The aim of this document is to present how the interpretation of the RVM (Recovery Voltage Measurement) test can be improved through the use of a Debye equivalent circuit. As it is described in the literature, the interpretation of the RVM test requires expertise and if the transformer presents a high interfacial polarization it is not possible to diagnose it in detail. The Debye model is proposed in this work for enhancing RVM interpretation. This model is based on an electrical circuit that includes basic R-C components, that allows two interesting features: on one hand, insulation physical effects can be separately represented and, on the other, the values of the R-C components can be calculated from the RVM response. A method is proposed in which using a sweep with a constant number of predefined time constants branches allows us to determine the areas of influence of the different compounds present in the dielectric. Finally, several case studies are presented, in which it is correlated a dielectric oil treatment carried out and the equivalent circuit changes using a sweep allows us to analyze different branches’ sensitivity and to identify the areas of influence of each compound.

The aim of this document is to present how the interpretation of the RVM (Recovery 12 Voltage Measurement) test can be improved through the use of a Debye equivalent circuit. As it is 13 described in the literature the interpretation of the RVM test requires expertise and if the 14 transformer presents a high interfacial polarization it is not possible to diagnose it in detail. Debye 15 model is proposed in this work for enhancing RVM interpretation. This model is based on an 16 electrical circuit that includes basic R-L-C components, that allows two interesting features: on one 17 hand, isolation physical effects can be separately represented and, on the other, the values of the R18 C components can be calculated from the RVM response (L components are not used in this work 19 as long as no magnetic field effects are taken into account). Thus, the different isolation effects that 20 are indistinguishable merged in the RVM transient response can be split into different R-C branches, 21 each one corresponding with a single (not merged) isolation effect. Finally, several case studies are 22 presented, in which it is correlated a dielectric oil treatment carried out and the equivalent circuit 23 changes. 24

Multiple cell upsets (MCU) is an issue that has to be dealt with when designing electronics for working in a radiated environment. Furthermore, the constant evolution of ICs integration density causes an increment in the MCUs span. These issues are typical in aviation applications, where, additionally, fault-tolerant (FT) performance is required. FT systems are typically based on a redundancy concept for storing and retrieving healthy information, for example, with a triple modular redundancy (TMR) scheme. The main issue with redundancy is design oversizing. On the other hand, reconfiguration-based techniques allow error scrubbing with a limited overhead. The main drawback here is overhead vulnerability to radiation, which is invalid for FT requirements. This paper proposes a new hybrid architecture that takes advantage of the optimized performance of reconfiguration-based techniques supported on extremely compressed redundant information nonvulnerable to radiation, referred to in this paper as hardwired seed bits (HSB). It also includes different known techniques, such as interleaving, error detection and correction (EDAC) algorithms, etc., for optimizing the final architecture as much as possible. As a result, the proposed approach meets FT requirements thanks to nonvulnerable tiny redundant information combined with an optimized performance through EDAC-based implementation.

The following article presents the results obtained in experiences that use the Impulse Frequency Response Analysis (IFRA) method with a transformer in service. The IFRA method has been implemented in order to transform the transient signals to the frequency domain using Discrete Fourier Transform (DFT). However, it can be considered that the DFT is not the most suitable tool for this type of analysis, since, by definition, this tool is useful for processing stationary signals. Taking that into consideration, the analysis of transient signals could be hypothetically improved by using continuous wavelet transform (CWT), given their variable time/frequency resolution. The analysis of transient signals in Wavelet domain has improved the repeatability of the frequency response curves, as it has been ob-served in experimental results. The proposed on-line IFRA method, based on Wavelet transform, was validated under load and no-load conditions on a 150 kVA three-phase transformer 13200/225 Volts, in the Campus of the Universidad del Valle, Cali, Colombia.

The design and characterization of a new toroidal planar transformer integrated in a PCB is presented in this study. The prototype consists of two sheets of fiberglass between which a toroidal ferrite core is inserted. The prototype is tested through experimental measurements taken from the linear to the saturation regions and have found that the PCB transformer can operate up to approximately 20 MHz without showing capacitive effects.

e development of the smart grids leads to new challenges on the power electronics equipment and power transformers. e use of power electronic transformer presents several advantages, but new problems related with the application of high frequency voltage and current components come across. us, an accurate knowledge of the transformer behavior in a wide frequency range is mandatory. A novel modeling procedure to relate the transformer physical behavior and its frequency response by means of electrical parameters is presented. Its usability is demonstrated by an example where a power transformer is used as �lter and voltage reducer in an AC-DC-AC converter.

This paper describes a new procedure which facilitates the frequency-response curve interpretation in the low-frequency bandwidth. The procedure is able to estimate the magnetization inductance and winding capacitance, for each transformer phase by only using data from its frequency response. The described calculation procedure uses an R-L-C electrical equivalent circuit developed to simulate the impedance measured in the frequency-response test. The procedure takes into account the magnetic coupling among different phases and allows their analysis separately, enabling the identification of a possible failure. This paper describes the procedure to obtain the parameters and its application for interpreting the low-frequency results of frequency-response analysis measurement cases.

We propose a model of an equivalent electrical circuit specifically designed for a ferrite inductor excited by a sinusoidal waveform. The purpose of this model is its use in a circuit simulator. We calculate the model parameters by means of Finite Elements in 2D which leads to significant computational advantages over the 3D model. We carry out the validation for a toroidal ferrite inductor by comparing the experimental results and computed ones. We consider the saturation and power losses in the core. In addition, we have tested the model for the case of square waveform in order to generalize the results. We find excellent agreement between the experimental data and the results obtained by numerical calculations.

This paper presents a practical assessment and validation for the new proposed approach based on the continuous wavelet transform (CWT) to obtain the frequency response from online transient signals for an actual transformer. Apart from the mathematical procedure, an electronic system was also designed and implemented in order to inject superimposed controlled pulses to the power system (50/60 Hz) wave. The results show improved performance of the wavelet transform compared to the Fourier transform, for transient signal analysis to be applied on a nonintrusive transformer monitoring approach. Particularly, this new approach enables overcoming some problems related to the signal filtering and the signal processing in an online frequency-response analysis transformer diagnosis. This paper is presented in three parts. Part I showed the main theoretical basis of this approach. The current Part II shows a practical assessment based on tests performed in a three-phase transformer of 1150/345 V-5 kVA and in a single-phase transformer of 13200/240 V-15 kVA. Part III shows the performance of this new approach on transformers being diagnosed under real conditions.

We present here a modeling procedure for inductors with an E-shaped ferrite core valid for calculating the inductance of an equivalent circuit from the linear operating region to the saturation region. The procedure was developed using Finite Elements in 2D. We demonstrate that using a 2D section of the real core the results obtained are similar to the real ones, which solves the problem of convergence that appeared when E type cores were simulated in 3D, while also saving computational cost. We also discuss the effect of the gap-thickness on the magnetic properties. The data obtained by simulation are compared with experimental results.

We propose a model of an equivalent electrical circuit specifically designed for a ferrite inductor excited by a non-sinusoidal waveform valid for use in an electronic circuit simulator. We estimate the model parameters by means of Finite Elements in 2D which leads to significant computational advantages over the 3D model. We carry out the validation of the procedure for an RM14/I core by comparing the experimental and simulated output waveforms obtained at different frequencies and levels of excitation from the linear to the saturation regions. In addition, we consider the effect of power losses in the core.

Ferrite inductors are widely used in the field of power electronics, a subject included in various curricula in the universities both at the undergraduate and postgraduate level. These inductors are difficult to model due to the wide variety of shapes, number of turns, and the nonlinear behavior of the core that exhibit saturation, hysteresis and power losses. For this reason, it is necessary to resort to numerical methods such as Finite Element Analysis. In this paper we give some guidelines and recommendations for students to correctly use Finite Element programs for modeling inductors with different shapes. We give a vision of the modeling procedure of inductors including the simplifications that students should make in the 3D inductor model to achieve convergence and the assigning of materials as well as boundary and meshing conditions. Finally, we show representative results of the procedure. In dex Terms - Power electronics, Research in education, Ferrite cores, Finite Element Analysis. I. Introduction Power electronics is taught in the majority of universities at both the undergraduate and postgraduate level. It is a multidisciplinary subject which involves knowledge about electromagnetic fields, modeling and simulation 1,2 . The conception, design and analysis of power electronic systems are important tasks often requiring the help of computers to perform fast and accurate computations or simulations 3

This paper introduces a new theoretical method to obtain the frequency-response curve with the transformer in service (online) from the transient signals analysis by applying the continuous wavelet transform. To validate the method, the transient signals were simulated in the Alternative Transient Program for two cases: 1) under injection of pulses over the 60-Hz wave and 2) under switching operations, respectively. To simulate the transformer, a suitable wide-bandwidth model was employed. This study proposes a new setup of the Morlet wavelet, denominated Morlet-Modified, which showed the best results obtained for our application purpose (FRA On-line). This paper is a contribution for signal processing for the online frequency-response analysis technique on transformers.

We propose a model of an equivalent electrical circuit specifically designed for a ferrite inductor excited by a nonsinusoidal waveform valid for use in an electronic circuit simulator. We estimate the model parameters by means of Finite Elements in 2-D which leads to significant computational advantages over the 3-D model. We carry out the validation of the procedure for an RM14/I core by comparing the experimental and simulated output waveforms obtained at different frequencies and levels of excitation from the linear to the saturation regions. In addition, we consider the effect of power losses in the core.

In this paper we propose and validate by experiment a practical method to compute by simulations the inductance of a ferrite inductor as a function of the current intensity level from the linear to the saturation regions. Our method combines the use of 2D Finite Element Analysis with experimental measurements taken in a laboratory environment. We also present and analyze results of the convergence and computational cost of the 2D and 3D simulations showing the reduction of computational cost when we chose the 2D simulation.

We present a methodological procedure valid for teaching the subject of power electronics. Our integrated teaching consists of modeling, simulation and experimentation using real inductors. We apply this procedure to the modeling and simulation of ferrite inductors widely used in the field of power electronics because of magnetic properties. It can be applied to undergraduate and postgraduate students with the main objective being to help them understand the behavior of the circuits and the nonlinear physical phenomena involved in power electronics. By means of some examples, we show how the use of computer simulation and measurements can make the education of this subject more effective and enjoyable for both the students as well as the instructor.

In this paper we show an application of the electromagnetic modeling in order to simulate nonlinear waveforms of power converters in a precise way. These power converters include inductors with soft ferrite cores. We show the simulated voltage and current waveforms of the ferrite inductor including the nonlinear effects of saturation and power losses in its core. We validate these results by comparison with those obtained by experiment. We present relevant results provided by the electromagnetic modeling.

We present a procedure that combines modeling, simulation and experimental measurements on real inductors. We apply this procedure to the modeling and simulation of ferrite inductors, widely used in the field of power electronics. It can be applied to undergraduate and Master level students to help them understand the behavior of circuits and the nonlinear physical phenomena involved in power electronics.

The development of the smart grids leads to new challenges on the power electronics equipment and power transformers. The use of power electronic transformer presents several advantages, but new problems related with the application of high frequency voltage and current components come across. Thus, an accurate knowledge of the transformer behavior in a wide frequency range is mandatory. A novel modeling procedure to relate the transformer physical behavior and its frequency response by means of electrical parameters is presented. Its usability is demonstrated by an example where a power transformer is used as filter and voltage reducer in an AC-DC-AC converter.