Bruno Velaerts

Two-dimensional analysis of the edge effect field and losses in high-frequency transformer foils

In design of high-frequency magnetic devices, various approaches have been used to provide calculation tools that are able to predict winding losses, including skin effect and proximity effect, in their two-dimensional (2-D) aspects. Up to now, these approaches have been mainly focused on giving quantitative results for specific cases. Because the final purpose of designers is not to perform single calculations, but to obtain optimal designs, we have looked for a complementary approach providing more general 2-D guidelines and understanding of the phenomena. In this paper, we examine the case of a foil winding undergoing edge effect, a typical situation where classical one-dimensional theories underestimate the real losses. Using a 2-D closed-form formula we developed in a previous work and the associated database of 400 2-D numerical models, we systematically analyze the dependence of the 2-D field and the corresponding extra losses with the geometrical design variables describing the dimension and position of the winding.

A novel approach to the generation and optimization of three-level PWM wave forms for induction motor inverters

The application of three-level pulsewidth modulation (PWM) to voltage source inverters feeding three-phase induction motors is considered. A subharmonic modulation method using two modulating waves is introduced. It is particularly well adapted to the elimination of specific harmonic bands. Systematic optimization of precalculated waveforms with respect to loss factor, shows that three-level PWM is very well suited to harmonic reduction. Transient behavior is discussed. It is concluded that three-level PWM yields significant improvements compared with two-level PWM, especially in high-power (gate-turn-off) GTO applications where the high DC link voltage requires a series connection of the switches.<<ETX>>

Eddy current losses in SMPS transformers round wire windings: a semi-analytical closed-form formula

We provide a new closed-form formula that instantly calculates the 2D high-frequency ohmic losses (skin and proximity effects) in round wire windings. It has been obtained by overwriting the classical definition (shown to be erroneous) of the layer copper factor introduced in 1D analytical theories. Compared to similar previous formulas, the average error is divided by a factor of thousand. Experimental validation is provided

Planar transformer technology applied to AC/DC conversion

Magnetic components play an important role in the technological evolution towards increased power density of AC/DC power converters. Planar transformers provide several advantages that have to be balanced with the latest evolution of more classical transformer technology. This paper analyses the interest of using planar transformer for AC/DC power conversion. Results of the implementation of a planar transformer in a 600 W AC/DC converter illustrate the analysis.

Adaptive remote powering solution for fast changing requirements of telecom networks: A real case experience

The widening need of DC back-up throughout broadband networks, coupled to reduced power consumption and growing need for DC power back-up, has brought remote powering technologies to a wider use in the last two years. Alpha Technologies has supported Telecom Italia in installing more than 20.000 “Fiber to the Cabinet” (FTTCab) nodes, equipped with Alpha Technologies Remote powering equipment units, tailored and customized throughout the full installation process, in co-operation with Alcatel-Lucent, to fulfill Telecom Italias requirements. This paper describes how the successive power solutions have been addressed and designed by Alpha Technologies to support the fast and massive deployment of small Optical Network Units (ONU) from early 2013 until today in 2014, in the main cities of Italy.

Microcontroller-Based, Multi-Mode 3-Level Pulse-Width Modulator

SummaryThe 3-levelvoltage inverter is an efficient solution for high power variable speed drives, as it combines high voltage capabilities(due to GTOs in series)and significant reduction of losses and/or switching frequency(due to the intermediate level leading to lower voltage harmonics). This paper shows how the subhar-monic and precalculated 3-level pulse-width modulation methods, used to control the inverter, can be implemented by a fully programmed modulator. The subharmonic modulation uses modulating and carrier waves to generate the commutations orders for the inverter. In addition to the classical bipolar 2-level and unipolar 3-level methods, our laboratory has developped a new “dipolar”3-level subharmonic modulation, which is described in the paper. The precalculated modulation, also present is based on optimized waveforms stored in EPROM, and reproduced in real time by the modulator. Concerning the implementation of these modulations, a new sampling method for the subharmonic modulation, and an ...