A Buck and Boost Based Grid Connected PV Inverter Maximizing Power Yield From Two PV Arrays in Mismatched Environmental Conditions

A single phase grid connected transformerless photovoltaic (PV) inverter, which can operate either in buck or in boost mode, and can extract maximum power simultaneously from two serially connected subarrays while each of the subarray is facing different environmental conditions, is presented in this paper. As the inverter can operate in buck as well as in boost mode, depending on the requirement, the constraint on the minimum number of serially connected solar PV modules that is required to form a subarray is greatly reduced. As a result, power yield from each of the subarray increases when they are exposed to different environmental conditions. The topological configuration of the inverter and its control strategy are designed so that the high-frequency components are not present in the common mode voltage, thereby restricting the magnitude of the leakage current associated with the PV arrays within the specified limit. Further, high operating efficiency is achieved throughout its operating range. A detailed analysis of the system leading to the development of its mathematical model is carried out. The viability of the scheme is confirmed by performing detailed simulation studies. A 1.5 kW laboratory prototype is developed, and detailed experimental studies are carried out to corroborate the validity of the scheme.