Stress and loss analysis of quasi-resonant converters

Abstract

Quasi-Resonant Converters (QRCs) have been proposed recently in the effort of increasing the switching frequency and reducing the switching losses. There are several merits and demerits of this class of converters. The most important aspects of this research are to assess the advantages and limitations of QRCs in terms of their device current and voltage stresses and a determination of the factors affecting them. The losses in the various elements are also determined to provide a reasonable estimate of the converter efficiency. The work in both tasks is normalized permitting a direct comparison of one topology with another without performing any detailed design or knowledge of the internal parameters of each converter. As a result of the analysis of switching losses, an accurate estimation of MOSFET switching times is presented providing more insight into the switching behavior of these converters. Experimental results confirm the accuracy of the theoretical predictions of device current and voltage stresses along with the converter losses and efficiency. Factors affecting the device stresses derived theoretically are demonstrated experimentally. Computer simulation is used to confirm the theoretical analysis of transistor switching times used in determining the switching losses in the devices.