Integrated auxiliary commutation circuits: a generalised approach

The concept of integrated auxiliary commutation circuits (iACCs) applied to systems with several power conversion stages is proposed. This concept has two main objectives, namely: to reduce the number of additional elements to accomplish the soft-switching and to use the circulating energy from one commutation to assist another one, so that the efficiency is improved without penalising the cost of the system. Some rules to obtain new iACCs are presented. New iZVT circuits are applied to a double-conversion UPS to illustrate the functionality and applicability of this concept. By using these circuits, the main switches operate under soft-commutation of ZVT type, and the auxiliary switches are turned on and off under ZCS or ZVS. Experimental results of three prototypes (1.2 kW at 100 kHz) are presented to demonstrate the good performance of the new integrated ZVT ACC and the feasibility of the proposed concept.