Asymmetric Topologies and PWM Modulation Strategy for Low-Cost and High-Quality Single-Phase Multilevel Inverter Choi, Woo-Seok Department of Electrical Engineering Graduate School of Chonnam National University

Asymmetric Topologies and PWM Modulation Strategy for Low-Cost and High-Quality Single-Phase Multilevel Inverter Choi, Woo-Seok Department of Electrical Engineering Graduate School of Chonnam National University (Supervised by Professor : Park, Sung-Jun) 

 (Abstract) Recently, the development of the renewable power industry has been accelerating due to climate change induces to make an effort is the greenhouse gas reduction, and as industrial growth increases the demand for electric power and the electricity generation costs, it has been changing to improve efficiency for power industry structure, and have necessary to develop suitable power converter. Power industry structure has been changing to system minimize demand variation in order to improve grid stability, with low cost. It appears that distributed powers based on renewable power are spreaded over the society at large. In order to fulfill the role of distributed power based on renewable power would be advantageous, using the small size of the distributed power, for grid in stabilized respect. In such cases, many power transmission applications have used the multilevel inverter because the power quality of the renewable distributed power is very important. The multilevel inverter has the advantage of being to generate the output voltage with lower loss and lowr EMC(Electro-Magnetic Compatibility) owing to its low dv/dt stress. The conventional multilevel inverter topologies can include the diode clamped multilevel inverter and flying capacitor multilevel inverter, cascaded multi-cell H-bridge inverter topology. The conventional inverter topologies have a series connection of switch groups, and are usually applied to high power applications with high input/output voltage. However, these topologies have a large increase in the number of switches as the output voltage level increases, and thus are not suitable for the single-phase grid or low voltage applications. The single-phase multilevel topology has the advantage of reducing the number of switches due to lower input/output voltage compared with the conventional multilevel inverter topology. Recently, research into single-phase multilevel inverters has been active as a way to improve power quality. The single-phase multilevel inverter topologies are classified as multilevel inverter based on H-bridge and multilevel inverter based on Half-bridge. This single-phase multilevel inverter based on H-bridge is needed to turn on more than two switches on the one voltage level.
However, the single-phase n-level inverter based on H-bridge is comprised of a smaller number of switches than 2n, and thus a switch is used on more than two output voltage levels.

LINKS
PART1: http://www.mediafire.com/file/ox76ybclip3mphq/SINGLE_PHASE_MULTILEVEL_INVERTER.pdf
PART2 :
http://www.mediafire.com/file/nbqmzi3nas5nkdg/SIMULATION_AND_HARMONIC_ANALYSIS.pdf