Performance Comparison of Different Modulation Techniques of Multilevel Inverter

Abstract

Multilevel converters are now widely used in power industry as it can be used in high level power equipments. In recent time the multilevel inverter is used in many industrial applications like ac power supply and VAR compensator and driving systems. In general two level converter has some limitations like high switching losses and device contains of higher harmonics regarding use of high frequency. Multi level inverter can attain high voltage and can synthesize waveforms with low distortion and better harmonic spectrum .so multilevel inverter is introduced in order to meet the drawbacks of two level inverter. Multilevel converter can be used in different way the simple technique is to use with different combination of series and parallel connection of conventional converter to produce the multilevel waveforms. Moreover it can also use renewal energy sources like photovoltaic, wind and fuel cells. The multilevel inverters don’t have disadvantages except in the need of more numbers of semiconductor switches. The major multilevel inverters are categorised in to three types like cascaded H bridge multilevel inverter, Neutral point diode clamped multi level inverter and flying capacitor multilevel inverter. By changing the combination of different semiconductor switches we can enhance to increase the number of levels of multilevel inverter. All these three multilevel with different number of levels are illustrated in the literature. Multilevel inverter uses different modulation techniques.Those are sinusoidal pulse width modulation, selective harmonic modulation (SHE-PWM), space vector modulation (SVM). This literature reviews the art of comparison of different types of modulation inverter with different number of levels of output by using modulation technique of SPWM (sinusoidal pulse width modulation)