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H. Ertl, J.W. Kolar, F. Zach:
"Analysis of an Extended DC-DC Flyback Converter with Inherent Input Voltage Symmetrization";
Poster: International Conference on Power Conversion and Intelligent Motion (PCIM), Nürnberg, Deutschland (invited); 1998-05-26 - 1998-05-28; in: "Proceedings", Proceedings of the 38th Int.Conf.on Power Conversi (1998), 501 - 506.

Abstract ¾ The paper presents a novel extension of a basic flyback topology which features a self-balancing of the partial DC input voltages. A switch-mode converter based on the proposed structure can be applied advantageously, e.g., for the auxiliary power supply of DC voltage link PWM AC drives. Due to the voltage level the DC link of such systems often is realized by a series connection of two (groups of) electrolytic capacitors. The simplest method to balance the capacitor voltages is the arrangement of a resistive voltage divider in parallel to the capacitors. However, this causes significant additional power losses which can be avoided if the auxiliary power supply unit of the drive system (which is connected to the DC link in most cases in order to enable a controlled shut down if the mains voltage fails) also performs the voltage balancing of the DC link capacitors. An auxiliary power supply unit employing the proposed extended flyback topology allows this symmetrization in a self-adjusting manner.