Switched capacitor circuit for 1/f noise generation using a power-law circuit

A simple switched capacitor (SC) circuit is given which realizes a one-dimensional discrete dynamical system X_n+1 = X_n + ux^z generating intermittent chaos with a 1/f-shaped power spectrum. an integrated circuit with a pair of logarithmic and antilogarithmic amplifiters can easily realize the power-law term x^z which plays a key role in generating l/fnoise. an inevitable small offset voltage ? in the SC circuit governs the cut-off frequency of 1/f noise, and when the dynamical system is modified by introducing an effective ?, the ‘indirect method’ enables us to get the precise power spectrum in the modified system.     

Efficient computer analysis of ideal switched-capacitor circuits using matrix compaction techniques

In this paper we describe how three simple observations can be used in order to obtain an efficient algorithm for the computer analysis of ideal switched-capacitor circuits. the resulting algorithm is linear in the number of phases. the first observation uses the structure of the r-domain MNA-matrix to come up with a new LU-decomposition scheme which is gradual per timeslot. the second observation allows a great reduction in size of the z-domain MNA-matrix by a matrix compaction algorithm which also operates gradually per timeslot and which can be interleaved with the first gradual LU-decomposition process. This leads to a small matrix which can then be used for a time- and direct frequency-domain analysis. Third, the computations of transfer functions, aliasing functions and sensitivities can be optimized by applying appropriate excitations and making appropriate combinations of the terms in the expressions. These algorithms have been implemented in the SC-analysis program DIANA.SC. the usefulness and efficiency of the program is then illustrated with some examples.     

A Contribution to the Frequency Analysis and Transient Response of Power Transformer Windings

Abstract—This article proposes a new approach to study the frequency response and the transient analysis of power transformer windings. For improved accuracy, the suggested model includes, among other equivalent circuit elements, the mutual magnetic couplings between any winding turn and all others. This implies that the equivalent inductance of any considered turn will be a location-dependent parameter. Accordingly, the winding will be analyzed as a non-uniform transmission line. Through the application of a recursive circuit reduction technique, a closed-form Laplace s-domain analytical expression for the winding's input impedance can be obtained for any neutral treatment. The resulting expression can be used to determine the winding's series and parallel resonance frequencies. The s-domain expression for the input impedance, in connection with the numerical inverse Laplace transform, will be utilized for determination of the winding's time-domain transient response for any input voltage or current time waveform. Accuracy increases with the assumed number of winding sections, which can be even increased to the actual number of turns, limited only by the available computation resources. The results of case studies are in good agreement with those available in the literature using the time-domain solution of the simultaneous differential equations in the state variables.     

A Computer-Aided Design Toolkit For Continuous/Discrete Systems Based On Continued Fractions

This paper presents new algorithms (1) to generate complete mathematical symbolic expressions of continued fraction expansion coefficients in the s-domain, (2) to determine their numeric values and (3) to perform continued fraction inversion in the s-domain. A software package in PASCAL and LISP to implement these algorithms is developed. In addition, a simple z-domain inversion algorithm used in the computer implementation of bilinear s-z transformation is also included in the software package. These algorithms play an important role in the analysis and synthesis of complex electrical networks and control systems. Especially, the s-domain expansion and inversion algorithms have potential applications in model simplification and system order reductions. the paper also shows that the package, as such, serves as a comprehensive computer-aided analysis and design (CAD) toolkit for both continuous and discrete systems. the software is interactive and runs on computers equipped with a PASCAL or LISP compiler. It is noted that the iterative implementation of these methods using the new continued fraction algorithms saves considerable memory space and processing time. Numerical examples and computer data are given to demonstrate the development of the new algorithms and the usefulness of the software toolkit in the CAD design of continuous and discrete systems.     

A new feasible method for the design of stray-insensitive optimum switched capacitor networks

On the basis of signal flow graphs a general method is described for the design of stray-insensitive switched capacitor networks. to be able to choose the optimum one, the method involves the search of all possible topologies for the specially formed signal flow graph of the given z-domain transfer function and is easily implemented by digital computer.     

CARMA-model-based j-step-ahead prediction for MIMO systems

The single-input single-output (SISO) j-step-ahead predictor for generalized predictive control (GPC) controllers was traditionally derived using the polynomial approach through the Diophantine equations. An equivalent version of the predictor in a state-space form is available in the literature. In this paper, a z-domain analysis of the multiple input multiple output (MIMO) extension of the state-space predictor is carried out, and then an MIMO j-step-ahead predictor in polynomial form based on the controlled autoregressive moving average model is derived. The predictor enables us to simplify the GPC algorithm design for multivariable systems. In the SISO case the predictor is just the traditional GPC predictor, therefore this paper gives rigorous proof of the equivalence between the traditional GPC predictor and the state-space predictor. Translated from Control and Decision, 2006, 21 (9): 1050–1053 [译自: 控制与决策]     

基于基波谐振原理的无源滤波新方法研究

非线性负载的增多导致了电力系统的谐波污染日益严重。针对有源滤波器的初期投资大,结构复杂,运行维护困难的缺点,提出一种无源滤波新方法,该方法在电网与无源滤波器之间三相线路中分别串联一组由电感和电容组合而成的基波谐振电路,该电路对基波电流无影响,但是对谐波电流呈现了高阻抗的特性,可以迫使谐波电流最大限度的流入无源滤波器,从而大幅度的提升滤波器的效率。对该新方法通过建立等值电路进行了滤波原理分析,与传统无源滤波方法进行了滤波效能比较,并分别通过单相和三相电路滤波实验进行验证,实验结果表明该方法与传统无源滤波器相比有较佳的滤波效果。     

Fast short-circuit protection under current imbalance condition for multi-paralleled SiC-MOSFETs

This paper proposes methodology and gate drive circuit that can immediately detect short-circuit (SC) of multiparalleled SiC-MOSFETs even under current imbalance condition. Proposed method detects SC current using an integration circuit that can sense di/dt. The detection level of SC current can be adjusted to a desired value regardless of the number of SiC-MOSFETs connected in parallel. The effectiveness of the proposed approach was experimentally validated for four-paralleled SiC-MOSFETs under extreme current imbalance in SC condition. SC was detected within 0.5 μs and all SiC-MOSFETs were protected without destruction at most 2.2 μs after the onset of SC, for all types of SC 1, 2, and 3.     

General rational approximation of Gaussian wavelet series and continuous-time gm-C filter implementation

A general method of rational approximation for Gaussian wavelet series and Gaussian wavelet filter circuit design with simple g_m-C integrators is presented in this work. Firstly, the multiorder derivatives of Gaussian function are analyzed and proved as wavelet base functions. Then a high-accuracy general approximation model of Gaussian wavelet series is constructed, and the transfer function of first-order derivative of Gaussian wavelet filter is obtained using quantum differential evolution (QDE) algorithm. Thirdly, as an example, a fifth-order continuous-time analog first-order derivative of Gaussian wavelet filter circuit is designed based on multiple loop feedback structure with a simple g_m-C integrator as the basic blocks. Finally, simulation results demonstrate that the proposed method is an excellent way for the wavelet transform implementation. The designed first-order derivative of Gaussian wavelet filter circuit operates from a 0.53-V supply voltage and a bias current 2.5 nA. The power dissipation of the wavelet filter circuit at the basic scale is 41.1 nW. Moreover, the high-accuracy QRS detection based on the designed wavelet filter has been validated in application analysis.     

一种Buck输出纹波比的简化计算及设计方法

Buck变换器是一种高效的DC-DC降压开关电路,其输出的直流电压受到纹波干扰。纹波比是一个重要的性能指标,它受开关频率、滤波电感电容、占空比和负载电流（或负载电阻）等参数共同影响,不易精确计算。先构建一种与Buck变换器（电感电流连续）完全等效的理想电路拓扑;分析此电路的频率响应特性后得到电路的稳态输出;进一步的纹波理论计算及仿真分析表明,电路输出纹波比的计算完全可以由基波纹波比代替。基于上述简化纹波比计算的结论,又提出了一种设计滤波元件L、C参数的方法,并将这种方法运用于实例设计中,最后的仿真及实验数据都说明采用此方法能有效地计算出满足纹波比指标要求的L、C参数范围。     

CLC型PWM逆变器端无源滤波器的设计

由于PWM逆变器输出电压中含有较多的高频分量,所以逆变器输出端必须加入低通滤波器来减小谐波含量.借鉴在PWM逆变器与电机之间插入共模变压器来消除逆变器输出端共模电压的方法,通过分析共模变压器带有漏感时的等效电路,提出了一种新型的CLC型逆变器端无源滤波器.利用共模变压器产生的漏感代替差模电感来抑制差模电压dv/dt,同...     

Low cost active low pass and band pass network

An active RC filter circuit is described which realizes second order lowpass and bandpass functions. The filter uses two I.C. Operational amplifiers and four passive components to achieve accurate Q values up to 50. Its Q sensitivity to component values is found to be very low. The results of an exhaustive computer simulation are given which clearly define the operating limits of the circuit. A practical design technique is outlined, and a sixth order example is given.     

一种新型的串联型有源电力滤波器

提出了一种基于等效电阻概念和功率平衡原理的串联型有源电力滤波器（APF），新串联型有源电力滤波器不需要进行复杂的谐波检测计算，通过简单的控制就可以获得电源电流的参考信号，实现对谐波和无功电流的同时补偿。研制了实验样机，实验结果与理论分析和仿真结果相吻合，验证了所提出控制方法的正确性，并显示所提出的串联型APF对电压型谐波源有良好的补偿特性。     

非同步机电源接入电网后的谐振问题分析及抑制

随着非同步机电源在电网中的占比越来越大，有别于传统功角振荡的电网谐振不稳定问题逐渐显现。为此，文中提出了一种基于s域节点导纳矩阵的网络谐振分析方法，用以分析及抑制含非同步机电源电力系统的谐振问题。首先，介绍了两种非同步机电源的s域阻抗建模方法——小干扰线性化法和测试信号法，重点考虑了内环控制器和锁相环的影响。然后，给出了一套基于s域节点导纳矩阵的网络谐振结构分析方法，并提出了两个描述谐振模式的特征指标，用以确定其主要影响区域和敏感元件参数。最后，以某风电场并网系统为例，对该系统的谐振结构进行了分析，并针对其存在的谐振问题提出了相应的改善措施。分析表明，由于电力电子装置的负电阻效应，含非同步机电源的电力系统确实存在谐振不稳定的风险，需要加以抑制。     

Z Copy‐Controlled Gain‐Current Differencing Buffered Amplifier and its applications

The Z Copy‐Controlled Gain‐Current Differencing Buffered Amplifier (ZC‐CG‐CDBA) is introduced in the paper. In addition to the well‐known CDBA, the input Current Differencing Unit (CDU) is modified and completed by special circuits. Analogously to the conventional CDBA, the z terminal is internally connected to the input of voltage buffer. The current gain from the difference input p, n to the output z can be controlled electronically or by an external device. In addition, an independent high‐impedance output zc is available, providing difference current I_p?I_n. In the paper, the extension of application range of the ZC‐CG‐CDBA compared with the conventional CDBA is referred to. The novel circuit element is assembled from commercial integrated circuits and its principle is verified experimentally on a universal second‐order filter. Copyright © 2010 John Wiley & Sons, Ltd.     

Existence condition of state equations of linear active networks over F(z)

If the physical parameter of each branch of a linear active network is considered to be an independently variable parameter, then it is called a network over the field F(z) of all rational functions in its physical parameters. This paper discusses the existence condition of state equation over F(z) for the active network. The condition depends only on the network structure, and is applied to two examples, which shows that the method is straightforward. Copyright © 2006 John Wiley & Sons, Ltd.     

A new combined system of active and passive filters to obtain harmonic compensation for large-capacity thyristor converters

Shunt passive filters, which are connected in parallel to harmonic-producing loads, have been used widely for harmonics suppression in power systems because of low cost and high efficiency. However, they have such inherent problems as series and parallel resonance. On the other hand, shunt active filters, which are also placed in parallel, have such an inherent problem as initial and running costs are high compared with those of shunt passive filters. To solve these inherent problems in shunt passive and shunt active filters, the authors have proposed a combined system of a shunt passive filter and a small rated series-active filter. The purpose of this paper is to reduce the required rating of the series-active filter, considering a practical application of the combined power filter to harmonic compensation for large-capacity thyristor converters. The points are summarized as follows:

• 1 The required rating of the series-active filter can be reduced less than one-tenth by connecting a series-resonant circuit in parallel to the secondary of current transformer.
• 2 It is clarified theoretically and verified experimentally that compensation characteristics of the new combined system are equivalent to those of the already-proposed system with no series-resonant circuit.

     

压电振动能量收集系统中二极管整流电路的RC等效模型分析

为了方便分析压电振动能量收集系统的电气特性,基于等效前后压电能量收集系统输出功率相同的原则,提出了将整流器和滤波电容等效为RC电路的方法。分别分析了全波整流、倍压整流电路的电学特性,推导了RC等效电路中等效电阻和电容的计算表达式,并仿真分析了负载等效前后的功率变化曲线。分析结果表明,整流器和滤波电容等效为RC电路的方法是可行的。     

Comparisons between a hybrid shunt active filter and a pure shunt active filter

This paper deals with the hybrid shunt active filter for harmonic compensation of a three‐phase diode rectifier in a 480‐V adjustable‐speed motor drive system. The hybrid filter is formed by a three‐phase LC filter tuned around the seventh harmonic frequency and a small‐rated three‐phase voltage‐source PWM inverter. The LC filter and PWM inverter are directly connected in series. As a result, the DC capacitor voltage of the PWM inverter in the hybrid filter is much lower than that of a conventional pure shunt active filter. This results in higher efficiency, less switching ripple, and less EMI emission. Computer simulation is carried out to compare the hybrid filter with the pure filter in terms of circuit configuration and filtering performance. Simulation results indicate that the hybrid filter is superior in effectiveness and viability to the pure filter. In addition, theoretical analysis based on vector loci confirms the validity of the simulation results. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(2): 61–70, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20145     

基于设计空间的基本开关电容电路滤波器设计

提出了一种运用符号和数值计算与离散非线性优化相结合的滤波器设计方法——设计空间法,把滤波器的技术指标,即滤波器设计中要用到的一组参数映射到设计空间,并根据给定的准则寻找这一设计空间的最佳解决方案。然后介绍了一种新型的具有独立零点设置的基本二阶开关电容电路,最后通过实例阐述了用设计空间法设计一开关电容（SC）低通滤波器,实验证明了该方法的可行性,并且得到了预期的效果。