Digital controller for an isolated Step-Up DC-DC converter based on three-phase high-frequency transformer for grid-connected PV applications

Abstract

This paper presents the control system design of a DC-DC converter with a three-phase high frequency transformer for dual-stage grid-connected PV applications. This converter is designed to be used in the input stage of parallel single-string PV arrangements for residential applications. The proposed control strategy uses a maximum power point tracking algorithm with an outer voltage loop and an inner current loop. The current loop includes a resonant control action in order to eliminate the 120Hz ripple of the DC bus in the PV modules. Simulation results are presented to validate the proposed control strategy.