Wide bandgap semiconductor transistors for microwave poweramplifiers

Explores the RF power performance of microwave amplifiers fabricated from wide bandgap semiconductor transistors and demonstrates that microwave power amplifiers fabricated from 4H-SiC and AlGaN/GaN transistors offer superior RF power performance, particularly at elevated temperatures. Theoretical models predict room temperature RF output power on the order of 4-6 W/mm and 10-12 W/mm, with power-added efficiency (PAE) approaching the ideal values for class A and B operation, available from 4H-SiC MESFETs and AlGaN/GaN HFETs, respectively. All calculations were thoroughly calibrated against dc and RF experimental data. The simulations indicate operation at elevated temperature at least up to 5000°C is possible. The RF output power capability of these devices compares very favorably with the 1 W/mm available from GaAs MESFETs. The wide bandgap semiconductor devices will find application in power amplifiers for base station transmitters for wireless telephone systems, HDTV transmitters, power modules for phased-array radars, and other applications. The devices are particularly attractive for applications that require operation at elevated temperature     

Tests on self-healing metallized polypropylene capacitors for powerapplications

Results of research carried out at the Institute of Industrial Electrical Engineering of the University of Bologna on self-healing metallized polypropylene (MPP) power capacitors are presented. The aim of the tests is to characterize the degradation of these capacitors when employed in automatic power factor correction systems or in power electronic applications with special reference to the disconnection of the `sprayed ends' from the electrode-edges, one of the main reasons for failure of MPP capacitors employed in the above systems. The research is carried out also in view of the definition of adequate type-test standards, presently not yet available for this kind of application     

宽带大动态范围自动电平控制技术研究

简要介绍了自动电平控制的作用及工作原理,深入分析了自动电平控制电路设计中的关键技术及难点,提出了一种应用于宽带大动态范围信号源中的自动电平控制技术方案,针对检波中根据输入信号的大小呈现的平方律线性特性,设计了双斜率对数放大电路,使对数放大器输出电压在大信号和小信号时始终与输入功率成线性比例关系,并对该电路进行了详细的理论分析,通过实验对设计的电路进行了验证,结果表明该设计稳定可靠,性能优良。     

Sr-Ca-La-Co型六角铁氧体微波与传统预烧工艺比较研究

在实验室采用微波预烧(MC)和传统马弗炉预烧(CC)两种方法制备了M型六角铁氧体预烧料,然后制备出烧结磁体。采用XRD、SEM和VSM分析样品的结构特征、微观形貌及磁特性。研究表明,MC技术能快速有效地生成六角铁氧体永磁材料,且能提升材料的Br和Hc J。对于配方Sr0.22La0.38Ca0.4Fe11.6Co0.24O19,当预烧温度和烧结温度分别为1250℃和1170℃时,对应MC预烧料的烧结样品的Br=444m T和Hc J=415k A/m,与相同温度下的CC预烧料的烧结样品指标相比分别提高1.6%和5%。     

Development of a microwave clothes dryer

A laboratory test model of a microwave clothes dryer was constructed and tested over a wide range of test variables, including number of magnetrons and use of auxiliary heat. The tests identified three distinct operating modes: (1) cool drying, which uses only microwave energy and drying occurs at less than 105°F; (2) fast drying, where microwave drying is superimposed on conventional drying; and (3) efficient drying, where the use of microwave energy with waste heat recovery from the power supply results in significant efficiency improvements compared to conventional dryers     

宽负荷区间PID比例自适应主动寻优技术

实际发电机组常处于变工况运行,工况改变前设置的PID控制器参数的控制效果无法满足工况改变后的控制要求,出现控制系统调节能力变差的问题.为了提升变工况下机组的控制品质,本文提出宽负荷区间PID比例自适应主动寻优技术,通过过零点判断逻辑及选取并保持最值逻辑,自辨识变参数动态修正PID控制器的比例参数,对PID控制器的比例作...     

微波通信工程中天线系统的校准技术

在微波通信中，天线方位角的校准通常采用经纬仪法，存在误差大、效率低的缺点。为此，提出重锤线法，使天线－天线系统角度的校准变得简易。在天线－反射板－天线系统校准中，提出采用分段调整法，简化了系统的调整过程。     

10G以太网技术在电力广域网中的应用

随着电力系统信息化业务的不断扩展与应用,大量语音、视频的应用对电力广域网1 G带宽提出了更高的要求,通过对10 G以太网进行技术分析,提出了采用10 G以太网技术升级电力广域网的切换方法。应用结果表明:10 G以太网技术实现了电力广城网10 G带宽传输,使信息交换速度大大提高,通过分层架构使网络层次清晰化,增强了广域网性能与可靠性,满足了电力系统信息化业务的要求。     

微波通信站本地监控系统研制

阐述通信网络管理系统的结构,研制了一种微波通信站本地监控系统.该系统可作为通信站的本地监控独立运行,也可作为网元层而构成全网的TMN系统.     

微波通信站本地监控系统研制

阐述通信网络管理系统的结构 ,研制了一种微波通信站本地监控系统。该系统可作为通信站的本地监控独立运行 ,也可作为网元层而构成全网的TMN系统。     

Underlying design advantages for GaN MOSFETs compared with GaN HFETs for power applications

This study investigates the underlying reasons and quantifies the advantages the GaN MOSFET has over the GaN HFET for high voltage and power applications. Calibrated simulations with equivalent material model files show that equivalent dimensioned devices are capable of producing similar on-state modes of operation, and achieve similar effective mobility at equivalent larger electric fields. However, during sub-threshold operation, the GaN MOSFET is shown to contain a much lower carrier concentration than the GaN HFET. This prolongs the breakdown avalanche effect in the GaN MOSFET (3500 V) by roughly five times larger than the GaN HFET (600 V) for devices of similar dimensions. Implementing the MOS structure can potentially resolve fundamental constraints for high voltage power applications caused by current device architects.     

贵州电网微波通信系统再利用及最新微波技术展望

微波通信为无线电通信,电力光纤通信是在跟着电力线路架设,应对自然灾害时,与光纤通信形成互补。微波通信是按地理位置建设,在物理构架上与光通信形成互补。光纤通信是环网结构,微波是树枝型结构,微波与光环网互联,就能形成更为强大的通信网络。技术接口上微波通信接口与光纤通信接口是一致的,都是同步网链路接口。     

GaN基MSM结构紫外探测器及其研究发展

本文主要介绍了GaN基紫外探测器,尤其是GaN基金属-半导体-金属(MSM)结构紫外探测器的工作机制、结构、特点及其应用,并且对GaN基MSM结构紫外探测器的研究进展进行回顾,并对目前较为热门的紫外焦平面阵列探测器的研究进展进行简单的介绍。     

电动车用蓄电池充电技术的进展

综述了电动车用蓄电池充电技术的历史、发展现状,总结了现代充电技术几个特点并展望了其未来的发展方向。     

广域测量技术在电力系统中的应用研究进展

大规模交直流混合电网的建设和发展,对电力系统稳定和控制在空间广度和时间维度上提出了更高的要求。广域测量系统(Wide Area Measurement System,WAMS)的同步量测数据在空间和时间上满足上述要求,因而研究WAMS技术在电力系统中的应用十分必要。从WAMS的结构和原理出发,总结了近五年来广域测量系统在电力系统动态监测与故障分析、辨识与估计、系统稳定控制和广域保护等方面的研究进展,并详细分析了其中存在的问题。最后展望了广域测量技术需要进一步研究的问题,指出基于WAMS技术构建大规模互联电力系统的广域安全监测及控制系统是一个很有意义的研究方向。     

Space solar power programs and microwave wireless power transmission technology

Future large-scale space solar power (SSP) will form a very complex integrated system of systems requiring numerous significant advances in current technology and capabilities. Ongoing technology developments have narrowed many of the gaps, but major technical, regulatory, and conceptual hurdles remain. Continuing systems concept studies and analyses will be critical to success, as will following a clear strategic R&T road map. This road map must assure both an incremental and evolutionary approach to developing needed technologies and systems is followed, with significant and broadly applicable advances with each increment. In particular, the technologies and systems needed for SPS must support highly leveraged applicability to needs in space science, robotic and human exploration, and the development of space. Considerable progress has been made in the critical area of microwave power transmission. At 5.8 GHz, DC-RF converters with efficiencies over 80% are achievable today. Rectennas developed at 5.8 GHz have also been measured with efficiencies greater than 80%. With optimized components in both the transmitter and rectenna, an SPS system has the potential of a DC-to-DC efficiency of 45%.     

数字实时补偿技术在现代微波合成扫频信号源中的应用

本文在介绍锁相扫频技术的基础上,论述了现代微波合成扫频信号源中针对振荡器预置非线性进行补偿的必要性,探索了一种数字实时补偿的实现方法,着重描述了补偿的原理框图、主要硬件电路及在同步时序的控制下补偿的过程,这种补偿方法已成功应用于宽带微波合成扫频信号源的设计中,经验证能够产生较好的补偿效果。     

微波硫灯补光技术在农业节电中的应用

通过挖掘农作物生长补光灯市场,采用微波硫灯进行农业大棚补光,降低传统大棚补光用能成本,提高农业产值,从而有效拓展农业用电需求。分析农作物补光用电潜力,介绍微波硫灯的工作原理和设备结构以及微波硫灯在农业生产中的优势。具体阐述实验项目的应用情况。经福州罗源农业实验证明,微波硫灯补光能够大幅提高农作物产量,能源消耗大幅降低,具有市场推广前景。     

分散控制系统自主可控技术的发展

分散控制系统（DCS）作为火力发电领域的核心控制系统,其软硬件长期严重依赖进口产品,存在重大安全隐患和断供风险。在说明国产品牌DCS发展历程及软硬件国产化现状的基础上,分析了国产化替代对于实现自主可控的必要性,并提出实现DCS国产化并非简单的硬件替代与软件移植,还需重点解决好专用芯片替代、芯片功能缺陷、软硬件适配及综合算力等问题;然后介绍了全国产、自主可控DCS如华能睿渥、华电睿蓝、国能智深、南京科远和浙江中控等发展应用现状,全国产DCS在300、600、1 000 MW等级机组相继投入运行,标志着我国DCS已实现完全自主可控,具备大规模推广应用的条件;最后对国产DCS推广应用中存在问题,如缺少嵌入式低功耗处理器、国产元器件性能存在批次性差异、国产软硬件性价比和供应链安全等进行分析,并提出了相关建议。     

微波仪器中即插即用技术的设计和应用

微波仪器由于频率高,分布参数影响严重,难于批量生产,为方便电路板的生产调试和维护,提高微波仪器的生产效率,本文设计了一种适用于微波测量仪器的即插即用技术包括电路单元和软件协议.该技术采用标准I2C总线实现,结构简单、可靠便于使用,对仪器EMC效果不会产生影响.采用该技术后微波仪器的应用软件能够自动识别电路板配置,加载特征数据,并实现软件功能组件的装载,使电路板在微波仪器中能够即插即用.该技术已成功应用于高灵敏度宽带EMI接收机中.