Analysis of quasi-resonant converters by using finite element method

A computer-aided analysis of zero-current switching and zero-voltage switching quasi-resonant converters is accomplished by using the 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