEM等对催化剂进行表征,结果表明,与常规溶液负载法制备的Pd-Ag/Al_2O_3催化剂相比,采用微乳法降低了催化剂表面酸性,提高了活性组分Pd分散度,Pd粒径分布更为均匀。在750 mL加氢反应器中,采用C_2后加氢原料对催化剂性能进行评价,结果表明,与常规溶液负载法相比,微乳法制备的催化剂在反应温度低4℃条件下,乙炔转化率相当,选择性高9.9个百分点,绿油生成量较低。微乳法制备Pd-Cu双金属催化剂具有良好的工业应用前景。