Modeling and Controller Design of an Autonomous PV Module for DMPPT PV Systems

This paper proposes the modeling and controller design of an autonomous PV module (APVM) which is composed of a PV panel and a four-switch buck-boost converter (FSBBC) for series-connected distributed maximum power point tracking (DMPPT) PV system applications. The FSBBC can operate in buck, boost, and buck-boost modes with less passive component counts and noninverted output voltage polarity. The switching strategy of the FSBBC with smooth transition during mode change is explained. The parameter design criteria and the small-signal ac model of the APVM are developed. Moreover, the design of controller based on the developed small-signal ac model and the stability analysis of the APVM are presented. Computer simulation and hardware experiment results are used to verify the accuracy of the small-signal model and the controller performance of the APVM.