RODRIGUES, M. A. T. A.; RODRIGUES, Marta Alessandra Tavares de Almeida.
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.
