Novel Method for the Estimation of Switching Losses in Resonant Converters

Abstract:
Resonant converters exhibit the ability to achieve nearly lossless switching by using zero current or zero voltage switching (ZCS/ZVS) for the input bridge. Since most switched-mode power supplies (SMPS) use MOSFETs as semiconductor devices today, a ZVS operation is typically preferred. However, with higher switching frequencies reaching of ZVS becomes more difficult. Thus, a (partial) loss of ZVS might be the consequence, making the need for a reasonable estimation of the occurring losses simply inevitable. Due to the half- or full-bridge configuration, this estimation becomes much more complex compared to a traditional hardswitched boost or buck converter. This paper gives a detailed insight into the switching transients of resonant converters and proposes a proper test circuit. A novel method is presented to estimate the generated switching and driving losses during the turn-on event of the switches in case of incomplete ZVS.