Analysis of active clamp fly back converter

Abstract

This paper proposes an active-clamp fly back dc-dc converter using an isolated transformer. This converter consists of two switches namely auxiliary and main switch. The auxiliary switch is mainly added to reduce the voltage ripples especially on the primary side of the isolated high frequency transformer. This in turn will reduce the voltage stress present at the main switch. Active clamping is done for the recycling of stored energy in the HT and also to ensure the ZVS operation. The voltage spikes during transistor turn offtime are clamped by active clamping. The Zero Voltage Switching (ZVS) of the main switch is obtained mainly using the auxiliary switch and the clamp capacitor. Analysis of active clamped fly back converter is done for 120W. The analysis is done for various switching frequencies and delay values for proper core reset.