带功率因数校正的LED日光灯驱动电源

文中提出了一种带功率因数校正的LED日光灯驱动电源,该电源具有电路简单、可靠的优点,实测数据表明,在较宽电压范围内,驱动电源工作稳定,其具有较高功率因数.     

低损耗软开关Boost变换器

介绍一种新的软开关Boost变换器。传统的Boost变换器在开通和关断时将产生开关损耗,因此使整个系统的效率下降。新的Boost变换器利用软开关方法增加了辅助开关管和谐振电路。这样,相比硬开关情况下,变换器减小了开关损耗。这种变换器可以应用在光伏系统、功率因子校正等装置中。详细分析电路的工作原理以及实现软开关的条件,利用Pspice9．2软件进行仿真验证。仿真结果表明,该变换器的所有开关器件都实现了软开关,从而使效率得到提高。     

CCM模式Boost开关变换器的非线性建模和仿真

在开关元件平均模型法的思想基础上,提出了一种工作在连续电感电流模式下的DC-DCBoost(升压)变换器模型。考虑开关电阻、电感电阻及纹波寄生参数的影响,推导出理想与非理想传递函数。对其开环传递函数进行仿真和比较后可以发现考虑电感纹波的模型与实际更加接近,精度更高。     

基于Boost变换器拓扑PFC电路的建模与分析

介绍了以Boost变换器为主拓扑结构，平均电流控制模式下PFC电路的工作原理，并在准静态分析法的基础上，建立了系统的简化小信号模型。在此基础上，以闭环系统的带宽fc和相位裕量Φ为设计指标，给出了实用的闭环反馈控制器的设计方法。仿真与实验结果表明，所建立的小信号模型及控制器设计方法不仅对模拟PFC电路中补偿器RC网络中参数的设计有实用意义，而且在考虑系统延时的情况下，也适合于数字PFC电路中控制器的设计。     

基于Ansoft SI MPLORER7.0的单相有源功率因数校正仿真研究

简要介绍了有源功率因数校正（APFC）的概念与基本控制方法。应用Ansoft公司的集成仿真软件Simplor-er7.0建立了Boost功率因数校正电路的仿真模型,并进行了仿真分析,给出了仿真波形。通过与未加功率因数校正电路的波形对比,结果表明功率因数明显提高。     

Recognizing object manipulation activities using depth and visual cues

We propose a framework, consisting of several algorithms to recognize human activities that involve manipulating objects. Our proposed algorithm identifies objects being manipulated and models high-level tasks being performed accordingly. Realistic settings for such tasks pose several problems for computer vision, including sporadic occlusion by subjects, non-frontal poses, and objects with few local features. We show how size and segmentation information derived from depth data can address these challenges using simple and fast techniques. In particular, we show how to robustly and without supervision find the manipulating hand, properly detect/recognize objects and properly use the temporal information to fill in the gaps between sporadically detected objects, all through careful inclusion of depth cues. We evaluate our approach on a challenging dataset of 12 kitchen tasks that involve 24 objects performed by 2 subjects. The entire framework yields 82%/84% precision (74%/83%recall) for task/object recognition. Our techniques outperform the state-of-the-art significantly in activity/object recognition.     

Boost型功率因数校正变换器的数字控制研究

数字控制逐渐和电力电子应用紧密结合，功率因数校正是电力电子技术的一个重要应用。文中针对Boost型功率因数校正电路建立了平均电流控制的数学模型，基于Motorola新型号DSP56F8323的高性能特性，完成了数字控制的功率因数校正应用原理样机，给出了详细的系统设计和控制参数。     

Primordial black hole as a source of the boost factor

Primordial black holes (PBHs) accumulate weakly interacting massive particles (WIMPs) around them and form ultracompact minihalos (UCMHs), if the WIMP is a dominant component of the dark matter (DM). In this Letter, we discuss that the UCMHs seeded by the PBHs with sub-earth mass enhance the WIMP annihilation in the present Universe and can successfully explain the positron and/or electron excess in cosmic ray observed by PAMELA/Fermi experiments. The signal is very similar to that from a decaying dark matter, which can explain the PAMELA and/or Fermi anomaly without conflict with any constraints as long as the decay mode is proper. In this scenario, the boost factor can be as large as 10⁵. In addition, we discuss testability of our scenario by gamma-ray point source and gravitational-wave experiments.     

电感电流连续模式下Boost变换器的分数阶建模与仿真分析

基于分数阶微积分理论以及实际电容和实际电感在本质上是分数阶的事实,建立电感电流连续模式下Boost变换器的分数阶数学模型以及分数阶状态平均模型并进行理论分析,给出Boost变换器运行于电感电流连续模式下的参数条件.最后,基于Matlab/Simulink软件建立运行于电感电流连续模式下Boost变换器的分数阶仿真模型,并进行数值仿真分析以验证分数阶建模与理论分析的正确性. 关键词： Boost变换器 电感电流连续模式 分数阶微积分 数值仿真     

一种新型两级APFC变换器设计

针对传统的两级APFC采用两套控制电路和多个功率开关管增加电路复杂程度及成本的问题,该文采用PFC/PWM复合控制芯片MLA824作为控制核心,并设计了一台160W单相两级式功率因数校正装置.分析了基于平均电流控制的单相两级有源功率因数校正电路的基本原理,提出了以ML4824为核心的单相两级有源功率因数校正装置的设计方...