三相整流桥直流侧和交流侧并联型有源电力滤波器比较研究

三相直流侧和交流侧有源电力滤波器均可用于三相不可控整流桥的谐波治理。从谐波补偿效果、有源滤波器的补偿容量、开关应力三个方面对二者进行了分析和对比。分析结果表明,由于直流侧有源电力滤波器并联在整流桥的直流侧,在换相处的负载电流变化率比交流侧小得多,因此直流侧有源电力滤波器的补偿性能优于交流侧有源电力滤波器。同时由于直流侧有源电力滤波器工作在电压电流两个象限,因此其补偿容量和开关应力远小于交流侧有源电力滤波器。     

一种高效开关电容AC—DC变换器

针对开关电容ＤＣ－ＤＣ变换器的效率会随着输入电压的增高而显著下降的现象，提出了一种新型的基于开关电容网络的ＡＣ－ＤＣ变换器，它采用根据输入电压变化而动态确定功率开关的导通和关断的方法，从原理上解决了开关电容ＤＣ－ＤＣ变换器的输入电压动态范围与变换器效率之间的矛盾。理论分析和实验结果表明，该转换器可以在较宽的输入电压范围获得较高的转换效率。     

开关电源新技术动态

本文介绍了开关电源的发展情况以及国外的最新成就，考察了各种新型开关电源，它们的主要优点及其存在的问题；综述了开关电源计算机辅助设计技术的研究和发展；最后简要介绍了国外目前正在研究的一些课题。     

单＋5V供电的计算机固态电源变换器

论述了一种可以从＋５Ｖ电源得到±１２Ｖ的新型开关电容ＤＣ－ＤＣ变换器。它的结构中不含电感，因而便于集成，使计算机系统组成和联接简化。对电路的工作原理、效率、纹波及设计作了深入的探讨。ＳＰＩＣＥ仿真和实验结果均证实了该设计方案的可行性     

新型三相三线制并联有源滤波器的滑模控制方法

为了提高有源滤波器的谐波补偿效果,设计了一种新型滑模控制器,用于三相三线制并联有源滤波器的参考电流跟踪控制.谐波电流检测方法采用基于瞬时无功功率理论的谐波电流检测方法,能快速、准确的检测出负载电流中的谐波分量.直流侧电压控制方法采用PI控制方法实现.Simulink仿真结果显示,与传统的滞环比较控制方法相比,所设计的新型滑模控制方法能够有效的降低跟踪误差,提高有源滤波器的谐波补偿效果.     

Thermal management of power electronics modules packaged by a stacked-plate technique

The research presented in this paper is part of a multidisciplinary research program of the Center for Power Electronics Systems at Virginia Tech. The program supported by the Office of Naval Research focuses on the development of innovative technologies for packaging power electronics building blocks. The primary objective of this research is to improve package performance and reliability through thermal management, i.e., reducing device temperatures for a given power level. The task of thermal management involves considering trade-offs in the electrical design, package layout and geometry, materials selection and processing, manufacturing feasibility, and production cost. Based on the electrical design of a simple building block, samples of packaged modules, rated at 600 V and 3.3 kW, were fabricated using a stacked-plate technique, termed metal posts interconnected parallel plate structure (MPIPPS). The MPIPPS technique allows the power devices to be interconnected between two direct-bond copper substrates via the use of metal posts. Thermal modeling results on the MPIPPS packaged modules indicate that the new packaging technique offers a superior thermal management means for packaging power electronics modules.     

Enhanced power conversion efficiency of organic photovoltaic devices due to the surface plasmonic resonance effect generated utilizing Au-WO3 nanocomposites

Au-WO₃ nanocomposites (NCs) were used as a hole transport layer (HTL) to enhance the power conversion efficiency (PCE) of organic photovoltaic (OPV) cells. The photon absorption of the active layer in the OPV cells was increased due to the plasmonic effect caused by the Au-WO₃ NCs, resulting in an enhanced short-circuit current density for the OPV cells with the Au-WO₃ NC HTL. The value of the root-mean-square roughness of the Au-WO₃ NC film was smaller than that of the WO₃ NP film, resulting in a more efficient transport of holes from the active layer. The PCE of the OPV cell with an Au-WO₃ NCs HTL with an Au NP concentration of 10 wt% was improved by 60.37% in comparison with that with WO₃ nanoparticles. The enhancement of the PCE was attributed to both an increase in the efficiency of the hole transport at an Au-WO₃ NCs HTL with an Au NP concentration of 10 wt%/active layer heterointerface and an enhanced photon absorption due to the localized surface plasmon resonance effect of the Au-WO₃ NCs.     

Physics-of-failure assessment methodology for power electronic systems

Driven by consumer markets and industrial needs, power electronic systems are operating at higher power densities, in smaller packages and in more exotic environments. As these trends continue, ensuring long-term operation in harsher conditions requires accurate reliability prediction models, most viably obtained through Physics-of-Failure (PoF) methodologies. This paper introduces a PoF-based system-level reliability assessment procedure in which the dominant failure mechanisms are identified for three primary subsystems: the power module, DC-link capacitors and the control circuitry. This report outlines the dominant failure modes and mechanisms for each subsystem and provides examples of how to improve subsystem reliability based upon the described assessment methodology. A case study is also presented in which the solder interconnect reliability of the gate-driver board in a mid-range variable frequency drive (VFD) was assessed.     

矩阵式三相/单相电源研究

运用矩阵变换器的优良特性实现其在感应加热领域的应用,采用四步法换流策略和分频段控制方案,有利于提高性能输出和降低CPU资源损耗;通过检测三相输入电压与设定的频率并分析、计算来切换不同的控制方案,实现参数可调的电能输出。基于该方案进行模拟器的建立,通过相应的输入/输出参数检测,表明控制策略的可行性和系统良好可应用性。     

Enhancement of the power conversion efficiency due to the plasmonic resonant effect of Au nanoparticles in ZnO nanoripples

Au-ZnO nanoripples (NRs) were synthesized by using a sol-gel method for utilization as an electron transport layer (ETL) in inverted organic photovoltaic (OPV) cells. Absorption spectra showed that the plasmonic broadband light absorption of the ZnO NRs was increased due to the embedded Au nanoparticles (NPs). In particular, as compared to regular inverted OPV cells with a ZnO NR ETL, the incident photon-to-current efficiency of the inverted OPV cells with a Au-ZnO NR ETL was significantly enhanced due to the localized surface plasmon resonance (LSPR) effect of the Au NRs. The enhancement of the short-circuit current density (10.05 mA/cm²) of the inverted OPV cells with a Au-ZnO NR ETL was achieved by the insertion of the Au NPs into the ZnO NRs. The power conversion efficiency (PCE) of the OPV cells with Au-ZnO NRs was 3.25%. The PCE of the inverted OPV cells fabricated with a Au-ZnO NR ETL was significantly improved by 20.37% in comparison with that of inverted OPV cells fabricated with a ZnO NR ETL. This improvement can mainly be attributed to an increase in light absorption in the active layer due to the generation of the LSPR effect resulting from the existence of the Au NPs embedded in the ZnO NRs.     

适合航天电子系统应用的DC－DC变换器

讨论了航天ＤＣ－ＤＣ混合集成电路的拓朴结构。通过对几种电路的性能比较，提出了适合航天应用的ＤＣ－ＤＣ变换器的最佳拓朴结构。论述了ＰＷＭ－ＬＩＮ变换器的控制方法，该方法对于确保二次稳压ＤＣ－ＤＣ变换器较高的效率具有重要意义，亦可大大提高混合集成电路的成品率。     

基于二象限APF的单相功率因数校正器

为消除单相整流装置产生的谐波,提出了一种基于二象限有源滤波器(APF)的单相功率因数校正器,包括其主回路拓扑与控制策略。使用T型拓扑可滤除高次谐波,在主回路加装二极管可削减有源滤波器电流峰值,并在控制回路中使用双前馈以实现快速响应。对该拓扑和控制方案进行了Matlab仿真,并设计了基于dsPIC33F系列数字控制器的实验样机。仿真和实验结果均表明该技术可在降低成本的情况下,仍将功率因数提升至99%。     

Junction temperature management of IGBT module in power electronic converters

IGBT power module is the key component of the power electronic converter, but it has the lowest reliability. The junction temperature is the crucial factor which affects power module’s reliability. To some extent, the power handling capability of the converter depends on the thermal stress of the power module. Thermal management is an effective method to improve the reliability of power device, as well as enhance the power capability. For this purpose, this paper introduces the reliability design to the power converter’s traditional compensation controller design for the first time. A new concept of generalized dual-loop controller, which includes temperature control loop and electric power control loop, is proposed. The reliability and stability of the system are both considered, with the help of the hybrid controller, the power converter can operate steadily with higher reliability. The novelty of this paper is to improve the thermal control method of carrier frequency adjustment through experimental implementation during the full life cycle of the converter. The target is to control the temperature variation to be almost a constant value as well as extend the lifetime of the converter. IR sensor is used to measure the chip temperature of the unpackaged IGBT module. The temperature variation and the average temperature are all considered in thermal management, from the reliability improvement point of view. At last, the idea is digital implemented based on a varying load of power inverter system with real-time measurement of the chip’s surface temperature.     

光纤喇曼放大器的功率转换效率分析

在定义光纤喇曼放大器(FRA)功率转换效率(PCE)的基础上,考察了不同工作条件下光纤喇曼放大器的功率转换效率,分析PCE与光纤喇曼放大器的输入信号功率、输入泵浦功率和光纤长度的关系,比较了分布式与集总式FRA的功率转换效率,给出提高FRA功率转换效率的途径。     

Thermo-electronic solar power conversion with a parabolic concentrator

We consider the energy dynamics of the power generation from the sun when the solar energy is concentrated on to the emitter of a thermo-electronic converter with the help of a parabolic mirror. We use the modified Richardson-Dushman equation. The emitter cross section is assumed to be exactly equal to the focused area at a height h from the base of the mirror to prevent loss of efficiency. We report the variation of output power with solar insolation, height h, reflectivity of the mirror, and anode temperature, initially assuming that there is no space charge effect. Our methodology allows us to predict the temperature at which the anode must be cooled in order to prevent loss of efficiency of power conversion. Novel ways of tackling the space charge problem have been discussed. The space charge effect is modeled through the introduction of a parameter f (0 < f < 1) in the thermos-electron emission equation. We find that the efficiency of the power conversion depends on solar insolation, height h, apart from radii R of the concentrator aperture and emitter, and the collector material properties. We have also considered solar thermos electronic power conversion by using single atom-layer graphene as an emitter.     

同向抽运喇曼放大器功率转换效率的数值分析

为了对同向抽运光纤喇曼放大器的功率转换效率进行研究,由耦合方程出发,采用龙格-库塔算法的数值模拟方法,详细分析了所有物理因素对同向抽运光纤喇曼放大器功率转换效率的影响. 结果表明,功率转换效率先随着光纤长度的增加而增加,当增加到最大值时保持数值不变;并且功率转换效率也随着初始信号光功率、光纤喇曼增益系数、信号光损耗系数的增加而增加,但随着光纤有效面积、抽运光损耗系数、抽运光与信号光的频率比的增加而减小;功率转换效率和初始抽运光功率呈抛物线曲线关系. 这对同向抽运光纤喇曼放大器功率转换效率的进一步研究以及光纤喇曼放大器的相关研究有一定参考意义.     

开关电容DC—DC变换器的效率

将开关电容网络应用到ＤＣ－ＤＣ变换器，并从能量的角度研究了其效率，得出一个对所有类型的开关电容变换器的适用的公式，提出了改善效率的新的拓扑结构，使升压与降压开关电容变换器有较高的效率，实验结果与计算机模拟均取得了与分析相同的结果。     

电力电子变换器中滤波电容参数设计方法

在电力电子变换器中,滤波电容可以抑制电压脉动,消除谐波,其参数大小对变换器的性能有着重要影响。本文首先分析滤波电容器的特性,得出影响电容器滤波效果的各个因素,然后介绍了几种常用的滤波电容器参数设计方法,最后通过一个全桥变换器进行了仿真验证,有助于学生更好地掌握滤波电容器的参数设计。     

开关功率变换器符号分析方法的原理

本文介绍了ＰＷＭ开关功率变换器的一种符号分析方法，着重阐述了该方法的一般原理，这一方法容易得到输出纹波的解析表达式以及系统的小信号模型，兼有计算过程简单和准确度较高的优点，可望成为功率电子学领域比较通用的一种方法。     

A disruptive technology for thermal to electrical energy conversion

A disruptive approach to thermal energy harvesting is presented. The new technique can be used for powering ultra-low power electronics. We propose a two-step conversion of heat into electricity: thermal to mechanical accomplished with thermal bimetals and mechanical to electrical accomplished with piezoelectrics. Devices can work in a wide range of temperatures: from −40 °C to 300 °C and the available mechanical power density is in the order of 1 mW/cm². The first electrical results and the first prototype built on a flexible substrate are presented in this work. We evidenced that one of the keys to improve the generated power density is downscaling of individual devices. To demonstrate this point, laws modeling downscaling have been established and show that the miniaturization of the devices by a factor k increases the generated power density by the same factor, due to the higher heat transfer rate. The path followed in order to establish the laws is given in this paper.