Comparison between Conventional and Modified Cascaded H-Bridge Multilevel Inverter-Fed Drive

Abstract: Inverters are static power electronics devices which convert dc input voltage to ac output voltage with the desired magnitude and frequency. The output voltage waveforms of ideal inverters should be sinusoidal. But practically it is square-wave or quasi-square-wave. To get better waveforms with low harmonic distortion, multi- level inverters are used. Multilevel inverter starts with a level of three. The topology used here is cascaded H-Bridge and the modulation technique is sinusoidal pulse width modulation. Here a comparison between conventional and modified cascaded H-Bridge inverter is done. The load of the inverter is induction motor. The number of output voltage level is five. Simulation is done in MATLAB 2011b environment and the waveforms are obtained. Finally, a prototype circuit of modified Cascaded H-Bridge inverter is implemented.. The results are analyzed using MATLAB/SIMULINK software. The hardware implementation is done using FPGA.

Keywords: Sinusoidal Pulse Width Modulation, Cascaded H-Bridge, Total Harmonic Distortion, FPGA.