Modified phase shifted PWM for cascaded H bridge multilevel inverter

This paper proposes a modified phase shift pulse width modulation technique which is suitable for both single phase and three phase system for a conventional cascaded H bridge multilevel inverter. The carrier phase shift PWM method which is proposed in this paper improves the output voltage waveform and reduces the total harmonic distortion when compared with the conventional phase shift PWM method. The modified pwm is analyzed using a seven level cascaded H bridge multilevel inverter for both single phase as well as for three phase system, and this pwm can also be applied to N number of levels for cascaded H bridge inverter depending upon their angle calculations. The comparative analysis of this proposed pwm is done with respect to conventional pwm and the results are shown in terms of the harmonic spectrum analysis. This is done using the MATLAB/SIMULINK.