ZVS-PWM正激变换器有源箝位磁复位技术的研究

在有源箝位ZVS-PWM正激变换器中,变压器的磁复位技术是其中最关键的一项技术。文章结合仿真和初步的试验结果对有源箝位ZVS-PWM正激变换器的整个工作过程中的能量流动进行分析,总结出使变压器有效磁复位以及开关管ZVS开通的方法。     

浅谈直流偏磁对变压器的影响

变压器在电网系统中占有重要的地位,是供给电的重要设备,在电网运行过程中,变压器受各种因素的影响,出现了直流偏磁现象.本文分析了直流偏磁对变压器的影响,提出抑制直流偏磁的方法.     

基于双判据融合的串联变压器磁饱和抑制系统

串联变压器磁饱和抑制系统在抑制过程中会出现电流畸变,无法取得较好的抑制效果。为此,基于双判据融合设计了一种新的串联变压器磁饱和抑制系统,通过串联变压器、保护工作器件和电流互感器设置系统硬件结构。采用二次电流波形斜度模块,检测串联变压器的磁饱和电流,计算二次电流谐波确定谐波基波数值,检测电流和电压波形状态,实现磁饱和抑制。实验结果表明,基于双判据融合的串联变压器磁饱和抑制系统能够有效解决电流畸变问题,抑制后二次测量电流波形和电压波形波动较为稳定,该文方法具有良好的抑制效果。     

采用双管正激拓扑构建高性能模块电源

引言高功率密度、高效率以及小外型尺寸已成为当前模块电源技术发展的关键驱动力。双管正激电路是实现这些要求的实用电路之一,被广泛应用在中、高功率电源设计中。双管正激转换器双管正激变换器的原理图与波形如图1所示。双管正激变换器的工作可以分为三个过程:能量转移阶段、变压器磁复位阶段和死区阶段。在能量转移阶段,原边的两个开关都导通,能量从输入端向输出端转移。在变压器磁复位阶段,原边的两个二极管都导通,使变压器绕组承受反相输入电压,从而实现变压器磁复位。当变压器完全复位后,变换器工作在死区阶段,即原边无电流、副边续流…     

大功率UV灯用的漏磁变压器

着重介绍大功率UV灯用的漏磁变压器的结构，自耦式漏磁变压器的设计和调试。     

采用磁集成技术的有源箝位正激变换器设计

针对3.3 V/10 A低压大电流输出、高功率密度电源模块的设计要求,结合有源箝位正激拓扑理论和磁集成技术,提出采用磁集成技术的有源箝位正激变换器;对变换器中的主变压器和输出电感进行集成,得到高效率、高功率密度的有源箝位正激变换器。     

无芯PCB 变压器的基本结构及其特性

本文主要介绍无芯印刷电路板变压器的基本概念、结构、特性。并介绍了无芯印刷电路板变压器的等效电路、电压增益、输入阻抗函数,同时说明了应用无芯PCB变压器的可靠性及其优点。无芯变压器消除了磁芯对频率、磁饱和度和磁芯损耗。运用现代化的印刷电路板技术,能够精确地控制印刷线圈的函数,易于大规模生产。它主要应用于高频的信号和能量转换,具有很大的应用潜能。     

高频变压器铜损的三维模拟仿真与分析

对高频变压器建立三维电磁分析模型,采用有限元法对变压器铜损进行数值求解.模拟分析次级绕组段间距、初级绕组以及磁芯漏磁对次级绕组损耗的影响,并引入了矩形导线和圆导线之间的等效因子.分析表明,在考虑次级绕组段间距、初级绕组以及磁芯漏磁后,高频变压器次级铜损为246.086W,大于Dowell模型的理论计算值107.500W,这为变压器的优化设计提供了参考.     

薄膜解耦集成磁件的结构设计与研究

文中分析了磁件解耦集成的基本原理,得出了磁件实现解耦集成所需的基本条件;根据抵消绕组间耦合作用的方法设计了一个解耦的集成磁件,将一个小功率变压器和一个电感集成在一起;采用薄膜化技术设计制作该集成磁件的薄膜磁芯;为了消除采用传统磁件结构时磁件两端的漏磁,设计了特殊的磁芯结构和与其相配套的绕组结构;对该磁件进行了仿真研究,验证了设计的有效性和可行性。     

直流屏逆变电源直流偏磁的抑制研究

全桥逆变电源输出变压器存在直流偏磁,会对逆变电源和交流负载产生不利影响,必须消除偏磁来保障逆变电源可靠运行.针对偏磁问题,深入分析了偏磁产生的原因,在此基础上提出了解决方案.从算法改进角度考虑对偏磁的抑制,通过检测变压器原边电流的直流分量,反馈给控制器进行PI调节以减少偏磁.并且在设计变压器时加强对抗偏磁能力的设计.该方案已经成功应用于一台1KVA的电力逆变器中.最后通过实验验证了该方法的可行性与有效性,实验结果表明,该方案产生的正弦波质量高,直流分量消除效果明显.     

Implementation of high-coupling and broadband transformer in RFCMOS technology

This paper proposes a structure for transformer with high-coupling, broadband, and small chip area characteristics using current silicon-based technology. The proposed device has tight coupling (k=0.92), wide bandwidth (f/sub SR/=30.8 GHz), and minimum chip area (OD=140 /spl mu/m). Furthermore, the analytical formula for calculating mutual inductance is derived in this study; experimental results indicate that the analytical formula is feasible. The proposed transformer will be useful in designing high-performance RF integrated circuits for wireless applications.     

Finite-element analysis of copper loss in 1-10 MHz transformers

Issues related to the copper loss in the planar windings of 1-1 MHz power transformers are discussed. The relationship between current distribution, copper loss, and core geometry is investigated with the aid of finite-element analysis. Magnetizing current proximity effects are shown to cause excessive copper loss in a simple sandwich transformer, a structure formed by sandwiching the planar winding between two plates of magnetic material. Three alternative transformer structures that reduce this problem are compared. These alternative structures are: the cofired transformer, the slotted gapped transformer, and the slotted ungapped transformer. It is concluded that a slotted transformer design should be used if the magnetizing current is relatively large. Both a slotted gapped and a slotted ungapped design relies strongly on the exact permeability of the material and may suffer from higher core losses because all of the energy is stored in the magnetic material, rather than in an air gap. In either case, the depth of the slot should be About 40% of its width     

平面集成磁件在片式开关电源中的应用研究

将TOPSw itch单片精密开关电源中的高频变压器和滤波电感利用解耦磁集成方法集成在一起,推导了磁件等效电路,作了仿真验证。同时设计了集成磁件,并把集成磁件应用到TOPSw itch单片精密开关电源中作了实验验证。经计算,结果表明该集成磁件的可行性。     

A CMOS IR-UWB Transceiver Design for Contact-Less Chip Testing Applications

This paper presents a novel CMOS impulse radio (IR) ultra-wide-band (UWB) transceiver system design for future contact-less chip testing applications using inductive magnetic coupling as wireless interconnect. The proposed architecture is composed of a simple and robust design of a Gaussian monocycle impulse generator at the transmitter, a wideband short-range on-chip transformer for data transmission, and a g_m-boosted common-gate low-noise amplifier in the UWB receiver path. SpectreRF post-layout simulation with a 90-nm CMOS technology shows that the transceiver operates up to a 5 Gb/s data rate, and consumes a total of 9 mW under a 1-V power supply.     

A 21 GHz Complementary Transformer Coupled CMOS VCO

A new topology for low power voltage controlled oscillators (VCOs) using a 0.18-mum CMOS foundry process is presented in this letter. From the measured results, the VCO exhibits a tuning range of 3% at 21.3 GHz. Using complementary topology, the core power consumption and the output power are 9.6 mW and -3 dBm, respectively. With the broadside coupled transformer, the VCO achieves a good phase noise of -106 dBc/Hz at 1 MHz offset and a compact chip size of 350 times 470 mum². It is the first time that the broadside coupled transformer approach is applied to transformer coupled CMOS VCOs.     

Compact and broad-band millimeter-wave monolithic transformer balanced mixers

Three broad-band miniature monolithic transformer singly balanced diode mixers for operation in the microwave and millimeter-wave bands are reported in this paper. The coupled-line equivalent models are used to synthesize the initial design of these transformers up to 50 GHz. The first one is a broad-band spiral transformer mixer, and the second one is a 21-GHz Marchand-type transformer mixer. These two mixers with chip sizes around 0.29 mm/sup 2/ exhibit bandwidths of 105% and 54.5%, respectively. We also propose a 30-GHz single-coiled transformer mixer, which has comparable performance with the first two mixers and reduced chip size. The single-coiled transformer mixer achieves a bandwidth of 100% with the chip size smaller than 0.25mm/sup 2/. In order to save chip area, all these transformers provide broad-band matching to the diodes directly. To the authors' knowledge, these mixers achieve the widest bandwidths with the smallest chip sizes among all passive balanced mixers using monolithic-microwave integrated-circuit processes in dc-40-GHz frequency range.     

A 17.1-17.3-GHz image-reject downconverter with phase-tunable LO using 3/spl times/ subharmonic injection locking

A 17-GHz RF receiver, consisting of a low-noise amplifier (LNA) and doubly balanced mixers coupled by a monolithic 3.7:1 step-down transformer, realizes over 75 dB of image rejection in a production 100-GHz f/sub T/ SiGe BiCMOS technology. A new coupling transformer winding improves the magnetic coupling coefficient by more than 20% compared to conventional designs, which reduces parasitic effects and increases the overall efficiency of the LNA/mixer combination. Quadrature LO signals with electronically tunable phase are generated by a subharmonically injection-locked oscillator. The measured receiver IIP3 is -5.1 dBm with 17.3-dB conversion gain and 6.5-dB noise figure (SSB 50 /spl Omega/) at 17.2 GHz. The 1.9/spl times/1.0 mm/sup 2/ IC consumes 62.5 mW from a 2.2-V supply.     

Magnetic Susceptibility Meter for In Vivo Estimation of Hepatic Iron Stores

An instrument is described for recording linear body scans of magnetic susceptibility in living rats. The sensor is a transformer which employs a toroid core with a large air gap. The magnetic properties of substances within the gap affect the reluctance of the core-gap magnetic circuit, thereby affecting the transformer characteristics. To minimize instability caused by temperature induced changes in core dimensions, the cores were made of the low expansion steel, Invar. The secondary voltage of the measuring transformer is compared with that of a similar reference transformer with differences in this comparison voltage processed by tuned amplification and phase-sensitive detection. The sensitivity of the instrument is limited by zero instability equivalent to ±0.06×10-6 EMU/cm3 over 30 seconds, with a precision of measurement of ±0.03×10-6 EMU/cm3 achieved by output filtering. Studies using live rats demonstrate that with this technique iron-loaded animals can be distinguished from control animals, because the high hepatic concentration of storage iron in the liver of the experimental group exhibits positive magnetic susceptibility. Consideration of the transformer characteristics suggests that similar, safe, and rapid measurements of magnetic susceptibility can be made in humans, although many other factors remain as variables which must be evaluated before such measurements can be used to quantitate iron stores in patients.     

Design of a CMOS oscillator with magnetic-field frequency modulation

A magnetosensitive n-channel split-drain MOSFET (MAGFET) integrated with a current-controlled oscillator on a single chip is described. This magnetically controlled oscillator (MCO), which was fabricated in 5-/spl mu/m CMOS technology, is sensitive to magnetic fields perpendicular to the chip surface. The output of the MCO is a square wave whose frequency varies linearly with, and is modulated by, the magnetic input signal.     

手机无线充电系统的设计与实现

设计了一种基于半桥式逆变技术和磁感应耦合技术的无线充电系统,整个系统由电源模块、整流滤波模块、高频逆变模块及分离式变压器4部分组成。采用多个初级线圈并联的方式为多个手机类负载同时供电,并通过分离式变压器线圈的优化设计提高了系统性能。测试结果表明该系统克服了采用单个初级线圈充电区域不足、各个设备充电效率低的缺点,减弱了待充电设备间的相互干扰,使其充电效率相当且都能获得基本恒定的电压,具有能量传输效果好、安全方便、成本低、适用范围广等优势。