Análise, projeto e implementação de um inversor PWM monofásico aplicado a UPS utilizando células de comutação suave

Abstract

This thesis presents an analysis, design and implementation soft switching inverters for UPS applications. The inverters considered are constituted of soft switching cells, which provide zero voltage switching (ZVS) for the main power semiconductors devices, and zero current switching (ZCS) for the auxiliary semiconductors devices. The auxiliary cells used in this implementation are based on the Auxiliary Resonant Commutated Pole (ARCP) circuit. Theoretical analyses of the main ARCP topologies existent are presented. All the topologies analyzed are implemented having as base the same layout of the power circuit, just the auxiliary circuit being replaced. In this way it has been possible to ensure a fair comparison among them. A generalized design methodology has been developed for the selection of the auxiliary cells components. This design methodology uses design curves, which have been generated from the solution of equations that describe the operation modes of the converters. Among these design curves are: the losses of duty-cycle, elapsing time of the auxiliary pulses, amplitude of the auxiliary sources, and turns ratio of the transformer. These ARCPs have been implemented in a full-bridge inverter, where one of the inverter leg operates at a low frequency (60Hz). As a result, the circuit could be simplified without penalizing the commutation losses. Experimental results are presented in order to validate the analysis carried out.