Optimizing the LLC–LC Resonant Converter Topology for Wide-Output-Voltage and Wide-Output-Load Applications

Abstract

LLC-LC resonant converter is a suitable circuit topology to design switched-mode power supplies for wide-output-voltage and wide-output-load applications. In this paper, a design procedure is introduced to optimize this converter. Unlike soft switching techniques for pulse width modulated converters, which usually apply an active auxiliary circuit to reduce switching losses and EMI, in the proposed converter, not only such circuits are not used, but also all of the parasitic elements are merged to the converter's main components. Zero-voltage switching (ZVS) operation is realized for all power devices under all operating conditions. Thus, this converter is a suitable choice for high-switching-frequency operation. The converter parameters have been designed to minimize the components' current and voltage stresses. In addition, the frequency variation range has been reduced in order to use the magnetic components, optimally. Developed prototype of the converter has been tested for different output voltages (25-165 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> ) under different loads (0-3 A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> ) and input voltages (320-370 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> ) for being used as ion implanter arc power supply. For regulating and adjusting the designed prototype converter output voltage, its switching frequency varies from 177 to 314 kHz. The converter's maximum efficiency is approximately equal to 96.6%.