Novel zero-voltage and zero-current-switching (ZVZCS) three level DC/DC converter using a simple auxiliary circuit

This paper proposes a zero voltage and zero current switching (ZVZCS) three-level (TL) DC/DC converter, which overcomes the drawbacks presented by the zero voltage switching (ZVS) three-level converter, such as high circulating energy, severe parasitic ring on the rectifier diodes, and limited ZVS load range for the lagging switches. A simple auxiliary circuit which consists of one small capacitor and two small diodes is added in the secondary to provides ZVZCS conditions to primary switches as well as to clamp secondary rectifier voltage. The additional clamp circuit for the secondary rectifier is not necessary. The auxiliary circuit includes neither lossy components nor additional active switches which makes the proposed converter efficient and cost effective. The principle of operation, features and design considerations are illustrated and verified by experimental circuit.