基于TMS320F28XX+UCD8K+HCPL-315J的两级逆变器

介绍以TMS320F28XX、UCD8K和HCPL-315J为核心的单个DSP控制"DC/DC直流变换器 DC/AC逆变器"两级变换逆变器.在介绍整体电路的基础上,详细分析了每个器件的特点及应用.并在500 VA 28 VDC/115 V 400 Hz逆变器样机上进行了实验,验证了设计电路的有效性.     

MDAC2475型DC／AC变换器

MDAC2475型DC／AC变换器是输入直流24V,输出交流75V（25Hz)的铃流模块,本文阐述了实现铃流源的几种方法及它们的优缺点,介绍了MDAC2475型DC／AC变换器的电路工作原理及工艺过程,重点介绍了研制过程中解决的几个关键技术问题。     

一种大功率厚膜混合集成DC/DC变换器设计

现有厚膜混合集成DC/DC变换器的最大输出功率仅为150 W,针对输出功率无法满足工程使用需求的问题,开展大功率厚膜混合集成DC/DC变换器技术研究。采用带次级同步整流的移相全桥拓扑结构,详细阐述了反馈控制电路、磁隔离驱动电路、同步整流控制电路等设计关键点的实现方式。研制了一款500 W厚膜混合集成DC/DC变换器试验样机,将厚膜混合集成DC/DC变换器的最大输出功率由150 W提升至500 W,最高功率密度由100 W/in³提升至167 W/in³,试验结果验证了整体方案的可行性。     

多模式AC/DC控制芯片的过载研究

多模式AC/DC控制芯片根据负载情况选定相应高效的工作模式以获得高效率.为了合理设定工作负载,在基于Verilog-A建立的反激式变换器仿真模型基础上,仿真研究了多模式AC/DC控制芯片的过载行为.结果表明,当负载过重后,变压器初级获得的能量不足以使输出电压稳定,输出电压开始下降.根据仿真曲线确定了输出电压20 V下的过载点为13.4 Ω.     

改善3G手机功放效率的方法

功率放大器是手机的重要组成部分,其效率是影响手机连续通话时间的重要因素。考虑第三代移动电话发射信号的特性,必须选用线性度较高的功放,这会限制功放效率。在不同输出信号功率下,功放效率将随信号的减小而下降。对于一些功放,在输出中小信号时,低功率偏压模式可改善功放效率。功放在低电压模式下具有较小的消耗电流,可以使用DC-DC电压变换器调整功放输入电压改善功放效率。     

六重交错并联双向DC/DC变换器设计

双向DC/DC变换器是根据需求调节能量双向传输的直流到直流的变换器.交错并联技术在大功率、多重化DC/DC变换器应用广泛,可以用较低的开关频率获得较高开关频率的输出效果,能够有效减小变换器的纹波值.本文在单相DC/DC变换器的基础上,设计一种六重交错并联双向DC/DC变换器,能够提高系统的开关频率、降低纹波电流,从而提高电压和电流精度.最后通过仿真及实验分析结果表明,六重交错并联DC/DC变换器的纹波明显小于单相DC/DC变换器,有利于电能质量的提高,证明了结论的正确性.     

悬浮型高压窄脉冲放大器的研究

悬浮型高压窄脉冲放大器输出的是脉宽100ns、上升/下降沿10ns的高压脉冲,运用其中的DC/DC变换器处于动态悬浮隔离供电状态.为使DC/DC变换器适用于高压瞬态跃变状态,首先要求DC/DC变换器的输入/输出耦合电容的存在不影响高压窄脉冲的质量,其次是输出高压窄脉冲时的高速瞬态跃变不会影响DC/DC变换器的供电稳定性.因此,研究悬浮型高压窄脉冲放大器的驱动方式,就是要着重分析动态运用中的DC/DC变换器的工作状态.     

一种应用于直流电源的热替换与冗余新技术

文中以一个DC/DC 电源子系统的设计为例,说明了应用在DC/DC变换器模块上的热替换与冗余技术的工作原理.特别提出一种称为互补隔离的新冗余技术,以此来解决传统输出冗余二极管的隔离功率损耗大的缺陷问题.互补隔离技术法为在输出二极管两个端子上并联功率电磁继电器的一对常开触点,并用冗余控制信号对触点的闭合或释放状态进行控制.     

微型降压式DC/DC模块LTM46OO

一般的DC/DC变换器集成电路由控制器、MOSFET开关管及一些功能电路组成.近年来,DC/DC变换器采用了同步整流技术,又集成了同步整流的MOSFET.凌特公司最近开发出一种微型降压式DC/DC模块,它不仅集成了控制器、开关及同步整流MOSFET及各种功能电路,并且还把可输出10A电流的电感器、软启动电容器做在一个贴片式IC中,外部只要接上输入、输出电容器及一个设定输出电压的电阻就成为完整的DC/DC模块电源.本文介绍这种微型DC/DC模块LTM4600及其应用电路.     

西安伟健电子代理WEIKING电源模块系列产品

近日西安伟健电子开始代理伟京电子制造公司推出的电源模块系列产品,包括DC-DC变换器、高压输出DC- DC变换器、高低压混合多路输出DC- DC变换器和大电流低压差线性稳压器等。     

A high performance amplitude/phase modulated digital-to-synchro switching power converters

In this paper, a high performance three-phase switching digital-to-synchro (D/S) power converter is proposed for driving high power synchro motors. An amplitude/phase modulation algorithm is implemented with digitally controlled sinusoidal pulse-width-modulation. Design methodology and synchronization improvement are also presented. The generated synchro format output is first verified by simulation and then by a digital signal processor controlled hardware prototype testing. Experimental results indicate that the switching amplifier based D/S converter not only shrinks the size over the conventional linear amplifier based unit, but also demonstrates superior performance to the commercially available unit.     

宽带直流放大器

针对小信号的幅度小、干扰大,线性放大难和提取难度大等问题,设计一种宽带直流放大器,是以单片机AT89C55WD和FPGA为控制核心,由可变增益放大器AD603为核心的放大电路、前级信号调理电路、后级功率放大电路和滤波电路组成。该放大器具有高增益且增益连续可调、输出波形无明显失真、有效抑制零点漂移和噪声、可输出大功率等特性．且在0-10MHz的频带内信号可放大0～75dB,带宽设置为5MHz或10MHz两种,输出信号峰峰值高达20V。     

5V单电源供电的低噪声宽带放大器

以单片机MSP430F449为控制核心,设计了一个5 V单电源供电的低噪声宽带放大器。采用单位增益稳定低噪声运放OPA820作为前级放大,高速运放THS3091作为末级放大,其中利用DC-DC变换器TPS61087将5 V电压转化为18 V从而为末级放大电路供电。此外,系统还采用12位高速A/D转换器ADS803实现了测量并数字显示放大器输出电压峰峰值的功能,测量误差小于5%。本系统最高电压增益达到43 dB,上限及下限截止频率达到15 MHz和20 Hz,在50Ω负载上,最大不失真输出电压峰峰值为4.2 V。系统的输出噪声小于200 mV。     

A Class B switch-mode assisted linear amplifier

A switch-mode assisted linear amplifier (SMALA) combining a linear (Class B) and a switch-mode (Class D) amplifier is presented. The usual single hysteretic controlled half-bridge current dumping stage is replaced by two parallel buck converter stages, in a parallel voltage controlled topology. These operate independently: one buck converter sources current to assist the upper Class B output device, and a complementary converter sinks current to assist the lower device. This topology lends itself to a novel control approach of a dead-band at low power levels where neither class D amplifier assists, allowing the class B amplifier to supply the load without interference, ensuring high fidelity. A 20 W implementation demonstrates 85% efficiency, with distortion below 0.08% measured across the full audio bandwidth at 15 W. The class D amplifier begins assisting at 2 W, and below this value, the distortion was below 0.03%. Complete circuitry is given, showing the simplicity of the additional class D amplifier and its corresponding control circuitry.     

Ultrafast Tracking Power Supply With Fourth-Order Output Filter and Fixed-Frequency Hysteretic Control

A practical solution is presented for the design of a non-isolated dc/dc power converter with very low output ripple voltage and very fast output voltage step response. The converter is intended for use as an envelope tracking power supply for a radio frequency power amplifier (RFPA) in a TETRA enhanced data service (TEDS) base station. A simple and effective fixed-frequency hysteretic control scheme for the converter (buck with fourth-order output filter) is developed and analyzed. The proposed approach is verified experimentally by a 500 W output prototype, capable of delivering any voltage in the range of 10–30 V within 10 $mu{hbox {s}}$ with 10 mVpp of output ripple and efficiencies in the 88%–95% range.      

A Cavity-Type Parametric Circuit as a Phase-Distortionless Limiter

This paper is a study of the properties of a diode parametric frequency converter (negative-conductance type) when used to perform microwave limiting. Unlike the parametric amplifier, the output power of a converter cannot exceed a certain level, regardless of the amplitude of the input signal. Thus, the ability to limit is a fundamental property of regenerative parametric frequency converters. An experimental limiter circuit, consisting of two stages of parametric frequency conversion, provided an output which was constant to within +- 1 db over a range of input of 50 db, and had 10db small-signal gain. The phase variation was less than seven degrees over the entire range of input power.     

An alternative method for controlling two-output DC-to-DCconverters using saturable core inductor

The method proposed in this paper is an alternative to the use of a conventional magnetic amplifier in the control of a second output in buck derived DC-to-DC power converters. This method avoids the use of linear devices in the magnetic amplifier and improves the power converter dynamic response. It is very simple and it is based on the use of a saturable core and in the double switching frequency and duty cycle modulation in the power transistor     

一种短波有源天线供电转换器的设计

设计了一种短波有源天线供电转换器,利用直流信号和高频信号的频率差异,通过一条传输线路完成射频信号的传输和天线放大器的直流供电,根据射频器件的高频特性实现2路信号的隔离和复用,采用ADS射频仿真软件建立仿真模型。仿真结果显示在工作带宽内射频阻抗特性和直流电压平稳。制作了一台四通道短波有源天线供电转换器,在1．5～30 M Hz的工作频率范围内实测结果和仿真计算结果相吻合,可与宽带接收机实现良好的匹配。同时,供电转换器各通道之间幅度和相位一致性很好,还可满足一些有源阵列天线的需求。     

一种带功率检测和自适应偏置的CDMA功率放大器

设计了一款包含功率检测和自适应线性化偏置电路的CDMA功率放大器,功率检测器能根据输入信号的大小来调整功率管的偏置点,大幅提升低功率输出时的效率,从而提升系统整体效率;自适应线性化偏置能有效抑制功率放大器的增益压缩和相位失真,改善其线性度.采用2 μm InGaP/GaAs HBT晶体管工艺成功流片,测试结果表明,与普...     

适合容性负载的高压大功率放大器

设计了一种适合压电陶瓷等容性负载的双极性可调高压大功率线性放大器,它由简单低廉的低压运算放大器、基于功率场效应管(MOSFET)的功率放大级组成主回路,通过电压负反馈构成闭环控制。对电路中各环节的特性进行了分析,并讨论了放大器的性能。该高压放大器在驱动等效电容为60nF的压电陶瓷时,单端到地输出电压为一600～ 600V,电压增益42dB,大信号带宽800Hz,小信号带宽7kHz,充放电电流可达200mA,静态电流可达1．4mA。实验与分析表明,高压直流放大器采用功率场效应管和电压闭环控制后,可拓展放大器通频带,提高放大器输出能力和长时间稳定性。