自适应多量程的太阳电池参数测试系统的研究

为了能获取真正的开路电压与短路电流,自动适应多种规格的太阳电池片的参数要求,对太阳电池的测试的电子模型与自适应多测试系统进行研究。首先在分析原有太阳电池测试系统的基础上,进行改进,使得跟随电压真正跟随到OV;然后采用多路电子开关等手段,使得测试线路实现了自适应多量程的测试。试验结果表明,系统能真正获取开路电压与短路电流,并且,能实现电压在0～50V,电流在0．7～5．6A之间的自适应测量,开路电压不一致性〈2．2％,短路电流不一致性〈3．2％,满足了单体太阳电池与小组件太阳电池的测量。     

压电执行器迟滞特性的自动采集及分析

压电微执行器用于纳米级微定位，预先获得其迟滞非线性特性是必要的，介绍了压电叠堆迟滞特性曲线的微机自动采集系统。系统基本部分是微机和通用数据采集板PCL-818L。高压运放输出作为高压驱动电源；电涡流位移传感器和后续减法放大电路承担测微位移任务，一定程度上可替代昂贵的精密电容位移传感器，测得了不同驱动电压范围的执行器迟滞特性曲线。     

一种DC-DC直流稳压电源及漏电保护装置的设计

利用稳压块TL430、TIP127大功率三极管等分离元件构成一种输入电压范围宽、输出电压为+5 V的DC-DC直流稳压电源。通过MSP430F149单片机实现输出电流、漏电流、输出电压和功率的测量,并根据漏电流大小能自动切断电压输出实现保护,具有测量精度高、漏电保护灵敏的特点。     

新型压电作动器驱动的直线电机驱动电源研究

基于压电作动器的大容性负载特性,通过电路匹配分析提出了基于直流升压变换器和谐振驱动控制电路;根据压电作动器驱动偏压要求,设计偏压电路使输出电压在-20~100 V之间;采用微处理器和D触发器设计驱动信号产生电路;将设计的驱动电源用于双作动器驱动的压电直线电机,电机运转平稳,电路功耗小,通过匹配不同的电感实现了宽频范围驱动.     

一种宽范围全桥移相ZVS电源

在全桥移相拓扑的基础上引入辅助支路,设计出零电压ZVS变换器,通过输入直流调压实现变换器50~500V宽范围可调输出。详细分析了系统工作原理及软开关和直流调压方案,设计了系统主要参数,最后给出移相及驱动脉冲波形。     

超宽输入电压范围三相开关电源的设计和优化

针对工业用三相开关电源的宽输入电压范围要求,给出了一款利用LM5021-1实现的超宽输入电压范围的三相开关电源的设计和优化过程,其输入电压范围为线电压有效值40 VAC~450 VAC,提供了9 V/100 mA和12 V/4 W两路直流输出。实验结果表明,该电源具有输入电压范围宽,输入/输出隔离度高、效率较高等优点,可应用于三相电表等电源中。     

Traceability of DC high voltage measurements using the Josephson voltage standard

This paper introduces a new methodology for obtaining high voltage DC measurements traceability to the International System of Units (SI) at the Egyptian National Institute for Standards (NIS). The traceability has been achieved via the NIS automated 10 V DC Josephson Voltage Standard (JVS). A 100 kV DC voltage divider with a nominal voltage ratio of 10,000:1 is being used with its display in parallel with a high sensitive digital voltmeter. The traceability has been realized by calibrating this digital voltmeter via the JVS system and then it has been used to calibrate the divider display readings. Moreover, the divider ratio has been accurately calibrated using a traceable calibrator source on its high voltage side and the calibrated digital voltmeter on its low voltage side. Accurate and traceable high voltage values have been obtained associated with their expanded uncertainties. Highly improved uncertainties have been achieved using this new calibration technique.     

高效同相的降压-升压DC/DC转换器的控制方法

采用一种四开关拓扑结构的降压-升压DC／DC转换器控制方法，能使转换器在输入电压高于、低于或等于输出电压的情况下操作，实现降压、降压-升压、升压3种模式自动并且平稳地转换，提供一种可在所有操作模式进行连续转换的功能。具有效率高、外围器件少、同相输出的优点。经HSPICE仿真，采用Hynix0．5μm 5V CMOS工艺，在输入电压2．5-5．5V、输出电压3．3V、频率1MHz时，效率高达95％以上。是输出电压处于电池电压范围内的单节锂离子电池、多节碱性电池或NiMH电池应用的理想选择，解决了在便携式电子设备电源设计过程中所遇到的问题。     

STC12C5608AD单片机的数字式一氧化碳浓度变送器设计

介绍了一种基于STC12C5608AD单片机的数字式一氧化碳浓度变送器的硬件原理及构成与软件设计方法。变送器利用STC12C5608AD单片机内置的A/D转换器对一氧化碳传感器输出的1～5V标准电压信号进行A/D转换,并计算出浓度值后通过RS485接口输出数据。系统具有外围元件少、集成度高、精度高、稳定性好、可多机组网、编程及控制简单方便,价格低廉等优点。在矿井通风监测方面具有良好的应用前景。     

电流源型高压隔离驱动电源研究

研究了一种应用于高压环境下的隔离驱动电源拓扑结构。采用半桥逆变或全桥逆变拓扑提供高频输入电压,提高对输出要求的适应性; 采用谐振网络获得稳定恒流源; 利用高压电缆线外绝缘材料的绝缘性实现高电压等级的隔离,以串联多输出的方式达到多路输出的目的。给出了电流源型高压隔离驱动电源的结构,并对变换器的组成和工作原理进行分析。根据参数设计要求对电流源型高压隔离驱动电源进行了仿真实验,得到一台单个支路输出10 V/0.5 A的高压隔离驱动电源仿真模型,结果证明具有良好多输出特性,验证了驱动电源结构的有效性。     

基于STC12C5A60S2单片机的简易电阻测试仪设计

为了实现对微小数值的电阻进行准确和高精度的测量,本文设计了以STC12C5A60S2单片机为核心,利用直流电压源和运算放大器组成一个多值恒流源,实现多量程电阻精确测量。利用单片机内部集成的A/D转换器对被测电阻两端的电压进行采样,通过数值比对,自动控制各个电阻档位继电器的开关,实现量程自动切换功能。用键盘输入筛选电阻阻值及误差值,通过单片机对步进电机的控制来实现电位器阻值的变化,由LCD12864显示测量数据和变化的曲线,符合筛选条件时,系统发出声音提示,实现准确、快速筛选电阻。     

AC current automatic calibration using two different TCC designs

AC currents are automatically calibrated by two different thermal current converter （TCC） designs.The two designs are different in the used number of the thermal-elements （TEs）.Consequently they differ in their output electro motive force （EMF）.Studying the effect of changing the output EMF is done in this paper through calibrating AC currents.5 mA and 5 A are accurately calibrated at different frequencies 55 Hz,1 kHz and 10 kHz by the two TCCs.A comparison is made between the results to evaluate the effect of the output EMF value on the accuracy and the uncertainty of the low and higher AC current calibration.A LabVIEW program is designed for this accurate automatic calibration to overcome the problems of the manual calibration on the thermal converters.     

基于STC系列单片机的车载逆变电源

针对传统逆变电源启动困难的问题,对控制策略进行了改进,设计了一款以单片机STC12C5A60S2为主控芯片的两级式级联车载逆变电源。该电源以12 V直流电压为输入,通过升压与逆变两个功率变换环节得到了220 V,50 Hz的正弦交流电。在升压环节,采用直流母线电压负反馈,确保了直流母线电压的稳定性;在逆变环节,采用正弦脉宽调制(SPWM)技术,将输出电压的谐波畸变率(THD)降低到了5%以内。此外还对电池电压检测电路、输出电压检测电路、输出电流检测电路、桥臂短路保护电路进行了设计,并研制了实验样机。研究结果表明,采用逆变电路先触发升压电路后触发、根据输出电压实时更新占空比的控制策略,该逆变电源能够顺利启动,稳压特性良好,为以后逆变电源的优化设计提供了参考。     

Logarithmic analog-to-digital converter using switched attenuators

One can construct a successive-approximation analog-to-digital converter (ADC) whose output is proportional to the logarithm of the input voltage, by using independent electronically switched attenuators. The output step size of such an ADC corresponds to a constant relative change in the voltage being measured, rather than a constant absolute change as in a linear ADC. The principle described here is fully 'digital' in that it depends only on the accuracy of resistors and not on the logarithmic I-V characteristic of any solid-state device. A practical ten-bit prototype conforms to the ideal logarithmic characteristic to about 1% over a four-decade input voltage range, 1 mV to 10 V; effectively, any input in that range is measured to about 1%. Complexity, cost, and speed are comparable to simple linear ADCs.     

AC-DC全自动测量系统中自动开关的研制

采用了三个双刀单掷簧片继电器研制了一个快速自动A-DC转换开关. 依据A-DC转化标准, 所研制的开关首次用于埃及国家标准化所的AD-DC全自动测量系统中. 对自动AC-DC转换开关的电路及保护电路进行了介绍, 并使用该转换开关实现了从AC电压源到DC电压源转换的标定, 标定的DC电压源量程为2、 6、 20和 60 V. 最后, 对校准值的不确定性进行了估算.     

基于C8051F的交流功率放大系统

以C8051F单片机为核心的交流功率放大系统的设计,采用C8051F内部的电压方式D/A转换器输出0～1V的正弦波,用于控制功率放大器输出电压按设定值变化.同时功率放大系统具有过流保护、过压保护与过热保护功能、输出电压稳定、带载能力强、控制精度高等特点.     

程控恒流源设计

介绍以集成电路LM2678电压转换芯片为核心,PIC单片机为控制器的程控恒流源基本电路。此电路结构简单,输出稳定。在0~5 A的范围内连续可调,且开环实验最大非线性误差小于3%。若加以程序校正或闭环控制,整机输出电流控制精度可超过0.1%。     

Application of channel electron multipliers in an electron detector for low‐voltage scanning electron microscopy

An electron detector containing channel electron multipliers was built and tested in the range of low‐voltage scanning electron microscopy as a detector of topographic contrast. The detector can detect backscattered electrons or the sum of backscattered electrons and secondary electrons, with different amount of secondary electrons. As a backscattered electron detector it collects backscattered electrons emitted in a specific range of take‐off angles and in a large range of azimuth angles enabling to obtain large solid collection angle and high collection efficiency. Two arrangements with different channel electron multipliers were studied theoretically with the use of the Monte Carlo method and one of them was built and tested experimentally. To shorten breaks in operation, a vacuum box preventing channel electron multipliers from an exposure to air during specimen exchanges was built and placed in the microscope chamber. The box is opened during microscope observations and is moved to the side of the scanning electron microscope chamber and closed during air admission and evacuation cycles enabling storing channel electron multipliers under vacuum for the whole time. Experimental tests of the detector included assessment of the type of detected electrons (secondary or backscattered), checking the tilt contrast, imaging the spatial collection efficiency, measuring the noise coefficient and recording images of different specimens.     

某型高速轮式工程机械热平衡系统设计

根据某高速轮式工程机械高原使用时热平衡系统出现的过热问题,分析了过热问题产生的原因,改进设计了热平衡系统,采用分离油水散热,冷却水、变矩器油、液压油使用各自的散热器,散热风扇采用液压马达驱动,控制器根据系统温度状态自动控制风扇转速等方法,经仿真分析及实车试验,解决了机械热平衡系统高原使用的过热问题,实现了平原、高原地区兼顾使用,拓展了装备的环境适应性及应用范围。     

压电驱动无针注射器脉冲电源设计

针对压电驱动无针注射对电源的需求,设计了与压电无针注射器配套的脉冲电源,该脉冲电源的驱动控制系统由电池提供12V的直流电压,通过Buck与推挽电路级联电路升压后整流滤波输出0～400V直流可调电压,由反馈电路对输出电压进行校正,最后全桥逆变电路实现输出频率与占空比可调,且输出电压在0～400V随占空比的改变成线性变化的瞬时高压脉冲信号。实验结果表明,该脉冲信号稳定可靠,输出纹波在范围0.5%以内,满足了压电驱动无针注射电源需求。