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The applications of multilevel converters (MCs) in industry have been increased because of their advantages such as high quality output waveform and lower harmonic distortions. This paper proposes an improved two-leg ladder topology for MC. For generating all levels at output voltage waveform, two methods are investigated for selecting the values of dc sources. The suggested structure generates a large number of levels at output voltage waveform with the least number of power electronic components such as insulated gate bipolar transistors, gate driver circuits, dc voltage sources and anti-parallel diodes in comparison with other similar topologies. Also, the magnitude of blocked voltage by switches is low. Power losses analysis on the proposed topology is provided. It is shown that the number of on-state switches in the presented structure is less than other similar topologies, which causes the voltage drop and power losses of proposed topology to be reduced. To show the merits of the proposed structure, comparison results are provided with other structures. To validate the analytical results of proposed topology, an experimental work for a 9-level converter and the simulation results for a 25-level converter are provided. PSCAD/EMTDC software is used for simulation works.

This paper presents a new switched-ladder structure for multilevel converter which consists of several bidirectional and unidirectional switches along with DC voltage sources. The values of DC sources in the proposed topology are determined based on a new mathematical algorithm. The proposed multilevel converter is an extended structure, which can produce any levels at output voltage waveform. To prove the merits of the proposed structure, the proposed converter is compared with other similar structures. According to comparison results, it is shown that the presented structure requires the least numbers of DC sources, IGBTs, drivers and on-state switches. Also, the value of voltage rating of the switches is analyzed. The experimental results are provided for the proposed 17-level converter to prove the performance of suggested structure.