Analysis of quasi-resonant converters by using finite element method

Abstract

A computer-aided analysis of zero-current switching and zero-voltage switching quasi-resonant converters is accomplished by using finite element method. Adopting the weighted residual approach with Galerkin's procedures, the state equations are replaced by recurrence formulas, and the solution is unconditionally stable. The recurrence formulas are so simple and efficient that they can be easily implemented in a PC. By successive calculation of these formulas and taking into account the parasitic resistances of the converter circuits, an accurate analysis of the transient and steady-state characteristics can be obtained. The dangerous peaks of the transient waveforms are pointed out, which are influenced by the mode of operation and the load value.