电磁驱动器放电电流数据采集系统设计

针对电磁驱动器的重要参数——放电电流所处的特殊测量环境,利用罗果夫斯基线圈,基于高速AD转换器Max113,设计了冲击大电流的数据采集系统。分析了系统的工作原理,介绍了硬件电路和数据采集程序。     

瞬态冲击电流测量传感系统的研究

本文根据瞬态冲击电流的特点 ,探讨了符合国际电工委员会标准要求的测量系统 ,并以对雷电浪涌发生器短路电流波形为例 ,提出了用罗柯夫斯基线圈作为测量传感器的测量系统设计方案 ,该测量系统可用于静电放电电流、雷电电流等瞬态电流的测量。     

基于Maxwell与Simplorer仿真分析磁通门磁场传感器瞬态响应

为分析磁通门磁场传感器的工作原理,基于Maxwell和Simplorer软件建立了磁通门磁场传感器的电磁联合仿真模型,仿真了磁通门非线性激励电路中电流波形和磁通门传感器的瞬态响应过程,分析计算了磁通门二次谐波灵敏度以及磁通门传感器的转换系数.为验证仿真模型的准确性,利用钴基非晶薄片制作了磁通门传感器探头并利用开关电源驱动电路激励磁通门工作.实际测量的激励电流波形与仿真结果基本一致,磁通门二次谐波灵敏度的测量值与仿真值误差小于1.1%.测量磁通门的频率响应曲线得到磁通门的转换系数为100 mV/μT,与仿真值几乎完全一致,两者误差小于1.5%.该仿真模型对理解磁通门传感器的工作原理、瞬态响应过程以及指导微型磁通门传感器设计具有重要意义.     

电磁炮多路脉冲大电流测试系统设计

为满足电磁炮多路瞬态脉冲大电流测试需求,以罗果夫斯基线圈为传感器,以PXI高性能数据采集卡和嵌入式控制器为硬件核心,以LabWindows/CVI为虚拟仪器软件开发平台,采用多线程技术设计并实现了多通道脉冲大电流测试系统,并通过数据库实现测试数据的管理.实际应用表明系统实时性高、准确可靠,具有较高的安全性和良好的可扩展性.     

基于Magnet-MATLAB的微型磁通门联合仿真研究

针对Magnet在微型磁通门仿真分析时时间过长的问题,提出了一种将Magnet与MATLAB联合进行仿真分析的方法.基于Magnet建立磁通门探头3D模型,经仿真计算,得到被测磁场对应的感应线圈磁通;联合MATLAB将得到的感应线圈磁通转换为等效的小电流,经与激励电流叠加后,通过软件Flux提供的公式分别计算出受被测磁场影响下感应线圈磁通的变化情况;总磁通对时间求导,获得感生电压.在微型跑道型铁芯磁通门条件下,通过对Magnet仿真与Magnet-MATLAB联合仿真的计算结果比较表明:当外磁场小于5 μT时,2种仿真磁通门输出信号最为接近;与对全模型采用Magnet仿真计算用时超过30 h相比,联合仿真计算时间大幅减小,不超过10 min.     

基于工控机和环形线圈传感器的车速测量系统

介绍了一种基于工控机和环形线圈传感器的车速测量系统，该系统主要依据车辆通过两个环形线圈感应探头时，经过检测器的整形，得到两个不同时刻的宽脉冲，再经过高分频，计数，然后把所采集的数据通过专用的PCI卡送入到工控机中进行处理，得到车辆通过环形线圈时的频率变化波形，最后利用波形的相关性，得到同一车辆经过两个线圈时的时间差，利用速度公式，计算出车辆的速度。     

基于解析法的激励器磁感应位置测量方法

针对空间用磁悬浮隔振平台六自由度运动量测量系统复杂、成本高、测量与驱动异位等问题，提出一种激励器磁感应位置测量方法。首先运用分子环流法、镜像法和Biot-Savar定律建立激励器气隙磁场精确解析模型；进而结合法拉第电磁感应定律建立激励线圈在单自由度方向以恒定速度运动时位置与感应电压的解析模型；最后通过有限元仿真和物理实验对上述位置与电压关系进行了验证。结果显示，所提出解析模型的计算结果与实验及仿真结果的满量程偏差均在±5%以内，拟用于测量的线性区的偏差在5%以内，可知所提出的激励器磁感应位置测量方法是可行的。     

电磁轨道炮膛内磁场环境仿真分析

为了考察电磁轨道炮膛内脉冲强磁场对智能弹药电子元器件的影响,分析轨道炮膛内磁场环境,提出建立轨道炮发射过程的磁扩散模型,利用COMSOL Multiphysics软件分析发射过程的速度趋肤效应,得到导轨与电枢上的磁场、电流及洛仑兹力分布.根据导轨与电枢上的电流扩散深度,建立轨道炮面电流分布模型,分析膛内智能弹药电子元器件位置处的磁场空间分布规律与时频特性.磁场最大值达2.71T,主要频率集中在5kHz以下低频段.轨道炮膛内磁场的高磁通密度、空间衰减迅速特点及低频特性,对轨道炮膛内磁场屏蔽设计具有指导意义.     

磨粒径向分布对电感式磨粒传感器测试结果的影响

根据电感平衡原理,设计了用于磨粒在线测量的电感式磨粒传感器.分析了传感器的测试原理和磨粒通过传感器线圈时径向分布对测试结果的影响.通过计算线圈内测试面的磁场分布,提出了提高线圈测试面磁场均匀性的设计准则.建立了磨粒位置偏离线圈中心时,磨粒磁化场的磁通求解模型.模型计算结果表明,磨粒径向位置的改变,使得线圈各横截面上磁化场的磁通发生了变化.当线圈达到一定长度后,磁化场的磁链变化很小.因此在保证传感器线圈测试面磁场均匀性和线圈长度的前提下,磨粒径向分布对测试结果的影响可忽略.研究结论为分析电感式磨粒传感器测试结果一致性和优化传感器的结构设计提供了理论依据.     

磁耦合共振双发单收系统特性仿真分析

针对电动汽车行驶过程中出现的多个能量发射端向一个能量接收端非接触供能的情形,基于磁耦合共振无线电能传输原理,建立“双发单收”式磁耦合共振理论模型,求解得到“双发单收”系统负载总功率数学表达式.选取3个典型位置,利用ANSYS仿真软件得到发射、接收线圈的磁感应强度云图和电流波形图,分析比较3个位置的电流传输特性与磁场特性.逐渐改变接收线圈与发射线圈的横向相对位置,模拟得到一个能量接收系统在两个能量发射系统之间运动时的充电过程,发现接收线圈运动时系统具有较为稳定的充电电流与充电功率,验证了“双发单收”系统的正确性.     

A pair of parallel differential magnetic‐field probes with high measurement accuracy and high electric‐field suppression ratio

Magnetic‐field probes can be used for electromagnetic interference measurement of high‐speed circuits. The main magnetic probe performance includes sensitivity, spatial resolution, electric‐field suppression ratio (EFSR), and measurement accuracy. In this article, a pair of differential magnetic‐field probes is proposed to improve measurement accuracy without reducing sensitivity. The proposed differential probes consist of two asymmetric loop probes, which are designed in the same plane and separated by a row of periodic vias. The proposed differential probes are fabricated under PCB process. High accuracy can be achieved by measuring difference between outputs of the two probes. In addition, EFSR can be improved by size optimization of the differential magnetic‐field probes. Simulation and measurement results show the operating bandwidth is from 100 MHz to 12 GHz, the measurement error is 3.4% and the EFSR is about 40 dB. The proposed probes have higher measurement accuracy and higher EFSR than the conventional single probe, and larger operation bandwidth than the stacked differential probes.     

基于离子电流的高温压力传感器机理研究

研究基于离子电流的高温环境压力传感器,旨在替代带冷却设备的高温压力传感器,为脉冲爆震发动机(PDE)上必需的高温压力测量提供具有工程实践意义的技术支持,为爆震发动机性能分析、控制规律和控制策略研究提供可靠的测试信号。通过2种类型离子探针的对比分析和探针长度、偏置压力的研究,设计了一种单针短探针型离子传感器,其离子电流信号波形与压力传感器信号相似,离子电流衰减速度可测,耐高温,可靠性高,成本低。为研究离子电流与压力的定量关系奠定了基础。     

Very‐sensitive direct measurement of plasma‐display exoemission

Abstract— The exoemission of electrons from the MgO cathode surface has a great impact on many properties of plasma displays and needs to be carefully engineered for successful display products. A method for direct measurement of this exoemission current using an ultra‐high‐impedance amplifier, which detects the integrated exoemission charge collected by a capacitance, is presented. The large discharge and displacement currents initiated by the changing sustain waveform, which could overload and saturate the sensitive amplifier, are shorted by a very low impedance switch in the form of a common reed relay. The exoemission current from the MgO cathode is significantly amplified by avalanches in the gas, and thus methods for directly measuring the avalanche amplification factor so as to correct the measured current and obtain the true exoemission current from the cathode are described. This highly variable avalanche amplification factor is measured and estimated to be as large as 500 when the voltage across the gas is just below breakdown. Methods are covered to correct for the small ion currents that flow in the plasma‐panel soda glass substrates and that add an unwanted error signal. Practical circuit techniques for measuring the very small exoemission currents are presented.     

A miniature shielded-loop active H-field probe design with high spatial resolution for near-field measurement

A miniature practical active magnetic field (H-field) probe with 0.5 mm × 0.15 mm loop size is designed for electromagnetic interference analysis in electronic systems from 150 kHz to 12 GHz. This probe is fabricated in a four-layer printed circuit board using high-performance and low-loss Rogers material (RO4350B). A low noise amplifier with 14 dB-gain is applied to amplify the radio frequency detect signal. The spatial resolution of the proposed probe is verified under the microstrip with different widths (1.55 and 0.24 mm). In addition, the verification results indicate that the proposed small loop active shielded H-field probe can obtain the better spatial resolution of 422 μm with liftoff = 100 μm. Regarding to the sensitivity of the probe, the proposed probe realizes 16.7 dB μA at 3 GHz with the liftoff = 100 μm. compared with other commercial probes and a reference probe, the proposed probe has better spatial resolution at 150 kHz–12 GHz and sensitivity at 1.5–12 GHz.     

EAST等离子体击穿计算

关于等离子体放电优化控制问题,由于在托卡马克等离子体放电中,等离子体击穿的条件是获得合适的环电压以及尽可能大的零场区。较好的零场只有通过调节极向场线圈电流才能实现,同时EAST极向场系统采用了一体化的设计,但还没有专门的补偿线圈来控制放电初期有较好的零场,根据要求计算零场区结果应与实际实验结果相符。为解决上述问题,提出调节极向场线圈电流以获得较好的零场区,使等离子体顺利击穿。根据提出的磁通环、磁探针等测量信号,计算出了等离子体击穿的零场区、击穿前后的涡流变化及分布,并利用高速CCD记录等离子体放电的击穿过程来验证结果的准确性,取得了与实验一致的结果,为EAST正常放电提供了很好的参考价值。     

Permalloy-coated tungsten probe for magnetic manipulation of micro droplets

In this work, we present the magnetic manipulation of biocompatible droplets using a probe-based approach. First, we describe a simple method to develop magnetic probes that are capable of delivering localized magnetic fields, which is important for precise manipulation. The fabrication of magnetic probes involves controlled electroplating of permalloy (Ni₈₀Fe₂₀) on commercially available tungsten needles with tip radii as small as 0.5 μm. Experimental validation of probe functionality was achieved by characterizing the magnetic response of the probe with a highly sensitive scanning Hall probe system. The magnetic probe was then employed in manipulating biocompatible alginate micro droplets with encapsulated magnetic particles. The synthesis of the droplets was carried out in-house and droplets of different sizes and magnetic particle concentrations were obtained for use in manipulation experiments. Multiple experiments were done to demonstrate the efficacy of the developed probe in manipulating droplets, which is crucial for constructing droplet-based microfluidic systems.     

脉冲涡流TR探头解析模型的快速求解方法

作为分析脉冲涡流响应的常用工具,解析模型因具有物理意义明确、精度高、计算速度快等优点而得到了广泛关注;近年来,随着脉冲涡流阵列探头的应用,对其阵列单元--即激励和接收线圈非同轴的Transmitter-Receiver阵列单元(以下简称TR探头)的解析分析需求迫切;而当前关于TR探头的解析模型大多数将试件缺陷等效为大面积壁厚减薄缺陷,模型精度较低;为提高TR传感器解析模型的求解精度,将构件缺陷等效为平底盲孔缺陷,建立了含平底盲孔构件脉冲涡流TR探头的解析模型,且提出了一种快速求解该模型解析解的方法:首先,通过分析典型模型解析解的形式,发现其由广义反射系数、线圈系数等乘积组成,且广义反射系数仅与构件结构有关,线圈系数仅与探头有关;然后,参考已有的含平底盲孔构件同轴式探头检测模型和均匀壁厚减薄缺陷的TR探头模型,分别获取广义反射系数和线圈系数解析表达式;最后,将其组合得到含平底盲孔构件脉冲涡流TR探头的解析解;通过和实验数据做比较验证了上述解析解的正确性;所提出的方法可应用到其他脉冲涡流解析模型的快速求解中,降低解析模型的求解难度。     

Asymmetric Dielectric Trilayer Cantilever Probe for Calorimetric High-Frequency Field Imaging

Multimaterial, microelectromechanical systems-based cantilever probes were developed for high-frequency magnetic field imaging. The basic configuration of the probe consists of a cantilever beam fabricated using surface micromachining and bulk micromachining techniques with dielectric silicon nitride and silicon oxide materials on a silicon wafer. A gold patterned metallization at the tip of the cantilever provides a source of eddy current heating due to the perpendicular component of the high-frequency magnetic field. This thermally absorbed power is converted to mechanical deflection by a multimaterial trilayer cantilever system. The deflection is measured with a beam-bounce optical technique employed in atomic force microscopy systems. We discuss the modeling, design, fabrication, and characterization of these field imaging probes     

Optimization of resistive loading of EMI/EMC near field probe

Near field studies must be carried out to insulate printed circuit boards and other circuits entirely from outer space. It can be achieved by utilizing the screen properly. These studies must always be made in the near field. The best way known to sense Radio Frequency energy is using a proper loop antenna. The loop probe can be used both as a transmitter and a receiver. If it is loaded resistively, desired flat response between low and high cut off frequency can be obtained. To get accurate results, its physical and electrical parameters must be chosen properly. The most important electrical parameter is inductance of such a loop conductor. Common inductance equations are in general form and they are derived for general calculations. However, loop probes have narrow physical range; they have diameters of a few-centimeters, a few-turn, and have a very thin conductor. So, a certain equation can be derived more accurately. It can be achieved by using conventional empirical derivations or by using modern optimization techniques.