NEW MICRO-INVERTER FOR PHOTOVOLTAIC APPLICATIONS

Abstract

Solar systems work by using special solar cells that absorb solar energy. These cells are interconnected on a panel or array of various sizes depending on the particular energy demand. No matter how large or small a solar panel may be, it is connected to what is known as an inverter, which is designed to take the direct current (DC) power gathered and generated by the PV cells and convert that power into an alternating current (AC) which is compatible with the existing electrical grid that powers your home or commercial property. The AC output from the solar PV system is sent to your electrical panel where it is distributed accordingly for convenient use. In photovoltaic applications, the micro inverter is well known for having large transformer turn ratio that results in large leakage inductance which will reduce the converters efficiency. The solution to the problem is the proposed new microinverter in this paper. This new inverter operates based on boostflyback/flyback(BF/F) modes, the BF mode is for the half grid cycle and the F is for the remaining parts. In BF operation mode, high voltage gain and low voltage stress is available in minimum transformer turn ratio. The leakage energy is then recovered and the turn-off voltage rise of the main switch is cut, as a result of a passive snub in the mode. The BF mode lacks a step-down function, the F mode is used to control the output voltage for values lower than the input voltage. The operation and characteristics of the micro-inverter in boundary condition mode are analysed in detail. A 240W prototype is enforced to validate the theory