课程文献中心 更多>>

关键词： MOSFET   Logic gates   Switching loss   Resistance   Capacitance   Voltage   Switching frequency   Switches   Transient analysis   Internet of Things   Analog-digital integrated circuits   DC-DC power converters   Low power electronics   Monolithic integrated circuits   Power MOSFET   Power system management   Power integrated circuits   PMICs   Switched mode power supplies  

摘要： This article presents a novel mixed-signal architecture for the extraction and online tracking of the maximum efficiency point in generic integrated dc-dc converters, called power segmentation optimum. This optimal condition is achieved by dynamically adjusting the size of the power switches to minimize total losses. Proposed system continuously tracks the optimal efficiency point under all operating conditions, adapting to both external factors (such as input/output voltage, switching frequency, temperature, and output current) and internal parameters (such as mosfet on-resistance, and gate capacitance). The operating principle consists in a A/D mixed signal implementation which continuously extracts and compares a proportional value of each loss contribution, deriving the corresponding configuration which minimizes the total losses. This technique is particularly suitable for IoT applications, characterized by long idle periods and high current pulse transients. In order to validate the theoretical results, proposed method is implemented inside a 5 A dc-dc fullyintegrated buck converter realized in 180 nm technology with 5 V input voltage rating and switching frequency up to 4 MHz.

关键词： Strain measurement  

摘要： Evaluating the mechanical performance and operational conditions of bridge structures relies on accurately measuringement of vibration displacement. Such measurement can provide essential parameters, such as mode and frequency, to assess the operational status and condition of damaged bridge structures. However, traditional displacement monitoring techniques have high cost, low accuracyare expensive, have low accuracy, and offer and limited measurement positions. This paper proposes a A low-cost, non-contact, and multi-point measurement method was proposed in this paper,based on the Kernelized correlation filters (KCF) algorithm to measure the vibration displacement of bridges. The proposed method used shaking Shaking table tests on a dual-column pier model were conducted,with energy dissipation links under different white noise sweeps. The recorded vibration displacement from a laser displacement sensor (LDS) was used as a reference for comparison. The natural frequencies and mode shapes of the dual-column pier and bridges were identified using the covariance-driven stochastic subspace identification method. The study verified the The reliability, feasibility, and accuracy of machine vision technology in identifying the natural frequencies and mode shapes of bridges were verified. The results showed that the small amplitude vibration displacement of the dual-column pier identified by the KCF algorithm is almost consistent with the waveforms, change trends, and peak values recorded by LDS, with a maximum peak error of 4%. The error between the natural frequencies identified by the KCF algorithm and the LDS results was within 2.5%. The confidence level of the mode shapes identified between both approaches was above 0.90. © 2025 Chinese Vibration Engineering Society. All rights reserved.

关键词： 功率控制   线性化   大动态   PID   定向耦合器  

摘要： 在电子对抗系统中,随着对抗领域的拓展和系统功能的提高,对发射机功率输出精准性的提高已得到越来越多的重视。在不同的功率控制方案中,数字闭环功率控制具有大动态、高精度、脉冲适应能力强、功率自动校准、不需要外部控制信号、具有自适应功能等优点。设计了一种数字闭环功率方案,通过实验验证,对0.35~2 GHz频段功放的输出功率控制精度可达到0.3 dB(r.m.s.),动态范围可达45 dB。

关键词： 煤矿变压器   顶层油温   门控时序卷积网络   注意力机制   长周期预测  

摘要： 顶层油温预测可以为煤矿油浸式变压器的故障预警和老化评估提供重要依据,有利于保障煤矿安全。针对传统方法在信息提取、油温长周期预测方面的局限性,提出一种基于GatedTCN-Attentions的煤矿变压器顶层油温预测方法。首先,通过K-近邻算法将数据规范化;然后,由门控时序卷积神经网络和通道注意力模块建立分支通道进行特征提取,再通过块注意力机制进行多模态特征融合;最后,由回归预测模块输出油温预测值。实验结果表明,相比于其他传统深度学习模型,所提模型在长周期油温预测的准确性和稳定性方面均具有明显优势,对煤矿变压器的健康监测具有指导意义。

关键词： LTCC   小型化   带阻滤波器   HFSS   电磁场仿真  

摘要： 采用LTCC工艺设计一种集总元件结构带阻滤波器,先用ADS软件优化仿真获得电路元件初始值,然后采用微波电磁场仿真软件HFSS对滤波器物理模型优化仿真。其中谐振单元采用左右对称结构,降低三维模型调试难度。螺旋电感以双层介质层线路为基础进行环绕降低耦合电容的值。成功设计了一种LTCC带阻滤波器,其中心频率为1500MHz,在带阻1450~1550MHz范围内衰减量大于32dB,在通带10~1200MHz和1800~4000 MHz范围内插入损耗小于1.5 dB,通带驻波比小于2.0。采用LTCC工艺制备该带阻滤波器,尺寸为4.5mm×3.2mm×1.5mm,样品实测结果与电磁仿真结果基本一致。

关键词： 充电功率   充电设备   快速充电   充电时间   负荷能力   电动汽车   电学参数   用户体验  

摘要： 当今,节能降碳工作积极推进。电动汽车技术虽日益成熟且普及,但充电耗时费力的状况影响用户体验。大功率自动充电技术应运而生,它可实现汽车的自动化快速充电,既节省充电时间,又避免人工插拔枪线的繁琐,极大地提高了用户的使用感受。一、大功率自动充电技术的原理1.充电功率的界定在探讨大功率自动充电技术时,充电功率的界定是一个基础且关键的要素。充电功率并非简单的一个数值概念,它涉及到多个电学参数的综合考量。从国内的情况来看,大功率充电功率的界定与电网的承载能力、充电设备的性能上限等密切相关。例如,在中国,随着电动汽车的普及,电网的负荷能力成为了一个重要的考量因素。

关键词： MOSFET-type gas sensor   Zinc indium tin oxide (ZITO)   Co-sputtering   X-ray photoelectron spectroscopy (XPS)  

摘要： The growing demand for high-sensitivity and low-power gas sensors has driven the exploration of advanced sensing materials. In this study, we fabricated MOSFET-type gas sensors using co-sputtered zinc indium tin oxide (ZITO) films as sensing layers, with five different films containing varying ratios of indium tin oxide (ITO) and ZnO mixtures. As the Zn content increased, the agglomeration sizes within the films decreased, exhibiting amorphous-like morphology. X-ray photoelectron spectroscopy (XPS) revealed that scarce Zn content induced oxygen vacancies, while the number of hydroxy groups increased with higher Zn content. These material properties of the sensing layers significantly influenced the gas sensing characteristics. At high temperatures (similar to 210 degrees C), the oxygen vacancy-rich sensor showed the highest gas response, whereas the hydroxy-rich sensor exhibited enhanced performance at low temperatures (similar to 150 degrees C). The adjustment of the co-sputtering ratio influences gas response, power consumption, and response time, allowing for the fabrication of sensors optimized for specific applications by comprehensively considering various performance factors. We believe that this method can be applied to the formation of a wide range of sensing materials.

关键词： 低压大功率电机   船舶电力系统   起动转矩   检修周期   试验项目  

摘要： 重点阐述船用低压大功率电机制造和使用特点,对船用低压大功率电机的检查和试验项目进行论述。

关键词： 小波分析   高压变频器   功率单元   故障检测分析  

摘要： 在现代工业中,高压变频器作为重要的电力调节设备,广泛应用于各种生产过程。然而,随着使用频率的提升,变频器的故障率也显著上升,因此,开发有效的故障检测技术、及时发现并处理潜在故障,已成为行业内亟待解决的问题。小波分析技术以其在信号处理中的独特优势,能有效提取电压信号的瞬时特性与频率成分,为故障识别提供了新的思路。本研究以小波分析为基础,通过分析高压变频器功率单元的电压信号,提出了一种基于小波包分解、信号特征熵、包络提取及支持向量机诊断模型相结合的故障检测方法,以提高故障诊断的精度和实时性,保障高压变频器的安全可靠运行。

关键词： 管壳式换热器   管束   两相流   激振力   功率谱密度  

摘要： 管壳式换热器内部管束长期受到气-水两相流冲刷容易发生磨损破坏,影响其使用寿命,因此准确计算两相流体力的功率谱密度对管束的磨损计算至关重要.由于缺乏两相流条件下的管间流场相关性实验数据,难以用激振力去直接计算其等效功率谱密度.为了探究管间两相流流场相关性,给出可靠的两相流激振力包络谱,设计搭建了两相水洞实验装置,创新性地将电子压力扫描阀引入两相流环境中,直接测量管表面的压力.对节径比为1.41的正三角形刚性管阵中单根弹性管在环境温度和压力下的横向流致振动进行了全面的实验研究.研究了直径为0.026 m、长度为0.237 m的柔性管在10%~90%含气率下激振力的频域特征并计算了相关长度,通过分析压力的变化、激振力自相关功率谱密度以及斯特劳哈尔数确定了周期性漩涡脱落现象的出现,获得了不同含气率下基于界面流速的激振力无量纲参考等效功率谱密度.结果表明,压力随界面流速大致呈抛物线形式增加,但涡流脱落会导致管周的压力骤降;管束内部激振力的相干函数在大范围内数值较低,相关长度不到1倍管径.使用1倍管径为相关长度计算了3种不同结构参数弹性管的激振力等效功率谱密度,采用基于界面流速的归一化因子进行了无量纲处理,给出了10%~30%含气率、40%~60%含气率以及70%~90%含气率时的激振力包络谱,其中激振力在40%~60%含气率下能量最高,70%~90%含气率次之,10%~30%含气率下能量最低.研究结果给壳程不同位置管束的磨损计算提供了符合工程实践的载荷谱.