| Abstract |
Recently introduced quasi-resonant-converter (QRC) create the supposition to raise switching frequency and power density of power supplies, by employing frequency- or pulse-width-modulated resonant-switches with reduced switching losses of the power devices. Examination of multiple resonant-switch-topologies with regard to the power switch stresses leads to the choice of a zero-current-switching (ZCS) QRC for realisation of a converter with high output power, low output voltage and a wide range of load variation. The mathematical model of a buck-resonant-converter with parasitics of the power switches shows the influence of conduction losses to the voltage conversion ratio and efficiency. Theoretical results are verified by measurements. Since new IGBT devices seem to be suitable to reduce conduction losses of ZCS-resonant-switches, measurements were taken on a buck-converter with a variaty of IGBT power switches. Experimental results permit to calculate the total losses of the switching device and determine individual losses caused by different physical mechanism when the clock frequency is increased. |
