Analysis and Modeling of a Switched Inductor Based Microinverter for Single Phase Grid Connected Photovoltaic Systems

A novel single phase single stage microinverter topology is proposed which draws maximum power out of a photovoltaic module and feeds the power at unity power factor (UPF) to the distribution end of the Indian grid system (220 – 230 V). The inverter operates as a switched inductor based Cuk topology for both positive and negative half cycles of the grid voltage. High voltage gain at the output stage is achieved by involving a coupled inductor having a moderate turns ratio, while ensuring the inverter to operate in discontinuous mode of conduction (DCM). Energy trapped in the leakage inductance is supplied back to the grid through the coupling capacitor used in this topology thereby improving the overall efficiency of the system. DCM strategy ensures inherent soft turn on of the power switch and the voltage stress during turn off process across the power switch is controlled by passive snubber. The operating principle of the proposed microinverter along with its detailed analytical studies have been presented in this paper. The viability of the proposed scheme is confirmed by performing detailed simulation studies under various operating conditions.