Design of Nine Level Inverter Topology for Three Phase Induction Motor Drives

A new approach of nine levels cascaded H-bridge multilevel inverter is proposed for three phase induction motor drives. Multilevel inverter is used synthesize a nearby sinusoidal voltage from various levels of dc voltages and the proposed cascade H bridge inverter is used to reduce the number of switches. The proposed nine level cascaded H-bridge multilevel inverters require less number of components to obtain same number of voltage levels when compared to diode clamped and flying capacitor type methods. Due to that, the switching loss gets reduced as same like the harmonic distortion occurs in the motor drive gets reduced. Also, it generally regularizes the stair ?case voltage waveform from several dc sources which has reduced harmonic content. The operational principle and key waveforms are analyzed and the performance of the proposed multilevel inverter is evaluated from the simulation results.