Dual-mode control of multi-functional converter in solar PV system for small off-grid applications

Solar PV system for off-grid applications is growing at a faster rate because of its compatibility and ease of implementation. The modern smart building consists of hybrid AC and DC loads. The solar PV system generates DC power and can also supply the DC loads. To supply the AC loads, the DC power need conversion to AC using a DC–AC converter. A general solar PV system consists of two stages, one is to extract the maximum power and the other one is to convert it into a suitable DC or AC. Here, a single-stage multi-functional converter (MFC) is employed, which extracts maximum power and supplies to both AC and DC loads. To overcome the intermittency of solar PV output, battery energy storage is interfaced through a non-isolated buck–boost converter. The MFC operates in two modes, i.e. hybrid power flow mode and inverter mode, depending upon the availability of solar PV output. The proposed system is simulated using the PSCAD/EMTDC software. An experimental test setup using solar array simulator and a multifunctional power electronics converter has been developed for demonstration of the results. The control algorithms are implemented using NI PXI-7842R series FPGA controller through LabVIEW platform.