Boost/Buck-boost Based Grid Connected Solar PV Micro-inverter with Reduced Number of Switches and Having Power Decoupling Capability

A boost/buck-boost based transformer-less micro-inverter suitable for interfacing a 35 V, 220 W PV module to a single phase 220 V ac grid is proposed in this paper. The intermediate capacitor between the the boost stage and the buck-boost stage helps in achieving power decoupling between the dc side and the ac side. Since the inverter is endowed with inherent power decoupling feature, it is more reliable compared to the inverters utilizing high value electrolytic capacitors. The micro-inverter utilizes six switches, two of them operating at high frequency, two at line frequency and the rest two switches operate at high frequency either during the positive half cycle or in the negative half cycle. Both the boost stage and buck-boost stage is operated in discontinuous conduction mode for all possible operating conditions in order to achieve higher voltage gain, and negligible turn on losses of the high frequency switches. The direct connection between the negative terminal of the PV module and the grid neutral ensures the leakage current flow to be zero. The analyses of the proposed micro-inverter is carried out. The viability if the proposed scheme is validated by detailed simulation studies in the MATLAB/Simulink platform.