Performance analysis of a modified Current Source Inverter for photovoltaic microinverter applications

This paper analyzes the performance of a grid-tied photovoltaic module integrated, transformerless, three-phase Current Source Inverter (CSI). The design exploits CSI inherent step-up capability to obtain a single stage power interfacing between the low voltage PV input and the high AC voltage output, to be fed into the distribution grid. A modified CSI converter topology is proposed along with a suitable PWM strategy and a simple closed loop control. The theoretical analysis and simple analytic expressions highlighted the performance and limitations of the topology when employed in single-stage PV microinverter supplied by a single low voltage PV panel. The principle of operation and control is described, and the traditional CSI topology has been simulated numerically in Matlab/Simulink environment. Results obtained with the proposed topology are presented and evaluated in order to validate the theoretical assumptions.