A Cascaded Multilevel Inverter Using THI Method for Electric Traction Drive

Abstract

Pu?lse Widt?h Modulation variabl?e s?peed dr?ives ar?e increasingl?y applie?d in ma?ny ne?w industrial applicat?ions that req?uire superior performance. Recent?ly, development?s in power electro?nics and semico?nductor technol?ogy have l?ead i?mprovements in power e?lectronic s?ystems. This propose?d technique pr?ovides more flexib?ility to desig?ners and can gener?ate more voltage levels withou?t l?osing an?y level which wo?rsens TH?D characteri?stics. The possib?ility of exten?sion o?r seri?es con?nection of t?his bas?ic in tw?o topolog?ies has be?en studie?d. As w?e increase the number of levels of the output voltage of the inverter, the output waveform has inc?reased number of s?teps, which prod?uces a staircas?e wave that appr?oximates to a sinusoidal waveform. Henc?e, a?s the level of the output voltage increase?s, the harmonic distortion of the output wave decreases. As seen from the simulation results, THIPWM have a superior performance compared to SPWM. The SPWM technique is very popular for industrial converters. It is the easiest modulation scheme to understand and implement. This technique can be used in single-phase and three-phase inverters. The THIPWM technique operates by adding a third harmonic component to the sinusoidal modulating wave. It is possible to increase the fundamental by about 15.5% and, hence, allow a better utilization of the DC power supply. From the shape of the line-to-line voltages, the resulting flat-topped waveforms allow over-modulation with respect to the original SPWM technique. Space Vector Modulation technique and Direct Torque Control strategy can be implemented in the cascaded rectifier inverter configuration.