Computation of time of occurence of ZVT for power converters based on quadratic functions

This paper provides numerical methods to compute the time of occurrence of ZVT for power converters with capacitor on the auxiliary resonant branch. The proposed methods are given by second order approximations of a nonlinear function which describes the voltage on the capacitor during a resonant stage. The results can be seen as applications of second order Taylor series and of quadratic interpolation. However, differently of simply finding the root of a given nonlinear equation, the conditions given here provide analytical expressions to compute the time of occurrence of ZVT based on the converter parameters. Then, the proposed conditions become useful for analysis and design, allowing evaluating operation sequence, total commutation time, resistive losses and other important parameters to describe the converter performance.