DC link embedded impedance source inverter for photovoltaic system

摘要

This paper is devoted to a new topology derived from traditional ZSI called dc link embedded E Z-source inverter (dc-EZSI) for photovoltaic (PV) system. Due to the embedded structure and ZSI topology, the proposed system inherits all the advantage of impedance inverter which can realize buck/boost function in a single stage with improved reliability and lower component rating and less power loss. In addition the dc link embedded topology has two interesting advantages as lowest voltage stresses across capacitances C1 and C2 for the same overall voltage gain. The second advantage is that it has symmetrical voltage and current distribution throughout the network no matter powered by one or two sources. This is a favourable advantage over EZSI topology and is more appropriate for solar application than their counterparts. Theoretical analysis of dc link EZSI in shoot through and non-shoot through operating modes are described.Simulink model of symmetric and asymmetric dc link EZSI system with closed loop control are presented. Simulation results prove the validity of the proposed system.