A Coupled Inductor-Based Buck–Boost Type Grid Connected Transformerless PV Inverter Having the Ability to Control Two Subarrays Simultaneously

Abstract

A coupled inductor-based buck-boost type single phase transformerless grid connected photo voltaic inverter which has the ability to extract maximum power simultaneously from two serially connected subarrays is proposed in this article. The series connection of the two subarrays, and the buck-boost nature of the inverter result in reduction of the number of modules which are connected in series in a subarray. Further, independent operation of the two subarrays enhances the overall power extracted from the subarrays while they are experiencing significant mismatch in their operating conditions. The deployment of the coupled inductors has reduced the component count and overall size, weight, and volume of the proposed inverter. On the other hand it helps to achieve moderately high overall operating efficiency at higher power level as compared to the single inductor-based buck-boost schemes. A new inductor current control technique which is independent of the mode of operation (CCM or DCM) is adopted to control the grid current. The topological structure of the inverter, and its control technique restrict the overall leakage current related to the subarrays within the permissible limit. A 1-kW experimental setup has been fabricated and thorough experimental analysis are performed to confirm the viability of the proposed inverter.