Power loss analysis of five-level inverters for grid tie photovoltaic system

By means of simulation-based study a loss analysis is performed on the five-level inverters for grid tie photovoltaic application. The essential objective of this analysis is the quantification of the possible improvement on the efficiency of the inverter by reducing the switching frequency applied in the conventional two-level inverter. Besides the benefit of five-level providing a higher power quality and lowering the switching loss, the drawback of high conduction loss involving many devices in series is evidenced in this paper. The simulation results show that the five-level inverter topologies achieve over 98% efficiency for switching frequencies ranging from 1 kHz to 8 kHz. However, the conduction loss of the inverter is significantly higher (over 10 times) than the switching loss.