PV Grid-Connected Inverter With DC Voltage Regulation in CCM and VCM Operation to Reduce Switching Losses

Abstract

In this paper, a photo-voltaic (PV) grid connected inverter (GCI) is employed for multi-functional control (i.e., real power flow control form PV panels, mitigation of current and voltage related power quality (PQ) problems) and the GCI input reference dc voltage is formulated as a function of GCI output currents for loss reduction during low currents through inverter switches. In the latest literature, PV GCI is used for mitigating current related PQ problems, and it is also used for mitigating minor voltage related PQ problems (voltage sag, voltage swell, and voltage imbalance). During voltage sag conditions, GCI output current is high enough to maintain rated voltage at the point of common coupling (PCC) and in this case the reference dc voltage requirement is high. But, during rated grid voltage condition, low power generation from PV, and minimum load condition keeping maximum dc voltage at the input of GCI leads to heavy burden on GCI switches. In the proposed method, in order to reduce losses in GCI, the input dc voltage of GCI is reduced during low GCI output current. The proposed method is validated with MATLAB simulation and hardware experiment by comparing data existing in literature with the proposed method.