Active Virtual Ground— Single-Phase Transformerless Grid-Connected Voltage Source Inverter Topology

An efficient single-phase Transformerless grid-connected voltage source inverter topology by using the proposed active virtual ground (AVG) technique is presented. With the AVG, the conventional output L filter can be reconfigured to LCL structure without adding additional inductor. High-frequency differential mode current ripple can be significantly suppressed comparing to the available single-phase grid-connected inverter topologies. Additionally, strong attenuation to the high-frequency common-mode current is achieved. It is particularly important for some applications such as photovoltaic and motor drives. High efficiency can be achieved due to fewer components involved in the conduction loss. Cost of the magnetic device can be reduced since the required inductance of the filter becomes smaller. Performance of the proposed inverter has been evaluated analytically. Experimental verification is performed on a 1-kW, 400-V input, and 110-V/60-Hz output prototype.