Meeting the analog world challenge. Nyquist-rate analog-to-digitalconverter architectures

To bring digital processing and its benefits to bear on real-world applications, the analog signal of interest must be translated into a format a digital computer can utilize. This is the function of the analog-to-digital converter (ADC). After processing by a digital computer or digital signal processor (DSP), the resulting digital stream of information must be returned to its analog form by a digital-to-analog converter (DAC). The methods by which a digital code is generated within the ADC are diverse. We introduce three popular Nyquist-rate ADC architectures used today: the counter ramp ADC, the successive approximation ADC and the flash ADC     

20位脉宽调制直流电压D/A转换器设计

本文设计了-种高精度脉宽调制D/A转换器,该方案采用双路脉宽调制电路,并进行比例叠加来实现20位的D/A转换,主要用于产生0～10 V可调直流电压基准信号,最小分辨率达到1×10-7.该文首先确定了双通道叠加原理的设计方案,对脉宽调制技术的实现进行了详细地阐述,并给出了具体的设计方案.该设计方案已经成功应用于100 A直流电流标准的设计中,对高精度标准研制过程中基准电压发生电路的设计具有指导意义.     

16位数/模转换芯片DAC702及其应用

Burr-Brown公司生产的DAC702芯片是一块完整的16位数／模转换芯片，该芯片具有低增益漂移和高精度等许多姝特性。本文介绍它的优良性能和典型应用电路以及应用该芯片为另一块D／A转换芯片提供一个可调的电压参考基准实例。     

A terabit-per-second all-optical four-bit digital-to-analog converter using quantum dot semiconductor optical amplifiers

An all-optical digital-to-analog converter (DAC) using quantum dot semiconductor optical amplifiers (QDSOAs) is proposed and analyzed. The device operates at low optical power (~?0.5 mW) at a speed of 1 Tbps. The resolution of the DAC is four bits, and the corresponding step size is 1.068 mW (compared with the ideal value of 1 mW). The dynamic range is found to be 11.47 dB (versus the ideal value of 11.76 dB). The average absolute error for all the states of the proposed optical DAC is 0.53%, with a maximum error of 1.85%, being the first time that such performance has been achieved to the best of the authors’ knowledge. It is shown that the amplified spontaneous emission (ASE) noise has no significant effect on the performance of the DAC.

     

Shifting the sampled input signal in successive approximation register analog-to-digital converters to reduce the digital-to-analog converter switching energy and area

In this paper, a switching scheme is presented to reduce the capacitive digital-to-analog converter (DAC) switching energy, area, and the number of switches in successive approximation register (SAR) analog-to-digital converters (ADCs). In the proposed DAC switching method, after a few most significant bits (MSBs) decision, the sampled differential input signal is shifted into two special regions where the required DAC switching energy and area is less than the other regions. This technique can be utilized in most of the previously reported DAC switching schemes to further reduce the capacitive DAC switching energy and area. The conventional and two recently presented DAC switching techniques are utilized in the proposed SAR ADC to evaluate its usefulness.     

矩阵式双向变流器改进型换流策略

针对基于矩阵式变换器的双向变流器电压电流型一步换流策略进行研究。通过分析电压电流型一步换流中存在的问题,指出其在输入相电压相对大小判断不准确时会使得输入电流波形畸变,并提出了基于过渡区间两步换流的改进型换流策略。通过在输入相电压大小相近时设置合适宽度的过渡区间,在过渡区间内采用两步换流,在过渡区间外采用一步换流,从而有效地避免了电压扇区判断错误的情况。最后通过仿真模型和实验样机,对所提出的改进型换流策略的有效性和正确性进行了仿真和实验验证,结果证明所提换流策略能准确地判断电压扇区所在空间,改善输入电流波形。     

矩阵变换器与双PWM变换器的比较研究

分析了矩阵变换器的虚拟交-直-交调制策略,并与电压型双PWM变换器进行了比较,对二者的主要性能指标进行了综合评价,得出矩阵变换器的虚拟交-直-交调制的实质就是电压型双PWM交-直-交变换器的综合协调控制目标一体化实现的结论。矩阵变换器的发展方向为实现模块化、集成化,与电机实现集成,形成机电一体化、集成化的新型电机控制系统体系结构。     

一种新型四象限多电平变流器

提出了一种新型四象限多电平变流器拓扑结构,由级联H桥型整流器、中频变压器和级联H桥型逆变器三部分构成。建立了变流器的能量传输模型,提出了相应的控制方法和调制策略;分析了输入侧变换器的输出电压模型,给出了相应的调制算法流程。阐述了各中频H桥的工作相位的作用,即达到了控制各电容电压平衡的目的,实现了变流器的四象限运行。实验结果验证了拓扑结构和控制方法的正确性。所提变流器拓扑结构省去了传统的工频变压器,降低了变换器体积和重量,可以应用于高压大容量场合。     

Heat-generating electromechanical converter

The design and theoretical aspects of a novel heat-generating electromechanical converter designed for heating and setting in motion a heat-transfer agent are considered.     

Three-level converter system

Despite the growing use of three-level converters, practical design guidelines for these systems are not readily available. This article describes such design guidelines for the construction and control of three-level converters. Closed-form loss equations that assist in thermal design and device sizing are provided along with current estimates for sizing link capacitors. The primary commutation mechanisms and the relevant parasitic effects are identified. A low-inductance busplane design is presented for designs featuring dual insulated gate bipolar transistor (IGBT) modules and low inductance snubber capacitor connections are shown. A discussion of the control implementation using a digital signal processor (DSP) and field-programmable gate array (FPGA) platform is also provided.     

机载DC-DC变换器的研究

介绍了DC-DC变换器在飞机变频电源中的应用,根据飞机用电设备及供电系统的特点,提出了一种带有阻断电容的DC-DC全桥变换器,建立了它的静态模型.在分析了稳定性后,利用Saber软件对系统进行仿真,设计出一台15kW的实验样机,并给出相应的过压、过流保护电路.实验结果表明该电路工作原理正常,完全可以满足飞机供电的要求.     

Processing architectures for smart pixel systems

Smart pixel architectures offer important new opportunities for low-cost, portable image processing systems. They provide greater I/O bandwidth and computing performance than systems based on CCD and microprocessors. However, finding a balance between performance, flexibility, efficiency, and cost depends on an evaluation of target applications. This paper describes several promising architectural approaches for the realization of videoputer systems and outlines example implementations being pursued at the Georgia Institute of Technology     

新型双输入Boost变换器

针对传统的多输入变换器(MIC)具有电路结构复杂、电压增益低或开关器件电压应力高的问题,提出了一种新型双输入Boost变换器拓扑结构.该拓扑由2个完全一致的基本Boost变换器子拓扑构成,每个基本Boost变换器的功率开关管分别并联一个功率二极管,在单输入状态时一个始终导通.另一个始终关断;在双输入状态时,2个功率二极管全部关断.分析了2种输入状态下的工作原理及各个阶段的工作模态,结果表明该变换器适合工作在双输入状态,且在此状态时可以实现2种不同性质的电源输入,具有电压增益高、开关器件电压应力低等优点.研制了一台输出功率为240 W的双输入Boost变换器原理样机,通过实验验证了理论分析的正确性.     

Isolated high voltage‐boosting converter derived from forward converter

A novel isolated high voltage‐boosting converter, derived from the traditional forward converter, is presented in this paper. As compared with the traditional forward converter, the demagnetizing winding of the transformer in the proposed converter is used not only to demagnetize but also to improve the voltage conversion ratio. Therefore, the duty cycle is not limited, and the utilization of the transformer, also called coupled inductor, can be increased also. Furthermore, the proposed converter maintains the advantage of possessing a non‐pulsating output current, leading to a small output voltage ripple. Moreover, by applying one additional voltage‐boosting winding to the transformer, the voltage conversion ratio can be significantly improved. In addition, an active clamp circuit is employed in the proposed converter to reduce the voltage stress of the main switch, caused by the leakage inductance in the transformer, and the switches can achieve zero‐voltage switching. Finally, the analysis of operating principles, choice of the turns, turns ratio, core size, and each wire size of the coupled inductor are described in detail, and the experimental results with a prototype with 12‐V input voltage, 100‐V output voltage, and 100‐W output power are provided to verify the feasibility and effectiveness of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.     

Information security considerations in open systems architectures

Information security and issues related to its achievement in open systems architectures are discussed. Beginning with a discussion of the goals of information security and their relation to open systems, examples are provided of the threats to electric utility computer systems and the consequences associated with these threats. Basic countermeasures applicable to all computer systems are presented. Issues specific to open systems architectures are discussed     

基于CLLC谐振变换器的三级电源变换器单元设计

三级电源变换器因其具备丰富特性而备受青睐.介绍了一种单相三级电源变换器单元的主要设计过程,包括独立控制的输入整流器、中间隔离CLLC谐振变换器以及输出逆变器三个模块.整流及逆变模块均引入比例谐振控制,采用单极性倍频调制.CLLC谐振变换器高频工作实现了开关管的软开关.在Matlab/Simulink中搭建各个模块并集成...     

新型高压变频器设计

开发了一款可能量反馈的级联型高压变频器,其电网侧变换器摒弃了传统的二极管不可控整流器,而采用三相PWM整流器为电机侧级联型逆变器各H桥单元提供独立的直流电源,使得在不引入多脉波整流技术的情况下,就能够实现单位功率因数的整流和逆变,且网侧电流呈正弦,谐波含量小.为验证该结构变频器适合应用于高压大功率交流变频调速领域,以高...     

Hybrid type energy converter

This paper presents the theory of a hybrid type energy converter (HEC) with dual induction motor and transformer functions. The stator core of the HEC has slots on the inside and on the outside. The armature winding of the induction motor is embedded in the inside slots. On the other hand, the primary and secondary windings of the transformer are embedded in the outside slots. Moreover, a laminated ring core of iron is attached around the stator core. Since this HEC is capable of motor operation and/or transformer operation, three states of operation can be realized. Based on the results from experiments, this paper also shows that we can almost independently use the circuits for the motor and for the transformer without interference in the HEC. © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 28–35, 1998     

Power converter design optimization

This article present GA-based design approach to optimization of power electronics circuits is shown to be a very effective and powerful tool for obtaining improved solutions compared to traditional design procedures. In the GA procedure, each design is represented using a "gene string" for the converter design problem, each gene string is used to represent the set of electrical components that define one possible converter design. The design of power electronics systems involves a large number of design variables and the application of knowledge from several different engineering fields.