基于IR1167的智能同步整流控制

引言 随着近年来数字处理电路电压的不断降低，电源功率密度的不断提高，对于电源次级整流的要求越来越高。整流器件已从最初的肖特基二极管整流，发展到用同步整流开关管替代二极管，以降低功耗。目前，控制同步整流开关管的方法主要有分立式和基于锁相环的控制芯片两种。用分立元件实现同步整流的缺点是响应过慢，系统可靠性相对差。单芯片同步整流是基于锁相环技术的，从初级取信号同步控制次级整流开关管，这种方法的缺点是不能保证在间隔模式（轻载或空载时发生）下可靠操作。     

LLC谐振变换器的数学建模和损耗分析

针对LLC谐振变换器在工作过程由于开关管和磁性元件所带来的损耗。分析了LLC谐振变换器的开关损耗和通态损耗,根据理论公式推导,建立了开关损耗的数学模型。结合同步整流技术,应用Mathcad软件分析了影响变换器效率的关键因素。通过仿真分析,验证了同步整流技术可提高LLC变换器谐振器效率的正确性。     

一种高效的同步整流Boost软开关变换器

针对同步整流Boost变换器的效率问题,提出一种同步整流Boost软开关拓扑。在辅助电路的帮助下,实现了主开关管的零电压通断和辅助开关管的零电流通断,显著改善了因开关管导致的变换器损耗严重的问题,使变换器的效率得到了有效提高。详细分析了所提变换器的工作原理并对主要参数的选取和变换器的特性进行了讨论,最后通过Pspice仿真实验对理论分析进行了验证。     

一种同步整流有源箝位正激变换器的研究

提出一种同步整流有源箝位正激变换器。该变换器是在传统的同步整流有源箝位正激变换器的原边增加一个由箝位电容和电感构成的辅助网络得到。该辅助网络可以使变换器在全负载范围内更容易实现主开关管和辅助开关管的ZVS(Zero-Voltage Switching),副边采用自激式同步整流技术,能进一步提升变换器效率,适用于低压、大电流输出场合。详细分析了变换器的工作原理,搭建了一台8 V/100 W试验样机证明了理论分析的正确性。     

具有同步整流功能的高效单端反激变换控制器ML4863的应用

近年来,为了提高低压变换器的效率,通常采用同步整流技术。为此,需要两种驱动信号,ＭＬ４８６３既可驱动单端反激式变换器初级功率开关（ＭＯＳＦＥＴ）,也可驱动作同步整流的ＭＯＳＦＥＴ。因此大大简化了电路结构,提高了效率,本文介绍了ＭＬ４８６３的内部结构和实际应用电路。     

同步整流Buck变换器的损耗分析

文中在以往只粗略计算电感损耗、电容损耗及开关损耗的基础上,以一款低电压大电流同步整流降压变换器为例,详细分析了各个元器件上功率损耗,包括电感上的铜损与铁损,电容等效串联电阻的损耗,MOSFET上的开关损耗、导通损耗、截止损耗、驱动损耗、寄生体二极管损耗等,从而得到直流降压变换器的整体损耗与实际效率。从效率曲线可以看出,变换器效率随着输出电流的增加而增加,并很快趋于饱和。而通过损耗分析可知,要降低损耗提高效率,尤其对于低电压大电流输出的降压变换器,不仅可以采用同步整流技术来降低导通压降,还可以根据各损耗所占比重大小选用更优元器件,如低直流电阻的电感,低导通电阻、低上升下降时间的NMOS管等。     

同步整流技术

DC／DC变换器的损耗主要由3部分组成：功率开关管的损耗，高频变压器的损耗，输出端整流管的损耗。在低电压、大电流输出的情况下，整流二极管的导通压降较高，输出端整流管的损耗尤为突出。快恢复二极管（FRD）或超快恢复二极管（SRD）可达1．0～12V，即使采用低压降的肖特基二极管（SBD），也会产生大约0．6V的压降，这就导致整流损耗增大，电源效率降低。     

新型容性整流ZVZCS三电平直流变换器

提出一种新型零电压零电流(ZVZCS)飞跨电容型不对称PWM半桥三电平变换器,该变换器原边开关器件的电压应力为输入电压的一半;所有开关器件在较宽负载范围内实现软开关,其中超前管实现ZVS开通,ZCS关断;滞后管实现ZCS开通,ZVS关断,从而降低开关损耗;副边采用容性整流,在续流阶段将原边电流降至0,使得开关器件的电流分布更加均衡并减小飞跨电容的电流应力;与此同时,消除二极管反向恢复损耗。文中讨论了电路的结构、工作原理和基础特性,为证明理论正确性,搭建一台500W实验样机来验证。     

基于LPC2214的ZVZCS-PWM全桥变换控制器的研究

针对传统ZVZCS-PWMDC／DC全桥变换器在实现滞后桥臂开关管零电流开关过程中,存在着辅助谐振电路附加损耗较大,软开关实现方式复杂,功率开关管电压应力和电流应力高等缺点,介绍了一种新型次级箝位移相控制的ZVZCSPWMDC／DC全桥变换器。文中分析了该变换器实现软开关的原理,同时设计了变换器数字控制系统,控制器采用LPC2214型ARM芯片,并通过一台实验样机验证了这种软开关变换器相关理论的正确性以及该数字控制系统的可行性。     

实用电源（4）

常用开关电源初级大多接市电（50赫兹）,整流器通常采用普通二极管整流。但DC—DC的次级需要专用高频整流二极管等器件。因为整流二极管和功率开关元件是工作在高频电压电流条件下,要求具有高速、快恢复和正向电阻小三种性能的整流二极管。不可使用市电网整流用的普通整流二极管!否则,就会发生意想不到的后果。     

A high-efficiency soft-switched AC/DC converter with current-doubler synchronous rectification

An improved ac/dc converter based on asymmetrical half-bridge topology is proposed in this paper. To substantially enhance the efficiency for low-voltage/high-current output applications, a current-doubler synchronous rectifier is combined with a modified asymmetrical half-bridge converter that retains the inherent zero-voltage-switching property. The power losses in the secondary rectification stage and the primary switches can be significantly reduced. The proposed architecture exhibits extreme simplicity and lower cost while providing unity power factor, well-regulated output, and high power density. The detailed operating principles and design procedures for the proposed converter are described in this paper. Simulation and experimental results for a laboratory prototype are discussed to verify the feasibility.     

A Novel High-Frequency Transformer-Linked Soft-Switching Half-Bridge DC–DC Converter With Constant-Frequency Asymmetrical PWM Scheme

This paper presents a novel soft-switching half-bridge dc–dc converter with high-frequency link. The newly proposed soft-switching dc–dc converter consists of a single-ended half-bridge inverter controlled by an asymmetrical pulsewidth-modulation scheme and a center-tapped diode rectifier. In order to attain the wide range of soft commutation under constant switching frequency, the single active edge-resonant snubber cell composed of a lossless inductor and a switched capacitor is employed for the half-bridge inverter leg, providing and assisting zero-current-switching operations in the switching power devices. The practical effectiveness of the proposed soft-switching dc–dc converter is demonstrated by the experimental results from an 800 W–55 kHz prototype. In addition, the feasibility of the dc–dc converter topology is proved from the viewpoints of the high efficiency and high power density.      

一种新型半桥不对称PW M控制变换器

介绍了一种适用于DC／DC半桥变换的不对称PWM控制方案，分析了电路的工作原理，给出了150W变换器的仿真波形和实验结论，结果表明，该控制方案能在恒定开关频率下对变换器实现高效率的软开关控制。     

A single-stage fast regulator with PFC based on an asymmetrical half-bridge topology

This work presents single-stage regulators with power-factor correction (PFC) based on an asymmetrical half-bridge topology. The proposed regulator is formed from a boost converter with two coupled inductors and an asymmetrical half-bridge converter with the synchronous switch technique, and it is controlled with pulsewidth modulation to achieve zero-voltage switching (ZVS). The boost converter is operated in discontinues conduction mode to achieve PFC. With the coupled inductors, input current ripple and power factor can be improved significantly. The proposed regulator has the features of constant-frequency operation, ZVS, and low voltage stress imposed on the active switches. Moreover, the regulator can achieve high power factor, high power density, high efficiency, low switching loss, and low component count, which makes its applications at medium-power levels feasible. Experimental results have verified the discussed features of the proposed regulator.     

Small-signal analysis and control design of asymmetrical half-bridge DC-DC converters

This paper presents the small-signal modeling, dynamic analysis, and control design of the asymmetrical half-bridge dc-dc converter that employs a clamp capacitor and a magnetizing inductor to accommodate pulsewidth-modulated operation with asymmetrical duty ratios. The circuit averaging technique is applied to extract the small-signal dynamics of the power stage, and a graphical loop-gain method is used to design the feedback compensation and analyze the closed-loop performance of the converter. The distinctive power-stage dynamics of the converter are addressed and design guidelines for voltage feedback compensation are established. The results of the control design and closed-loop analysis are substantiated by experiments using an experimental converter.     

Design of a power-factor-correction converter based on half-bridgetopology

A single-stage AC/DC converter based on a half-bridge topology suitable for low-power-level applications is proposed. The proposed converter has high power factor, low harmonic distortion, and tight output regulations. An asymmetrical control and synchronous rectification are employed to reduce the switching and rectification losses, respectively. The modeling and detailed analysis are performed to derive the design equations. Based on these design equations, a prototype converter has been designed and tested by experiment. This prototype meets the IEC 61000-3-2 regulations with near-unity power factor and high efficiency     

新型有源饱和电抗器不对称半桥软开关变换器研究

提出了一种新型基于饱和电抗器的零电压不对称PWM半桥变换器。它有低的开关损耗，低的导电损失，恒频控制等许多优点，并对它的工作原理和稳态电路作了分析，同时制作的一个150W、200KHZ的软开关DC-DC变换器样机，证实了上述这些特点和性能。     

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

This paper presents a new single-stage power factor correction ac/dc converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant dc/dc converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the dc-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant dc-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90–265 Vrms).      

A novel single-stage half-bridge AC-DC converter with high powerfactor

A new single-stage AC-DC power converter based on a half-bridge converter suitable for low-power applications is proposed. The proposed converter offers high power factor and direct conversion from the line voltage to an isolated DC output voltage. High power factor is achieved by adding a resonant circuit between the rectifying diodes and half-bridge leg. For soft switching, a half-bridge series-loaded resonant converter is adopted as a DC-DC converter part. A prototype is built and tested to show the validity of the proposed converter     

Design and performance evaluation of low-voltage/high-current DC/DCon-board modules

The topology selection, design, and performance evaluation of an on-board DC/DC converter, which delivers power from a 48 V input to a 1.2-1.65 V/70 A microprocessor load, are presented. It was shown that the symmetrical half-bridge topology with the current doubler and synchronous rectifiers is a suitable approach for this application. The measured full-load efficiency of a 200 kHz experimental half-bridge converter was higher than 82% in the entire output and input voltage range