Investigating the Harmonic Content of a PWM Inverter with Varying Modulation Index

Abstract

Photovoltaic energy is a clean and endless vital renewable energy. In order to generate electricity from solar energy an inverter is required to transform the direct current into alternating current. Also, with the emerging of new ultra-high voltage direct current transmission technology, the rectification and inverters play a great role. Most three phase two-level inverters draw harmonics that cause heat dissipation, waveform distortions hence affect the electrical loads. Knowing that Total Harmonic Distortion content of voltage source inverter is important and must be within the allowable range. Several schemes are suggested to mitigate the distortion in order to produce as much a sinusoidal output signal as would be possible. The most widely used control process of the semiconductor switches is Pulse Width Modulation technique. One of such schemes is using a Sinusoidal Pulse Width Modulation -based inverter which is usually used in inverters for industrial applications. In this paper, a study of the performance of the SPWM technique is presented for a three-phase H-bridge inverter and the simulation results obtained in MATLAB/Simulink demonstrate that the significantly investigation on the harmonics when varying the modulation index. These results confirm that the total harmonic distortion factor of the inverter output voltage decreases as the modulation index increases as a result, reduces the waveform distortion rate and suppresses the effects of harmonics. This is of great significance for the safe, stable, and efficient operation of the power system.