高性能微加速度计接口电路的研究

介绍一种可用于微机械电容式加速度计检测的接口电路，该电路利用电荷放大器把电容变化转变成电压变化，再对被加速度信号调制的载波信号进行解调，经过低通放大滤波，最后得到与加速度信号成正比的直流电压信号，具有测量差分电容变化的功能和灵敏度高、线性好的特点。整体电路通过Pspice进行了仿真，优化后制成PCB板进行实验。实验结果线性度为5％，灵敏度为19．5V／pF，表明该电路是一种具有实用价值的电容式加速度计检测接口电路。     

电网电容电流外加信号单频测量法的研究与应用

针对高压电力系统发生单相接地时,流经故障点的电流急剧增加,产生很强的间隙弧光接地过电压问题,对电网电容电流外加信号测量控制器的方法进行了详细的分析,充分论证了测量电网电容电流的必要性,对电网电容电流外加信号单频测量控制器的方法进行了研究,将外加信号单频测量法的原理计算分析与其他测量方法进行了比较。研究结果表明,电容电流外加信号单频测量法具有测量准确,特别是电网系统阻尼大,回路Q值低或位移电压很小时,更能显示外加信号单频测量法的优势,为进一步进行优化电网电容电流测量法的设计与应用奠定了基础。     

Generalized four-point characterization method using capacitive and ohmic contacts

In this paper, a four-point characterization method is developed for samples that have either capacitive or ohmic contacts. When capacitive contacts are used, capacitive current- and voltage-dividers result in a capacitive scaling factor not present in four-point measurements with only ohmic contacts. From a circuit equivalent of the complete measurement system, one can determine both the measurement frequency band and capacitive scaling factor for various four-point characterization configurations. This technique is first demonstrated with a discrete element four-point test device and then with a capacitively and ohmically contacted Hall bar sample over a wide frequency range (1 Hz-100 kHz) using lock-in measurement techniques. In all the cases, data fit well to a circuit simulation of the entire measurement system, and best results are achieved with large area capacitive contacts and a high input-impedance preamplifier stage. An undesirable asymmetry offset in the measurement signal is described which can arise due to asymmetric voltage contacts.     

基于PC机数学处理与二维零件加工精度的自动检测方式

利用电容传感器原理,采用RC电路为基体组建的测量电路,通过采样电路将机械加工零件的二维空间内误差转换成相应的电信号,由数控系统读取RC电路中的电压值获取二维空间内测量点的误差。应用数学建模方式,将测量误差通过PC机进行数学处理,输出机械加工零件二维空间内的平面度误差,这样就实现了自动检测机械加工过程中的平面度误差方法。     

750 kV电容式电压互感器现场检验系统的研究

针对目前750 kV电容式电压互感器(CVT)测试中传统比较测差法和"低校高"法存在的问题,研究并开发出750 kV CVT测试和检验系统。通过对750 kV CVT的工作原理、等效电路和误差组成的分析,提出了750 kV CVT空载误差、负荷误差的测试方法和测试线路,研制了30.6 kV带升压器标准电压互感器、变频电子电源和低频互感器检验仪,组成了一套完整的检验系统。通过现场试验,测试数据准确可靠,可以满足0.2级750 kV CVT量值溯源的要求,具有较高的实用和推广价值。     

旁路励磁的钢缆索索力传感器磁路分析

基于钢缆索逆磁致伸缩索力测量原理,讨论了一种旁路励磁的索力传感器。用磁导分析法对磁路做了详细的推导,结果表明可通过检测感应线圈的感应电压反映材料所受的外力,传感器输出与外力信号本身的变化、感应线圈的匝数、材料截面积、外激励磁化场及该磁场下的材料磁导率有关。在外力是缓慢变化情况下,可通过求感应积分电压得到外力;从激励磁化方式、参考工作点的选取,传感器的尺寸设计原则等三个方面做了讨论,确定传感器的参数。最后,利用万能拉力机对该种结构的传感器做了拉力模拟实验,实验结果表明旁路励磁的传感器磁路分析与参数设计比较合理,可用于钢缆索的索力测量。     

Post-arc current measurement based on current transfer characteristic

The paper proposes a novel post-arc current measuring equipment (PACME), which is composed of vacuum switch, transfer resistance, protective gap and high-precision current sensor. The principle of the measurement is based on current transfer characteristic between the vacuum switch and transfer resistance. The current-transfer model of the post-arc current measurement is established to gain the characteristic of vacuum arc conductance and the completion time of current transfer influenced by the transfer resistance, current of main circuit and the contacts opening time. The vacuum arc of PACME extinguished just before the main current approach zero while the main current is completely transferred to the transfer resistance. According to the simulation result, the PACME is designed, especially; the transfer resistance is non inductive and over current protection. The post-arc current of vacuum switch with axial magnetic field (AMF) and transverse magnetic field (TMF) contacts was measured in synthetic short-circuit test. The measuring result of post-arc current is accurate and small interference, which satisfied the post-arc current measurement of vacuum circuit breakers.     

基于十字单元的可调谐互补屏频率选择表面

为实现频率选择表面（FSS）工作频点的可调谐,将环型孔径FSS负载分离后形成感性表面与容性表面,利用两者之间的耦合机制设计了一种互补屏FSS。建立了互补屏FSS等效电路模型,定性分析了它的变频机理。采用耦合积分方程法计算了负载贴片旋转角,耦合电介质厚度和相对介电常数对互补屏传输特性的影响。利用镀膜与光刻方法在耦合电介质两侧制备容性表面与感性表面,并用自由空间法测试250 mm×250 mm样件的传输特性。计算与测试结果均表明：当十字贴片从0°旋转至10°,互补屏FSS的谐振频点会从18.2 GHz向低频漂移至14.8 GHz。当耦合电介质的物理厚度从0.1 mm变化到1 mm时,互补屏FSS的容性表面和感性表面之间的耦合效应逐渐消失。耦合电介质相对介电常数增加使互补屏间的耦合增强,其工作频点向低频漂移。实验显示：随着负载贴片旋转角的变化,互补屏FSS能够实现主动变频功能,为设计和制备主动FSS提供借鉴。     

基于阻抗变换的非接触电压测量自校准方法

电容耦合式非接触电压测量在实际测量中,探头-导线之间的耦合电容受导线线径、绝缘材质、相对位置偏差的影响,造成分压关系难以确定从而无法准确重构电压。本文提出一种基于阻抗变换的非接触电压测量自校准方法,以实现在实际测量中传感器增益的自标定。首先介绍电容耦合电压测量的基本原理,从中凝练存在的问题并提出基于阻抗变换的自校准方法,随后通过仿真对系统参数进行校准精度影响分析并给出参数选取原则。在此基础上,开发传感器探头及电路拓扑。最后进行传感器样机精度测试、抗干扰能力测试、场景适应性测试,精度测试显示电压幅值最大相对误差为0.59%,相位相对误差为0.76%,抗干扰能力测试表明同轴探头对周围耦合电场具有良好的屏蔽作用。场景适应性测试显示在进行不同类型线路的测试中,最大相对误差为1.24%。     

采用虚拟仪器的一阶RC电路测量实验

主要介绍虚拟仪器技术在一阶RC电路测量实验中的应用。详细介绍了由LabVIEW6i虚拟仪器开发平台、相应的硬件电路和PC机组成的一阶RC电路测试／测量系统。     

补偿电网脱谐度自动测量系统

对于补偿电网的重要技术参数－脱谐度的测量,历来都是以消弧线圈的补偿电流和电网电容电流为关键变量,然后根据相关公式“间接”得到。本文设计的脱谐度自动测量系统,采用新的测试理论,并与微机技术相结合,从而使脱谐度的“直接”测量得以实现。     

Resistive loss compensation in the power supply system of the toroidal field winding in the TUMAN-3M tokamak

In the tokamak, in which the winding generating the toroidal field with induction B _t is powered from an inductive energy storage, resistive losses are the main factor that causes B _t to decrease during a discharge. Upgrading of the power supply circuit of the toroidal magnetic field winding (TFW) in the TUMAN-3M tokamak is aimed, primarily, at increasing B _t in the injection heating phase and, second, at maintaining B _t quasi-stationarity during the whole tokamak discharge. To do this, an additional two-section capacitive storage commuted by two thyristor switches has been introduced into the available circuit. Either section of the storage is characterized by a charging voltage of 0.25 kV, a capacitance of 4.32 F, and an energy capacity of 135 kJ. The maximum discharge current of the section is 40 kA. The upgraded circuit compensates for the resistive loss in the TFW and ensures thereby a 50% increase in the magnetic field during injection heating relative to the old circuit: B _t = 1.0 T instead of 0.68 T. In this case, the circuit maintains a TFW current of 110 kA with an accuracy of 10% for ∼60 ms.     

电动汽车传导性干扰的电磁兼容性研究

电动汽车产生的电磁干扰强于传统汽车,尤其是驱动系统产生的共模传导电流不但严重干扰车辆内部电子设备的整车运行,还向周围环境辐射强烈的电磁干扰。为通过减小驱动系统的共模电流,来降低电动车辆的磁场辐射强度,介绍了阻性耦合、感性耦合和容性耦合,并且给出了在电动汽车布线中减小感性耦合与容性耦合的具体措施;从电池的物理结构和电路模型入手,建立了电动汽车电池组与底盘之间的分布电容模型;着重分析了驱动系统的共模干扰源和共模干扰路径,提出了抑制共模干扰的具体办法;最后进行了电动汽车辐射强度试验。研究结果表明,通过抑制电动汽车驱动系统的共模电流,可以有效抑制车辆的磁场辐射强度,使车辆满足GB/T 18387对电动汽车磁场辐射发射限值的要求。     

一种基于光强调制的电流测量方法

文中介绍了一种基于光强调制原理的电流测量方法,它是把被测电流转换成电压,然后与偏置电源共同作用,使ＬＥＤ发出受电流强度调制的光,ＰＩＮ探测器把光信号转化成电信号,经电路处理,最后得到与被测电流成正比的电压。     

A High-Current Nanosecond Electron Accelerator with Inductive Energy Storage

A nanosecond electron accelerator with an output energy as great as 600 keV, a beam current of 16 kA, and an accelerating voltage half-height duration of ～180 ns is described. The accelerator is based on an inductive energy storage composed of two coils. A wire explosive current chopper is used in the inductive storage as a release. The circuit diagram of the accelerator is shown, the design for the accelerator is described, and results from its testing are presented.     

四极杆并联振荡电子学系统和反馈控制

四极杆质谱的电场是由随时间变化的射频交变电压(RF)及直流电压(DC)分别加在两对极杆上产生的。通常射频交流电压由电感电容谐振振荡电路产生,根据电感电容的连接方式不同分为并联振荡电路和串联振荡电路。本综述主要解读并联振荡电子学系统及其反馈控制的核心技术原理。并联谐振的优势在于对射频振荡源的内阻要求不高,容许高内阻的振荡源,使电路的设计与研制更加简单;其缺点是需要采用双调谐振荡回路,在阻抗匹配方面有较高的要求。另外,并联振荡回路的升压主要依靠次级线圈与初级线圈的匝数比,因此仅适合于升压较小,即所需RF输出电压较低的场合。     

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.     

Note: Piezoelectric strain voltage sensing at ultra-low frequencies

Piezoelectric sensors have emerged as a versatile tool for measurement of various quantities such as pressure, acceleration, strain, or force across many industrial applications. When mechanically strained, electric charges are produced inside a piezoelectric transducer. These charges result in an electric field that may be measured as a voltage difference between two electrodes, from which the strain can be inferred. To measure this voltage the sensor must be interfaced with an external device that would typically have a finite input impedance. This, together with the capacitive nature of the piezoelectric sensor, results in an inability to measure strain at low frequencies. We propose a method, based on using a varactor diode in an oscillator circuit, which can result in accurate measurements of the piezoelectric voltage at ultra-low frequencies. We demonstrate successful measurements at 1 mHz.     

基于双差压法测液位的研究与设计

介绍了用双差压法测量液位的基本原理,选用变极距型的电容式差压传感器实现差压检测,给出了通过变压器电桥处理后的差压比与电压比的具体关系,选择并介绍了信号处理电路及其工作原理,设计了用双差压法来测量液位的总体电路。解决了普通差压法当被测液体的密度随环境变化而变化时带来测量误差较大的问题,也可适应比较复杂的测量环境。     

VIBRATION MEASUREMENT OF DOUBLE-ENDED TUNING FORKS RESONATOR

To enhance the coherence and reliability of the double-ended tuning fork (DETF) resonator, a measurement system of resonator vibration is presented to check its dynamic characteristics. Laser Doppler techniques are utilized and the relation between DETF vibration velocity and output current of photodetector is obtained. Resonator vibration equation is also analyzed and its driving power only depends on the direct current bias voltage and the amplitude of alternative voltage. Furthermore, a special resonator driving control circuit based on measurement is designed. The amplitude and frequency of circuit is controlled by a computer so that highly stable and strong driving signal can be output. Experiments on driving and measuring double-ended tuning fork have been done. The frequency of driving signal is 8 kHz and the peak-to-peak value of driving voltage is 140 V. Experimental results indicate resonator can be drived stably by driving control circuit and dynamic characteristics of DETF may be measured in real time.