A New High Gain Transformerless Inverter for Single Phase Grid-connected Solar PV Application

Generally low voltage solar PV modules use a high gain DC-DC converter as a front end interface as traditional DC-DC converters cannot offer high gains with higher efficiencies. This paper proposes an integrated high gain transformerless inverter topology for solar PV application. The proposed topology is derived by combining the high gain DC- DC converter with the traditional full-bridge DC-AC converter. The main features of the proposed topologies are: it has zero leakage current due to the negative terminal of PV is directly connected to the grid neutral and due to its high gain nature, it can be used as interface converter to feed power from low voltage PV module into the grid and no need for extreme duty cycles. Furthermore, the proposed topology consists of only six controllable devices for the inverter operation which makes the system compact and cost-effective. Additionally, a simple sine-triangle pulse width modulation technique is introduced to control the inverter. The design of the proposed converter and its important modes of operation are presented in detail. The theoretical efficiency of the proposed inverter topology is estimated to be 95.4% at full load. The proposed high gain inverter topology is validated with OPAL-RT for 300W grid connected system and the maximum efficiency of the system is measured to be 96.4 %.