Novel single-phase nine-level PWM inverter for grid connected solar PV farms

This paper introduces a new asymmetrical multilevel inverter (MLI) for photovoltaic generation systems (PVGS). The proposed MLI utilizes a single dc source, PV array, and four series-connected capacitors to generate the nine-level output voltage at reduced number of switching devices. The proposed inverter is composed of the main and auxiliary circuits. The main circuit is a single-phase H-bridge inverter, which is responsible for the output voltage polarity. The auxiliary circuit is a special structure of switching devices to achieve the multilevel output voltage. Perturb and observe technique (P&O) is used for maximum power point tracking (MPPT) of the PV array. Capacitors voltage balancing and MPPT are executed using Multilevel Boost Converter (MLBC). The suggested MLI provides number of advantages over traditional ones such as; an increased output voltage levels at a reduced switches number, single isolated dc supply is needed, low switching loss, low total harmonic distortion (THD), low dv/dt stress on the switches and hence, low switches ratings and cost. The grid-tied PVGS, which applies the MLI, is simulated using MATLAB/SIMULINK software. A real time validation of the PVGS has been carried out.