Derivation of boost-buck converter based high-efficiency robust PV inverter

A single-phase grid connected transformerless PV inverter for residential application is presented. The inverter is derived from a boost cascaded with buck converter along with a line frequency unfolding circuit. High efficiency can be achieved because the converter allows the use of power MOSFET and ultra fast reverse recovery diode, which also features a robust structure because the phase-leg does not have shoot-through issue. By interleaving multiple phases, the ripple can be reduced, and thus the inductor size can also be reduced. This paper begins with theoretical analysis and modeling of this boost-buck converter based inverter to define the operation limit and to design the closed-loop controller. A two-phase interleaved inverter is then designed accordingly. Finally, the simulation and experiment results are shown to verify the concept.