Modified Modulation Techniques for Cascaded Multilevel Inverter Fed Induction Motor Drive

This paper presents modified Space Vector Pulse Width Modulation (SVPWM) techniques for Cascaded Multilevel Inverter. In the proposed SVPWM technique the reference signals are generated by adding offset voltage to the reference phase voltages. This SVPWM technique does not involve region identification, sector identification or look up tables for switching vector determination as are required in the conventional multilevel SVPWM technique It is also reduces the computation time compared to the conventional space vector PWM technique. The modulation signals are generated by comparing the reference phase voltages with triangular carrier signals. Cascaded multilevel inverter fed with Induction Motor and RL load is simulated for various carrier PWM techniques like PDPWM, PODPWM, APODPWM and PSCPWM. The simulation results are analysed and compared. Among the various modulation techniques, PDPWM is themost efficient one and has better spectral performance and better induction motor performance.