Zero-voltage-ripple rectifiers and DC/DC resonant converters

Class E zero-voltage-ripple (ZVR) rectifiers are introduced. The proposed circuits offer a new means of a significant improvement in suppressing the output voltage ripple compared with their predecessors. Therefore, the size of the output filter can be considerably reduced, the rI_rms² conduction power loss in the equivalent series resistance of the filter capacitor can be lowered, aluminum or tantalum electrolytic capacitors may be entirely eliminated, filter capacitors with low capacitances and thereby high self-resonant frequencies can be used, and a faster dynamic response becomes achievable. ZVR is accomplished by reducing the AC component of the current at the input of the output filter. Class E² and Class D-E ZVR resonant DC/DC power converters are derived using the Class E ZVR rectifiers. An experimental prototype of a Class E² 30 W/500 kHz DC/DC converter was built and tested. Its output voltage ripple was as much as 20 times lower than that of the corresponding conventional converter. The new converters are suitable for noise-sensitive high-output-current applications     

Single-cycle resonant converters: a new group of quasi-resonantconverters suitable for high-performance DC/DC and AC/AC conversionapplications

A novel resonant switch and a family of zero-current and zero-voltage mixed-mode switching quasi-resonant converters (QRCs) called single-cycle resonant converters (SCRCs) are proposed to improve the performance of the conventional QRCs. The SCRCs, which include two active switches operated with zero-current switching (ZCS) and zero-voltage switching (ZVS), respectively, show very simple operation and ease of control and analysis, and they overcome the limited load range characteristics of the conventional ZCS QRCs. The SCRCs can be applied even for a high-frequency AC chopper by replacing unidirectional switches with bidirectional ones. Steady-state operation and characteristics of the buck-type SCRCs are analyzed and compared with those of the buck-type full-wave QRC (FW-QRC). Experimental results at a a 200 kHz, 1 kW level are shown to verify the operational principle and characteristics     

Benchmark of power packaging for DC/DC and AC/DC converters

This paper presents the first reported final results of a benchmarking project "StatPEP" which investigated the Status of Power Electronic Packaging used in commercial DC/DC and AC/DC switch mode power supplies. The methodology of the project is first described. Some of the salient results of a comprehensive benchmarking of DC/DC converters (rated power of 100 W) and AC/DC converters (rated power up to 576 W) are presented. Examples for figures-of-merit are presented. The results of the investigation are presented in a generic form, which does not identify individual products. A comparison of the performance of the units shows that the measured power density of the AC/DC units is approximately 10% that of the DC/DC while the thermal density based on footprint is 50%. Also the switching frequency of the AC/DC is 50% that of the DC/DC. Some of the reasons for these differences are discussed     

Lagrangian modeling and passivity-based control of three-phase AC/DC voltage-source converters

In this paper, we investigate the dc-bus voltage regulation problem for a three-phase boost-type pulsewidth-modulated (PWM) ac/dc converter using passivity-based control theory of Euler-Lagrange (EL) systems. The three-phase PWM ac/dc converters modeled in the a-b-c reference frame are first shown to be EL systems whose EL parameters are explicitly identified. The energy-dissipative properties of this model are fully retained under the d-q-axis transformation. Based on the transformed d-q EL model, passivity-based controllers are then synthesized using the techniques of energy shaping and damping injection. Two possible passivity-based feedback designs are discussed, leading to a feasible dynamic current-loop controller. Motivated from the usual power electronics control schemes and the study of Lee, the internal dc-bus voltage dynamics are regulated via an outer loop proportional plus integral (PI) controller cascaded to the d-axis current loop. Nonlinear PI control results of Desoer and Lin are applied to theoretically validate the proposed outer loop control scheme. The PWM ac/dc converter controlled by the proposed passivity-based current control scheme with outer loop PI compensation has the features of enhanced robustness under model uncertainties, decoupled current-loop dynamics, guaranteed zero steady-state error, and asymptotic rejection of constant load disturbance. Experimental results on a 1.5-kVA PC-based controlled prototype provide verification of these salient features. The experimental responses of a classical linear PI scheme are also included for comparative study.     

高可靠性DC/DC变换器磁隔离反馈设计

采用磁性器件隔离并传输反馈信号的输入输出隔离设计方案,是提高隔离式DC/DC变换器可靠性的有效途径之一。文中系统地介绍了实现输入输出磁隔离的基本途径,重点阐述了误差调频(EFM)、误差调宽(EWM)及误差调幅(EAM)三种误差调制信号变压器耦合反馈控制原理。对应用集成化的DC/DC变换器的误差调幅(EAM)磁隔离反馈控制原理进行了较为详细的分析,并给出它的实际应用结果。     

Flyboost power factor correction cell and a new family of single-stage AC/DC converters

A novel power factor correction (PFC) cell, called flyboost, is presented. The proposed PFC cell combines power conversion characteristics of conventional flyback and boost converters. Based on the flyboost PFC cell, a new family of single-stage (S/sup 2/) ac/dc converters can be derived. Prominent features of newly derived S/sup 2/ converters include: three power conversions, i.e., boost, flyback, and another isolated dc/dc power conversions are simultaneously realized that typically uses only one power switch and one simple controller; part of the power delivered to the load is processed only once; bulk capacitor voltage can be clamped to the desired level; and capable of operating under continuous current mode. Experimental results on example converters verify that while still achieving high power factor and tight output regulation, the flyboost PFC cell substantially improve the efficiency of the converter.     

A comparison of piezoelectric transformer AC/DC converters with current doubler and voltage doubler rectifiers

The objective of this study was to develop recommendations for an optimal design of piezoelectric transformer (PT) AC/DC converters. The paper presents a comprehensive comparison of the two commonly used rectifier topologies in a PT based power converters: current doubler and voltage doubler rectifiers. The advantages and disadvantages of the two rectifiers were investigated and the range of their applications with respect to output current, voltage, power capability, load resistance etc.-was delineated. Generic parameters are proposed and used to derive normalized and closed form equations that can help choosing a PT for a given set of requirements. Simulation and experimental results were found to be in a good agreement with the derivation of the theoretical analysis.     

低成本DC/DC转换器34063的应用

34063由于价格便宜,开关峰值电流达1.5A,电路简单且效率满足一般要求,所以得到广泛使用.在ADSL应用中,34063的开关频率对传输速率有很大影响,在器件选择及PCB设计时需要仔细考虑.     

Voltage and current stress reduction in single-stage power factorcorrection AC/DC converters with bulk capacitor voltage feedback

Single-stage power factor correction (PFC) AC/DC converters integrate a boost-derived input current shaper (ICS) with a flyback or forward DC/DC converter in one single stage. The ICS can be operated in either discontinuous current mode (DCM) or continuous current mode (CCM), while the flyback or forward DC/DC converter is operated in CCM. Almost all single-stage PFC AC/DC converters suffer from high bulk capacitor voltage stress and extra switch current stress. The bulk capacitor voltage feedback with a coupled winding structure is widely used to reduce both the voltage and current stresses in practical single-stage PFC AC/DC converters. This paper presents a detailed analysis of the bulk capacitor voltage feedback, including the relationship between bulk capacitor voltage, input current harmonics, voltage feedback ratio, and load condition. The maximum bulk capacitor voltage appears when the DC/DC converter operates at the boundary between CCM and DCM. This paper also reveals that only the voltage feedback ratio determines the input current harmonics under DCM ICS and CCM DC/DC operation. The theoretical prediction of the bulk capacitor voltage as well as the predicted input harmonic contents is verified experimentally on a 60 W AC/DC converter with universal-line input     

A comparison of two micromachined inductors (bar- and meander-type)for fully integrated boost DC/DC power converters

Two micromachined integrated inductors (bar- and meander-type) are realized on a silicon wafer by using modified, IC-compatible, multilevel metallization techniques. Efforts are made to minimize both the coil resistance and the magnetic reluctance by using thick electroplated conductors, cores, and vias. In the bar-type inductor, a 25-μm thick nickel-iron permalloy magnetic core bar is wrapped with 30-μm thick multilevel copper conductor lines. For an inductor size of 4 mm×1.0 mm×110 μm thickness having 33 turns of multilevel coils, the achieved specific inductance is approximately 30 nH/mm² at 1 MHz. In the meander-type inductor, the roles of conductor wire and magnetic core are switched, i.e., a magnetic core is wrapped around a conductor wire. This inductor size is 4 mm×1.0 mm×130 μm and consists of 30 turns of a 35-μm thick nickel-iron permalloy magnetic core around a 10-μm thick sputtered aluminum conductor lines. A specific inductance of 35 nH/mm² is achieved at a frequency of 1 MHz. Using these two inductors, switched DC/DC boost converters are demonstrated in a hybrid fashion. The obtained maximum output voltage is approximately double an input voltage of 3 V at switching frequencies of 300 kHz and a duty cycle of 50% for both inductors, demonstrating the usefulness of these integrated planar inductors     

Application of neural networks and State-space averaging to DC/DC PWM converters in sliding-mode operation

A novel output feedback neural controller is presented in This work for the implementation of sliding-mode control of dc/dc converters. The controller, which consists of a multilayer perceptron, has been trained in order to be robust for large variations of system parameters and state variables. Fast dynamic behavior is the other main advantage of the proposed controller, which allows realization of all beneficial features of the sliding-mode control technique. Other advantages of the controller are simplicity and low cost. Computer simulations have been carried out to investigate the effectiveness of the controller in voltage regulation for a relatively complex dc/dc converter topology of the Cuk converter. Simulation results confirm the excellent performance of the control system in response to large signal variations. In order to verify the simulation results, a controller prototype has been designed and built using analog components. The controller is applied to regulate the output voltage of the Cuk converter. Experimental results confirm the analytical and simulation achievements.     

Configurable front-end converters for multicurrent locomotives operated on 16 2/3 Hz AC and 3 kV DC systems

A configurable converter topology is presented as front-end converter for a locomotive that can be operated as well on a high voltage AC-system as on a medium voltage DC-system. The configurable converter is realized on the base of a multilevel chain, where all modules are fed through reversible and isolated DC-DC stages. The medium frequency transformers used in the isolation stages of the DC-DC converters allow a significant weight reduction of the locomotive, in comparison with the classical low-frequency voltage-transformers. A first solution using hard switching techniques is presented, using a three-times silicon-conversion. A second solution based on ZVT/ZCS techniques is then presented, with the advantage of having ideally only a two times silicon conduction. Prototype modules have been realized with association of diodes and IGBTs in order to provide reverse-blocking devices. First results of the two-stage conversion are also presented.     

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 of transient and steady-state processes in the series (resonant)inverter

This paper deals with analysis of the transient and steady-state processes in series (resonant) inverters. Sets of differential and difference equations governing the transient and steady state processes are obtained and solved. The solution is found in closed analytical form. Theoretical and experimental results, both for transient and steady-state conditions, are compared and satisfactory agreement shown.     

Affine transformation and its application to antenna arrays

The application of affine transformations to antenna arrays is discussed in this paper. Arrays related by this transformation can define a pattern invariant group. Thus, pattern functions of many arrays of a general type can be written down immediately from that of a simple type which is affine-equlvalent: for example, the pattern of an elliptical array from that of a circular one, the pattern of a periodic array with parallelogram or parallelepiped cells from that of a conventional one with square or cubic cells. This method also leads to an optimum design for the cophasal periodic arrays in the sense that the number of elements is a minimum under the condition that there are no grating lobes in the visible region for any given scanning range. For example, in the case of full scan, the number of elements can be reduced by 13.4 percent and 29.3 percent from those of conventional two- and three-dimensional arrays, respectively.     

LED显示驱动芯片BN5279(A)及其串行接口应用

BN5279(A)是贝能科技有限公司生产的集成LED显示驱动器，具有工作电压低、串行接口、带有64键的键盘矩阵控制等特点。文中介绍了该电路的主要特性及工作原理，给出了BN5279(A)与AT89C2052微处理器的连接电路及程序代码。     

Simple method to determine series resistance and its temperature dependence in AlAs/GaAs/AlAs double barrier resonant tunnelling diodes

The author presents a simple empirical method to quickly determine the series resistance R/sub s/ of AlAs/GaAs/AlAs double barrier resonant tunnelling diodes, and its temperature dependence over the temperature range 198-295 K. At high voltage biases, the quantum well diode current-voltage characteristics were modelled with the empirical expression I/sub D/ approximately= exp (q(V/sub A/-I/sub D/.R/sub s/)/kT). From this current-voltage relationship, R/sub s/ can be extracted from plots of the total resistance dV/sub A//dI/sub D/ against 1/I/sub D/ in the limit of 1/I/sub D/ to 0. The results showed that R/sub s/ decreased with temperature from 5.3 Omega at 198 K to 4.7 Omega at 295 K. R/sub s/ values extracted using the Nelder-Meade simplex algorithm agreed with those from the dV/sub A//dI/sub D/ against 1/I/sub D/ technique to within 10%.<>     

Single-inductor dual-output (SIDO) DC–DC converters for minimized cross regulation and high efficiency in soc supplying systems

A compact size and high efficiency single-inductor dual-output (SIDO) DC–DC converter is proposed. The proposed SIDO DC–DC converter not only provides dual output sources (one buck and one boost outputs) but also has minimized cross regulation without using any external compensation components. Generally speaking, it is important to minimize the number of components and footprint area in the design of SIDO converters. However, usually large external compensation resistors and capacitors are required to stabilize DC–DC converters. Importantly, our proposed hysteresis mode operation can effectively avoid the oscillation problems that may exist in many SIMO designs. Furthermore, the dynamic dc current level like that in the continuous conduction mode (CCM) operation can make the proposed SIDO DC–DC converter achieve high conversion efficiency at light loads owing to small conduction loss. Experimental results show a high efficiency from 85% at light loads to 94% at heavy loads.     

DC coefficient restoration technique and its application to image coding

In the traditional approach of block transform image coding, a large number of bits are allocated to the DC coefficients. A technique called DC coefficient restoration (DCCR) has been proposed to further improve the compression ability of block transform image coding by not transmitting the DC coefficients but estimating them from the transmitted AC coefficients. Images thus generated, however, have inherent errors that degrade the image visual quality. In the paper, a global estimation DCCR scheme is proposed that can eliminate the inherent errors. The scheme estimates all the DC coefficients of the blocks simultaneously by minimising the sum of the energy of all the edge difference vectors of the image. The performance of the global estimation DCCR is evaluated using a mathematical model and experiments. Fast algorithms are also developed for efficient implementation of the proposed scheme.     

抗干扰AC/DC开关电源芯片的研究与设计

近些年来,随着新能源技术的飞速发展,研发一种高效节能、使用年限长的电源芯片成为热点。AC/DC开关电源转换器源以其价格、效率和体积等优势在小功率电源领域得到了广泛的应用。基于AC/DC开关电源转换器的工作原理,发现误差放大器对整个电源芯片的精度影响很大,据此提出一种组合式的误差放大器,将轻载到满载的电压输出降低到40 m V;并提出智能抗尖峰电路,减少了LEB结束与开关断开的时间差,使安全性能提高;最后,对本芯片进行试验测试,发现抗ESD能力达到10 k V,芯片性能稳定。希望对今后电源芯片设计提供参考。