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.

Parameter Design of Current Double Closed Loop for T-Type Three-Level Grid-Connected Inverter

To reduce current harmonics caused by switching frequency,T-type grid-connected inverter topology with LCL filter is adopted.In view of the disadvantages of the slow response speed of the traditional current control and the failure to eliminate the influence of the LCL filter on the grid-connected current by using current PI control alone,a current double closed loop PI current tracking control is proposed.Through the theoretical analysis of the grid-connected inverter control principle,the grid-connected inverter control model is designed,and the transfer functionmodel of each control link is deduced,and the current loop PI regulator is designed at last.The simulation results show that the control strategy is feasible.

连续热电偶检定炉的设计与研制

连续热电偶是基于塞贝克效应制成的一种新型温度传感器。在校准连续热电偶时,热电偶检定炉是较为重要的热源之一。该研究在传统检定炉的基础之上设计四温区检定炉,通过对炉体和温度控制的改造,对多种控温模式的设计,研制出能够适用连续热电偶等多种高温传感器校准的热源。

旋转部件温度参数同步无线测量技术研究

针对旋转部件温度参数原位同步测量和数据无线传输应用需求,研究了电能无线传输技术和空间光通信技术,设计了一套8通道小型温度参数遥测系统。该系统通过热电偶和铂电阻传感器实现8路温度参数的高精度准确测量,采用电磁感应和红外光通信技术实现电能和采集数据的同步无线传输。系统分析软件完成数据的实时存储、解析和可视化显示。搭建了20000 r/min的模拟旋转环境测试平台,进行系统功能和性能验证。系统温度采集精度优于0.15%,无线传输距离为15 mm,电能传输输出峰值功率可达5 V/400 mA,实测通信速率为10 Mbit/s,8通道同步采样速率为56 kHz。该系统实现了温度参数的分布式、高精度获取,为旋转部件的研制和维护提供了准确的温度依据。

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。

连续热电偶的计量特性

通过研制四温区测量炉组成热电偶校准装置,对连续热电偶进行校准及不确定度评定,了解和掌握该型传感器的计量特性。最终得出连续热电偶对K型分度表的整体偏移修正为+28℃,扩展不确定度为3.2℃,均匀性为5~8℃,为使用人员和研究人员修正提供技术依据。

火星探测器进入过程防热层温度测量方法

火星探测器进入过程中的防热层烧蚀温度是防热结构设计和气动热环境辨识的关键参数之一。为了满足防热层温度在轨测量的需求,提出采用柱塞式结构大底分层测温探头和U形结构背罩测温探头,与电缆和多通道温度变换器共同组成温度传感器进行在轨测温的方法。设计内容包括测温探头热电偶元件选取、结构形式和安装方式,以及信号集中放大变换和自动冷端补偿等。开展全量程标定和风洞专项试验验证,证明所设计的温度传感器可以实现1300℃以下烧蚀温度变化全过程测量,测量精度达到0.28%。该温度传感器已在我国首次火星探测任务“天问一号”探测器的着陆巡视器上成功应用,可为进/再入航天器烧蚀温度在轨测量的实施提供借鉴和参考。

基于Al_(2)O_(3)陶瓷的Pt/PtRh型厚膜热电偶封装测试

设计了一种基于氧化铝(Al_(2)O_(3))柱体的Pt/PtRh型厚膜热电偶。采用丝网印刷工艺完成传感器功能层的制备,这种方法工艺简单、可操作性强、成本低廉。对所制备的厚膜热电偶进行封装设计并进行测试。实验结果表明:带封装热电偶的迟滞大小为4.10%,小于无封装的7.65%,而且带封装热电偶在高温阶段与标准热电偶极其吻合,其平均塞贝克系数更接近于标准热电偶。实验结果均表明封装设计有利于膜状热电偶测试的准确性,达到了工程化需要。

Research on dynamic error compensation for an armored K type thermocouple

A new method was proposed, in which a high-power CO2 laser modulated by high frequency was used as the driv- ing source to heat up a surface-temperature sensor. The continual beam and the pulsed beam sent out by the same laser could be used in the same system to carry on the static calibration of the radiation thermometer and the dynamic calibration of the temperature sensor to be checked. The frequency-response characteristics of high-speed radiation thermometer surpassed that of the temperature sensor, therefore it could be used as the reference value to calibrate the latter and let system error be cor- rected. Differences in the environment of the sensor installing and the error caused by the change of thermo-physical proper- ty could be avoided. Thus, the difficult problem of traceable dynamic calibration of temperature was solved. In experiment, to obtain the frequency characteristics of the thermocouple and the dynamic performance of the K type thermocouple, which could compensate the dynamic characteristics of the sensor, the sensor was dynamically corrected by using the method, and then the mathematical model was established.

Research on measuring time constant of NANMAC thermocouple

The theory for measuring the time constant of thermocouple was introduced, and the method for measuring the time constant of NANMAC thermocouple by using dynamic calibration system of transient surface temperature sensor was proposed. In this system, static and dynamic calibrations were conducted for infrared detectors and thermocouples, and then both temperature-time curves were obtained. Since the frequency response of infrared detector is superior to that of calibrat- ed thermocouple, the values measured by infrared detectors are taken as true values. Through dividing the values measured with thermocouples by those with infrared detectors, a normalized curve was obtained, based on which the time constant of thermocouple was measured. With this method, the experiments were carried out with NANMAC thermocouple to obtain its time constant. The results show that the method for measuring the time constant is feasible and the dynamic calibration of thermocouples can be achieved at microsecond and millisecond level. This research has a certain reference value for research and application of NANMAC thermocouple temperature sensor.

基于改进天鹰优化算法的热电偶动态补偿方法

为解决因热电偶时间常数大,不能准确反映被测温度瞬态变化的问题,提出基于改进天鹰优化算法(IAO)的热电偶动态补偿方法。通过引入Sobol序列初始化种群与动态反向学习策略对天鹰优化算法(AO)进行改进,对实测热电偶动态响应数据进行补偿实验。实验结果表明,经改进算法补偿后,热电偶时间常数由0.097 s缩短至0.009 s,减少近90.7%。IAO补偿可以有效改善热电偶动态特性,减小动态误差。

Design of a distributed power amplifier based on T-type matching networks

The impedance characteristics of distributed amplifiers are analyzed based on T-type matching networks, and a distributed power amplifier consisting of three gain cells is proposed. Non-uniform T-type matching networks are adopted to make the impedance of artificial transmission lines connected to the gate and drain change stage by stage gradually, which provides good impedance matching and improves the output power and efficiency. The measurement results show that the amplifier gives an average forward gain of 6 dB from 3 to 16. 5 GHz. In the desired band, the input return loss is typically less than - 9. 5 dB, and the output return loss is better than -8.5 dB. The output power at 1-dB gain compression point is from 3.6 to 10. 6 dBm in the band of 2 to 16 GHz while the power added efficiency （PAE） is from 2% to 12. 5% . The power consumption of the amplifier is 81 mW with a supply of 1.8 V, and the chip area is 0.91 mm × 0.45 mm.

NADCAP热处理认证高温测量技术研究

NADCAP认证是国际航空工业范围内一致认可的审核标准,取得NADCAP认证资质是企业进军国际航空市场,加入航空供应链的必备条件,基于NADCAP热处理认证要求,结合自身NADCAP认证项目工作经验,深入论述了AMS2750G高温测量技术,首先介绍了AMS2750G高温测量法对于热处理设备的等级分类要求和6种不同类型的仪表配置,然后展示了8种标准热电偶的材料成分和热电特性,归纳总结出了不同用途下廉金属热电偶和贵金属热电偶的校准周期、允差要求,其次解析了高温测量的基本方法,包括温度均匀性测试中传感器的布置要求、测试温度点的选择方法,最后介绍了系统精度测试的原理、技术要求和过程注意事项,该研究为冶金热处理行业和高温测量技术人员提供了思路,为航空制造业国际贸易往来提供了技术基础。

热障涂层服役温度测试与隔热机理

热障涂层(TBC)被用于航空发动机涡轮叶片表面的热防护,主要由粘结层和陶瓷层组成,准确测量陶瓷层表面与粘结层/陶瓷层界面温度分布对指导涂层高隔热结构设计与制备具有重要意义。现有非接触式与接触式测温技术可测量表面温度,接触式测温技术可测量界面温度。主要介绍了3种用于测量航空发动机涡轮叶片表面温度的技术,其中,适用于TBC表面测温的包括以光学原理为主的红外辐射、荧光、晶体、光纤测温技术;以热致变原理为主的示温漆测温技术;适用于TBC界面测温的以热电原理为主的填埋式热电偶、薄膜热电偶测温技术,并介绍了其测温的原理、优势和局限性。进一步对TBC隔热机理及性能优化进行了介绍,并对TBC表/界面测温技术及涂层结构设计方向进行了展望。

基于磁控溅射的Pt/PtRh高温薄膜热电偶传感器集成工艺

Pt/PtRh为高温薄膜热电偶敏感材料,Al_(2)O_(3)和SiO_(2)为复合绝缘层材料,采用磁控溅射法成功制备Pt/PtRh薄膜热电偶及Al_(2)O_(3)/SiO_(2)复合型上下绝缘层,并通过掩膜-沉积法实现薄膜热电偶图案化制备。结果表明:制备的复合绝缘层Al_(2)O_(3)/SiO_(2)能够有效保证高温薄膜热电偶传感器在1200℃高温下的绝缘性和化学稳定性。Pt/PtRh热电偶阵列精度达到200μm,可在1200℃下稳定工作超过2200 min,经过4000 min升降温循环测试后,热电偶输出热电动势偏差小于1%。热电偶传感器整体厚度小于20μm,集成于合金与热障涂层之间的热电偶在高温服役环境下可稳定工作并测量合金表面温度。多层结构的样件在服役测试中无分层、脱落现象,热电偶稳定输出信号。

高温测量降本增效实践与研究

旨在研究高温测量过程降本增效的关键策略:聚焦加热炉测温优化、热偶使用管理降本方法、计量过程数据高效处理。在探究这些策略的过程中,炉顶穿孔引导测温方法、热偶维修技术以及帆软数据分析展示模块成为实现高温测量过程降本增效目标的重要手段。穿孔引导测温方法操作便捷,不仅提升了测温效率,还提升了测温过程的稳定性和准确性。同时,针对热电偶使用,开发出了热电偶维修裁剪工艺,增加了热电偶循环利用率,减少了热电偶使用成本。在数据处理方面,帆软数据报表模块的应用彰显了其在实现计量过程数据高效处理上的优势。通过该平台,生产数据可以更为直观、清晰地呈现,同时也提供了对数据进行深入分析的功能。通过实际生产案例的验证,这些优化措施显著提高了生产效率、降低了成本。更重要的是,这些策略的实施对于冶金行业的可持续发展和提升竞争力具有重要意义。

微纳陶瓷基铂铑10-铂热电偶技术研究

针对燃气轮机温度检测高温热电偶存在的热容大、响应时间慢、无法表贴安装等诸多技术问题,利用陶瓷微纳加工技术制造出50μm厚度的柔性芯片基底,经薄膜工艺形成冗余结构的铂铑10-铂热电偶电极,通过“三明治”封装形成全陶瓷密封型热电偶,开展微纳陶瓷基高温热电偶性能与功能试验。试验表明,所设计的微纳陶瓷基高温热电偶具有快响应特点,能实现在圆滑表面进行柔性表贴安装,在0~1 000℃温度范围内,热电偶输出灵敏度与二级标准铂铑10-铂热电偶比对,偏差在±0.3%,90%响应时间优于0.1 s,热电偶具有良好的高温稳定性。

温压炸药爆炸瞬态高温测试技术研究

为评估温压炸药的热毁伤性能,针对其爆炸瞬间产生高温高压场温度变化剧烈、持续时间短、测量难度大且难以测到爆炸瞬间火球温度分布的问题,提出了一种接触式与非接触式测温混合测试方法,搭建了红外热像仪和热电偶测温系统,对洞内外两发温压炸药的爆炸过程进行测试;使用两台红外热像仪分别以高低帧频拍摄,同时在距离爆心一定距离处布置钨铼热电偶,从不同时间不同位置获取了火球不同维度的信息,实现了爆炸温度变化全过程的高帧频、高分辨率完整记录;对温压爆炸过程中温度变化进行了精细化研究;其中,洞内爆炸最高温度可达1 800℃以上,火球最大直径约为8.3 m,洞外爆炸最高温度可达1 700℃以上,火球最大直径约为7.7 m,山洞的限制作用使得火球最高温度更高,1 800℃以上持续时间为14 ms,热毁伤效果更强;洞内外温压弹爆炸最高温度测试结果的最大偏差分别为5.1%和5.8%,平均偏差为5.45%,处于一定合理的范围内,可以满足爆炸场测试需求。

基于沉积温度的氧化铟锡微结构调控及性能

为提高薄膜热电偶在航空发动机高温零部件表面瞬时测温的性能,采用直流磁控溅射法制备氧化铟锡(ITO)薄膜。通过沉积温度变化调控薄膜的微结构,并采用X射线衍射仪、扫描电子显微镜、塞贝克测试仪、纳米划痕测试仪等分别表征薄膜的微观结构、表面形貌、热电性能及界面结合力。结果表明:沉积温度直接决定溅射原子的表面扩散、生长能力及ITO载流子迁移率,从而改善其结晶性和热电性能。沉积温度为450℃时,ITO薄膜表面呈三角形晶粒形貌,薄膜中In_(2)O_(3)沿(400)择优取向,相比低温沉积的薄膜展现出优异的结晶性,界面结合力达到10.89 mN,同时ITO功率因子显著提高,在900℃测试温度下功率因子约为400μW/(m·K^(2)),表现出较好的热电性能和高温结构稳定性。

氢气压缩机缓冲罐热电偶接管开裂失效分析

由于承受交变压力载荷的作用,氢气缓冲罐接管易发生开裂失效导致介质泄漏。对开裂部位进行宏观观察、化学成分分析、常规拉伸试验、显微硬度测试、扫描电镜与能谱分析检测后可知,某氢气压缩机缓冲罐热电偶接管开裂是由于裂纹源位于加强筋板与接管焊缝外表面的焊趾处,并伴有夹杂、未熔合等缺陷;连接焊缝的焊缝区与热影响区中存在粗大柱状晶、魏氏体和保持马氏体位相的回火组织,提高了焊缝的淬硬性与裂纹敏感性;加强筋与接管连接焊缝结构处的应力集中程度较高,焊接残余应力以及外加交变载荷为裂纹扩展甚至开裂提供了必要条件。