Vasile Topa - Academia.edu (original) (raw)

Papers by Vasile Topa

ECS Meeting Abstracts, 2013

not Available.

IEEE Transactions on Device and Materials Reliability, Mar 16, 2016

Power devices have to withstand fast thermal cycling in automotive applications. In order to guar... more Power devices have to withstand fast thermal cycling in automotive applications. In order to guarantee reliability in these applications, a detailed understanding of the degradation mechanisms is required. One of these mechanisms is interlayer dielectric cracking, caused by the progressive plastic deformation of metal lines. In a previous publication, we have shown that DMOS transistors, with different active areas, which operate in similar conditions, have dissimilar reliabilities. This cannot be explained by state-of-the-art methods, which estimate reliability from the peak junction temperature. In this paper, extended measurement results of a DMOS transistor will be analyzed with the aid of electrothermal and thermomechanical simulations, and a new approach for reliability estimation will be proposed.

2020 IEEE 26th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2020

An electro-thermal simulation setup using a FEM-based simulator is being calibrated for adequate ... more An electro-thermal simulation setup using a FEM-based simulator is being calibrated for adequate modelling of the thermal behavior of a DMOS power transistor operating under fast thermal cycling. The computational domain is defined by selecting the essential geometry details of the chip. A method of homogenization is used to reduce the complexity of the chip metallization. Equivalent anisotropic thermal properties and their temperature dependencies are extracted for the homogenized regions. The simulation stimuli are adjusted so that they replicate the testing conditions. Transient electro-thermal simulations are performed and their accuracy is assessed by comparison with the experimental data. A second comparison is performed between a highly detailed model and the homogenized one in order to assess the reduction in simulation time and possible accuracy loss.

2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC), 2019

A finite element method analysis using the concepts of representative volume element and periodic... more A finite element method analysis using the concepts of representative volume element and periodic boundary conditions is carried out in order to determine the equivalent linear-elastic properties for a multi-level routing metallization typically found in power integrated circuits. Some theoretical aspects regarding homogenization are discussed, a typical metallization structure is presented, a substructure is chosen as a representative volume element and then mechanical loads are applied to it through adequate use of periodic boundary conditions in a stationary mechanical simulation. The resulting stress and strain distributions are analysed and their volume averages are used to calculate the anisotropic linear-elastic properties of the routing metallization. The procedure is repeated at a larger scale to validate the method. Conclusions are drawn regarding the accuracy and the advantages of the method.

This paper describes a new on line web course on Electromagnetics for Engineering, designed by th... more This paper describes a new on line web course on Electromagnetics for Engineering, designed by the authors and delivered at the Technical University of Cluj-Napoca (TUCN), Romania. The main results presented are related to the design of the on line course components: graphical interfaces, dynamic web pages created for glossary of terms and virtual library, multimedia applications for the virtual laboratory and interactive pages for the autoevaluation and final tests.

2019 8th International Conference on Modern Power Systems (MPS), 2019

Due to weakened electrical contacts in the interior of circuit breakers an undesired phenomenon a... more Due to weakened electrical contacts in the interior of circuit breakers an undesired phenomenon appears which leads to unwanted effects in the global energetic system. Due to this effect in the circuit breaker, an electrical arc appears which can lead to heating of the respective material and the appearance of network harmonics, aging of materials and influence on the device's functionality. A low cost temperature measurement system in automated circuit breakers has been devised. This system can aid us in identifying the eventual problems during the functioning of the device.

2021 9th International Conference on Modern Power Systems (MPS), 2021

The wireless power systems of millimetre dimensions are nowadays used for a wide range of high te... more The wireless power systems of millimetre dimensions are nowadays used for a wide range of high technology applications. In this paper we aim to extract the planar spiral inductors parameters to optimal design them for the design of a wireless power supply system used to supply the peacemaker or other similar devices. The planar spiral inductors are analysed first to extract their specific parameter. Then the influence of the ferrite on the spiral inductors parameters is analysed to improve the inductor performances by increase its inductance. Next using the optimized inductor, a wireless power supply system is designed and 3D numerical modelled to also extract its parameters. Different distances between emitter and receiver inductors are considered trying to estimate the real possible distance that can exist between them if they will form the wireless power supply of a peacemaker. Finally, we analyse the influence of ferrite, considering different thicknesses, also on the wireless system’s parameters, aiming to increase them for improvement of device performances.

2014 16th International Conference on Harmonics and Quality of Power (ICHQP), 2014

ABSTRACT This paper outlines a method for the suppression of the parasitic inside electromagnetic... more ABSTRACT This paper outlines a method for the suppression of the parasitic inside electromagnetic interferences (EMI) filters that are used in power supply devices. The paper focuses on EMI filters designed using the electromagnetic integrated planar technology. To accomplish this task the authors set up an optimal design algorithm named OptimCond that is able to find out the optimal arrangement of the windings in order to minimize the structural parasitic capacitance of the filter. The algorithm proposed is applied to increase the EMI filtering performances for a well-known filter realized in planar technology.

2007 14th IEEE International Conference on Electronics, Circuits and Systems, 2007

Abstract The paper presents the structure and the performance of signal processing algorithms tha... more Abstract The paper presents the structure and the performance of signal processing algorithms that simulate natural room reverberation. It deals with three digital complete artificial reverberators, built up of Schroeder's early reverberator and a late reverberator ...

IEEJ Transactions on Electrical and Electronic Engineering, 2010

IEEE Transactions on Power Delivery, 2006

AbstractThis paper presents a recently developed simulation software tool for ac predictive and ... more AbstractThis paper presents a recently developed simulation software tool for ac predictive and mitigation techniques for pipeline networks influenced by high-voltage (HV) power lines. The software can deal with any configuration (no limitation on number of pipes, ...

IEEE Journal of the Electron Devices Society

2020 International Conference and Exposition on Electrical And Power Engineering (EPE), 2020

Electricity is a commodity traded from the market through various products, but this level of acc... more Electricity is a commodity traded from the market through various products, but this level of accessibility represents a great opportunity and challenge for energy suppliers. Storing electricity in large quantities is not yet possible, meaning that the delivery to the customers needs to happen at the time of production. Energy suppliers must have a reliable strategy to buy or sell on the power market. The strategy efficiency determines if the supplier can optimally balance the portfolio, with the lowest impact on the overall costs. Energy imbalance is the difference between energy forecast and real consumption/ generation per portfolio. The cost of imbalances can negatively impact the margin of a portfolio that aggregates production, consumption, and trading. In this paper, the authors present complex situations for an energy supplier who needs to balance a portfolio consisting of consumption (industrial and commercial consumers), generation (photovoltaic and hydropower plants), and...

Corrosion, 2003

Cases of close proximity of high voltage transmission lines and metallic pipelines become more an... more Cases of close proximity of high voltage transmission lines and metallic pipelines become more and more frequent. Therefore, there is a growing concern about possible hazards resulting from the influence of electrical systems: safety of people making contact with the pipeline, ...

− One of the major goals in designing of the integrated EMI filters is to improve their highfrequ... more − One of the major goals in designing of the integrated EMI filters is to improve their highfrequency characteristics. To achieve this, special technologies need to be developed, including the mechanisms for suppression of the equivalent parallel capacitance (EPC) and of the equivalent series inductance (ESL), in spite of increasing the highfrequency losses. In this light, the paper studies the technologies used to reduce the Equivalent Series Inductance (ESL) for EMI filters integration. The ESL of integrated L-C with three different connection methods are proposed, namely: the L-C series connection method, the two-point capacitance connection method and the four-point transmission line connection method, as they are described below. Final conclusions will end the paper.

Electronics

This paper deals with high frequency analysis of spiral inductors, used in microelectronics circu... more This paper deals with high frequency analysis of spiral inductors, used in microelectronics circuits, to optimize their configuration. Software developed, designed, and implemented by the authors for nano and micrometre spiral inductor high frequency analysis, named ABSIF, is presented in this paper. ABSIF determines the inductance, quality factor, and electrical parameters for square, hexagonal, octagonal, and circular spiral inductors and their configuration optimization for energy efficiency. ABSIF is a good tool for spiral inductor design optimization in high frequency applications and takes into account the imposed technological limits and/or the designers’ constraints. A set of spiral inductors are considered and analysed for high frequency values using ABSIF, and the results are presented in the paper. The validation of ABSIF was completed by comparing the results with those obtained using a similar commercial software, Sonnet LiteTM, which is dedicated to high frequency elec...

2017 International Conference on Modern Power Systems (MPS), 2017

The paper emphasizes a study regarding the efficiency of the passive loops usage for the mitigati... more The paper emphasizes a study regarding the efficiency of the passive loops usage for the mitigation of the magnetic field values in the neighborhood of high voltage overhead power lines. In the first part of the paper the basic principles of the suppression method are introduced. In the second part of the paper analytical computation results are presented and discussed. The efficiency of the proposed mitigation solution is outlined. Final conclusions end the paper.

... Ioan T. Pop Adina Racasan Department of Electrotechnics Technical University of Cluj-Napoca B... more ... Ioan T. Pop Adina Racasan Department of Electrotechnics Technical University of Cluj-Napoca Baritiu 26-28, RO-400027 Cluj-Napoca, ROMANIA Tel: +40264401244, Fax: 40264592903 Ioan.Pop@transelectrica.ro ... REFERENCES [1]. C. Munteanu, G. Visan, IT Pop, V. Topa, E ...

Thermo-mechanical stress accumulation in the power electronic integrated circuit (PIC) devices in... more Thermo-mechanical stress accumulation in the power electronic integrated circuit (PIC) devices influences their lifetime and reliability. In order to determine both the temperature and the stress accumulation, numerical simulation is a very important tool in the design of PIC devices for quantifying and enhancing their lifetime and reliability. An open source solution integrated in Salome-Meca and Code_Aster based on the finite element method (FEM) is used in this paper to analyze the thermo-mechanical behavior on a simple metal-semiconductor structure, which is typically found in a PIC. The computational time and accuracy of the simulations results is improved by finding the optimal mesh configuration. A convergence study is computed for five different cases by progressively reducing the size of the discretization elements (hence, increasing the number of mesh elements) in the area of interest. The results for an optimal relative error and computational time are compared with the r...

Spiral inductors are very often used in integrated circuits for many applications. To design spir... more Spiral inductors are very often used in integrated circuits for many applications. To design spiral inductors or to improve the spiral inductors performances is absolutely necessary to calculate theirs inductances and/or to optimize theirs layouts. In this effect we create a software program, named CIBSOC (Spiral Inductors Inductance Calculation and Layout Optimization). The program is dedicated to calculate dc inductances and to optimize layouts for spiral inductors. We use a wide range of inductors in the applications made with our program. We compare the results of our applications with the measurements results existing in the literature and also with the results that we have obtained using a commercial field solver in order to validate our program. Our program is accurate enough, has a very friendly interface, is very easy to use and it calculates the problems in a very sort running time compared with other similar programs. Since spiral inductors tolerance is generally on the o...