Third harmonic injected binary hybrid multilevel inverter for grid connected photovoltaic system

A 29-level three phase binary hybrid multilevel inverter is proposed. Only three basic switching cells (single phase H bridge cell) are used in each phase. Third harmonic voltage is injected in order to increase the number of levels, and to increase the DC bus utilization. Also, increase in number of levels gives more flexibility to reduce THD (Total Harmonic Distortion) of the system and in turn reduction in cost and size of the system. Use of less number of switches results in reduction of switching-loss. Fundamental frequency switching is adapted for the design in order to reduce the switching loss and voltage stress. Nearest voltage level control modulation technique is used. This work is intended to use in grid connected photovoltaic systems. Power injection to grid is controlled by controlling the firing angle of the inverter. The photovoltaic modules are divided in groups of multiple lower voltage arrays instead of a single central array to facilitate the easy implementation of the proposed configuration. The converter is simulated in MATLAB/Simulink. Authors are presently developing an experimental prototype and experimental results will be presented in the final manuscript.