Auto protected ZVS-ZCS half bridge with parallel power regulation

ESTEC has developed and patented in 1988 a ZVS-ZCS topology which is essentially a current fed resonant push-pull or half-bridge. This topology provides only voltage adaptation. When voltage regulation is needed, a buck converter is usually put up-front. The disadvantage of this combined concept is to handle the full power through two stages and to request an input filter, while its advantage is to offer a protection feature. The concept presented in the paper tries to combine, in the ZVS-ZCS topology alone, the protection aspects and the regulation capability in a defined input voltage range and does not request an additional input filter due to the current fed nature of the topology. Test results of breadboarding activities are presented.