Periodic noise analysis of electric circuits: Artifacts,singularities and a numerical method

In this paper it is shown that a numerical method largely adopted for the simulation of noise in autonomous circuits is affected by singularities that manifest when the frequency at which the noise analysis is carried out approaches a harmonic of the autonomous circuit. The resulting noise power spectral density (PSD) is thus characterized by spurious spikes. The presence of these singularities is for the first time justified from an analytical standpoint and their effects are shown by simulating some oscillators, employed as benchmarks. Furthermore, the presented approach justifies the 1/(f_s?f)² shape of the PSD of noise at the output when the f_s frequency approaches the f fundamental of a stable oscillator and the 1/|f_s?f|³ shape when the effects of flicker noise are manifest. Copyright © 2009 John Wiley & Sons, Ltd.     

工频三相电能国家计量副基准和谐波计量标准的研究

该项目由辽宁省计量科学研究院和中国计量科学研究;院合作研究成功，它以三相标准功率源和三相多功能标准表为主体，实现了高准确度的三相功率／电能等交流电量的输出与测量，通过传递标准获得其有功功率、交流电流、电压的量值，并在正弦和包含谐波两种状态下，以两种方式实现了量程扩展。同时首次提出并实现了无功功率／电能和谐波参量的计量溯源，从而获得了一个宽量程、多参数、全功能的三相电能计量国家副基准（0．01级）和交注电量、谐波计量标准。     

Energy balance in electric circuits with nonsinusoidal voltage andcurrent

An approach to apparent power components determination in nonsinusoidal voltage and current circuits has been presented. It is based on the use of mathematics of trigonometric rows, the Parseval equation in particular. The proposed method gives a possibility to avoid mistakes of a formal approach and to evaluate apparent power components more precisely as compared to the well-known methods     

Instrument current transducer for measurements in asymmetrical conditions in three-phase circuits with upper harmonics

The theme of the article is protection of electrical circuits against negative sequence currents both with sinusoidal and trapezoidal waveforms. The suggested solution is enhancement of instrument current transducers used in industrial relaying and control applications. The instrument negative sequence current transducer connected to Rogowski coils designed by the authors is presented in the article. To protect circuits with extremely non-sinusoidal currents (such as trapezoidal waveforms), instrument transducers with 2nd order low pass filter are suggested. In the presence of higher-order harmonics in the protected three-phase circuit the low pass filter will reduce the THD in the output voltage of instrument negative sequence current transducer (as compared to harmonics in currents of the protected circuit) and compensate for the differentiation effect typical of such transducer schemes.The paper may be of interest for investigators and engineers engaged in research, design and commissioning of protection and control equipment, current instrument and measurement devices used in industrial applications, and also for undergraduate and postgraduate students in electrical engineering.     

Determination of aging-model constants under high frequency andhigh electric fields

Polypropylene film is tested for life under HV, frequencies up to 30 kHz, and aging and breakdown studies are conducted. The life data obtained is applied to three different aging models relating electric stress to time to failure: the inverse power, the exponential and the thermodynamic model. The dependency of the constants of these models on the frequency of the applied voltage is determined. The results show that the aging model constants are dependent on applied voltage and frequency     

Analysis of three-phase chopper circuits controlled by asymmetrical firing of thyristors

Contents Using thyristor and thyristor-diode a.c. choppers causes distortion of currents and voltages in electrical power networks. In this paper the currents in three-phase, three-wire circuits with thyristor and thyristor-diode a.c. choppers are analysed, making allowances for asymmetrical phase-angle triggering. The computation results of the extinction angles versus firing angles, phase shift angles of the load and degree of asymmetry are shown. The d.c. and harmonic components of the current waveforms were calculated by applying Fourier analysis. The computation results of the magnitudes, which are characteristic of deformed waveforms are also presented.

---

Übersicht Der Einsatz von Thyristoren und Thyristordioden verursacht Verzerrungen von Strömen und Spannungen in elektrischen Versorgungsnetzen. In diesem Beitrag werden Stromverläufe in Drehstromnetzen unter Berücksichtigung unsymmetrischer Ansteuerung durch Thyristoren analysiert. Die errechneten Abhängigkeiten des Löschwinkels von der Phasenlage der Last und der Unsymmetrie der Ansteuerung werden dargestellt. Mit Hilfe der Fourieranalyse werden Gleichstromanteil und Oberschwingungen der Ströme ermittelt. Berechnet und dargestellt werden auch andere Größen, die für nichtlinear verzerrte Vorgänge charakteristisch sind.

     

Mathematical modelling of three-phase electrode salt-bath furnace with the two-dimensional electric field

Contents After a short historical survey of the attempts to solve the problem of designing and determining the dimensions of a three-phase electrode salt-bath furnace, the authors apply the theory of the three-phase transmission line with uniformly distributed parameters to the phenomena in the electrode furnace. Taking all necessary boundary conditions and permissible simplifications, formulae for most widely sprcad types of the furnaces are derived, which allow the calculation of input admittance and input power of the furnace, as well as other important electric quantities.

---

Ein mathematisches Modell des dreiphasigen Elektroden-Salzbadofens mit zweidimensionalem elektrischen Feld

Übersicht Nach einer kurzen historischen Übersicht der Versuche einen dreiphasigen Elektroden-Salzbadofen zu projektieren und seine Abmessungen zu berechnen, wenden die Verfasser die Theorie der dreiphasigen Übertragungsleitung mit gleichmäßig verteilten Parametern auf die Erscheinungen im Elektroden-Salzbad-Ofen an. Mit Hilfe notwendiger Randbedingungen und zulässigen Vernachlässigungen werden die Formeln für die am meisten verbeiteten Ofentypen hergeleitet, die die Berechnung der Eingangsadmittanz und der Anschlußleistung des Ofens wie auch andere wichtige elektrische Größen ermöglichen.

     

On the noise performances of fractal-fractional electrical circuits

In this work, the noise performances of the fractal-fractional electrical circuits have been addressed. The nonlocal fractal calculus has been adopted as our mathematical basis. The fractal time component has also been included for the physical measurability of electrical quantities. The derivations of crucial stochastic parameters of circuit responses, which determine their noise performances, have been performed. Numerical simulations have also been conducted where the influences of Hausdorff dimension of the fractal set, orders of fractal-fractional reactive components, and other parameters on the noise performances have been studied. Regardless to any specific circuit, we have found that the noise performances can be improved by increasing the orders of fractal-fractional reactive components. The optimum Hausdorff dimensions, which the best noise performances can be achieved given the orders of fractal-fractional reactive components, have also been calculated. The results proposed in this work serve as the foundation for understanding noise in fractal-fractional electrical circuits and can be extensively applied to large-scaled circuits, for example, the infinite circuit networks and so forth.     

三相PWM驱动电机系统干扰源的数学模型

针对三相PWM驱动电机系统难以建立用于预测干扰的准确的高频干扰源数学模型这一问题,提出将整流桥和逆变器两个干扰源分开进行研究的方法.采用傅里叶变换法建立整流桥的干扰源模型,采用双重傅里叶积分法建立逆变桥产生的共模和差模干扰的干扰源数学模型,把PWM载波和基波用两个独立周期的时变函数来描述,将其共同作用的函数作为被积函数,并详细推导了正弦脉宽调制技术的内外积分线的确定过程.最后通过实验结果和仿真结果的比较,验证了所建立整流桥和逆变器的干扰源模型的正确性,因此该数学模型可作为三相PWM驱动电机系统的传导干扰预测的干扰激励源.     

Misinterpretations of some power properties of electric circuits

It might be expected that the meaning of the apparent power S, a quantity of innumerable everyday applications for almost a century, is well understood. It occurs, however, that this meaning is still a matter of discussion and some interpretations hard to accept are published. Also it is suggested in some papers published recently that only oscillations of the instantaneous power may cause an increase of the apparent power S, which is not true. Misinterpretations that refer to fundamental notions such as powers could be particularly harmful for electrical engineering and should be eliminated as much as possible. Therefore, this paper shows that the apparent power does not have the physical meaning suggested recently. Also it shows that load unbalance in three-phase power systems does not cause any oscillation of the instantaneous power. The conclusion that load unbalance causes oscillations of the instantaneous power is a consequence of a substantial misinterpretation of this quantity in three-phase power systems     

Fundamental operation of direct linked frequency changer with bilateral switching circuits

This paper describes a direct linked‐type frequency changer (DLT‐FC) proposed by the authors. The DLT‐FC is a converter circuit with a new configuration for direct frequency change. The DLT‐FC does not require a dc link circuit, nor bilateral switches. In addition, dc snubber circuits can be applied without the need for a regenerative circuit of snubber energy. Therefore, the DLT‐FC can be designed to be compact and light, and has a long life. The authors manufactured a prototype of the DLT‐FC and experimentally checked its CVCF and VVVF operation. The results indicate that the performance of the DLT‐FC makes it suitable for industrial use. © 1999 Scripta Technica, Electr Eng Jpn, 128(1): 53–61, 1999     

基于ICA的含噪电力系统信号的频率测量

为提高在噪声环境下频率测量的准确性,提出一种结合独立分量分析(ICA)和加汉宁窗插值算法的含噪电力系统信号的频率测量方法.该方法使用ICA对混有噪声的信号进行分离获得电力系统信号后,使用加汉宁窗插值的傅里叶算法获得电力系统频率.由于ICA对噪声和有用信号进行了很好的分离,因此频率测量的精确度得到了显著提高.仿真分析了含有白噪声和脉冲噪声的情况.即使噪声的幅值大于信号幅值数百倍时,使用所提出算法后频率误差绝对值的最大值从2.4 Hz左右分别减少到了0.0028 Hz和0.0005 Hz,表明所提出算法在极低信噪比时仍具有较高的精确度.     

High electric stress and insulation challenges in integratedmicroelectronic circuits

The insulating layer in the transistor has decreased from 100 nm in the early 1970s to only a few nanometers today. This thin insulating layer gives rise to very high electric fields approaching 1000 kV/mm for an operating voltage of 1 V. Degradation of the insulation during ageing takes place due to the high field and may eventually lead to a breakdown. Currently it seems that the reliability of the insulating layer is one of the factors that may limit a further scaling of the transistor technology. Another threat to the thin insulating layer is electrostatic discharges (ESD) caused by human or machine handling. ESD can generate voltage and current pulses far outside the normal operating regime, and cause breakdown of the insulating layer. This article intends to give a brief introduction to the above-mentioned insulation challenges in integrated microelectronic circuits     

Qualitative analysis of an interrupted electric circuit with spike noise

Switching non‐ideality and its effects have been reported in DC‐DC converters. In this paper, we examine the qualitative property of an interrupted electric circuit with spike noise. First, we show the circuit model that have the switch interrupted by its own state and a periodic interval. Here, we artificially add spike noise via every switching action. Then, we explain its dynamics and derive the Poincaré map for the rigorous analysis in a circuit with ideal switching and a circuit with spike noise, respectively. Finally, we discuss the dynamical effects of spike noise from experimental and analytical viewpoints based on the Poincaré map and bifurcation diagrams. As a result, some dynamical effects of spike noise are clarified in terms of the invariant set, bifurcations, and existence regions of coexisting attractor. Copyright © 2010 John Wiley & Sons, Ltd.     

A method of measuring the phase current in low-voltage three-phase electric drives

A method of measuring the phase current of an electric energy transducer is proposed. The method is implemented by measuring the voltage drop across an open power MIS (MOSFET) transistor and, if compared to the use of current shunts and Hall-effect sensors, offers the advantage of lowering the device size, its cost, and losses in the power circuit. Experimental data verify the applicability of this circuit design when using modern elements and microprocessor control systems.     

Structural analysis of electric circuits and consequences for MNA

The development of integrated circuits requires powerful numerical simulation programs. Naturally, there is no method that treats all the different kinds of circuits successfully. The numerical simulation tools provide reliable results only if the circuit model meets the assumptions that guarantee a successful application of the integration software. Owing to the large dimension of many circuits (about 10⁷ circuit elements) it is often difficult to find the circuit configurations that lead to numerical difficulties. In this paper, we analyse electric circuits with respect to their structural properties in order to give circuit designers some help for fixing modelling problems if the numerical simulation fails. We consider one of the most frequently used modelling techniques, the modified nodal analysis (MNA), and discuss the index of the differential algebraic equations (DAEs) obtained by this kind of modelling. Copyright © 2000 John Wiley & Sons, Ltd.