Integrated Auxiliary Commutation Circuits: A Generalized Approach

This paper presents the concept of integrated auxiliary commutation circuits applied to multi-stage power conversion systems. This concept has two main objectives, which are: to reduce the number of additional elements to obtain the soft-switching and to reutilize the reactive energy of one commutation to assist another one, so that the efficiency improves without penalizing the cost. A symbolic representation is proposed to make the understanding and analysis of the integration concept easier. A new integrated ZVT (iZVT) auxiliary commutation circuit composed of only one additional active switch is applied to a double-conversion UPS to demonstrate the functionality of this new concept and its symbolic representation. By using this new integrated circuit, the main switches operate under soft-switching of ZVT type, and auxiliary switch under ZCS type for all operating modes of the converters that composes the UPS, namely they are: preregulator (boost), battery charger (buck), backup converter (boost) and inverter (full-bridge). Experimental results of a 1.2 kW@100 kHz prototype ensure the feasibility of the proposed iZVT