PV Emulator Based on a Four-Switch Buck-Boost DC-DC Converter

Currently, there is a growing need to develop and evaluate power converters that integrates photovoltaic (PV) systems to the grid. It is a complex task to develop such converters using PV panels exposed to environmental conditions that may vary abruptly. Thus, it becomes difficult to evaluate developing converters in all operating points during the sunshine hours. One solution is the use of panel emulators that provide controlled output independent of external conditions. This work proposes a low-cost PV emulator using a four-switch buck-boost (FSBB) dc-dc converter. As the voltage/current output can be controlled in a dc-dc converter, an algorithm emulates the I-V curve at the converter's terminals based on the estimated load connected to it. From this value, a linear approximation of the I-V curve is used in association with the Newton method to obtain the voltage reference. The voltage reference value dictates the FSBB operation mode (buck, boost, buck-boost) and PI controllers are used to track it. Finally, simulation results of the proposed PV emulator working in different operation modes are reported to validate the effectiveness of the approach.