一种低压大电流直流电源的输出电压补偿设计

文中基于一种采用VICOR DC-DC转换器设计的低压大电流直流电源,通过采样负载点电压,外加反馈电路来调节转换器输出电压,以补偿在大电流传输时负载线上的电压降,从而达到稳定负载点电压的目的。本文详细分析了电压补偿电路的原理,介绍了元器件选择方法,并通过电压补偿电路的设计和测试验证了该电路的可行性。     

电流型PWM控制器在电源中的应用

介绍了双环电流型脉宽调制(PWM)控制器UC3842的工作原理、特点以及使用中的功率因数校正和斜坡补偿方法.双环电流型PWM控制器是在普通电压反馈PWM控制环内部增加了电流反馈的控制环节,因而除了包含电压型PWM控制器的功能外,还能检测开关电流或电感电流,实现电压电流的双环控制.     

基于AD8205型高端电流传感器的 PWM电流控制器

高精度大电流控制器有着广泛的应用,但在高共模电压情况下输出电流的检测电路比较复杂.AD8205型高端电流传感器可以简化检测电路,采用AD8205和UC3842电流型PWM控制电路实现PWM可调电流源,电路结构简单可靠,输出电流精度高.     

一种双输出PWM型电流模式控制的DC/DC转换器的设计

提出了一个基于脉宽调制(PWM)技术并在非连续电流导通模式控制下工作的双输出DC／DC转换器的设计，该转换器在5V输入电压下利用一个电感实现升压和反压两路电压输出。详细介绍了该转换器实现双电压输出的工作原理和驱动逻辑，并采用HSPICE电路模拟软件进行了仿真验证。     

超低速线性扫描电流源

采用调节斜坡发生器充电电阻两端电压的方法，本文介绍用这种方法设计的自动扫描电流源的工作原理，功能、具体电路、调试与使用。     

一种高效率可编程力矩电机电流源设计

本文介绍一种基于ＭＡＸ７８７的可编程脉宽调制型电流源电路，该电路与通常的线性电流源电路相比，有数字化１２位程控接口，采用脉宽调制控制模式，大大提高了电原效率；高精度电流反馈设计增强了输出电流的稳定性。电路在８－４０Ｖ电压输入时，能够在０－５Ａ范围内输出稳定的可调电流，无需外接功率管进行电流扩展。     

BJT参数测试仪中数控微电流源研究与实现

对BJT参数测试仪中数控微电流源进行研究与设计。系统采用Howland电流泵构成高精度V/I转换器,V/I转换器输入为数/模转换器的输出电压,微控制器通过改变输入数/模转换器的数字量实现对电流源输出电流控制。对数控微电流源的工作原理做了定性和定量分析,并通过实验验证设计的正确性。该数控微电流源通过双电阻反馈网络构成闭环控制系统,其输出电流精度高、稳定性好,具有良好的负载特性。     

一种峰值电流模式DC-DC转换器控制电路设计

基于中科渝芯40 V双极型工艺,完成了一种峰值电流模式DC-DC电压转换器控制电路的模块设计、芯片版图设计和流片验证,其通用于升压、降压、反相的场景,并可以实现输出电压可调。电路采用峰值电流模式的PWM控制方式,能够更好的提供瞬态特性以及重载下的输出性能。芯片集成功率开关管,采用类三角形分布式发射极版图设计,保证足够发射区面积的同时有效降低了基极电阻,减弱了电流集边效应,弥补了发射极去偏置效应,并且不增加额外面积。实测数据表明：外接1 nF的定时电容可产生约32 kHz的振荡频率,功率开关管关态集电极电流低至52 nA,功率管直流电流增益约为131,基准电压温度系数约为0.09 mV/℃,静态电源电流低,约为2.7 mA。     

一种X射线发生装置电流源的设计

目前工业主要用高能电子轰击金属的方法产生X射线。在此设计一种基于开关电源原理的自反馈型直流电流源。该电流源通过DC-DC转换芯片XL4015为开关电源模块提供可调的直流输入电压,Buck型开关电源模块为负载提供稳定的电压,从而流过负载的电流一定。将采样电阻的电压通过OPA2340差分放大,并用SG3525反馈给开关电源模块,从而形成闭环控制。经过试验测试,该电流源输出稳定,精度满足产生X射线的要求,且具有效率高、性能可靠、电路简单易懂、成本低廉等优点。     

利用TRUECURRENT技术实现初级端调节(PSR)控制器精确调节输出电流

TRUECURRENT是一种创新的输出电流调节技术,它利用初级端调节器(PSR)控制反激式转换器来调节输出电流,无需次级反馈电路.其主要应用的原理为输出电流大小可由初级端电流和次级端放电时间两者的关系来决定,所以PSR控制器可通过侦测变压器的初级端辅助线圈上的电压波形,获得次级端放电时间,并检测初级端电流(与功率转换器的输出电流成比例),再利用两者运算的结果来确定MOSFET导通时间,便可实现无需次级反馈电路,维持恒定输出电流.     

A new power converter for fuel cells with high system efficiency

This paper presents a new high-efficiency grid-connected single-phase converter for fuel cells. It consists of a two-stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25?V–45?V) this voltage must be transformed to around 350–400?V in order to be able to invert this dc power into ac power to the grid. The proposed converter consists of an isolated dc–dc converter cascaded with a single-phase H-bridge inverter. The dc–dc converter is a current-fed push-pull converter. The inverter is controlled as a standard single-phase power factor controller with resistor emulation at the output. Experimental results of converter efficiency, grid performance and fuel cell dynamic response are shown for a 1?kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92%) and the inverter operates with a near-unity power factor and a low current THD.     

An accurate integrated voltage-to-current converter

Presents a monolithic integrated differential voltage-to-current converter. The transconductance of the converter is determined accurately by one external resistor. A total error in the conversion factor as low as /spl plusmn/0.5 percent is obtained by using composite transistors and by using the mutual equality of integrated resistors. The transconductance has a nonlinearity of 0.02 percent and a temperature coefficient of 4/spl times/10/SUP -5///spl deg/C. The output impedance is 5 M/spl Omega/. The voltage-to-current converter is a versatile building block. It can be applied as an instrumentation amplifier, a universal current mirror or current follower, etc.     

Characterization, Modeling, and Application of 10-kV SiC MOSFET

Ten-kilovolt SiC MOSFETs are currently under development by a number of organizations in the United States, with the aim of enabling their applications in high-voltage high-frequency power conversions. The aim of this paper is to obtain the key device characteristics of SiC MOSFETs so that their realistic application prospect can be provided. In particular, the emphasis is on obtaining their losses in various operation conditions from the extensive characterization study and a proposed behavioral SPICE model. Using the validated MOSFET SPICE model, a 20-kHz 370-W dc/dc boost converter based on a 10-kV 4H-SiC DMOSFET and diodes is designed and experimentally demonstrated. In the steady state of the boost converter, the total power loss in the 15.45- $hbox{mm}^{2}$ SiC MOSFET is 23.6 W for the input power of 428 W. The characterization study of the experimental SiC MOSFET and the experiment of the SiC MOSFET-based boost converter indicate that the turn-on losses of SiC MOSFETs are the dominant factors in determining their maximum operation frequency in hard-switched circuits with conventional thermal management. Replacing a 10-kV SiC PiN diode with a 10-kV SiC JBS diode as a boost diode and using a small external gate resistor, the turn-on loss of the SiC MOSFET can be reduced, and the 10-kV 5-A SiC MOSFET-based boost converter is predicted to be capable of a 20-kHz operation with a 5-kV dc output voltage and a 1.25-kW output power by the PSpice simulation with the MOSFET model. The low losses and fast switching speed of 10-kV SiC MOSFETs shown in the characterization study and the preliminary demonstration of the boost converter make them attractive in high-frequency high-voltage power-conversion applications.      

A 12-bit monolithic 70 ns DAC

Describes a 12-bit monolithic digital-to-analog converter with 70 ns settling time and a low output glitch content. The device is fabricated on a standard high speed digital process and needs no post-processing trimming to achieve the required accuracy and monotonicity. The output from this device is in the form of two complementary output currents, which may be terminated in resistive loads or amplified by a virtual earth input stage. Included on the chip are a temperature compensated voltage reference and reference loop amplifier. Essential external components are limited to a single current range setting resistor and decoupling/compensation capacitors.     

A novel self-oscillating, boost-derived DC-DC converter with load regulation

This paper proposes a novel self-oscillating, boost-derived (SOBD) dc-dc converter with load regulation. This proposed topology utilizes saturable cores (SCs) to offer self-oscillating and output regulation capabilities. Conventionally, the self-oscillating dc transformer (SODT) type of scheme can be implemented in a very cost-effective manner. The ideal dc transformer provides both input and output currents as pure, ripple-free dc quantities. However, the structure of an SODT-type converter will not provide regulation, and its oscillating frequency will change in accordance with the load. The proposed converter with SCs will allow output-voltage regulation to be accomplished by varying only the control current between the transformers, as occurs in a pulse-width modulation (PWM) converter. A control network that combines PWM schemes with a regenerative function is used for this converter. The optimum duty cycle is implemented to achieve low levels of input- and output-current ripples, which are characteristic of an ideal dc transformer. The oscillating frequency will spontaneously be kept near-constant, regardless of the load, without adding any auxiliary or compensation circuits. The typical voltage waveforms of the transistors are found to be close to quasisquare. The switching surges are well suppressed, and the voltage stress of the component is well clamped. The turn-on/turn-off of the switch is zero-voltage switching (ZVS), and its resonant transition can occur over a wide range of load current levels. A prototype circuit of an SOBD converter shows 86% efficiency at 48-V input, with 12-V, 100-W output, and presents an operating frequency of 100 kHz.     

An Improved Topology of SEPIC Converter With Reduced Output Voltage Ripple

An improved version of a single-ended primary inductor converter (SEPIC) is presented. The converter consists of a conventional SEPIC converter plus an additional high-frequency transformer and diode to maintain a freewheeling mode of the dc inductor currents during the switch on state. The voltage conversion ratio characteristics and semiconductor device voltage and current stresses are characterized. The main advantages of this converter are the continuous output current, smaller output voltage ripple, and lower semiconductors current stress compared with the conventional SEPIC converter. The design and simulation of the concept is verified by an experiment with a 48-V input and 12-V/3.75-A output converter.      

Practical Implementation of a High-Frequency Current-Sense Technique for VRM

To track the inductor current in high-frequency dc/dc converters is not effortless, particularly when high output currents and low output voltages are demanded by the load. This paper proposes a simple technique to obtain a good accuracy in the inductor current measurement in voltage regulator module (VRM) applications. The main idea is to obtain an equivalent voltage image which can be used for the high-frequency pulsewidth modulation controller to generate the converter control law. This strategy of measurement is generic, and it has been previously validated by simulations. Afterward, some experimental results are obtained by using several prototypes of dc/dc converters delivering a very low output voltage and owning several loads from 10-mA to 100-A currents. This wide range covers the power requirements of portable and embedded VRM applications. Moreover, this sense technique has also been validated in a digital high-frequency current-mode-controlled dc/dc converter.      

A High Efficiency Dual-Mode Buck Converter IC For Portable Applications

This paper presents the design of a novel wide output current range dual-mode dc to dc step-down (Buck) switching regulator/converter. The converter can adaptively switch between pulsewidth modulation (PWM) and pulse-frequency modulation (PFM) both with very high conversion efficiency. Under light load condition the converter enters PFM mode. The function of closing internal idle circuits is implemented to save unnecessary switching losses. The converter can be switched to PWM mode when the load current is greater than 100 mA. Soft start operation is designed to eliminate the excess large current at the start up of the regulator. The chip has been fabricated with a TSMC 2P4M 0.35 mum polycide CMOS process. The range of the operation voltage is from 2.7 to 5 V, which is suitable for single-cell lithium-ion battery supply applications. The maximum conversion efficiency is 95% at 50 mA load current. Above 85 % conversion efficiency can be reached for load current from 3 to 460 mA.     

A current-tripler dc/dc converter

This paper proposes a novel zero-voltage-switching (ZVS) current-tripler dc/dc converter. Compared to the conventional phase-shifted ZVS full-bridge dc/dc converter with current-doubler rectifier, the proposed current-tripler dc/dc converter reduces the synchronous rectifier (SR) conduction loss as well as the transformer winding loss. Furthermore, the proposed transformer structure is very compact, and thus the power density of the converter could be greatly increased. Analysis and experimental results show that the proposed topology offers great advantages when the converter output current goes higher and the voltage goes lower, as demanded by future microprocessors and telecommunications systems. A 48-V/1.0-V, 100-A, 300-kHz prototype is implemented, and the experimental results show that it can achieve 87% efficiency at full load.