Wide Input Voltage Range Photovoltaic Microconverter With Reconfigurable Buck–Boost Switching Stage

This paper presents a novel soft-switching galvanically isolated buck-boost dc-dc converter as a module-integrated converter for photovoltaic (PV) applications. It features three major operating modes: boost, normal, and buck mode. Their proper distribution over the input voltage range enables wide voltage regulation capabilities, i.e., close to those of nonisolated power optimizers. The proposed control algorithm requires only one buck-boost switching stage that performs voltage regulation by means of the switching stage reconfiguration with smooth transition between the modes. The design guidelines and the digital control system for PV applications are provided. The module-integrated converter was verified experimentally with a solar array simulator. The converter showed good maximum power point tracking performance and a peak efficiency of nearly 97%.

I. Introduction

Module-level power electronics (MLPE) is an emerging trend in modern photovoltaic (PV) power systems, which enables monitoring of the power production of each individual PV module [1]. Typically, the MLPE systems are more efficient than the traditional string inverters and allow tracking the maximum power point (MPP) locally, which results in an increased energy yield from a PV module [2]. In the MLPE-based PV installation, the overall tolerance of the system against irradiance mismatches is improved because no PV modules are affected by the operating conditions of their neighbors [3]. Therefore, the MLPE technology provides a more reliable and efficient energy capturing approach for PV applications.