Comparing the Phase-Shifted and Level-Shifted PWM Techniques for Multilevel Flying Converters

This paper evaluates the performance of two common carrier-based techniques to control the voltage of the flying capacitor multi-level inverter (FC_MLI). These two techniques are Phase shifted Pulse Width Modulation (PS-PWM), and Level shifted Pulse Width Modulation(LS-PWM). First, the structure of FC-MLI is studied. Also, the principle of operation of PS-PWM and LS-PWM are explained. Then using the PSIM simulation software a three-level and five-level flying capacitor inverters are simulated. The effect of PS-PWM and LS-PWM on ۳ levels and ۵ level FCI performance is investigated. The time-domain simulation and harmonic analysis results indicate that the PS-PWM has a better performance than the LS-PWM. Also, these results show that increasing the voltage level in the flying capacitor structure decreases the voltage and current harmonics.

Keywords:

Multilevel converter , flying capacitor inverter , carrier-based , Phase shifted PWM , Level Shifted PWM , FFT analysis