Analysis and simulation of cascaded H-bridge multi level inverter using level-shift PWM technique

For medium voltage and high power applications, multilevel inverter has been accepted as a better alternative; as it has better waveform quality, low stresses on switching devices and better performance. Among the various topology of multi level inverter cascaded H-bridge inverter has been found as more reliable, easy to implement and better performance. This paper analyses the performance of cascaded H-bridge inverter for 5-level, 7-level, 9-level, 11-level, 13-level and 21-level for single phase and also three phases. The performance of mentioned level has been analyzed through simulation using level-shift PWM technique i.e. for all the levels using In Phase Disposition, Phase Opposition Disposition and Alternate Phase Opposition Disposition. A comparison between total harmonic distortions at modulating frequency 1 KHz and 4 KHz for all levels has been done for various methods of level shifted PWM techniques.