Design and Analysis of a Novel ZVZCT Boost Converter with Coupling Effect

Abstract

In this paper, a new zero voltage zero current transition (ZVZCT) boost DC-DC converter using a coupled inductor is proposed. This topology provides the main switch ZVZCT for the turn-on and zero voltage switching (ZVS) for the turn-off. Moreover, the auxiliary switch turns on at zero current switching (ZCS) and turns off at ZVS. The main diode turns on with ZVT and turns off with ZCS, and other diodes also operate under soft switching (SS) conditions. Besides, due to the coupling effect, the proposed converter improves efficiency additionally since resonant energy in the resonance tank could be transferred to the output, and the circulating current can be limited as well. The soft switching can be realized in almost all the load rang. In this design, there always exist energy releasing circuits to conduct magnetic flux leakage currents, such that the surge currents are eliminated and switch current stress can be accordingly reduced. All the devices resonate in a unique direction within less than half of a resonance period, so power losses with respect to the resonance can be decreased. In this paper, the converter design and operation principles of the converter are given.

Existing System

Soft-Switching Boost Converter.

Proposed System

In this study, a novel ZVZCT boost converter with coupling effect is proposed, which solves most of the problems mentioned above. In order to reduce the iron core loss, size and cost of the converter, three inductors share the same iron core. Moreover, it is not necessary to have all inductors coupled totally. Since the new topology is capable of conducting the leakage inductance current through energy releasing loops, the parasitic oscillations and surge current can be eliminated as mentioned above. In the meantime, the auxiliary winding in the coupled inductor can help implement ZVS conditions. The coupled inductor transfers electromagnetic energy in the resonance tank to the output due to the coupling effect, reducing the current of the auxiliary switch, so its conduction loss is reduced and the efficiency is improved additionally. The new converter provides the main switch ZVZCT turn-on and ZVS turn-off. The auxiliary switch operates with ZCS turn-on and ZVS turn-off, respectively. The main diode turns on at ZVT and turn off at ZCS, and the rest of diodes are also under soft-switching conditions. All the devices resonate in a unique direction within less than half of resonance period, which can improve efficiency, as well. Soft-switching maintains for almost all input voltage and load ranges.

Architecture

The proposed soft switching boost converter topology. (a) Boost converter. (b) Equivalent circuit