Conversor CA/CA monofásico/trifásico isolado por transformador de alta frequência: estratégias de comando.

Abstract

This work is concerned with the study of a single-phase to three-phase AC-to-AC converter isolated by a high frequency transformer. In the primary of the scheme the conversion is effected by a single-phase rectifier and a single-phase inverter, of which the output is a square-wave voltage. The secondary consists of a cycloconverter with six bidirectional switches that converts the square-wave voltage into a three-phase output voltage. Although considerations regarding the primary converter are introduced (topologies, power factor control, etc.), major emphasis is given to the operation and control of the cycloconverter. The use of the square-wave with discontinuous current mode, sinusoidal modulation, space vector modulation and hybrid modulation strategies for the cycloconverter control is discussed. I n special, great attention is given to the hybrid modulation strategy, which is applied to the cycloconverter for the first time. As a result, an AC-to-AC non-resonant soft-switched converter that use both zero-voltage and zero-current switching techniques is obtained. Experimental results corroborate the principles used for the control circuit. A l l these strategies and techniques are extended to the analysis of a three phase four-bidirectional-switch cycloconverter with the purpose of reducing the number of components i n the overall system, with a consequent reduction i n its weight, volume and cost.