Discrete Time Nested-Loop Controller for the Output Stage of a Photovoltaic Microinverter

Abstract

This paper presents a comprehensive study of the digital implementation of the control requirements of the output stage of a two-stage solar microinverter. This approach uses a synchronized nested-loop controller which ensures the tracking of an internally generated high-quality current reference, the estimation and cancelation of the effect of the DC-link voltage ripple in the control loops and the regulation of the average value of the DC-link voltage. The proposed control architecture is validated by means of simulation results comparing operation of the inverter using continuous time, quasi-discrete time and discrete time implementations.