一种改进型同步整流正激变换器研究

针对传统同步整流正激变换器效率较低、不适用于宽输入电压场合以及共态导通等问题,提出了一种改进型同步整流正激变换器。改进后的同步整流正激变换器利用辅助绕组两端电压驱动MOSFET管,该变换器效率较高,适用于宽输入电压场合,能够很好地解决共态导通问题。分析了改进型同步整流正激变换器的工作原理、工作模态,建立了改进型同步整流正激变换器的EL(Euler-lagrange, EL)模型,基于无源控制理论,采用阻尼注入方法设计了改进型同步整流正激变换器的无源控制器。无源控制器可使改进后的同步整流正激变换器具有良好的动、静态性能和对负载变化的鲁棒性。仿真及试验结果表明该变换器及其无源控制器是可行的。     

基于介质阻挡放电原理的安瓿瓶检漏系统研究

为了克服传统系统存在的问题,提出了改进安瓿瓶检漏系统的设计方法。分析了安瓿瓶检漏系统的工作原理以及和介质阻挡放电的原理与特性,分析了安瓿瓶检漏系统的电路原理,概述了影响检漏精度的各种因素,依据整流电路、软启动电路、直流调压电路、单相全桥逆变电路、保护电路、放电电路、嵌入式监控系统和上位机监控系统介绍了各模块的设计,完善了系统总体设计方案。这些研究成果为安瓿瓶检漏系统的设计与实现提供了一定的参考。     

三相逆变器带整流性负载建模与设计

基于非线性系统的分段线性化原理将三相整流性负载分解成3种状态,简化逆变器带整流性负载的建模与设计。同时基于结合重复控制、电容电压微分反馈和双环控制器的策略,详细分析使用所提出三相整流性负载模型的三相逆变器工作特性及其控制器设计方法。针对系统非线性特点,分别使用二阶阻尼理论、相平面法和奈奎斯特图分析稳定性。最后,根据以上的分析在三相逆变器平台进行实验,验证三相逆变器带整流性负载的建模以及基于所提出模型控制器设计和稳定性判断方法的有效性。     

铜电解整流电源的系统设计

在为某厂Ⅲ期铜电解扩建工程设计中，兼顾Ⅰ、Ⅱ期电解原有整流装置设备陈旧，效率低的状况，将三期电解综合考虑，选用一套大容量的高效、节能新型整流装置，并设计了合理的全系统主结线，达到了节省投资，提高效率，节约电能，增强生产灵活性，提高全电解系统经济效益之目的。     

多节漂浮型机械式波浪能发电装置的研制

为了探究波浪能发电原理,研制由多节段机械式漂浮型波浪能发电装置和整流稳压电路组成的试验装置,并实现试验演示与数据测试分析。该装置由多节圆柱浮筒、变向增速机构、发电机以及整流稳压电路部分组成。根据确定性波浪运动规律,设计多节漂浮型波浪能俘获装置的结构和参数;由波浪能俘获装置的运动特点,设计曲柄摇杆及齿轮增速机构组成的变向增速机构,实现波浪运动转换为旋转机械运动;由发电机输出规律,设计桥式整流稳压电路,实现稳态直流电输出。试验研究表明,在给定的试验波浪条件下所开发波浪能发电试验装置的发电效率为45.8%。     

高效的电机串调及其节能效果

一 电机串调系统的组成 电机串调系统由绕线式异步电动机、串调设备和水泵组成。其中,串调设备包括整流控制柜、开关柜和直流电机等设备。原理框图见图1。 整流控制柜内装有整流元件、频敏变阻器、直流电动机的励磁电源和齐全的保护系统。改变直流电机的励磁电流(亦即改变电枢电压),可以在较宽的范围内调节转差率使异步电动机获得平滑无节调速。它的调速原理基本上与可     

脉冲爆震发动机起爆点火系统方案研究

在分析爆震波的基本理论、脉冲爆震发动机(PDE)的工作原理及对现有航空发动机和汽车点火系统进行研究的基础上,根据PDE对起爆系统点火能量和火花频率可调的要求,提出了以晶闸管为开关控制元件和电容储能的半导体高能点火系统方案．设计的倍压整流、半波整流和直流供电的脉冲爆震发动机起爆点火系统实现了点火能量和火花放电频率的控制．电路模拟仿真表明,设计的起爆点火系统可满足脉冲爆震发动机的要求．     

巨型水电机组励磁系统环形热管整流柜的研制与应用

针对巨型水电机组励磁整流柜散热问题，介绍了利用环形热管散热的工作原理和自冷型环形热管整流柜的研制改进过程，分析了一体式环形热管散热器和水平对称结构的优势及其在乌东德水电站的应用。结果表明，采用完全自冷方式的环形热管励磁整流柜可在现场长期稳定运行，从设计原理上解决了灰尘、噪声、工作电源、维护等一系列问题，提高了设备的安全可靠性和自动化水平，同时降低了能耗，节能环保效益显著。     

基于场协同原理的容腔内气流场温度均匀化方法数值研究

为研究场协同原理对气流场温度均匀化的适用性,设计了一个温差可控并能形成具有梯度的气流速度场与温度场的加热器,然后在加热器整流区内布置3种特殊的整流网,利用Fluent进行三维数值模拟。结果表明,场协同原理对于提高气流场温度的均匀性是有效的,并依此原理提出了气流场温度均匀化的最佳方法。     

城市轨道24脉波整流机组研究分析

阐述了当前城市轨道交通直流供电系统24脉波整流的原理,并且使用MATLAB/SIMULINK编程软件对直流供电牵引系统的整流设备进行建模与仿真,根据其仿真结果分析了24脉波整流机组的工作特性,给出了其仿真波形,并根据仿真波形介绍24脉冲整流的优劣;同时也对24脉波整流直流侧的谐波进行了分析,并根据模型仿真的结果以及相关谐波的分析给出了抑制谐波的方法。     

Output power variations with solar power satellites

The first comprehensive evaluation of output power variations expected from Solar Power Satellites is presented. The various factors are classified in a two tier manner as: deterministic (either periodic or non-periodic) and statistical (either constant with system life or changing with life). The largest variations are due to seasonal periodic factors, namely variations in the solar constant (± 3.3 per cent) and a solar illumination variation with the photovoltaic array held perpendicular to the orbit plane (± 4.2 per cent). Other key factors delineated which are being quantified presently include power reductions due to microwave power tube failure and silicon solar cell radiation damage, while multiple shadowing of adjacent power stations in geosynchronous orbit and rectenna structural factors and combining efficiency variations are representative of areas that need further study.     

共振磁耦合无线电能传输系统参数与电磁分布特性仿真研究

为进一步改进共振磁耦合式无线充电系统的低频化问题,利用二端口网络参数理论对共振磁耦合无线电能传输系统进行建模,分析了系统传输效率与功率和S参数的关系,指出传输效率最大化的条件,提出了降低无线电能传输系统工作频率的必要性,并结合低频化设计思路,针对铜贴片改变进行HFSS本征频率仿真,得到系统共振频率和贴片厚度、距离、摆放位置等之间的关联,基于仿真结果为共振线圈选择合适的品质因数和共振频率。最后针对典型的共振磁耦合传输系统传输通道上的电磁场分布特性进行计算,得到磁场强度分布,比较了加入屏蔽体之后对传输系统的性能影响和屏蔽体效果,提高了系统传输效率。     

An approach to develop space solar power as a new energy system for developing countries

The idea of space solar power proposed by Glaser was explained as a set of a solar power power station in geostationary earth orbit to transmit microwave power and a ground station to receive the microwave power. Most of the ideas and concepts since Glaser used the same context. On the other hand, Collins et al. (Proceedings SPS '91, pp. 132–141, 1991) introduced the concept of microwave “fuel” to assess the commercial relations of power from space, in which space solar power stations are considered to sell microwave power to any unspecified rectenna. This concept changed the theoretical context of “power from space” to an industrial and economic relation of producers and buyers of an industrial product. This new context has been applied to the SPS 2000 conceptual study. As a result, if 2.45 GHz microwave power transmission is used, each rectenna can be planned and engineered independently from the space sector by local users, especially in developing countries, who are familiar with such activities as introducing solar energy systems.     

玉米秸秆粉碎特性试验研究

对不同含水率、筛孔直径、锤片数量下玉米秸秆粉碎机的吨料电耗、锤片厚度及度电产量等性能参数进行了试验研究。结果表明:对于相同筛孔直径,随着含水率的增大,负荷输入功率基本不变,吨料电耗增加,生产率降低;对于相同含水率的玉米秸秆,随着筛孔直径的增大,吨料电耗、负荷输入功率降低;度电产量和粉碎效率随着锤片厚度的减薄而增加,当锤片厚度为4mm时,既能够保持较高的粉碎效率,又保证了一定的耐用度。     

镍基渗层螺旋翅片式省煤器在410t/h煤粉炉上的应用

齐鲁石化热电厂410t／h煤粉锅炉原下级省煤器为光管式省煤器，运行中存在烟气阻力大、磨损严重以及换热效果差等问题，导致泄漏频繁，产品使用寿命短，检修工作量大，影响锅炉热效率。更换镍基渗层螺旋翅片式省煤器后，烟气阻力大、磨损严重现象明显改善，换热效果充分加强，运行周期大大延长，锅炉热效率显著提高。     

Dry patch formed boiling and burnout in potassium pool boiling

Experimental results are presented on dry patch formed boiling and burnout in saturated potassium pool boiling on a horizontal plane heater for system pressures from 30 to 760 torr and liquid levels from 5 to 50 mm. The dry patch formed boiling is a peculiar boiling state where the dry patch formation and the rewetting are alternately repeated in intermittent boiling at a heat flux smaller than burnout heat flux of continuous nucleate boiling and is considered to be a local phenomenon in transient transition boiling from the observations of the wall and liquid temperature fluctuations. The dry patch formation occurs in the intermittent boiling which is often encountered when liquid alkali metals are used under relatively low pressure conditions. Burnout is caused from both continuous nucleate and dry patch formed boiling. The burnout heat flux together with nucleate boiling heat transfer coefficients are empirically correlated with system pressures. A model is also proposed to predict the minimum heat flux to form the dry patch.     

户用光伏系统发电量与系统综合效率分析

为了解户用光伏系统发电量和系统各效率衰减情况,持续跟踪、记录容量为6 kW的户用光伏系统近几年的发电量相关数据。通过理论计算和电站记录的各项数据分析发现：上海地区2015 ~ 2017年发电量逐年增加;在这三年中,组件方阵每年衰减率在4.5% ~ 6.5%之间,系统综合效率总的相对衰减不超过4%;晴天各时段方阵转换效率与系统综合效率变化趋势相同;雨天各时段逆变器效率、方阵转换效率、系统综合效率变化趋势几乎相同。     

Energy harvesting in wireless sensor networks: A taxonomic survey

Wireless sensor networks (WSNs) have aroused the conspectus attention of scholars due to their extensive deployment in the emerging fields of the Internet of Things (IoT's) and self‐driven devices. But WSNs technologies having a major bottleneck has been associated with limited energy. Mostly research in WSNs has been focused on minimizing energy usage to extend the survival time of limited power source in a network. Energy harvesting can be addressing its energy‐scarcity problem of WSNs, so it is giving popularity to Energy Harvesting in Wireless Sensor Networks (EH‐WSNs). The paper presents a comprehensive taxonomic survey on recently energy harvesting techniques and algorithms that proposed by various authors and also examined the work done by the various researchers in the field of EH‐WSNs. For the ready reference of the researchers, a concise summary and comparative analysis of various promising techniques for energy harvesting have also been included in the systematic survey. However, many equipment developed using the hybridization method in a singular package to get full advantages of available free energy, are explored in this review. The review on hybrid energy harvesting (HEH) systems can be considered as the originality of this article. However, the outdoor photovoltaics have been provided maximum power density about ≈100 mW/cm³, and the piezoelectric harvesters have been given maximum voltage about 325 V but the current in very minute amount. The thermoelectric, rectenna and hybrid energy harvesters (EHs) have been given high efficiency more than 80%. Additionally, hybrid EHs have location/time‐independent characteristics which harnessed power from more than one source that can be became more popular for upcoming leading technologies of self‐driven or autonomous devices shifting from battery operated devices. Finally, the survey also identifies often challenges and various significant issues that still essential to be addressed to develop a cost effective, efficient, long‐lasting, and almost maintenance‐free energy harvesting systems for WSNs along with trail to their possible solutions for future perspectives.     

耦合有机朗肯循环的液化空气储能系统性能研究

为解决液化空气储能系统(LAES)压缩热利用不完全的问题,构建了耦合有机朗肯循环的液化空气储能系统(ORC-LAES)。对ORC-LAES系统建立热力学性能计算模型,在设计参数下分析压缩机出口压力、膨胀机入口压力、加压水初温、加压水流量比及膨胀机级数对ORC-LAES系统性能的影响。结果表明,当压缩机出口压力由6 MPa上升到16 MPa、加压水初温从293 K上升到323 K时,系统的循环效率、火用效率和液化率均下降;当膨胀机入口压力由8 MPa上升到18 MPa时,系统循环效率和火用效率均增加;当加压水流量比由0.51上升到0.96时,系统循环效率和火用效率先增加再减少,流量比为0.71时,系统的循环效率和火用效率达到最大;在压缩热利用上耦合有机朗肯循环要优于增加膨胀机级数;ORC-LAES系统与LAES系统相比,循环效率提高4.8%,火用效率提升5.1%。     

Exergy analysis of a regional-distributed PEM fuel cell system

In this paper, the exergy flow and exergy efficiency of a 3 kW proton-exchange-membrane fuel cell were investigated, and the regional characteristic of the distributed energy system was considered. In the environmental temperature range of 263–313 K, the difference in the total efficiency of the proposed system was 6%. On the other hand, the difference in the exergy total efficiency of the same temperature range was 30%. Moreover, as a result of examining how to improve the exergy efficiency of this system, certain improvement methods were proposed: (a) preheat the city-gas and air supplied to the system using exhaust heat and raise the combustion temperature; (b) preheat the water supplied to the system using exhaust heat; (c) change the catalyst material of each unit and reduce the amount of cooling of the reformed gas; and (d) examine the combined cycle power generation. The exergy efficiency, in the case of introducing the proposed system into individual homes in Sapporo, Tokyo, and Kagoshima, was evaluated. Consequently, when the system was introduced into a community with low outside air temperatures, exergy efficiency increased compared with communities with high outside air temperatures.