THD Analysis of 5-Level, 7-Level and 9-Level CHB-Multilevel Inverters Using SPWM Switching Approach

Abstract

The advantages of multilevel inverter over traditional inverter mainly for high power applications are very high. Due to increase in voltage level, the multilevel technology is very attractive for high power application and also for photovoltaic application due to the need of several sources on DC side. The output voltage waveforms of multilevel inverters are nearly sinusoidal, due to this, inverter efficiency improves, and total harmonic distortion (THD) minimizes. This paper basically presents the THD analysis, waveform pattern, harmonic spectrum and output voltage of 5-level, 7-level and 9-level inverters using a approach of sinusoidal pulse width modulation (SPWM). This has been analyzed as the inverter level increases the total harmonic distortion decreases and output voltages improve. The multilevel inverter models are based on MATLAB/Simulink.