Coupled-inductor single-stage boost inverter for grid-connected photovoltaic system

摘要

This study presents a coupled-inductor single-stage boost inverter for grid-connected photovoltaic (PV) system, which can realise boosting when the PV array voltage is lower than the grid voltage, converting dc voltage into ac voltage, feeding current to the grid with high-power factor and maximum power point tracking (MPPT) together. By introducing an impedance network including coupled inductor in front of the three-phase inverter bridge, and adjusting the previously forbidden shoot-through zero state, the converter can step up input voltage to a higher voltage level. System reliability is also improved by using shoot-through zero state as a normal operation mode. Cost can be reduced by single-stage operation and also by using economical MPPT method only via grid current. Theoretical analysis, simulation and experimental results are presented to verify its good performance.