Design, Modelling and Implementation of a Push - Pull Converter used in Grid Connected Photovoltaic Systems

Abstract

This paper presents the modelling, design and implementation of a DC-DC converter integrated into a two-stage photovoltaic microinverter operating in grid connected mode. A push-pull topology has been chosen because it provides galvanic insulation and adjusts the DC voltage from the photovoltaic panel to an appropriate voltage with the implementation of a current-injected control (CIC). The push-pull electrical design is presented for a power of 200 W and an output voltage of 380 VDC. Also, the small signal model is presented, and the required transfer functions have been derived in order to design and implement the controllers that regulate the output current (detection of the peak current in the inductor) and the input voltage (PI controller) fixed by the reference imposed by a MPPT algorithm. Finally, the experimental results and conclusions are presented.