Quasi current resonant DC link AC/AC converter

A new quasi current resonant DC link (QCRDCL) topology has been developed in this paper. Although prototype current resonant DC link topologies for AC/AC power conversion have had such problems as irregular high current peaks, uncontrollable pulse width, etc., this new topology enables the AC/AC conversion system to have the properties wherein the current peak is limited and the pulse width is adjustable. The system begins to assume an adjustable-width flat-topped current shape, whereby the system becomes particularly suitable for high power application. With control of the pulse width a very fine load current regulation can be obtained. In this system, an open loop PWM control has been adopted and almost the same quality of output waveforms as the conventional current source inverter has been achieved     

A single-stage power-factor-corrected AC/DC converter

This paper presents a single-stage isolated converter topology designed to achieve a regulated DC output voltage having no low-frequency components and a high-input power factor. The topology is derived from the basic two-switch forward converter, but incorporates an additional transformer winding, inductor and a few diodes. The proposed circuit inherently forces the input current to be discontinuous and AC modulated to achieve high-input power factor. The converter output is operated in discontinuous mode to minimize the bulk capacitor voltage variations when the output load is varied. Analysis of the converter is presented, and performance characteristics are given. Design guidelines to select critical components of the circuit are presented. Experimental results on a 150 W 50 kHz universal input (90-265 V) 54.75 V output AC/DC converter are given which confirm the predicted performance of the proposed topology     

BUCK DC/DC变换器最优化设计

为了设计出高性能的开关电源,选择性能更为优越的功率半导体器件,改进电路拓扑结构,选择和改进控制电路的控制方式,优化器件的排列布局等成为必然途径.从BUCK DC/DC变换器的基本工作原理着手,设计了主电路参数,运用非线性规划技术对该电路进行优化设计,得到最优化模型,然后运用ORCAD PSPICE软件对电路进行仿真,仿真结果表明:运用最优化设计所体现的优越性明显,提高电路设计质量.     

一种双向DC/DC变换器的研究与设计

本系统以TPS4530为核心设计了高效率的DC/DC变换电路,此电路是用脉宽调制工作方式,通过开关管把直流电斩成方波并调节方波的占空比来改变电压,来达到对电池恒流充电的效果;通过L7805CV正电压稳压器模块作为系统的辅助电源,方便控制。本系统具有过流保护及热关断功能,并以数码管显示其电流的变化。     

Analysis,design and implementation of an interleaved three-level PWM DC/DC ZVS converter

This paper presents a new parallel three-level soft switching pulse-width modulation (PWM) converter. The proposed converter has two circuit cells operated by the interleaved PWM modulation. Thus, the ripple currents at input and output sides are reduced. Each circuit cell has two three-level zero voltage switching circuits sharing the same power switches. Therefore, the current and power rating of the secondary side components are reduced. Current double rectifier topology is selected on the secondary side to decrease output ripple current. The main advantages of the proposed converter are soft switching of power switches, low ripple current on the output side and low-voltage rating of power switches for medium-power applications. Finally, the performance of the proposed converter is verified by experiments with 1 kW prototype circuit.     

Flexible and low cost design for a flyback AC/DC converter with harmonic current correction

This study presents a new simple flyback ac/dc converter with harmonic current correction and fast output voltage regulation. In the proposed ac/dc converter, an extra winding wound in the transformer provides two key advantages. The size of the bulk inductor used in the conventional boost-based power factor correction cell can be significantly reduced in the proposed converter. The voltage across bulk capacitor can be held under 450V by tuning the transformer winding ratio even though the converter operates in a wide range of input voltages (90 V/spl sim/265V/ac). This new converter complies with IEC 61000-3-2 under the load range of 200 W, and can achieve fast output voltage regulation.     

Single-switch AC/DC converter with power factor correction

A single-switch, one-stage power factor correction converter with output electrical isolation is proposed. To relieve the voltage spike caused by the leakage inductance of the power transformer, two bulk storage capacitors are used. The proposed converter has both a good power factor correction and excellent line and load regulation capabilities with an efficiency of 87%     

单片高压AC／DC转换器TOPSwitch—GX系列

输出功率范围从5W至250W,高度设计灵活性,待机功耗低,最大限度降低了系统成本     

An AC/DC converter with high power factor

The television receiver often employs a capacitor-input-type rectifier. In this case, it is regulated as a class D piece of equipment. This paper presents a novel ringing-choke-converter-type switching regulator, which functions as an active filter. The proposed circuit features a simple circuit configuration and cost effectiveness. It achieves a high power factor of about 0.95 and reduces current harmonics (third, fifth, and seventh) in the AC input current to less than 40% of the limit value for class D. The voltage across the input smoothing capacitor does not show large variations and the components in the conventional ringing-choke converter can be used unmodified. Ripple content of the DC output voltage shows a slight increase and is the subject for future research.     

Integral 3-D thermal, electrical and mechanical design of an automotive DC/DC converter

Power electronics is finding increasingly more applications in high temperature environments where power density is also a driving factor. The engine compartment of a passenger vehicle is one such example. In this paper, an integral thermal, electrical, and mechanical design of a high power density dc/dc converter operating in the thermally harsh automotive environment is discussed. The interactions and interdependencies between the three design disciplines are considered. It is illustrated how these interactions can be manipulated and used to an advantage in meeting the harsh temperature and high power density requirements of the automotive converter. Packaging and circuit techniques are identified that can be used to this end. Two case studies of a 2-kW 14-V/42-V dc/dc converter for application in the automotive environment are considered. The first prototype achieved a power density of 170 W/in/sup 3/ while the second prototype, operating with a higher environmental temperature achieved a power density of 120 W/in/sup 3/. The experimental structures and practical results are presented. Technology issues concerning the three-dimensional construction of the prototypes that need research attention are also identified.     

Modeling PWM DC/DC converters out of basic converter units

An alternative approach to modeling pulsewidth-modulated (PWM) DC/DC converters out of basic converter units (BCUs) is presented in this paper. Typical PWM DC/DC converters include the well-known buck, boost, buck-boost, Cuk, Zeta, and Sepic. With proper reconfiguration, these converters can be represented in terms of either buck or boost converter and linear devices, thus, the buck and boost converters are named BCUs. The PWM converters are, consequently, categorized into buck and boost families. With this categorization, the small-signal models of these converters are readily derived in terms of h parameter (for buck family) and g parameter (for boost family). Using the proposed approach, not only can one find a general configuration for converters in a family, but one can yield the same small-signal models as those derived from the direct state-space averaging method. Additionally, modeling of quasi-resonant converters and multiresonant converters can be simplified when adopting the proposed approach     

Steady-state analysis and design of a buck zero-current-switchingresonant DC/DC converter

An analytic basis is provided for a buck high-efficiency high-frequency zero-current-switching resonant DC/DC power converter. The current and voltage waveforms are derived for the steady-state operation. Design equations are then introduced for the switch duty cycle, maximum switching frequency, DC transfer function, peak currents and voltages, output power, and power conversion capability. Finally, the design procedure is presented along with the advantages and disadvantages of the converter, which are discussed in detail     

Self-oscillating resonant AC/DC converter topology for inputpower-factor correction

This paper presents the analysis and design of a single-phase single-stage high-power-factor AC/DC converter employing a series-parallel resonant topology operating in self-sustained oscillating mode. A control approach is proposed to achieve low total harmonic distortion of the input current. This approach does not require sensing of the input current. In addition, the inverter output current is limited during transients, and the converter operates with zero voltage switching for all operating conditions including open and short circuit. The performance of the proposed scheme is verified experimentally on a 500 W prototype     

桥式直流PWM变换器的建模与仿真研究

首先介绍了PWM控制技术的基本原理,然后结合无源逆变器,详细地阐述了桥式直流PWM变换器的工作原理。最后在MATLAB/Simulink建立了桥式直流PWM变换器的仿真模型,然后对仿真结果进行了分析,仿真结果表明通过调节占空比,可以改变电压和电流的大小和方向,与理论分析完全一致。     

A new control strategy for an AC/DC converter based on a piezoelectric transformer

Piezoelectric transformers (PTs) are an attractive solution to reduce size and weight in ac/dc converters. In this paper, a PT-based topology is presented together with a control method. As an application, an 8-W ac/dc adapter (110 V/sub AC/ input, 12 V/sub DC/ output) is presented operating at frequencies around 500 kHz.     

Performance of MCT's in a current-regulated AC/DC PDM converter

An AC/DC current-regulated pulse density modulated (PDM) power converter is presented. The MOS-controlled thyristor (MCT) is used in this power converter because of its promising advantages over existing power devices. A unique bidirectional switch configuration is used, which allows the MCT to switch easily at zero voltage. The converter performance is evaluated driving a 5 hp induction motor. MCT switching was performed satisfactorily, but the device fails before its ratings are reached. The MCT will be better than other devices when used in applications that require critical timing and high voltage blocking capability     

LM2717型双降压直流/直流变换器的原理及其应用设计

LM2717是美国国家半导体公司推出的一款全新的高性能变换器,内含两个脉宽调制(PWM)直流/直流转换器,功能强大.介绍了该器件的主要参数、工作原理和引脚功能,讨论利用LM2717进行应用设计时选择外部器件的原则及设计中应注意的问题.     

Analysis and design of a DC/DC converter using square-wave outputresonant inverter

The operating modes of a square-wave output resonant inverter when used in a high-frequency link DC/DC converter are presented and analyzed. The condition of minimum turn-off time for the switches in the discontinuous current mode is obtained. A simple design procedure for the DC/DC converter is presented and illustrated by an example. Experimental results obtained from a prototype converter are presented to verify the theory