An isolated ZVS/ZCS flyback converter using the leakage inductance of the coupled inductor

This paper describes a simple and effective way to modify an existing hard-switched flyback converter into a circuit with zero-voltage switching (ZVS) and zero-current switching (ZCS). The key improvement is to turn the unattractive features of the coupled inductor leakage inductance and snubber capacitor into attractive ones. The coupled inductor leakage inductance and snubber are used to form a quasiresonant circuit to facilitate ZVS/ZCS of all power devices. The operating principles of the converter and experimental results are presented. Index Terms-Converter, power electronics, power supplies, resonant power conversion. © 1998 IEEE.