81 Levels Trinary Hybrid Cascaded Multilevel Inverter

摘要

Multilevel inverters are increasingly used in medium and high power applications owing to advantages such as modularity, low power dissipation on switching devices and reduced harmonic distortion at the output of the inverter. The MLI structure used in this paper incorporates four H-bridges cascaded together with trinary mode of selection of dc power supply that facilitates 81 levels of output voltage. The designed 81 level Trinary Hybrid Cascaded Multilevel Inverter (THCMLI) uses bipolar multi-carrier pulse width modulation strategy. The performance quality in terms of THD, crest factor, form factor, and power distortion factor are evaluated for different modulation indices. From simulated results it is observed that the THD of the 81level is reduced satisfactorily in POD PWM and power distortion is reduced in PD PWM strategy and high RMS value of output voltage is achieved in APOD PWM strategy when compared with other strategies with FAFF and FAVF for THCMLI. Increased number of voltage levels upto 81 levels in the output waveform is obtained shows the improved quality and nearness to sinewave with sixteen switches.