基于AD590四路巡检数字温度计的设计

本文介绍了一种可对四路温度进行数字显示的温度巡检仪,其包含:温度信号检测及转换部分、四路巡检部分、A/D转换及数字显示三大部分。该系统的工作原理为:AD590传感器将温度信号转化成电流信号,经放大电路变换成与温度成线性关系的电压信号,再由数字控制电路送到A/D转换器,最后通过数字显示器显示出测量的温度.其测量范围为-55℃~150℃,具有实用性强、可靠性高、测量精度高等特点。     

便携式原子力显微镜扫描驱动器的设计与实现

设计了一种便携式原子力显微镜压电陶瓷管驱动器,该驱动器使用5～12V宽幅直流电源,产生+215V和±15V的电源供给高压放大模块和信号调理模块,可将输入的-10V～+10V控制信号,放大为-200V～+200V的电压驱动压电陶瓷扫描管,功耗仅为2W左右,体积为150mm×60mm,可以使用电池供电并连续工作7～8h。该驱动器是便携式原子力显微镜的一个重要模块,该模块功能的实现使原子力显微镜在工业现场和野外环境进行测量成为可能。     

基于Proteus的脉冲发生器设计与仿真

针对脉冲涡流检测的需要,设计了可调频的脉冲信号发生器.以简单、可调的比较电压发生电路为控制源,先将比较电压经μA741放大后送入ADC0832进行A/D转换,再将所得的数字信号送人单片机AT89S51,在单片机软件控制下输出一定频率的脉冲信号.硬件设计省去了传统的调频电路,简化了结构;软件设计采用中断控制A/D转换,避免了数据的重复采集.Proteus仿真结果表明,系统设计正确,运行可靠.     

金属表面裂纹涡流检测系统

针对现实生活中由于金属裂纹引发的众多灾难性事故,研究设计了一种结构简单、灵敏度高而且便于携带的金属表面裂纹涡流检测装置.该装置应用涡流探伤的基本原理,采用磁性材料,制作了一种精细的涡流传感器,用于前端提取微弱的裂纹信号;后台应用单片机控制电路,处理提取的滤波、放大、A/D转换等信号,最后由单片机驱动声、光报警,显示裂纹缺陷的相对大小,实现了防患于未然的目的.     

一种高帧频EMCCD驱动电路设计

为满足自适应光学系统波前传感器需要高帧频、高灵敏度的要求,针对E2V公司的高帧频、低照度EMCCD 芯片CCD60设计了外围驱动电路.系统采用FPGA作为主要的逻辑控制和时序信号发生器件,采用EL7156管脚驱动器将TTL电平转换为CCD60需要的驱动电平,并用DDS(直接数字合成器)产生正弦波通过高压放大模块来产生高...     

一种数字式钳形电表校验仪

本试验仪是利用A/D转换技术,将交流电流、电压信号精确的转换为直流电流、电压信号。该仪器具有显示直观、使用方便、价格便宜等特点。     

数字显示调节仪常见故障检修四则

数字显示调节仪是目前常用精密温度测量仪表 ,具有测量直观、准确度高、使用方便等特点 ,它主要由电源部分、信号预处理及前置放大电路、线形化电路、A/D转换及LED显示电路、时间比例调节电路组成。下面以XMT系列数字温度显示调节仪为例介绍常见几种故障。1 仪表接通电源后 ,L     

一种新型的分布式数据采集器(二)

4 系统结构和工作原理 900系列分布式数据采集系统由900系列数据采集模块、电源、通讯电缆、主机构成.可以在1.2 km的范围内,根据现场使用需要随意组成最少1个模块、20个测量点;最多不超过99个模块、1980个测量点(取决于模块)的测量系统.前端传感器输入信号可以是模拟信号(如温度、压力、电压、电流、应变等);也可以是数字信号(如开关状态监测、事件捕获、测频计数等).测量结果经模块内部A/D转换后,用RS485通讯方式,经屏蔽双绞线送至主计算机进行采集,并以固定的数据格式输出,用户可根据需要,采用相应的软件对采集到的信号进行处理.典型测量系统组成如图1所示.     

直流纹波测量标准模块

探讨直流稳定电源的输出纹波测量方法,设计了放大模块,对待测纹波信号进行预处理,利用有效值转换技术,将直流纹波的测量转换为直流电压的测量,从而形成直流纹波测量标准模块.采用标准信号源和纹波测量标准表分别对标准模块进行性能测量,结果表明直流纹波测量标准模块符合技术指标要求,并已应用于动力电池综合测试系统校准装置中.     

一种隧道式硅微加速度计隧道电流处理电路的设计

本文研究了一种隧道式硅微加速度计隧道电流处理电路.与多数处理电路不同的是,本文以精密仪表运放为核心,设计了一种低温漂,高放大倍数的纳安级电流放大和反馈电路,该电路包括A/V转换、差分放大、信号滤波、电压跟随、电压反馈五部分组成,电路采用了尽量少的分立元件.分析了隧道电流与反馈控制电压及隧道电极问距离的关系.实验证明,该电路不但能榆测并放大纳安级的电流,而且能为隧道式硅微加速度计提供适当的反馈电压,其温漂系数小,体积小,可用作隧道式硅微加速度计隧道电流的处理电路.     

基于FPGA的数字化中频磁控溅射电源设计

介绍了一种全数字控制的中频磁控溅射电源设计.主电路前级采用直流斩波调压,后级采用全桥逆变的电路结构.控制电路由现场可编程门阵列(FPGA)计算产生高分辨率的数字脉宽调制信号(DPWM)实现.电源工作于恒流模式,通过PID算法调节Buck斩波电路的驱动DPWM来实现闭环控制.全桥逆变电路的驱动信号由FPGA计算产生,通过按键可设置驱动的DPWM,输出所需的固定频率和占空比的矩形波.对于靶面微打弧和强打弧,FPGA采取不同的保护措施.最后制作了5kW的样机进行验证,实验证明,方法可行,具有好的应用前景.     

以溶胶-凝胶法PZT薄膜为驱动的微泵研制

采用溶胶-凝胶法(sol-gel)制备技术制作了Pb(Zr,Ti)O3(PZT)压电薄膜,并以PZT薄膜为驱动制作了微泵.采用了V型微阀的微泵主要利用PZT的压电效应.针对微泵的关键结构--复合驱动膜,探索了一种Si/SiO2/Ti/Au/PZT/Cr/Au多层驱动膜结构制备方法,解决了在硅基底上制备PZT薄膜的问题,同时探讨并解决了硅各向异性刻蚀微泵的微驱动腔、单向阀的工艺问题,并通过SEM照片对V型阀和多层驱动膜进行了表征.研究结果表明,采用MEMS技术成功地完成了微驱动器的研制,得到的驱动腔硅杯平坦均匀.在V型阀微泵整体设计中需要的硅片数目少,降低了器件的复杂性,可以满足功耗低、小型化和批量生产的要求.     

A novel multi-degree-of-freedom thick-film ultrasonic motor

This paper describes a new multi-degree-of-freedom (MDOF) ultrasonic motor that comprises few parts and is based on low-cost thick-film technology. Conventional ultrasonic motors using bulk lead zirconate titanate (PZT) or thin-film PZT layers are relatively expensive at the present time. Thick-film printed PZT technology provides the opportunity to reduce the costs of ultrasonic motors. To demonstrate the feasibility of this approach, an ultrasonic motor was fabricated from alumina using thick-film printed PZT actuators. The thick-film PZT and electrode layers were printed on a thin alumina plate, and a tiny cylinder was mounted at its center. This cylinder magnifies the lateral displacement of the stator, holds the spherical rotor, and transmits the driving force to the sphere. Three bending vibrations, B₂₂, B₃₀, B₀₃, of the plate were applied to rotate the sphere. Sufficient displacements for rotating the sphere were obtained near the resonance of B₂₂ by applying an excitation voltage of 200 V peak-to-peak via a three-phase drive circuit. Rotations in three orthogonal directions have been observed by controlling the phase of the driving signal to the PZT electrodes, and a MDOF ultrasonic motor was successfully realized     

基于希尔伯特变换的信号解调算法及其在飞机供电特性参数测试系统中的应用

电压调制幅度、频率调制幅度和畸变频谱是对飞机机载电源系统供电特性参数进行测试时与信号调制相关的重要参数。为了更好地测试这些参数,提出了一种基于希尔伯特变换原理的数字解调算法,可以将采集的幅度或频率调制信号进行解调分析;同时,构建了一套飞机供电特性参数测试系统,将解调程序与硬件设备结合,通过程序控制数据采集卡对机载电源信号采样与解调分析;设计了实验对波形发生器产生的调制信号进行采样与解调,验证了该系统具有良好的效果,可以应用于飞机供电特性参数的测试中。     

Estimation of Electric Charge Output for Piezoelectric Energy Harvesting

Abstract: Piezoelectric materials (PZT) can be used as mechanisms to transfer mechanical energy, usually ambient vibration, into electrical energy that can be stored and used to power other devices. With the recent advances in wireless and micro‐electro‐mechanical‐systems (MEMS) technology, sensors can be placed in exotic and remote locations. As these devices are wireless it becomes necessary that they have their own power supply. The power supply in most cases is the conventional battery; however, problems can occur when using batteries because of their finite life span. Because most sensors are being developed so that they can be placed in remote locations such as structural sensors on a bridge or global positioning service (GPS) tracking devices on animals in the wild, obtaining the sensor simply to replace the battery can become a very expensive task. Furthermore, in the case of sensors located on civil structures, it is often advantageous to embed them, making access impossible. Therefore, if a method of obtaining the untapped energy surrounding these sensors was implemented, significant life could be added to the power supply. One method is to use PZT materials to obtain ambient energy surrounding the test specimen. This captured energy could then be used to prolong the power supply or in the ideal case provide endless energy for the sensors lifespan. The goal of this study is to develop a model of the PZT power harvesting device. This model would simplify the design procedure necessary for determining the appropriate size and vibration levels necessary for sufficient energy to be produced and supplied to the electronic devices. An experimental verification of the model is also performed to ensure its accuracy.     

基于CCD探测器的全视场层析成像方法研究

由正弦信号驱动PZT调制参考镜以实现参考光相位调制,CCD光探测器的曝光时间为正弦驱动信号的四分之一周期,利用频率-同步探测技术,在一个参考光调制周期共提取四帧全视场参考光与样品反射和散射光干涉图像.为了获得最优的参考光信号调制参数,一种基于PID控制器的闭环控制技术与数字移相相结合的方法用于调制系统,采用50Hz的理想正弦曲线的数字离散量来控制PZT的调制幅度,数字移相电路调整PZT的振动相位来保证最优调制参数的获得.CCD(频率f=200Hz)由软件驱动,采用积分算法,实现了由CCD探测器提取微弱全视场层析信号的方法.     

Integrated power management circuit for piezoelectronic generator in wireless monitoring system of orthopaedic implants

Piezoelectric (PZT) materials are capable of converting the mechanical energy of compression into electrical energy. With the recent advent of extremely low-power electrical devices, PZT generators have become attractive in many kinds of applications, especially for biomedical applications. Piezoelectronic generators are used in a wireless monitoring system of orthopaedic implants. Due to their poor source characteristics, the efficiency of PZT generator is low. A hybrid direct current (DC)?DC, comprising a switched capacitor (SC) DC?DC converter and a low dropout (LDO) linear voltage regulator, is presented to improve conversion efficiency. A bandgap reference (BGR) circuit which works in sub-threshold region is also presented. Because SC DC?DC converter works in the highest voltage region in this system, small power supply current, including supply current through BGR and other auxiliary modules, means low power consumption. BGR?s power supply voltage can be varied from 3 to 16 V. Its supply current is only 3.2 μA at 125 C and its temperature coefficient is 46 ppm. Stacked switches technique is proposed to reduce leakage current in switching process of SC converter. Simulation results show that the efficiency of SC?s converter can reach 88%, that of LDO can reach 80% and that of the overall system can reach 66%, including power consumption of all auxiliary components, which is far higher than previous work.     

溶胶-凝胶法制作PZT微驱动器的研究

采用溶胶-凝胶法(Sol-gel)制备了PZT压电薄膜,利用PZT的压电效应制作以PZT薄膜为驱动的V型阀微驱动器.针对微驱动器的关键结构驱动膜,探索了Si/SiO2/Ti/Au/PZT/Cr/Au多层驱动膜结构制备方法,解决了在硅基底上制备PZT薄膜的问题,同时详细探讨了硅各向异性刻蚀微驱动器的关键部件驱动腔、单向阀的工艺,解决了集成制作的V型阀微驱动器的关键工艺问题,并通过SEM照片对V型阀和多层驱动膜进行了表征.研究结果表明,采用MEMS与IC技术结合的方法成功地完成了微驱动器的研制,得到的驱动腔硅杯平坦均匀.在V型阀微驱动器整体设计中需要的硅片数目少,降低了器件的复杂性,可以满足低功耗、小型化和批量生产的要求.     

基于双电荷放大器的数字式两线制HART涡街流量变送器

针对耐高温涡街流量传感器灵敏度低及引入HART通信增加数字式两线制仪表的功耗且通信稳定性容易受电源影响的问题,研制了基于双电荷放大器的数字式两线制HART涡街流量变送器。采用两级电荷放大器和两级低通滤波器的信号调理电路,对耐高温涡街流量传感器输出的幅值较小的信号进行放大和滤波,获得稳定的流量信号;采用两路隔离电源的电源设计方案,提高电源的负载能力,并保证通信的稳定性,在进行数字信号处理的同时,实现两线制HART通信。实验结果表明,该变送器测量精度较高、量程下限较低,且满足低功耗要求。     

磁通门CMoS接口电路设计

为实现三端式磁通门接口电路的集成．提出一种新颖的包括驱动和检测功能的磁通门CMOS接口电路．驱动电路采用开关网络和负反馈环实现全差分驱动来替代传统的隔离变压器驱动．通过实时平衡驱动电极上的电压信号来抑制电源电压的漂移以及温度变化的影响．检测电路利用驱动信号二倍频为基准的开关相敏解调实现二次谐波提取,同时采用闭环检测．以提高系统线性度．该电路基于0．5IxmCMOS工艺实现．测试结果表明,该微型磁通门磁力计（三端式探头和CMOS接口电路）的灵敏度为30．8μV／nT,非线性度为0．62％,电源电压为10V,功耗为100mW,芯片面积仅为15．54mm2．