Single-Phase Single-Stage Transformer less Grid-Connected PV System

In this paper, a single-phase, single-stage current source inverter-based photovoltaic system for grid connection is proposed. The system utilizes transformer-less single-stage conversion for tracking the maximum power point and interfacing the photovoltaic array to the grid. The maximum power point is maintained with a fuzzy logic controller. A proportional-resonant controller is used to control the current injected into the grid. To improve the power quality and system efficiency, a double-tuned parallel resonant circuit is proposed to attenuate the second-and fourth-order harmonics at the inverter dc side. A modified carrier-based modulation technique for the current source inverter is proposed to magnetize the dc-link inductor by shorting one of the bridge converter legs after every active switching cycle. Simulation and practical results validate and confirm the dynamic performance and power quality of the proposed system.