A new PV converter for grid connection through a high-leg delta transformer using cooperative control of boost converters and inverters

This paper proposes a new high-efficiency PV converter for grid connection through a high-leg delta transformer. The converter is composed of a symmetrically-connected boost converter and three half-bridge inverters. One of the three half-bridge inverters is connected to the boost converter, and the others are directly connected to the PV terminals. As a result, this circuit configuration enables to reduce the power losses in both boost converter and inverters. This paper also proposes a new cooperative control method between the symmetrically-connected boost converter and inverter. The control method can reduce the average switching frequency to 75% of that in a conventional one, resulting in a great reduction in the switching power loss. Experimental results confirm that the proposed circuit configuration makes it possible to improve its European efficiency from 91.6% to 94.5%.