EPE Journal Volume 11-2 
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EPE Journal Volume 11-2 - Editorial
EPE Journal Volume 11-2 - Papers



 EPE Journal Volume 11-2 - Editorial 

EPE 2001 - A meeting of Friends  [Details]
By H. Weiss

The Editorial of the EPE Journal Volume 11 N2, "EPE 2001 - A meeting of friends", written by Prof. Helmut Weiss, the Conference Chairman of EPE 2001.


 EPE Journal Volume 11-2 - Papers 

Theoretical and Experimental Analysis of Microchannels Heat Sink Obtained by Silicon Micromachining  [Details]
By C. Perret; C. Schaeffer; J. Boussey

The use of microchannels in silicon substrates as a forced liquid cooling device for power integrated circuits is investigated. The new concept presented in this work consists in placing water cooled heat sink structure directly inside the silicon substrate. This configuration allows the refrigerant liquid to be as close as possible to the heat generation source (circuit) which increases its efficiency. On the other hand, the integration of the microchannels inside silicon substrate reduces the number of heterojunctions involved in the cooling device which has a benefic impact on the thermal stress. Thanks to the use of two commercially available softwares Flux3D abd Pascosma, thermal dissipation characteristics of serveral prototypes were simulated. On the base of some simplifying hypothesis clearly stated, a theoretical optimization of these prototypes were carried out allowing to find out the optimum dimensions of a cooling device operating under a given set of experimental constraints. Finally, a first prototype realization within fully compatible silicon integrated circuits technology is described and its preliminary experimental characteristics are presented.

Modeling and Simulation of non-Linear Magnetic Cores at High Frequencies Using PSpice  [Details]
By R. Garcia; J. A. Carrasco; J. M. Espi; E. J. Dede; J. Castello

Popularizer Using PSpice of MiscroSim to simulate power converters sometimes brings awkward complications such as the simulation of real magnetic components. It deals a little bit of work to bring a good agreement between experimental and simulated results. Simulation with linear inductors or transformers does not produce good results. The reason is that real magnetic components present saturation and hysteresis, a phenomenon that characterises magnetic materials. The hysteresis or B-H loop of a magnetic component, shown in figure below, is highly dependent on frequency, waveform (not very important for ferrite material), temperature, excitation level, etc. Although PSpice includes in its magnetic library a list of non-linear components, rarely these parameters are coincident with our working conditions or simply they are not specified. In all of these cases it is necessary the modelling of non-linear magnetic cores in our particular application. Here we present a systematic procedure to obtain real PSpice parameters to model magnetic materials using the Jiles & Atherton theory. The procedure is totally general and models the static B-H loop given by any manufacturer as well as the one that can be obtained in accordance with specific working conditions. The later is really important, since it helps the designer in obtaining model parameters for any high frequency applications, which are not correctly presented in PSpice libraries. With this procedure a good concurrence between experimental and simulated B-H loop is obtained.

A Novel Method Oriented to Evaluate the Real Characteristics of Practical Boost Zero-Voltage Switching Quasi-Resonant Converters  [Details]
By E. C. Tatakis; N. N. Polyzos

The output characteristics of Boost Zero-Voltage Switching Quasi-Resonant Converters, presented in previously published works, are calculated considering equal input and output energies. Nevertheless, measurements that were taken with different breadboarded Boost ZVS-QRCs demonstrate an important deviation between thge results of the theoretical analysis and the experimental ones. The deviation becomes greater when the load current increases. This paper deals with a novel simulation method to approximate the real behavioural characteristics of Boost ZVS-QRCs. Analytical expressions are derived to calculate the power losses at each converter component as well as the d.c.-voltage conversion ratio. The computer simulation results are confronted to experimental ones proving the effectiveness of the proposed method.

Detection through the Measurements of Perturbing Instants for te EMC in a Current Waveform  [Details]
By F. Guitton; D. Magnon

Energy converters use power components whose commutation generates conducted or radiated electromagnetic perturbations. Whether they spread through conductors or by hertzian way, they can lead to malfunctions or breakdowns in the equipment used, which are more or less close to the perturbing source. Traditionally, filters and shielding limited the pollution level to the values imposed by the standards. Yet modifying the devices implies bulkiness and higher cost. Thus we have aimed at reducing and if possible removing filter and power converters. Regarding the conducted ElectroMagnetic Compatibility (EMC), the filters inserted on power converters can be suppressed by controlling the commutation of the switches. For that, it is compulsory to detect perturbing instants contained in a temporal waveform: To achieve this, we have made a theoretical study and correlated the results obtained with experimental measurements. This paper presents a measurement setup allowing this detection.

Improving AC Regulator Input Power Factor by Multiplexed Asymetrical Phase-Control  [Details]
By H. E. Tacca

A method to improve the power factor of resistive loaded a.c. regulators is based on the association of multiple fractional power regulators sequentially turned-on using assymetrical phase-control. Load subdivision is required in order to gradually connect each fractional load in a progressive sequence to keep the power input factor between acceptable limits. Moreover, the multiple load division decreases the switched current values reducing the EMI problems. Finally, the multiple fractional power regulator topology presents a control flexibility plus an inherent redundancy which improves reliability.