A single-stage CCM zeta microinverter for solar photovoltaic AC (PVAC) module

Microinverters mounted on each photovoltaic (PV) panels are gaining popularity due to their benefits such as incremented energy harvest and plug-play operation. This paper proposes a single-stage zeta microinverter for PV applications. The proposed topology is based on a high frequency (HF) transformer isolated zeta converter with a single low side switch on the primary side of transformer. The unique feature of the proposed inverter is its ability to work in continuous conduction mode (CCM) over a wide load range. This will result in high efficiency, reduced current stress, and low components´ rating. In this inverter, all secondary switches work at line frequency, thus reducing switching losses significantly. A complete study of the proposed microinverter, which includes steady-state analysis, design, and key components´ selection, has been reported. A 220 W microinverter has been designed, developed, and tested in the laboratory to verify the operation and design of the proposed topology. Simulation and experimental results are presented which demonstrates the effectiveness of the proposed microinverter.