Design of Cold-Junction Compensation and Disconnection Detection Circuits of Various Thermocouples and Implementation of Multi-Channel Interfaces Using Them-A Secondary Publication

Cold-junction compensation(CJC)and disconnection detection circuit design of various thermocouples(TC)and multi-channel TC interface circuits were designed.The CJC and disconnection detection circuit consists of a CJC semiconductor device,an instrumentation amplifier(IA),two resistors,and a diode for disconnection detection.Based on the basic circuit,a multi-channel interface circuit was also implemented.The CJC was implemented using compensation semiconductor and IA,and disconnection detection was detected by using two resistors and a diode so that IA input voltage became-0.42 V.As a result of the experiment using R-type TC,the error of the designed circuit was reduced from 0.14 mV to 3μV after CJC in the temperature range of 0°C to 1400°C.In addition,it was confirmed that the output voltage of IA was saturated from 88 mV to-14.2 V when TC was disconnected from normal.The output voltage of the designed circuit was 0 V to 10 V in the temperature range of 0°C to 1400°C.The results of the 4-channel interface experiment using R-type TC were almost identical to the CJC and disconnection detection results for each channel.The implemented multi-channel interface has a feature that can be applied equally to E,J,K,T,R,and S-type TCs by changing the terminals of CJC semiconductor devices and adjusting the IA gain.

The Method for Measuring Circuit Breaker Overtravel Based on Operating Process

At present,the over-travel measurement of high-voltage circuit breakers is mostly carried out after the circuit breaker is completely dismantled.The disadvantage of the measurement is that it can only be measured when the circuit breaker is dismantled and overhauled.Defects are diagnosed in a timely and effective manner,and capacity causes hidden troubles.This article provides a method for direct measurement of hydraulic circuit breakers without any adjustment or disassembly.The method can be carried out in various situations such as minor repairs,major repairs,and temporary repairs,which not only saves time,but also improves accuracy of the measurement.The comparative test results show that this method can be simple,convenient and effective to measure the overtravel of the high-voltage circuit breaker.

General Consideration of Measuring System for Operational Test of Thyristor Valves of Ultra High Voltage DC Power Transmission

Thyristor valve is one of the key equipments for ultra high voltage direct current(UHVDC) power transmission projects.Before being installed on site,they need to be tested in a laboratory in order to verify their operational performance to satisfy the technical specification of project related.Test facilities for operational tests of thyristor valves are supposed to enable to undertake more severe electrical stresses than those being applied in the thyristor valves under test(test objects).On the other hand,the stresses applied into the test objects are neither higher nor lower than specified by the specification,because inappropriate stresses applied would result in incorrect evaluation of performance on the test objects,more seriously,would cuase the damage of test objects with expensive cost losing.Generally,the process of operational tests is complicated and performed in a complex synthetic test circuit(hereafter as STC),where there are a lot of sensors used for measuring,monitoring and protection on line to ensure that the test circuit functions in good condition.Therefore,the measuring systems embedded play a core role in STC,acting like "eyes".Based on the first project of building up a STC in China,experience of planning measuring systems is summarized so as to be referenced by related engineers.

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.

Temperature Effects on the Electrical Performance of Large Area Multicrystalline Silicon Solar Cells Using the Current Shunt Measuring Technique

The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5oC up to 50oC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed.

Multi-channel FIR Interferometer for Electron Density Measurement on HT-7 Superconducting Tokamak

A five-channel far-infrared (FIR) hydrogen cyanide (HCN) laser interferometer was developed to measure plasma electron density profile on the HT-7 superconducting tokamak. The principle and structure of the five-channel FIR laser interferometer is described. The laser source used in the interferometer was a continuous wave glow discharge HCN laser with a 3.4 m cavity length and a 100 mW power output at 337μm wavelength. The temporal resolution was 0.1 ms and the detection sensitivity was 1/12 fringe. Preliminary experimental results measured by the interferometer on HT-7 tokamak are reported.

A novel wide-range precision instrument for measuring three-dimensional surface topography

We developed a measuring instrument that had wide range, high precision, small measuring touch force. The instrument for three-dimensional (3D) surface topography measurement was composed of a high precision displacement sensor based on the Michelson interference principle, a 3D platform based on vertical scanning, a measuring and control circuit, and an industrial control computer. It was a closed loop control system, which changed the traditional moving stylus scanning style into a moving platform scanning style. When the workpiece was measured, the lever of the displacement sensor returned to the balanced position in every sample interval according to the zero offset of the displacement sensor. The non-linear error caused by the rotation of the lever was, therefore, very small even if the measuring range was wide. The instrument can measure the roughness and the profile size of a curved surface.

Fault Locator Using Two-end Unsynchronized Measurements for UHV Series Compensated Double-circuit Lines

An accurate fault location algorithm for double-circuit series compensated lines is presented.Use of two-end unsynchronized measurements of current and voltage signals is considered.The algorithm applies two subroutines,designated for locating faults on particular line sections,and additionally the procedure for selecting the valid subroutine.The subroutines are formulated with use of the generalized fault loop model and the distributed parameter line model is applied.Performed ATP-EMTP based evaluation has shown the validity of the derived fault location algorithm and its high accuracy.

基于阻抗在线测量的锂离子电池过放电诱发内短路识别研究

锂离子电池的过放电行为可诱发内短路进而可能导致热失控。由于单体电池一致性差异和过放电导致的内短路初期电、热特征不明显,使得电压和温度等常规物理参数难以可靠实现故障预警,而阻抗可以反映电池内部信息,对故障状态具有较好的指示能力。该文通过分析锂离子电池过放电诱发内短路引起阻抗变化的机理,基于设计的阻抗在线测量装置,确定用于监测电池内短路故障的特征阻抗频率为70 Hz,获取过放电诱发内短路过程中特征频率下动态阻抗及阻抗变化率,提出一种基于动态阻抗特征的内短路在线识别方法并验证了方法的可靠性。实验结果表明,锂离子电池放电过程中动态阻抗半正弦变化特征可提前约144 s实现过放电预警,动态阻抗针状变化特征可提前约152 s实现内短路故障预警,动态阻抗明显回升特征可作为内短路发生的标志。此外,阻抗变化率特征有助于实现锂离子电池故障识别及预警,该方法在锂离子电池故障在线快速诊断中具有重要的应用潜力。

高精度NiCr/NiSi薄膜热电偶高温测试系统

针对航空发动机涡轮叶片和燃烧室内壁等高温恶劣环境下对温度测量的迫切需求,提出了一种基于薄膜热电偶的高精度测温方法。采用磁控溅射法在SiC衬底上制备了NiCr/NiSi薄膜热电偶。完成了薄膜热电偶的设计与制备,并设计了一套高精度温度数据采集系统,主控芯片采用STM32,数据采集芯片采用16位高精度芯片ADS1118,实现了对高温恶劣环境下温度数据的实时采集。结果表明:设计制备的NiCr/NiSi薄膜热电偶能够实现-40~1000℃温度区间稳定测温,高精度测温系统与标准温度测量系统相比误差优于±0.4%,为高温恶劣环境下温度测量提供了有效且可靠的解决方法。

面向工程教育认证的电子测量与电子电路实验课程教学改革研究

电子测量与电子电路实验是一门实践性非常强的课程。为保证毕业生质量,面向工程教育认证,适应新时代人才需求类型的变化,充分贯彻以学生为中心的理念,针对电子测量与电子电路实验课程分别从教学目标、课程内容、教学模式和考核评价系统几个方面进行研究改革,建立多元化、新时代的教学改革方案,注重学生全方面能力的培养。实践证明改革对提升该课程的教学质量有明显的效果。

塑壳断路器短路分断能力提升方法研究

短路分断是断路器的核心功能,提高断路器的短路分断能力是市场的持续需求。针对有效提升塑壳断路器(Moulded Case Circuit Breaker,MCCB)短路分断能力的方法开展了研究。利用栅片电压测量分析法可以检测灭弧栅片在短路分断时切割电弧的情况,评估各灭弧栅片切割电弧的性能以及电弧在灭弧室内的动态特性,为电弧优化提供参考数据。利用有限元仿真的方法进行电磁力计算,有利于快速验证优化设计方案而免去实际的试验验证,节约产品的研发成本,缩短产品的研发周期。蒸汽喷射控制(Vapour Jet Control,VJC)产气材料的运用也能够进一步提高产品的短路分断能力。综合运用以上设计方法,能够在不会大幅增加研发成本的基础上,快速提升MCCB的短路分断能力,工程应用价值较好。

基于在机测量的曲面共形电路3D打印误差补偿方法

基于3D打印技术制备曲面共形电路具有广阔的应用前景,然而,由于曲面基材加工误差和导电线路定位误差的影响,导致曲面电路3D打印头高度难以精确控制,进而影响打印精度。为此,本文以气动式直写打印为研究对象,提出了一种“在机测量+线路模型重构”的打印头高度误差补偿方法。设计了一种曲率自适应测量点选取方法,利用NURBS曲线反算法对测量数据进行重构,还原真实线路模型。通过生成真实线路的打印轨迹,替换原始理论打印轨迹,补偿了打印头高度误差。自主搭建了一套集成了在机测量系统的曲面共形电路3D打印平台,设计了直线、圆弧与NURBS自由曲线3种形状的线路,进行补偿前后电路打印的对比实验。结果表明,未进行补偿前,在线路曲率较大的地方,线路在基板上的波峰处会产生拉丝现象,波谷处会产生堆叠现象,而补偿后的导线线宽比较均匀;进一步对每条导线的电阻进行测量,发现各条线路补偿前的电阻值波动较大,补偿后的电路的电阻值均匀,且相较补偿前平均降低65.99%,最大电阻降幅达85.75%。

用于小电流测量的柔性罗氏线圈设计

保障电力系统的安全运行对国家和人民至关重要。因此,须及时监测设备的性能与可靠性。其中,对设备电流的测量是相当必要的。基于罗氏线圈具有出色的线性度并且精度高,选择采用罗氏线圈作为电流传感器。但以往的线圈在测量小电流时,灵敏度低,精度低,适合对大电流的测量。针对以上问题,进行用于小电流测量的柔性线圈设计,相比刚性线圈,其轻便且安装快捷。该线圈使用硅橡胶电缆作为骨架,双层绕线增大线圈互感,有效提高了线圈的灵敏度。通过对工频电流的测量,最终灵敏度约为40mV/A,满足电力系统中的小电流测量要求,可应用于实际工程中。

集成结温在线监测功能的IGBT智能驱动器

结温是表征功率器件寿命的重要参数,对功率器件结温进行监测具有重要意义。基于热敏电参数法,选取对温度敏感的电参量饱和导通压降V_(CE(sat))作为研究对象,在IGBT驱动器中集成高精度结温参数测量电路,使系统可在线监测功率器件结温。同时为了得到更加精准的热-电参量对应关系,通过分段拟合的方式对IGBT模块在工作状态下结温与V_(CE(sat))的关系进行数学建模。在此基础上,还设计了相应的退饱和检测电路和分级驱动电路。经过实验验证,最终解决了传统结温测量方式工程应用性差的问题,提高了参数采集精度,将热敏电参数的结温预测误差控制在±5℃以内。

基于LC并联谐振的轴向自感式位移传感器设计

为了满足磁悬浮轴承面向更高精度的发展需求,提出基于LC并联谐振的轴向自感式位移传感器.通过增大谐振回路的等效电感变化率,提高传感器的灵敏度.分析传感器的工作原理.通过有限元仿真,研究传感器设计参数与灵敏度之间的关系.设计传感器的测量电路,结合有限元仿真和数值仿真,分析LC并联谐振对传感器灵敏度的影响.搭建实验台,对传感器的静态性能进行测试.结果表明,相对于传统的位移传感器,提出的传感器具有更高的灵敏度与更低的线性度.

塑壳断路器可靠性试验电源的光纤校准技术研究

针对塑壳断路器可靠性试验电流的大幅值、短时、交直流混合等特点以及现场复杂工况对大电流标准传感器的严苛要求,提出了基于光纤电流传感技术的塑壳断路器可靠性试验电源现场校准方法。根据光纤电流传感器的闭环检测原理建立了系统的动态模型,分析了阶跃响应和频率响应特性,仿真结果表明:通过调节系统的前向增益及滑动滤波器阶数,传感器的上升时间优于9.09μs,-3 dB带宽可达39.91 kHz,证明了光纤电流传感器对塑壳断路器可靠性试验电流的跟踪响应能力。基于等安匝法对光纤电流传感器进行校准,评定了校准结果的不确定度,结果表明:在2.5~60 kA范围内,传感器的直流、工频电流测量准确度优于0.2%。对塑壳断路器可靠性试验电流进行了现场测试,为塑壳断路器可靠性试验电源的现场校准提供了一条技术途径。

高速铁路动车组主断路器转换阀射流噪声模拟分析及其降噪措施

[目的]高速铁路动车组主断路器转换阀的射流噪声非常高,严重影响了旅客的乘坐舒适性,因此有必要研究有效的降噪措施。[方法]进行了转换阀射流噪声的现场试验,测得其噪声高达96 dB,且呈现明显的间歇性与脉冲性。采用大涡模拟方法建立了转换阀射流噪声仿真数学模型,选取四种不同形状的喷口,计算得到了这四种喷口的流场速度云图。将射流流场计算结果导入LMS.Virtual.Lab软件,采用声学边界元方法模拟计算这四种喷口的射流声场,并将计算得到的四种喷口1/3倍频程频谱的模拟值与试验实测值进行对比。选取了既有的四种工业消声器,以及研发的新型结构复合材料消声器,对转换阀的降噪效果进行测试。[结果及结论]转换阀因断开主断路器而产生射流噪声。转换阀射流噪声与排气口形状密切相关,射流噪声为中高频噪声。五种消声器均能显著降低转换阀射流噪声,新型结构复合材料消声器的降噪效果最好,其降噪量可达20 dB。

Application of geophysical methods in fine detection of urban concealed karst:A case study of Wuhan City,China

The construction of modern livable cities faces challenges in karst areas,including ground collapse and engineering problems.Wuhan,with a population of 13.74×10^(6) and approximately 1161 km^(2)of soluble rocks in the urban area of 8569.15 km^(2),predominantly consists of concealed karst areas where occasional ground collapse events occur,posing significant threats to underground engineering projects.To address these challenges,a comprehensive geological survey was conducted in Wuhan,focusing on major karstrelated issues.Geophysical methods offer advantages over drilling in detecting concealed karst areas due to their efficiency,non-destructiveness,and flexibility.This paper reviewed the karst geological characteristics in Wuhan and the geophysical exploration methods for karst,selected eight effective geophysical methods for field experimentation,evaluated their suitability,and proposed method combinations for different karst scenarios.The results show that different geophysical methods have varying applicability for karst detection in Wuhan,and combining multiple methods enhances detection effectiveness.The specific recommendations for method combinations provided in this study serve as a valuable reference for karst detection in Wuhan.

核测量系统关键电路故障诊断与预测方法研究

探讨了一种可实现核测量系统关键电路故障诊断与预测的方法。以核测量系统放大电路为研究对象,采用PSPICE对电路进行建模,通过小波包变换从电路脉冲响应信号中提取出代表电路状态的故障特征信息,将故障特征信息输入BP神经网络模型开展故障诊断研究,同时,基于相关向量机模型(RVM)开展故障预测研究。研究结果表明:该故障诊断模型对不同故障模式的识别准确率高达99%,且基于量子粒子群滤波算法(QPSO)的RVM模型能够实现电路故障指标发展趋势的准确预测。本项研究可为核测量系统关键电路的维护、保障提供更充实的理论支撑。