An electrical DC-to-AC power conversion apparatus is disclosed that is
primarily intended for use with solar photovoltaic sources in electric
utility grid-interactive applications. The invention improves the
conversion efficiency and lowers the cost of DC-to-AC inverters. The
enabling technology is a novel inverter circuit topology, where the bulk
of the throughput power, from DC source to AC utility, is processed only
once. The inverter does not require an isolation transformer and can be
connected directly to a 480/277 Vac utility grid. The invention also
allows the power converter to start into photovoltaic array having higher
open circuit voltages. The invention also uses active ripple current
cancellation to substantially reduce the cost, size and weight of the
main filter inductors.