Realization of a smart electrolytic capacitor circuit

The object of this paper is to present an economic electronic module integrated on an electrolytic capacitor that is able to indicate the moment when it must be changed. First, with a switchmode power supply as an example, the high probability of electrolytic capacitor failure with respect to other power components is noted. Second, the authors recall that the increase of the equivalent series resistance (ESR) of the capacitor is the best indicator of their faulty state. From the measurements of the voltage ripple and the capacitor current, one can deduce the ESR; the latter is compared to the ESR value of the sound capacitor deduced from the component case temperature. Thus, the capacitor deterioration can be diagnosed     

Origin of common-mode noise in two-dimensional finite-size circuit and reduction of the noise using a symmetric three-line circuit

In this paper, we investigate common-mode (CM) noise caused by a connection to a two-dimensional finite-size ground plane. Numerical calculations are conducted to visualize the time variation of potentials that leads to CM noise. A connection of the signal line to the ground plane, which is conventionally used in circuits, causes an imbalance in the circuit that makes the potential of the ground plane fluctuate, which results in CM noise. CM noise does not occur in a symmetric three-line circuit because the potential of the middle line is always kept at 0 V. Furthermore, the middle line prevents an externally induced potential fluctuation of the ground plane from being converted to a normal-mode voltage (i.e., CM noise).     

Switched capacitor filters with a row dominant nodal admittance matrix

Stray capacitance insensitive switched capacitor filters are studied, whose nodal admittance matrix is row-dominant for arbitrary capacitor values. Such filters have low passband sensitivities, because their transfer function is intrinsically bounded by 1, as is the case for LC-filters. Furthermore, row-dominant filters have the additional advantage that internal voltages are bounded by one, and reach this bound at each attenuation zero, which ensures optimal dynamic range. However, we show that the attenuation zeros of row-dominant filters are located at the frequencies z² with (z²)^m = 1, where m is smaller than or equal to the number of operational amplifiers. Therefore, such filters are not suitable for conventional filter applications. Two examples of such filters are given.     

Switched current circuit using fixed gate‐potential transistor and automatic tuning circuit

Clock feedthrough (CFT) error is one of the most important problems for switched current (SI) circuits. This paper proposes a SI circuit which can reduce CFT error drastically. The proposed circuit will theoretically reduce both signal‐dependent and independent errors by using CMOS switches under a fixed and appropriate bias. Although conventional circuits based on a similar idea need operational amplifiers or additional capacitors, our proposed circuit requires only MOSFETs. The proposed circuit can reduce CFT current with less power consumption and chip area compared to those of conventional circuits. An automatic tuning circuit, which controls the gate potential appropriately, is also proposed. Simulation results demonstrate the effectiveness of the proposed circuits. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 21–29, 1999     

An investigation of flying capacitor converter for circuit integration

Output power density of power converters has been increased. In power converters with lower harmonic distortion and lower electromagnetic interference (EMI) which are required in many applications, bulky harmonic and EMI filters are usually connected. The volume of the harmonic filters can be reduced by increasing the switching frequency. However, higher switching frequency will cause larger switching loss and severe EMI. As another approach, there is possibility of intrinsic elimination of harmonics and EMI by introducing multilevel converters. However, as the number of levels increases, the number of circuit components will exceed the practical limit of the implementation. Thus, from a practical viewpoint, the main circuit and related circuits should be integrated. However, it has not been clarified which multilevel topology is suitable for circuit integration. In addition, the effectiveness in reducing total device loss considering chip size has not been evaluated. In this paper, the advantage of a flying capacitor multilevel topology for circuit integration is clarified by theoretical and experimental investigations. Also, the total device loss and chip size of the flying capacitor converter are estimated. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

一种新的X电容泄放回路设计方案

本文主要论述一种新的X电容泄放回路设计方案,此方案既能达到防止插头电击的目的,又能降低整机特别是待机状态下的能耗.     

光伏发电系统中超级电容器充电策略

利用超级电容器改进型RC模型对不同充电方法下超级电容器的充电效率进行了分析。提出了基于Boost级联Buck变换器(Bo CBB)的光伏电池对超级电容器充电系统,前级Boost变换器与光伏发电系统连接,使用改进型扰动观察法进行光伏电池的最大功率点跟踪控制,后级Buck变换器使用分段式充电策略对超级电容器进行充电。基于该电路,提出了完整的超级电容器充电系统控制方法。提出了使用等效电流源分别对Bo CBB的前后级电路进行建模的方法,基于该方法进行了充电系统主电路的建模以及电流环控制器设计。最后对不同光照情况下的光伏电池对超级电容器充电效率进行了仿真分析,并搭建了实验平台,通过2组对比实验,验证所提出的充电策略能够有效提高光伏电池对超级电容器的充电效率。     

Chaos in a series circuit with a nonlinear capacitor and a nonlinear inductor

This paper proposes a nonlinear circuit that generates chaotic oscillations. The proposed nonlinear circuit includes a nonlinear capacitor and a nonlinear inductor by using Generalized Impedance Converters. Both computational experiments and experiments on real circuits show that the region for chaotic oscillation is very wide, demonstrating that the proposed circuit is effective as a chaos generator. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 35–42, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10361     

电容器储能型轨道电磁炮的理论分析与动态仿真

为分析电容器储能型轨道电磁炮发射过程中的影响因素,介绍了轨道电磁炮的基本原理,建立了电容储能型轨道电磁炮的电路模型,根据此电路模型和电路、电磁场及电动力学原理建立了用于描述轨道电磁炮中电磁过程的微积分方程。同时,建立了用于分析轨道电磁炮的动态仿真模型。仿真结果表明,被发射体的速度随驱动电容容量的增加而增加,随被发射体的质量增加而下降。     

A simple low-cost laboratory hardware for noise generation

Circuit hardware for custom noise generation is presented, described, and explained. Its very low circuit complexity, along with the spectral and statistical features of the noise signal obtained, make it specially suitable for student use in laboratory sessions related to digital and analog communications systems     

A novel clamp circuit for a regenerative rectifier using AC/AC matrix converter theory

The main contribution of this paper is the design of a new clamp circuit for an AC/DC converter topology based on ac/ac matrix converter theory. The drive is capable of delivering 250-A DC from a three-phase 480-V AC source while keeping the insulated gate bipolar transistor voltage and current within the safe operating area of the devices. The power level required by the dc drive discussed in This work presents several design challenges which have been overcome with innovative solutions. An example is the clamp circuitry, necessary for the safe operation of the bidirectional switches, which is described, analyzed and demonstrated experimentally.     

WKBCⅠ装置电力电容器欠压保护定值异常原因分析

根据WKBCⅠ型微机控制台电力电容器欠压保护在现场调试过程中表现出来的异常现象 ,依据其保护电路原理建立起了满足不同约束条件下的数学分析模型 ,获得了取样电位器相应的参数调整范围 ,找到了导致异常现象的原因 ,由此得到的改进措施完全满足现场用户要求     

Analog filter pair design on the basis of a gyrator–capacitor prototype circuit

The paper presents an algorithmic approach to a low‐sensitivity design strategy for analog filter pairs based on a gyrator–capacitor prototype circuit. The general structure of the prototype circuit is proposed. It assumed that the generic structure of the prototype circuit can evolve, with the use of additional gyrators, into a circuit with increased redundancy. It is shown that symbolic analysis of the prototype circuit, used to formulate a set of nonlinear algebraic equations, is necessary to achieve a sufficiently high algorithm operation speed. To find a solution to this specific system of nonlinear algebraic equations, different numerical methods are compared. The modified Hooke and Jeeves algorithm is found to be the most effective. The elaborated algorithms and programs are illustrated with the seventh‐order filter pair example. The obtained filter is better than the filter obtained using LC ladder structures with respect to chip area and power consumption, and these improvements are obtained without loss of sensitivity properties. Copyright © 2010 John Wiley & Sons, Ltd.     

Modified static VAR compensator using a large value AC capacitor

To overcome some of the limitations of conventional static VAR compensators (SVCs) which are widely used for reactive power compensation, a modified SVC (MSVC) has been proposed. MSVC uses a large value AC capacitor. The large value AC capacitor is realized using unipolar DC capacitors and power semiconductor devices. Unlike the conventional SVCs, the proposed MSVC does not require additional shunt passive filters for harmonic filtering. MSVC has been verified through analysis and simulation. A practical implementation of MSVC has been realized and tested.     

Hydrothermal growth of BaTiO3 thin films on printed circuit boards for integral capacitor applications

Polycrystalline BaTiO₃ films were hydrothermally grown on Ti-coated substrates from 80^∘C to 200^∘C. Films grown at 200^∘C exhibited the lowest dielectric loss of around 0.1. Proton incorporation was more severe for the 80^∘C film resulting in higher dielectric losses and leakage currents about two orders of magnitude higher. Post deposition oxygen plasma treatment removed incorporated protons and reduced the loss tangent but did not reduce defect density. As such, the leakage current of the 80^∘C film remained high. The films had dielectric constants of 275 to 675 from 100 Hz to 100 kHz and a value of 67 from 100 MHz to 3 GHz.     

新一代110 kV真空断路器挂网试运行研究

为了使高压断路器满足超大规模电网进一步发展的要求,研究了一种新一代高压大容量真空断路器。该断路器通过对40.5 kV断路器模块的串并联使得其额定工作电压、电流分别提升至126 kV和5 000A,短路开断电流达到80 kA。并通过紧耦合分裂电抗器自动均流/限流技术和动态均压技术提高了设备的可靠性。完成了该断路器的整机安装和挂网试运行的工作,并对运行中的断路器进行了相关的数据测量,包括电流、温度和漏磁。由该断路器正常稳定运行以及变电站挂网运行的数据验证了该断路器的设计方案的有效性,该工作为今后真空断路器的发展方向提供了很好的思路。     

Power Quality Improvement in a Four-Phase Switched Reluctance Motor Drive using Twelve-Pulse AC/DC Converter

This article deals with a 12-pulse AC/DC converter for improving power quality in a midpoint converter based switched reluctance motor drive at AC mains. The conventional six-pulse AC/DC converter fed midpoint converter based switched reluctance motor drive injects high content of current harmonics into AC mains. The proposed 12-pulse AC/DC converter with a small rating passive filter is capable of eliminating harmonic currents from light load to full load with a high power factor. The proposed switched reluctance motor drive system is designed, modeled and simulated in Matlab/Simulink environment and its performance is compared with a conventional six-pulse AC/DC converter fed switched reluctance motor to demonstrate the power quality at AC mains. The simulated performance of the proposed 12-pulse AC/DC converter fed switched reluctance motor drive is experimentally validated for power quality improvement.