Microinverter Architecture with Submodule-Level Balancing and Active Power Decoupling

A power decoupling approach that combines submodule level balancing and a series stacked buffer (SSB) is presented for microinverters in photovoltaic (PV) systems. Although the SSB is one of the existing solutions to achieve power pulsation decoupling in grid-interfaced applications, it usually requires an additional support capacitor and complex control methods for its proper operation. In this paper, the input of the SSB is connected to the secondary side of the differential power processing converters that provide submodule-level balancing, thus removing the need of additional support capacitors. Besides improving the power density of the system, the differential power processing converters can easily regulate the voltage of the support capacitor, which reduces the complexity of the SSB control and improves its efficiency. The design of the SSB converter and the proposed control approach are discussed in a microinverter architecture. Besides, PSIM simulation results are presented for a microinverter with a rated power of 150 W to validate the theorical analysis.