Single-Phase Transformerless Grid-Connected Impedance Source Inverter

This paper presents a design and control of single-phase transformerless grid-connected impedance source inverter. The conventional tranformerless grid-connected inverters might cause the DC offset in the injected currents to the grid due to the leakage current from deteriorated PV panels. The three-switch three-state impedance source inverter can mitigate the leakage current problem by using the grounded pole topology. The introduced single-stage inverter has buck-boost feature, which provides the desired output AC voltage. The single-phase decoupling control method is designed and implemented based on MATLAB/Simulink with the dSPACE DS1104 controller board. Experimental results show the good performance in the transfer power as well as the sinusoidal injected current.