Mathematical formulation of multilevel voltage source inverter switching instants

Abstract

Modular structured multilevel inverter is very useful for electrical application especially in high power and high voltage applications. The main function of this multilevel inverter is to produce multilevel AC output voltage from several separate DC sources. This project is to derive a new mathematical formulation of multilevel voltage source inverter switching instants. The proposed method for this project is based on the sinusoidal natural sampling PWM (SPWM) by comparing several modified modulation signal with a triangular carrier signal. This resulting intersection points between this modulation and carrier signal become the switching instants of the PWM pulses. Derivation also based on two dispossition method that is Alternative phase opposition dispossion (APOD) and Phase opposition dispossion (POD). A cascaded multilevel inverter is selected as a topology for this project due to major advantages compare with other topology. The derived formula is analyzed by using MATLAB simulation software. It is found that the result that use the derived formula is almost identical to simulation result.