高Q值超低功耗谐振式磁传感器的设计与实现

针对现有谐振式磁传感器原理不能同时实现高品质因数(Q)和低功耗的缺点,利用双端固定石英音叉谐振器与铁镓磁致伸缩合金片复合,设计了一种隔离磁机阻尼的高Q值、数字频率输出的超低功耗谐振式磁传感器。利用音叉谐振器结构的解耦特性,设计应力耦合传递结构,隔离了磁致伸缩材料磁机阻尼,从而保证复合传感器Q值与音叉谐振器Q值相当。在磁场作用下,磁致伸缩力传递到音叉谐振器,由于音叉力敏感特性,实现磁-力-频率转换。制备了铁镓合金/石英音叉谐振器复合敏感结构,测试表明,在低气压封装条件下的品质因数约为16 764,门振荡电路功耗约为124.8μW,在线性区灵敏度为3.05 Hz/Oe,分辨率为6 mOe。     

脉冲方波激励下的无线电能传输仿真与实验

磁谐振式无线电能传输技术是基于谐振耦合现象利用近区磁场进行非辐射性、中距离输电的新技术。自MIT发表基于磁谐振的无线电能传输实验论文以来,各国学者相继进行了大量研究。许多结果都基于正弦交变电流作激励,以此分析计算线圈的耦合特性,计算耦合电压和功率。脉冲电流也可以产生交变磁场,脉冲激励下的无线电能传输有其自身的特性。本文分析了脉冲激励下的电路响应过程及谐振耦合机理,其耦合过程也是一种正弦波耦合,由场路耦合仿真分析和实验验证可知,与正弦激励相比,用脉冲方波作激励负载可获得较大的传输电压,此方式也可实现有效的无线电能传输。     

电动汽车无线充电新型DD耦合机构设计与优化

基于磁耦合谐振式无线能量传输技术,文中设计一种新型DD线圈结构用于电磁耦合谐振式无线充电系统。通过分析无线充电耦合机构数学模型,确定传输效率与频率、互感、等效负载以及原副边绕组的电阻之间的关系。通过搭建不同的磁耦合线圈结构的ANSYS仿真模型,比较磁耦合线圈结构的改变对线圈参数的影响,确立优化方向。最后搭建系统实验平台对磁耦合机构的优化方案进行验证。在线圈偏移量和输入功率变化的情况下,磁耦合机构效率能够保持在95%左右,实验结果与仿真分析结果一致。     

基于UCC3895的谐振式无线电能传输系统分析与设计

通过对谐振式无线电能传输系统原理结构的分析,针对无线电能传输系统中磁耦合结构固有的松耦合特性,导致磁耦合结构耦合系数小、漏感大、消耗大量的无功功率,提出了一种在传统谐振网络中加入阻抗匹配网络的更适合于实际工程应用的改进型谐振网络,并给出谐振网络参数的设计要点.最后搭建了基于UCC3895控制芯片的移相全桥无线电能传输系统的试验平台,对系统的提离特性、偏移特性以及负载特性等进行了测量与分析.结果表明,在一定的距离范围内该系统具有良好的电能传输效果.     

电磁继电器静态吸反力特性测试方法的探讨

电磁继电器静态吸反力特性的配合技术是保证电磁继电器可靠性动作的关键技术。针对以往电磁继电器静态吸反力特性测试方法中存在的问题，提出一种基于悬臂梁式力传感器和直线光栅位移传感器的电磁继电器静态吸反力特性测试方法。以某型号平衡力式磁保持磁电器为分析实例，给出了力传感器和直线光栅位移传感器的选择方法。     

一种新型光学电流传感器结构设计与仿真研究

本文设计对称光程反射式光学电流传感器实验系统,使用COMSOL多模场耦合仿真软件对所设计的光学传感系统的传输场进行模拟仿真,得到对称光程反射式光学电流传感器对法拉第磁光效应的响应度,其理论灵敏度高于传统结构的灵敏度580倍。未来将基于所建立的实验系统对传感器的潜在应用做进一步的深入研究。     

GMM-FBG光纤电流传感器结构优化及温补模型

为解决FBG中心波长和GMM磁致伸缩系数温度敏感而影响GMM-FBG光纤电流传感器交流响应灵敏度和准确度的问题,提出在GMM-FBG传感模型中引入温度参数校准电流输出值的方法。依据法拉第电磁理论,采用有限元分析方法设计提高GMM磁耦率和均化磁场分布的磁路结构。构建波长解调系统实验平台,测试温度在20～70℃范围传感器不同电流对应的波长响应幅值,实验研究表明:GMM-FBG电流传感器灵敏度随温度升高而下降,且与被测电流值大小正相关。在分析传感器温度响应特性基础上,利用数学拟合方法建立了具有温度补偿系数的GMM-FBG电流传感数学模型,且将该模型用于40℃时60 A电流检测实验,电流检测准确度提高了4. 8%。     

电磁机械同步共振无接触传能与转换方法研究

基于电磁耦合谐振式无线电能传输技术,为电能-机械能的无线传输、转换和控制提供途径,从而为不易拖带电线的微型机器人等用电机构的供能提供便利.建立漏感等效电路并分析了系统整体性能,然后针对超磁致伸缩材料特性建立了电、磁、机械(力)场路耦合模型,并得出系统整体传递函数.实验制作了电磁-机械同步共振系统样机,其测量结果表明由示波器监测的励磁电压频率与通过上位机采集的磁致伸缩棒振动频率一致,同时实现了在间距为30 cm频率为10.07 kHz时电能-机械能的同步转换.     

磁耦合谐振式无线电能传输系统传输损耗的研究

相比于传统的有线充电,无线充电是一种更加方便和可靠的充电方式,在电动汽车、生物医学等领域具有较为广泛的应用前景。然而传输效率的低下却限制了无线电能传输技术的进一步推广。磁耦合谐振式做为一种最主要的无线电能传输技术,其主要由高频电源,补偿结构,磁耦合结构以及整流滤波四部分构成。目前磁耦合谐振式无线电能传输系统的传输效率分析时大多仅考虑磁耦合结构的损耗,对系统中高频电源以及整流滤波的损耗考虑欠少。文章在预定效率以及恒功率条件下计算磁耦合谐振式无线电能传输系统中各部分损耗与互感之间的关系,寻求满足系统要求的互感值。最后设计了一套传输功率为1000W,传输效率为85%的磁耦合谐振式无线电能传输系统,实验结果表明文中的损耗计算方法具有较高的准确性。本文研究结果为无线充电系统分析及性能改善起到积极推动作用。     

基于谐振式推挽结构的三端口MMC-SST波动功率耦合方案研究

文中提出一种控制简单的基于模块化多电平变换器的固态变压器(modular multilevel converter based solid state transformer,MMC-SST)拓扑方案,利用谐振式推挽(resonant push-pull converter,RPPC)结构的高频链将 MMC 子模块(sub-module,SM)互联,形成一条低压直流母线。RPPC 采用定频定占空比的开环控制使其工作在谐振频率,利用高频链的低阻抗特性实现三相对称的低频波动功率自然耦合,从而大幅降低 SM 电容的尺寸,明显提升了系统的功率密度,同时实现了桥臂2倍频循环电流的自然消除以及SM电压的自动均衡。文中首先对 MMC-SST 的波动特性进行介绍,进一步对高频链实现波动功率耦合的过程进行建模分析。最后,仿真与实验验证所提拓扑的优良性能。     

Cantilever beam temperature sensors for biological applications

This review presents two types of cantilever beams employed as highly sensitive temperature sensors. One type is fabricated from composite materials and is operated in the deflection mode. The second type, used as a temperature sensor and presented in this review, is a resonant cantilever beam. The materials used for the fabrication of the bimaterial cantilever beam are silicon or silicon nitride and thin metallic films such as gold or aluminum. When the temperature changes, the different coefficients of thermal expansion of the metal and silicon cause the sensor to deflect. Considering the models of temperature measurement for biological cells, the heat should be applied locally at the tip of the cantilever beam. Formulas for the calculation of the deflection as a function of incident power applied at the free end of the cantilever beam operated in a liquid are presented in this review. The natural convective heat transfer coefficient was estimated by using the mathematical model and experimental values. For biological applications, the cantilever beam temperature sensor was operated in a liquid, and the heat transfer coefficients were between 381 and 642 W/m²K when the temperature applied to the cantilever's free end varied from 28 to 71.8 °C. The resonant cantilever beam was also demonstrated as a sensitive temperature sensor for biological applications. As a thermogenic sample, brown fat cells (BFCs ), which are related to metabolic heat production, are employed. The working principle of the resonator cantilever beam temperature sensor is based on the shift in resonant frequency in response to temperature changes. The resonant frequency and the temperature coefficient were 960 kHz and 22.0 ppm/K, respectively. The measurements were performed by stimulating the activity of BFCs by flowing a norepinephrine (NE ) solution (1 µM ).     

A Novel Wireless Passive Temperature-Pressure SAW-based Sensor

A novel wireless and passive surface acoustic wave (SAW) sensor is developed for measuring temperature and pressure. The sensor has two single-port resonators on a substrate. One resonator, acting as the temperature sensor, is located at the fixed end without pressure deformation, and the other one, acting as the pressure sensor, is located at the free end to detect pressure changes due to substrate deformation. Pressure at the free end bends the cantilever, causing a relative change in the acoustic propagation characteristics of the SAW traveling along the surface of the substrate and a relative change in the resonant frequency of the resulting signal. The temperature acts on the entire substrate, affecting the propagation speed of the SAW on the substrate and directly affecting the resonant frequency characteristic parameters. The temperature and pressure performance of this new antenna-connected sensor is tested by using a network analyzer, a constant temperature heating station, and a force gauge. A temperature sensitivity of 1.5015 kHz/°C and a pressure sensitivity of 10.6 kHz/gf at the ambient temperature have been observed by wireless measurements. This work should result in practical engineering applications for high-temperature devices.     

Measurement of tongue–artificial nipple contact pressure during infant sucking

To clarify the motor function of the infant tongue during sucking, we developed an artificial nipple that contained multiple small built‐in force sensors integrated with a PC‐based system which is capable of measuring tongue–artificial nipple contact pressures in real time. The force sensor is a cantilever structure with a small, thin stainless steel beam where an all‐purpose foil strain gauge is attached to the surface of the beam. An artificial nipple made of an elastomer containing these sensors is connected through an amplifier and an A/D converter to a PC via a USB port. Using this system, measurements were taken in three infants whose oral feeding was well established and in one infant of low birth weight. The results from each force sensor showed a pressure waveform of a nearly simple harmonic motion that indicated a peristalsis‐like movement of the tongue; the sucking frequency was found to be about two times per second. In addition, in the low‐birth‐weight infant, the pressure changed as the infant grew. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

磁耦合谐振式无线能量传输技术效率分析

详细阐述了磁耦合谐振式无线能量传输技术的原理,建立了系统等效模型并分析得到系统传输效率公式,从而得出影响系统传输效率的因素,具体包括负载阻抗、系统频率、线圈线径、线圈半径、线圈匝数、线圈位置和传输距离。针对理论分析得到的各个影响因素,逐一仿真验证了它们对效率的影响效果,为提高磁场谐振耦合式无线能量传输系统的效率提供了理论依据。     

Nanophotonics Sensor Based on Microcantilever for Chemical Analysis

A Si-based cantilever sensor with photonic crystal (PC) resonator as readout for chemical sensing and analysis has been developed. The resonant wavelength shift of PC resonator is resulted from PC deformation induced by cantilever bending, in which this optical readout scheme facilitates cantilever deflection measurements in liquid. Through numerical simulation, we demonstrate that the detection capability of this micromechanical sensor operated in water is better than that of sensor operated in air. The minimum detectable Z-displacement and strain of Si/SiO₂ cantilever sensor are derived as 0.6 mum and 0.0098% in water and 0.812 mum and 0.0144% in air, respectively. This novel micromechanical sensor shows its promising future in applications such as detection of proteins and DNA in solution.     

硅微机械谐振式压力传感器闭环方法

提高硅微机械谐振式压力传感器的性能指标有很多方法,如何对已知敏感结构的输出量程范围内所有谐振频率点进行实时闭环跟踪是其中之一。对几种比较常用硅微机械谐振式压力传感器的激励-拾振方式进行介绍,对所调研的国内外文献给出的谐振式微结构传感器闭环控制方法进行比较分析,提出一种新的针对电热激励-压阻拾振方式的复合敏感结构进行闭环控制的方法,同时给出了提高该类型传感器性能的有效手段和研究方向。     

DEVELOPMENT OF SELF-SENSITIVE PIEZOELECTRIC CANTILEVER UTILIZING PZT THIN FILM DEPOSITED ON SOI WAFER

ABSTRACT

Piezoelectric micro cantilevers were applied to a resonant type mass sensor, biosensor, vapor sensor and probe for scanning force microscopes. These devices utilize impedance, phase, and charge as output signals. However, the measurement system could be greatly simplified if an output voltage were utilized. Therefore, a self-sensitive piezoelectric cantilever with separated electrode for actuation and sensing was developed. The self-sensitive piezoelectric cantilever was fabricated from a multilayer of Pt/Ti/PZT/Pt/Ti/SiO₂/SOI through MEMS bulk micromachining. The cantilever was oscillated by a sweep sine wave and the output voltage was measured as a function of the input frequency. The resonant frequency determined from the output voltage spectrum agrees well with that measured by a laser Doppler vibrometer.     

200W级磁耦合谐振式无线电能传输频率特性的研究

采用磁耦合谐振技术提供了一种新型无线电能传输方式,其安全、可靠、灵活的特点受到广泛关注。为进一步扩展无线电能传输的应用领域,设计较大功率的无线电能传输系统是十分必要的。基于串并结构谐振电路等效模型,通过电路理论推导出补偿电容、电压增益、效率等表达式,应用Matlab软件对系统的谐振频率进行了仿真分析,得出谐振频率偏移对系统性能影响规律。在此基础上设计了一套无线电能传输实验平台,传输距离为1~7 cm,该装置负载端获得功率可达200 W,最高传输效率为80%。     

基于单谐振结构的金属裂纹CRFID传感器设计

为实现单结构谐振器对金属裂纹参数的无损检测,设计了一款同时检测裂纹宽度及方向的无芯片射频识别(CRFID)金属裂纹传感器。将圆形、切角矩形谐振器一体化设计,利用HFSS有限元分析软件对传感器进行结构优化与性能仿真。深层次探究了不同裂纹缺陷下传感器雷达散射截面(RCS)的响应特征。结果表明金属结构的裂纹方向和裂纹宽度可以通过传感器谐振频率的变化进行识别。双极化下RCS幅频特性的频偏方向对应裂纹的方向,而频偏量与裂纹宽度成正比。设计的CRFID传感器能够检测0°水平方向、90°竖直方向、45°或135°斜向等三类方向下的亚毫米宽度裂纹,其中裂纹宽度检测灵敏度最高可达43.5 MHz/0.1 mm。     

Energy harvesting MEMS device based on thin film piezoelectric cantilevers

A thin film lead zirconate titanate Pb(Zr,Ti)O₃ (PZT), energy harvesting MEMS device is developed to enable self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. It is designed to resonate at specific frequencies of an external vibrational energy source, thereby creating electrical energy via the piezoelectric effect. Our cantilever device has a PZT/SiN_x bimorph structure with a proof mass added to the end. The Pt/Ti top electrode is patterned into an interdigitated shape on top of the sol-gel-spin coated PZT thin film in order to employ the d ₃₃ mode. The base-shaking experiment at the first resonant frequency of the cantilever (170 × 260 μm) generates 1 μW of continuous electrical power to a 5.2 MΩ resistive load at 2.4 V DC. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A spiral cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously.