Analysis of Oscillation Between Transformer Leakage Inductance and Schottky Diode Capacitance in DC–DC Converters

This letter presents an analysis of the transient voltage ringing across the Schottky diodes of the output stage of isolated dc–dc converters due to the interaction between the leakage inductance of the high-frequency transformer and the nonlinear and voltage-dependent capacitance of the diodes. The study addresses only the converters with output
LC
filters, such as the phase-shifted ZVS-PWM converter, excluding
LLC
and series resonant converter (SRC) resonant converters with capacitive filters. An explicit solution for the pair of nonlinear differential equations describing the equivalent circuit behavior is presented, enabling determination of both voltage overshoot across the diodes and the resonant frequency of the oscillation. The theoretical analysis findings were validated through laboratory experiments.