单级PFC恒流驱动及蓝牙调光技术的研究

LED 智能照明系统逐渐应用到室内照明,具有智能控制、高效节能、绿色的特点。国内 LED 智能照明系统仍不完善,存在不易控制、能源浪费、功率因数低、谐波干扰大等问题,使得 LED 照明的优势没有很好的体现出来,并阻碍其推广。对智能调光控制技术进行研究,设计单级 PFC 反激式恒流驱动电路和蓝牙调光方案,Android 智能手机作为客户端以蓝牙无线技术传输调光控制信号,对 LED 恒流驱动电路进行开关、调光控制实现智能照明,具有便捷可靠、电源转换效率和功率因数高、电流总谐波低的性能。     

基于单片机的线阵CCD驱动模块硬件设计与实现

根据线阵CCD驱动时序的特点,给出一种线阵CCD驱动电路的设计方法。采用具有增强型内核的单片机产生CCD所需的驱动波形,能充分发挥单片机可编程的特点, 为用户提供丰富的驱动信号接口,并实现了电子快门功能。首先介绍CCD驱动模块的基本工作原理、主要特点和驱动时序的设计思路,接着完成驱动模块软硬件的设计,最后通过大量实验验证该驱动模块的有效性。实验结果表明: 该驱动模块所产生的驱动信号满足CCD的需要,当该驱动模块集成到其他无接触测量系统中时, 该测量系统能正常稳定工作,测量结果准确,精度达到了μm级。     

2014年国际大电网会议变电站专委会情况综述

简要介绍了2014年第45届国际大电网会议(CIGRE)的总体情况,概述了SC B3(变电站)专委会的工作范围、职责,以及本届大会的相关活动和会议,并结合B3专委会的会议情况详细介绍了变电站专委会近年重点研究领域和方向。     

微电网的电能质量及改善方法研究

对微电网中的分布式电源的电能质量问题进行了分析,结合微电网运行的特点提出了相应的电能质量改善方法及控制策略。提出了有源滤波器(APF)和静止无功补偿器(SVC)联合运行改善电能质量的方法,APF和负载并联接入微电网,通过滤除谐波电流,其电流检测常用ip-iq方法;由于晶闸管控制电抗器(TCR)与晶闸管投切电容器(TSC)构成的静止无功补偿器,装设在微电网负载侧,采用对称分量法计算。通过Matlab/Simulink的仿真结果表明,该有源滤波器和静止无功补偿器联合运行的方法对改善微电网电能质量是有效的。     

电动汽车参与下的虚拟电厂多目标优化调度

为了实现虚拟电厂中分布式发电机组的经济调度,同时减少虚拟电厂运行产生的污染,结合电动汽车与电力系统之间能量双向流动的特点,考虑虚拟电厂运行对环境的影响,建立了电动汽车参与下的虚拟电厂多目标优化调度模型。为了求解该模型,采用基于向量求值的粒子群优化算法(Vector Evaluated Particle Swarm Optimization,VEPSO),并通过8节点虚拟电厂仿真,对比分析多目标与单目标条件下优化调度结果,验证了所提出的方法可以使虚拟电厂以低成本运行,同时实现良好的环境效益。     

Effect of graphene oxide on the behavior of poly(amide‐6‐b‐ethylene oxide)/graphene oxide mixed‐matrix membranes in the permeation process

Polyether‐block‐amide (Pebax)/graphene oxide (GO) mixed‐matrix membranes (MMMs) were prepared with a solution casting method, and their gas‐separation performance and mechanical properties were investigated. Compared with the pristine Pebax membrane, the crystallinity of the Pebax/GO MMMs showed a little increase. The incorporation of GO induced an increase in the elastic modulus, whereas the strain at break and tensile strength decreased. The apparent activation energies (E_p) of CO₂, N₂, H₂, and CH₄ permeation through the Pebax/GO MMMs increased because of the greater difficulty of polymer chain rotation. The E_p value of CO₂ changed from 16.5 kJ/mol of the pristine Pebax to 23.7 kJ/mol of the Pebax/GO MMMs with 3.85 vol % GO. Because of the impermeable nature of GO, the gas permeabilities of the Pebax/GO MMMs decreased remarkably with increasing GO content, in particular for the larger gases. The CO₂ permeability of the Pebax/GO MMMs with 3.85 vol % GO decreased by about 70% of that of the pristine Pebax membrane. Rather than the Maxwell model, the permeation properties of the Pebax/GO MMMs could be described successfully with the Lape model, which considered the influence of the geometrical shape and arrangement pattern of GO on the gas transport. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42624.     

Enhanced Ferroelectric Phase Stability and High Temperature Piezoelectricity in PN Ceramics via Multisite Co‐Doping

The tungsten bronze‐type lead metaniobate (PbNb₂O₆, PN) is a promising material for high‐temperature piezoelectric devices, while its application is limited by the difficulty in fabrication. In this study, the microstructure and electrical properties of Ca‐doped PN and Ca, Mn‐co‐doped PN ceramics sintered at different temperatures were investigated. Doping promoted the formation of the originally metastable ferroelectric orthorhombic phase. This might be partly attributed to the increased lattice distortion of the orthorhombic phase in the doped samples compared to that reported for pure PN. However, in single A‐site Ca‐doped PN the ferroelectric orthorhombic structure showed a low stability and started to transform to paraelectric phase far below 300°C, resulting in unstable high temperature piezoelectric properties. Interestingly, such a phase transition was completely depressed by A‐site Ca and multisite Mn‐co‐doping, which also improved the piezoelectric performance (d₃₃ = 71 pC/N) and thermal stability in both structure and piezoelectricity. The better stability and performance of the co‐doped samples were explained by the improved sintering behavior and poling efficiency as well as its ability to occupy different sites in the TTB lattice.     

考虑电压稳定裕度约束的点估计随机最优无功调度方法

传统无功优化方法通常采用确定型的模型,但新能源大量接入以后,节点注入功率并不确定,针对其随机性,提出一种考虑电压稳定裕度约束的随机无功优化方法,使用基于点估计的随机潮流方法将机会约束转换为确定型约束,并采用带共轭梯度算子的改进遗传算法对优化问题进行求解。数值计算的结果表明该方法可以降低电压的越限风险。相比于确定型方法,使用该方法后网损优化结果略有增加,但同时电压稳定裕度得到了较大的提升。     

基于全阶模型的异步电机磁链观测收敛性分析与对策

高性能交流驱动系统中,电机磁链位置能否准确获取将影响系统的动态与稳态性能。异步电机全阶模型同时实现了电机转速作为参数的在线辨识以及电机电流与磁链作为状态变量的实时观测。本文将对全阶模型在估计异步电机参数与变量过程中的磁链收敛特性进行研究。由于全阶模型的非线性特性,采用奇异摄动理论,将全阶模型分解为转速辨识模型与磁链观测模型,两个模型在时间尺度上分离,通过分析磁链观测子系统中系统特征值的分布与阻尼特性,研究了磁链观测的收敛性与影响收敛速度的影响因子。研究结果表明磁链系统在中高速的阻尼特性需要改善,并提出了改善收敛性的对策。仿真和实验验证了分析方法的正确性与所提对策的可行性。     

融合RFID的无线湿度传感器节点设计研究

针对融合RFID的无线湿度传感器节点设计的需求,采用中芯国际0.18μm CMOS工艺设计并制造了一种集成湿度传感器节点。该传感器节点采用湿度传感器与其它标签电路集成设计,制造成本低。湿度传感器单元采用聚酰亚胺作为感湿材料,利用顶层金属层制作叉指结构电极,无需任何后处理工艺。整流电路采用自偏置结构降低了MOS开关管的有效导通电压,避免了高成本肖特基工艺的使用。接口电路基于锁相环原理,采用全数字电容-数字直接转换结构,能够工作在超低电源电压下。后期测试结果显示,该无源湿度传感器标签在常温下灵敏度为18.75 f F/%RH,最大回滞偏差7%,整体功耗约为4μW,在阅读器发射功率为2 W条件下,最大工作距离达到14 m。