Simulation of quasi-resonant converters in half-wave mode operation by using the modified equations

A quantitative and qualitative analysis of current-mode quasi-resonant converters is accomplished by using the alternor definition. The alternor is a two-port circuit element which contains the switching devices of the converter. Its modified nodal equations are defined in order to cope with the four-stage-per-cycle dynamic behavior of the converter. The simulation is performed first in the complex frequency domain and then in the time domain. The solutions of the converter waveforms are determined analytically for each switch configuration, regardless of cycle. The transient waveforms are depicted analytically for start-up and for disturbances due to changes in the line voltage and load, including output open circuit. Accurate results are obtained even for large-signal perturbations. The influence of the load value on the transient current and voltage peaks is pointed out