Estudo de um equalizador de tensão empregando o conversor Forward operando em modo de condução descontínuo

Abstract

This work aims to study a voltage equalizer for lithium batteries associated in series, based on an isolated dc-dc Forward converter operating in discontinuous conduction mode (DCM). As a voltage equalizer, the Forward converter will operate in open loop, that is, with a fixed and imposed duty cycle. Voltage equalization will occur as a natural characteristic of the converter to find a stable operating point. The self-balancing of the converter output voltages (battery voltages) will lead to exactly the same output voltages if the secondary-sides are perfectly symmetrical. In practice, parametric differences, such as the number of turns of the output inductors, can lead to slightly different output voltages, and if such a difference does not compromise operation as a voltage equalizer, this control mechanism is adequate. The work presents the analysis of the converter operation in discontinuous conduction, the main design equations as well as numerical simulation results to prove the applicability of the Forwad converter as a voltage equalizer. Numerical simulation results consider the following design specifications: power of 100 W, switching frequency of 50 kHz and two 12 V batteries associated in series with a maximum unbalance of 2 V.