A Simplified Digital Closed-Loop Current Control Of Three-Phase Pv Inverter Operating In Triangular Conduction Mode

An adoption of SiC device brings benefits on performances of three-phase photovoltaic (PV) inverters. As the switching loss of SIC devices is concentrated at a turn-on instant, triangular conduction mode (TCM) can be utilized to achieve zero-voltage switching (ZVS) for SiC-MOSFETs thus minimizing the switching energy. When the three-phases are coupled through a neutral point of the load, the dynamics of three-phases interact with each other. Such a coupling complicates conventional current-control methods based on a single-phase TCM inverter to be extended to the three-phase applications. In this paper, a simplified digital closed-loop control for three-phase TCM inverter has been presented. A new reference frame has been proposed based on the conduction-mode with a simple conduction mode decision method. Issues for the current control on the proposed reference frame are identified, and an architecture for the current controller has been investigated. The proposed control architecture has been experimentally verified with three-phase three-level 40 kW PV inverter with a digital control hoard with TMS320F28343.