Abstract
This paper presents results of research of modulation
processes in power conversion system with triple voltage source
inverters, supplied by photovoltaic (PV) strings, and connected
to a four-winding transformer. The transformer has in this case
specific connections between the secondary windings and
inverters, allowing providing of multilevel voltages at secondary
windings of the transformer. Specialized space-vector-based
strategy of pulsewidth modulation (PWM) has been used for
control of inverters, insuring quarter-wave symmetry of winding
voltages for any modulation indices and switching frequency of
inverters. Analysis and comparison of harmonic composition of
winding voltages and output voltages of inverters has been done.
The validity of the analyzed processes has been verified by
simulations: three basic variants of the scheme of modulation
have been applied for control of inverters.