基于锁相放大的超级电容内阻检测装置研究

超级电容模块组在使用时存在电压均衡问题,为保证其在使用的过程中的可靠性,安全性、延长超级电容的使用寿命,需对超级电容内阻进行检测。首先阐述了锁相放大的超级电容内阻测量原理,在此基础上设计了一种基于锁相放大的超级电容内阻测量电路,包括交流信号源电路、信号调理电路、锁相放大电路、低通滤波电路等。实验结果表明,超级电容内阻检测系统能有效地检测超级电容的内阻,其检测结果的重复性误差小于3%,达到了超级电容内阻检测的要求。     

超级电容在直流操作电源系统中的应用

超级电容（双电层电容器EDLC）是一种新型储能元件,其与蓄电池相比具有一定的互补性。利用超级电容构成直流操作电源系统中的储能部件,可以解决蓄电池直流操作电源系统中存在的问题,提高电源系统的可靠性和可维性。提出了超级电容在直流操作电源系统中的多种应用方案。     

金属与粉末冶金

美科学家研制出铌金属超级电容材料美国加州大学洛杉矶分校亨利·萨穆埃利工程与应用科学学院的研究人员,成功研制出一种新的超级电容材料,并证明其能快速地存储和释放能量,有望广泛应用于城市电网、混合动力汽车的再生制动系统等能源传送系统。据了解,由材料科学和工程学教授布鲁斯·杜恩领导的科研团队合成出了一种氧化铌,并证明其拥有稳定的储能能力。这种新材料将被用在"超级电容"     

基于buck-boost变换器的超级电容组均衡管理系统

为了克服电动车用串联超级电容组因其单体电容器性能差异造成的供电性能缺陷,提出了通过脉宽调制(PWM)信号控制完成电容组中相邻单体电容电压均衡的策略,并研制出了基于buck-boost变换器的超级电容组均衡管理系统.在电动车中的试验结果表明,该系统在串联超级电容组的充放电过程中能够有效地完成单体电压的均衡,避免了性能较差的单体电容器的过充或过放,同时提高了电容器有限容量的利用率.     

浅析提高直流操作电源系统可靠性的主要方法

超级电容（双电层电容器EDLC）是一种新型储能元件,其与蓄电池相比具有一定的互补性。利用超级电容（或与蓄电池一起）构成直流操作电源系统中的储能部件,可以解决蓄电池直流操作电源系统中存在的问题,提高电源系统的可靠性和可维性。本文提出了超级电容在直流操作电源系统中的多种应用方案。     

全固态三维结构碳电极之碳电池/超级电容

正为了能够将发电厂晚间多余的电力储存起来以供白天使用,台湾逢甲大学柯泽豪教授投入此领域研究长达25年,最后研发出碳电池/超级电容。碳电池/超级电容使用全固态三维结构碳电极的特殊储能组件,可搭配太阳能电池形成绿色电网,兼具超级电容以及储能电池二者的功能。碳电池/超级电容大电流操作特性远胜于锂电池,接近超级电容,储能容量远高于超级电容。考虑全组件质量与体积,碳电池/超级电容储电容量     

混合动力客车用超级电容参数匹配及性能分析

超级电容具有大电流充放电能力、充放电效率高、循环寿命长和低温性能好的优点,但是能量密度低、电压保持能力较差、成本相对较高,在混合动力客车上应用较多.本文基于某车厂二代混合动力客车对电源系统的性能要求和超级电容的充放电特性,进行电源系统参数匹配及仿真分析.分析结果表明超级电容满足混合动力客车性能要求,应用效果较好.     

基于超级电容的地铁列车再生制动能量利用分析

由于城市地铁列车运行的特殊性,需要频繁起停,进而容易造成电能的损耗。为了有效地回收列车制动能量,降低列车起停的电能损耗,通过构建超级电容储能系统,高效地处理列车制动能量。在非隔离双向DC/DC变换器的系统运行下,可以将列车制动的能量进行合理的转化储存,当列车加速驱动时,可以释放出储存的能力,提高了能量的利用效率。该文基于超级电容的地铁列车再生制动能量利用设想,在仿真模拟实验下论证该技术方案的可行性与安全性。     

Adaptive control of a hybrid power system in electric vehicles

在由双向电源变换器连接动力电池组和超级电容组形成的电动汽车混合电源系统中,实现了双向电源变换器的电源外特性设计,通过实时检测动力电池组的放电电流,实现了超级电容组的充放电状态和电流的自适应控制.建立了电源变换器外特性模型,描述了动力电池组放电电流和超级电容组充放电电流之间的定量关系.在此基础上,设计了双向电源变换器的控制电路.试验结果表明,在城市工况下,混合电源系统中动力电池组的峰值放电电流降低了60%,这有利于提高动力电池组的使用耐久性.     

钙钛矿镧基氧化物超级电容器的研究进展

对近年来国内外对基于氧阴离子嵌入型钙钛矿超级电容的研究做了一定的归纳和总结。通过以往人们对钙钛矿超级电容理论和影响因素的研究的分析,对钙钛矿电容阴离子嵌入理论做了概括,并总结了影响其电化学性能的因素。通过对以往实验设计思路的归纳,提出了钙钛矿材料研究的大体方向。同时结合超级电容器应用于汽车动力源时需满足的实际条件,为以后汽车超级电容中钙钛矿材料的设计提供一定的思路。     

太阳能光伏发电最大功率点跟踪控制器设计

为提高光伏发电系统的效率,设计一种太阳能光伏发电最大功率点跟踪控制器。该控制器采用升降压式DCDC变换电路,利用变步长占空比扰动法实现最大功率点跟踪。设计以超级电容和蓄电池混合储能的充电方式,该方法在太阳光强较弱时用小电流继续对蓄电池充电,实现对蓄电池实时充电。对太阳能充电进行相关实验,结果表明:设计的最大功率点跟踪控制器可以在任何光照条件下完成充电,超级电容与蓄电池混合充电比蓄电池单独充电时的充电电流增加了29.1%,提高光伏发电系统的效率。     

Test and Operation of the WHMFC 12.6 MJ Capacitor Bank Power Supply System

The 12.6 MJ capacitor bank power supply system of the Wuhan National High Magnetic Field Center (WHMFC) at Huazhong University of Science and Technology (HUST) consists of 11 independent 1 MJ modules and 2 independent 0.8 MJ modules; it was tested and put into operation in October 2010. The capacitor bank power supply system connects to 8 measurement cells through three current collectors and four selectors. A number of nondestructive magnets for different bore sizes and peak fields have been energized by this system, including an 83 T dual stage magnet. The results of tests and operation are presented in this paper.     

一种用于声呐发射机的超级电容被动均压简易实用电路

超级电容器的性能不一致性会造成处于串联模式的电容组中个别电容器首先发生过压失效,进而加速整个储能组的失效。现有的均压电路一般工作在线性状态,电路也较复杂,不便于调试和生产。介绍了一种仅由5个元器件组成的简易、实用、高效的开关型被动均压电路,分析了其工作原理及均压特性。该电路在声呐发射机的储能电源中可长期使用,很好地保护了超级电容组。     

High-performance light emitting diode backlight driving system for large-screen liquid crystal display

A high-performance light emitting diode backlight driving system is proposed for large-screen liquid crystal display. The proposed system consists of a boost converter for power factor correction (PFC) and an active-clamp converter for dc-dc power conversion. With coupled inductors and simple passive components, the proposed PFC circuit minimises the switching losses by reducing the reverse-recovery current. The active-clamp converter operates under zero-voltage switching for the power switches and its output rectifier is composed of a current doubler and a synchronous rectifier for reducing conduction loss. The proposed backlight driving system is analysed and its design consideration is discussed in detail. Experimental results for a 300 W (3.3 V/90 A) prototype at a constant switching frequency of 100 kHz are presented to verify the analysis and the performance of the proposed system.     

无功补偿装置选型对改善电网质量和治理谐波污染的影响

在迁钢制氧一期10 kV供电系统中,无功补偿装置运行中出现电流突然激增现象,一些正在运行的其他设备绕组绝缘突然击穿等一系列问题。从电容器无功补偿装置的设计参数和供电电网的质量两方面分析异常发生的原因,对无功补偿装置和与其配套的电抗器的电抗率重新选型,保证供电质量和设备的运行可靠性。     

单相无电解电容永磁同步电机驱动系统控制方法研究

针对传统单相无电解电容电机驱动系统中直流母线电压波动较大而导致控制不稳的问题,提出一种单相无电解电容永磁同步电机驱动系统控制方法。通过对传统单相无电解电容电机驱动系统输入、输出功率进行分析,在q轴电流注入正弦分量,对输出功率进行控制,调节输入功率,达到改善输入电流波形的目的;通过设计一种积分比例控制器替代传统的比例积分控制器对母线电压进行调节,能够有效抑制母线电容充电时的电流、电压过冲。理论分析、仿真结果与试验结果均验证所提控制策略的有效性。     

Analyzing small suprathreshold differences of LCD-generated colors

Small suprathreshold color differences around five CIE color centers were investigated on a typical liquid crystal display (LCD) with fluorescent backlight using the method of constant stimuli. The results were evaluated using probit analysis and compared with surface-color differences of the RIT-DuPont dataset. We focused especially on the relationship between T50 distances obtained from LCD and surface-color stimuli and on the influence of the display's narrowband primaries and its relatively low luminance level on interobserver uncertainty. The low luminance level of the LCD decreases the perceived color differences. However, considering the visual uncertainty of the experimental data, we could not reject the hypothesis that T50 distances from the RIT-DuPont and our experiment agree up to a constant scaling factor. In addition, we found significantly higher interobserver variability in the estimation of small color differences if the colors are viewed on an LCD. There are some indications that color-difference perception might be influenced by individual color-matching functions and, thus, by the spectral power distribution of the stimuli. We provide the experimental data, including all spectral stimuli shown to the observers, on our website.     

Integrated power management circuit for piezoelectronic generator in wireless monitoring system of orthopaedic implants

Piezoelectric (PZT) materials are capable of converting the mechanical energy of compression into electrical energy. With the recent advent of extremely low-power electrical devices, PZT generators have become attractive in many kinds of applications, especially for biomedical applications. Piezoelectronic generators are used in a wireless monitoring system of orthopaedic implants. Due to their poor source characteristics, the efficiency of PZT generator is low. A hybrid direct current (DC)?DC, comprising a switched capacitor (SC) DC?DC converter and a low dropout (LDO) linear voltage regulator, is presented to improve conversion efficiency. A bandgap reference (BGR) circuit which works in sub-threshold region is also presented. Because SC DC?DC converter works in the highest voltage region in this system, small power supply current, including supply current through BGR and other auxiliary modules, means low power consumption. BGR?s power supply voltage can be varied from 3 to 16 V. Its supply current is only 3.2 μA at 125 C and its temperature coefficient is 46 ppm. Stacked switches technique is proposed to reduce leakage current in switching process of SC converter. Simulation results show that the efficiency of SC?s converter can reach 88%, that of LDO can reach 80% and that of the overall system can reach 66%, including power consumption of all auxiliary components, which is far higher than previous work.     

Pre-charging of module capacitors of MMC when the module switches are driven by a source derived from the module capacitor

A modular multilevel converter (MMC) is one of the latest multilevel converters used for high and medium-voltage power conversion. It is based on cascade connection of multiple identical modules using IGBTs as switching devices. Module switches of MMC are preferably driven by a source derived from the module capacitor. In each MMC module, the control circuit, consisting of gate drivers, is powered from a dc supply derived from the local capacitor. The module capacitors need to be pre-charged, to power the control circuit. The problem faced while doing so experimentally for MMC with two modules per arm and a solution have been reported earlier. If a fly-back converter is used to generate the power supply for driving the control circuit, the module capacitor voltages become unstable during uncontrolled pre-charging. It has been reported earlier that the reason for this is approximately constant power load on the module capacitor. This work provides theoretical understanding of the problem and shows by analysis that the power supply can be made stable if the load on the module capacitor is made a positive resistance load. As the complexity of MMC with more than two modules per arm is higher, the phenomenon is studied by simulation for MMC with four modules per arm. It shows that when a fly-back converter is used for generating the power supply, similar instability occurs in MMC with four modules per arm. It shows that when the module capacitor is made to have a load with positive resistance characteristics, the module capacitor voltages and consequently the power supplies stabilize even for MMC with four modules per arm. It further shows that even if the load on the module capacitor is negative resistance type, when fly-back converter is used to generate the module power supply, by switching devices in those modules where power supply becomes available first, followed by sorting algorithm, stable power supplies can be developed on all the modules and the capacitors can be fully charged to the desired voltage.     

Polarized backlight based on selective total internal reflection at microgrooves

A polarized backlight for LCD illumination is designed and fabricated in which s-polarized light is extracted owing to selective total internal reflection at microstructures in the anisotropic layer. From the measurement, the contrast ratio in normal viewing direction can be as high as 64. Luminous uniformity of higher than 80% is achieved for polarized backlights. Furthermore, 1.6 gain in efficiency is obtained aiming for high-efficiency LCD illumination.