Single Phase Current Source Inverter With Multiloop Control for Transformerless Grid–PV Interface

Abstract

In this paper, a modified single-phase current source inverter (CSI) with improved multiloop control is proposed for a transformerless grid-photovoltaic interface application. A split capacitor arrangement with the middle point connected to the grid neutral and a common mode choke are used to modify the conventional CSI structure to attenuate the ground leakage current. The proposed control method permits the use of reduced value of dc side inductor by maintaining the quality of the grid current as if a high value of input inductor is used. Furthermore, virtual resistance damping is incorporated in the control loop to reduce the effect of LC resonance without compromising the efficiency, thus proving the feasibility of using CSI for the grid interface. Rigorous study, analysis, and validation of the modified CSI structure with the proposed control technique are carried out with exhaustive simulations and experiments. The experimental results on a 250 W laboratory prototype using the controller TMS320F28335 prove the effectiveness of the proposed CSI structure and its control.