Input-parallel output-series connection of isolated quasi-Z-source DC-DC converters

This paper proposes an input-parallel-output-series (IPOS) power system based on the isolated qZS DC-DC converter. Reported as a solution for the integration of renewable energy sources into the medium voltage grid, such power systems can also be used to integrate low voltage energy sources into a 230V/400V grid. We examined the basic switching stage with three different rectifier topologies whereas the steady state analysis was made for each topology. Criteria for our comparison were implementation complexity and current and voltage stress of the components. An experimental prototype of the proposed IPOS power system composed of two converters was built at a rated output power of 400 W. DC gain characteristics and efficiency curves are presented. The experimental waveforms for the input voltage 80 V and the output voltage 400 V were measured.