一种用于恒压AC-DC变换器的新型模拟指数波产生电路

本文提出了一种用于恒压AC-DC变换器的新型模拟指数波产生电路,并据此设计了一种受误差放大器输出动态调节幅值的可变指数波产生电路。该结构能够解决传统三角波恒压控制负载调节范围窄的问题,且相比于其他指数波电路,本文电路结构简单,可以有效节省版图面积,输出波形平滑,误差较小。本文对提出的指数波产生电路输出电压进行了完整的分析和公式推导,并基于Nuvoton 0.35um BCD工艺在Cadence Spectre仿真平台上验证了指数波产生电路的可行性和有效性。经仿真验证,轻载下的开关频率能够降低为三角波控制方式下的1/4,有效降低了轻载开关频率。且改进后指数波应用于恒压AC-DC变换器系统中负载调整率仅为0.542mV/mA。     

大屏幕彩电开关电源对冲击电流的抑制措施

在大屏幕彩电电视机中，要求开关是源在电网电压从１４０Ｖ至２８０Ｖ的范围内都能保证稳定的电压输出和足够的功率输出，当电网电压偏高时开机，有较大的冲击电流，很容易损坏开关管。文章分析了形成冲击电流的原因，并提出了解决方案。     

基于不可控整流的单相PFC研究

电力电子设备在各工业领域的广泛应用造成了日益严重的谐波污染问题,有源功率因数校正技术成为解决这一问题的有效方法。文章在分析传统Boost电路导致功率因数降低的原因和Boost APFC原理的基础上,针对目前功率因数校正效果偏低的问题,提出了双闭环融合电流前馈技术的控制策略,搭建了单相Boost APFC实验平台加以验证。实验结果表明,本控制方式具有功率因数高、输出电压稳定、动态响应效果好等优点。     

不连续导通模式PSM PT控制开关变换器

脉冲跳周期调制（Pulse Skip Modulation,PSM）采用ON/OFF控制对输出电压进行调整,提高了开关变换器的轻载效率,但存在输出电压纹波大的缺点。文中结合开关变换器的脉冲序列调制（Pulse Train,PT）控制与PSM技术,提出了开关变换器的PSM PT控制技术,其降低了输出电压的纹波,并使PT控制开关变换器在空载时能稳定工作。     

一种宽负载范围低纹波高效率能量收集系统北大核心

针对环境能量收集系统输出电压纹波高以及效率随负载变化等缺点，提出了一种在宽负载范围内转换效率高且输出电压纹波低的能量收集系统。该系统基于最优化导通时间(OOT)控制方法对输出纹波进行调控，解决了传统控制方法在小负载电容和轻载情况下纹波较大的问题；此外，基于自适应系统时钟频率(ACF)控制方法改善了传统方法在轻载时效率大幅度下降的问题，实现系统在较宽负载范围内保持较高的效率。采用180 nm CMOS工艺对能量收集系统进行设计验证。仿真结果显示，所设计的能量收集系统在1 mA负载电流范围内峰值效率为89.75%,最低效率为83.75%,其最低效率比同类系统提高了7个百分点以上；在0.2μF负载电容下纹波从177.96 mV下降到23.56 mV。     

基于推挽拓扑的输入并联输出串联变换器研究与设计

在输出高电压场合,由于存在高压存在,使得输出端器件承受较大的输出高电压和高电压应力。为解决输出端电压应力高等问题,提出以推挽变换器为基本单元,采用多个基本单元在输入端并联且在输出端并联,以此构成以推挽变换器为单元的输入串联输出并联组合式变换,给出了组合式变换器系统的小信号模型以及均压稳定条件,根据建立系统小信号模型以及实验样机参数要求,给出变换器驱动电路、变压器磁参数以及逐周期保护电路设计方式。最后经试验验证了理论分析 的正确性。     

轻载高效Buck转换器设计及其纹波控制方案

提出了一种峰值电流模式PWM下的轻载高效Buck DC-DC控制方案。该方案根据负载大小来自适应调节开关频率和电感电流峰值,实现宽负载范围内高的转换效率和对输出纹波的控制。把误差信号与负载自适应的门限相比较,以判定转换器工作模式。在轻载模式下,通过循环开启或者关闭振荡器来降低转换器的开关频率,降低开关损耗。详细推导了在保持输出电压纹波不变的情况下,负载自适应门限与负载大小之间的关系,并在典型应用下得到二者呈线性关系的结论。采用0.5μm BCD工艺进行仿真,结果显示,在输入电压12 V,输出电压3.3 V下,轻载时最高有94.2%的转换效率,在负载从10 mA到500 mA变化时,轻载模式纹波为120~140 mV,与理论分析的控制纹波130 mV较为符合。     

雷达发射机浮动板调制器与故障检测电路的设计

提出了一种改进的浮动板调制器和对正负偏电压的故障检测电路,利用MOSFET寄生电容特性,通过固定脉宽窄脉冲控制调制脉宽,通过增加负偏MOSFET提高输出负偏电压。对故障检测电路进行仿真实验,通过模拟故障,验证故障检测报警信号发生时间均在微秒级别。完成样机的搭建,利用多重方式解决高压绝缘问题,并对其加电进行试验验证,分析实验波形,证明此电路满足设计要求并且具有可行性。     

一种用于Flash的新型电荷泵调节技术

在Flash、带电可擦可编程只读存储器(EEROM)等存储器中,电荷泵电路是用于提供编程、擦除和读取高压的重要模块。电荷泵调节电路用于输出稳定的电压和电流。文章提出了一种新型Flash电荷泵调节电路,以解决传统电路在轻负载时纹波过大而难以适用多位Flash的问题。其电路结构特征是对传统频率调节电路增加了时钟幅度调节模块,使得在电流轻载时电荷泵在较小的时钟幅度下工作,而在电流重载时切换到最大时钟幅度,并且通过锁存控制电路避免临界负载时的时钟幅度反复改变。基于XMC 65 nm浮栅工艺的Cadence Spectre仿真表明,该电荷泵调节技术能够在轻载和重载两个状态下都保持40 mV的纹波电压,有效减少了轻载情况下Flash电荷泵输出纹波。     

一种高效率反激同步整流DC-DC

目前,小型机载电子设备对二次电源体积、输入电压范围、输出电压种类、功率及效率的要求越来越高。基于单端反激拓扑和辅助绕组自驱动同步整流结构,设计了一种多路输出DC-DC电路。分析了多路电源的损耗组成、影响因素和解决措施,以指导电路设计和元器件选型,最终确定系统设计方案。重点对反激变压器设计、同步整流驱动设计和同步整流轻载损耗较大的原因开展分析和研究。实验电路测试结果表明,设计的反激同步整流DC-DC电路满足指标要求。     

A novel method to achieve zero-voltage regulation in buck converter

The function control law for a buck converter is derived to achieve zero voltage regulation of the output voltage. A new method to retrieve the low frequency component of the inductor voltage is proposed and analyzed. The stability of the closed loop system using a proportional and differential controller is analyzed. The effect of the supply voltage and load current disturbance is also studied. The analysis, computer simulation by PSPICE and experimental results illustrate that excellent performance can be achieved by the function control law     

开关DC-DC变换器的自适应占空比跨周期控制方法

针对脉冲跨周期调制(PSM)开关DC-DC变换器输出电压纹波较大的问题,该文提出一种新型的自适应占空比跨周期(ADPS)控制方法。在ADPS控制的变换器中,轻载下,每个周期变换器控制脉冲的占空比与该周期开始时输出电压与参考电压误差的平方根近似成正比;负载越轻,变换器的输出电压纹波越小。研究表明,ADPS控制的DC-DC变换器不仅具有比PSM控制的变换器更低的输出电压纹波,同时具有优异的鲁棒性和瞬态响应能力。     

纯电动汽车实验台架用直流电源稳压控制器设计

针对纯电动汽车实验台架使用蓄电池作为实验能源存在难以保证实验连续性与长期性的问题,提出了用整流电路代替蓄电池作为实验台架设备能源这一方案。采用电容滤波加单片机闭环控制稳压的方法克服了整流电路输出电压纹波系数过大、输出电压随负载变化等缺点,保证了整流电源输出电压动态稳定。实验测试表明,该电源近似具有恒压源的输出特性．可以...     

一种动态补偿、高稳定性的LDO设计

设计并实现了一种动态补偿、高稳定性的LDO.针对LDO控制环路稳定性随负载电流变化的特点,给出一种新颖的动态补偿电路.这种补偿电路能很好地跟踪负载电流的变化,从而使控制环路的稳定性几乎与负载电流无关.设计采用CSMC 0.5μm标准CMOS工艺,利用Cadence的EDA工具完成电路设计、版图绘制和流片测试,最终芯片面...     

Adaptive duty ratio modulation technique in switching DC–DC converter operating in discontinuous conduction mode

Adaptive duty ratio (ADR) modulation technique in switching DC–DC converter operating in discontinuous conduction mode is proposed in this paper. The proposed ADR modulation technique can regulate the output voltage of the DC–DC converter by generating a series of duty ratios with very simple circuit architecture. The duty ratio is approximately proportional to the square root of the voltage difference between the regulated output voltage and the reference voltage at the beginning of the switching cycle at the light load. As a result, the proposed ADR modulation technique can achieve smaller ripple than the conventional pulse skip modulation over the whole load range. Moreover, the compromise between the light-load ripple and the output power range in the design stage in previous works is solved in the ADR modulation technique. Theoretical analysis, simulation and experimental results are presented to show the operation principle and the advantage of the proposed ADR modulation technique.     

Adaptive current-threshold detector for an adaptive on-time Buck converter at light load

The adaptive on-time control technique has been tremendously utilized in DC–DC converters for its fast transient response, easier design and high efficiency at light load. In some applications the output voltage ripple of DC–DC converters has to be maintained within an acceptable level to achieve superior performance, which depends largely on the load current for adaptive on-time buck converters when operating in discontinuous conduction mode. This paper proposes an adaptive current-threshold detection method for reducing the output voltage ripple. An actual detector circuit is presented to implement the method. This circuit monitors the relationship between the peak inductor current and the load current at light load. Then it outputs a logic signal which controls the turn-on time of the main power MOSFET and hence the peak inductor current. Therefore, the magnitude of the output voltage ripple is controlled. The current-threshold detection method has been verified in an adaptive on-time buck converter by simulation and experimental results. The proposed method can also be used in other constant on-time converters.     

带跨周期调制的斜坡补偿电路

提出一种带跨周期调制(PSM)的斜坡补偿电路,既能实现斜坡补偿、维持系统稳定,同时电感电流最大值和带载能力不受斜坡补偿的影响,轻载时也能实现PSM控制,使输出电压稳定,并且提高了效率。与一般PSM设计电路相比,该电路设计简单、易于实现。仿真结果表明,在15%~90%的占空比范围内,电感电流最大值变化量微小,PSM控制在轻载时大幅提高了转换器的效率。     

Self‐Powered Vehicle Emission Testing System Based on Coupling of Triboelectric and Chemoresistive Effects

Traditional triboelectric nanogenerator (TENG)‐based self‐powered chemical‐sensing systems are demonstrated by measuring the triboelectric effect of the sensing materials altered by the external stimulus. However, the limitations of triboelectric sensing materials and instable outputs caused by ambient environment significantly restrict their practical applications. In this work, a stable and reliable self‐powered chemical‐sensing system is proposed by coupling triboelectric effect and chemoresistive effect. The whole system is constructed as the demo of a self‐powered vehicle emission test system by connecting a vertical contact–separate mode TENG as energy harvester with a series‐connection resistance‐type gas sensor as exhaust detector and the parallel‐connection commercial light‐emitting diodes (LEDs) as alarm. The output voltage of TENG varies with the variable working states of the gas sensor and then directly reflects on the on/off status of the LEDs. The working mechanism can be ascribed to the specific output characteristics of the TENG tuned by the load resistance of the gas sensor, which is responded to the gas environment. This self‐powered sensing system is not affected by working frequency and requires no external power supply, which is favorable to improve the stability and reliability for practical application.     

A fully on-chip 1-μW capacitor-free low-dropout regulator with adaptive output stage

A fully on-chip 1-μW fast-transient response capacitor-free low-dropout regulator (LDO) using adaptive output stage (AOS) is presented in this paper in standard 0.13-μm CMOS process. The AOS circuit is proposed to deliver extra four times of output current of the operational amplifier at medium to heavy load to extend the bandwidth of the LDO and enhance the slew rate at the gate of the power transistor. And the AOS circuit is shut off at light load to reduce the quiescent current and maintain the stability without requiring area-consuming on-chip capacitor. Meanwhile, the proposed AOS circuit introduces V_OUT offset at medium to heavy load to counteract the V_OUT drop, which is caused by I_LOAD increase. Hence, transient performances of LDO and V_OUT drop between light load and full load are improved significantly with 1.1-μA quiescent current at light load. From the post simulation results, the LDO regulates the output voltage at 0.7 V from a 0.9-V supply voltage with a 100-mA maximum load current. The undershoot, the overshoot and the recovery time of the proposed LDO with I_LOAD switching from 50 μA to 100 mA in 1 μs are about 130 mV, 130 mV and 1.5 μs, respectively. And the V_OUT drop between light load and full load reduces to 0.16 mV.     

一种具有快速瞬态负载响应的DC-DC变换器

分析了开关电源瞬态负载的基本原理、输出电压跌落幅度与电源环路之间的相互关系,比较了减小输出电压跌落幅度的几种控制方式,提出了采用数字非线性控制方式提升瞬态负载响应的方法。基于以上分析,全面评估了环路带宽、整流方式、非线性控制对开关电源瞬态响应的影响。最后采用非线性控制方法,设计了一种具有快速瞬态负载响应的DC-DC变换器。实验结果表明,脉冲负载时输出电压跌落可减小60%,恢复时间缩短30%,试验结果满足设计要求。