Sensorless Control of Series Stacked Buffer Converter in a Microinverter Architecture

This paper presents a sensorless open-loop control of the series stacked buffer converter (SSBC) in a two-stage microinverter for photovoltaic (PV) applications. Previously, the SSBC has been demonstrated for power pulsation decoupling with complex controllers and expensive current sensors. This paper shows a novel sensorless approach that is based on acquiring the average power of the system, the DC bus voltage, and the isolated port capacitor voltage of submodule integrated converters (subMICs). Given that these quantities are readily available from the control loops of the microinverter, there is no need of costly current and voltage sensors. Besides, the proposed approach is inherently simpler, and it does not require a support energy storage capacitor since this function is provided by the isolated port capacitor of subMICs. The design guidelines of the sensorless control of the SSBC in a microinverter is presented. The PSIM simulations and experimental result with 180 W power rated commercial PV module validates the theoretical analysis.