Comparative analysis of a 3-phase, 3-level diode clamped ZSI based on modified shoot through PWM techniques

In this paper, a Z-source fed 3-phase, 3-level diode clamped inverter topology implementing modified reference and carrier based modulation techniques have been analyzed for different shoot through states of operation. Performance of the system based on respective carrier and reference frame of control has been thoroughly evaluated and simulation results pertaining to magnitudes of Total Harmonic Distortion (THD) as well as fundamental output voltage have been tabulated. From the obtained values of fundamental voltage, suitable graphs have been drawn showing its variation with shoot through factor. Results reveal that there is a serious need to formulate an optimal modulation strategy which can limit the magnitude of THD and achieve desired fundamental voltage without compromising on the efficiency. The study aids selection of best possible modulation technique for a chosen 3-phase adjustable speed drive operation implementing diode clamped inverter.