SYMMETRICAL MULTILEVEL CASCADED H-BRIDGE INVERTER USING MULTICARRIER SINUSOIDAL PULSE WIDTH MODULATION TECHNIQUE

Abstract

This paper investigates and analyses an efficient multicarrier SPWM switching method for cascaded H-Bridge symmetrical multilevel inverter.The H-Bridge based symmetrical multilevel inverter can increase the number of levels of output voltage by adding number of input DC sources. If two DC sources are applied then it gives five levels at output and three DC sources gives seven levels of output. To reduce the THD as per requirement it needs output filter.In this papermulticarrierSPWM switching is provided to the multilevel inverter switches. In this switching method two signals are used, one is reference and another is carrier signal. For SPWM technique reference signal is sinusoidal wave and triangular wave is carrier signal. This type of inverters have an ability to produce waveforms with better harmonic spectrum and realistic output results. The simulation results shows that Total Harmonic Distortion is reduced with sinusoidal pulse width modulation. The simulation results shows that quality of output voltage waveform gets improved with less loss as well as lower THD.