Two-Stage Resonant Three-Phase Micro-inverter for Grid-Tie PV Application

摘要

Micro-inverters recently become more attractive due to its modularity and independent maximum power point tracking for each individual photovoltaic (PV) module. Micro-Inverters designed for PV applications requires to perform different tasks such as extracting maximum power from PV, boost low PV voltage to a higher level and convert DC-voltage into AC voltage. Typically, a Micro-Inverter consists of two stages; a DC-DC Converter and DC-AC Inverter. This paper proposed a novel two-stage micro-inverter based on LLC resonant converter for grid integrated PV system. LLC resonant converter is presented as a first stage for the PV micro-inverter. and the second stage implemented from the three-phase inverter. The selection of the LLC resonant converter comes from its inherent features such as high efficiency converter for a wide range of input voltage and load variation, due to its capability to work under soft switching techniques like Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS), possibility of achieving high voltage gain due to the presence of the HF transformer achieved. A complete feedback system is implemented in order to control maximum power of PV panel, maintain a fixed DC link voltage, and inject a sinusoidal current injected into the grid. The results have been validated by simulation and experimental topology vai OPAL-RT OP4510.