Performance analysis of cascaded multilevel inverter using modified multicarrier PWM technique

The Cascaded Multi Level Inverters (CMLI) are most suitable for DC to AC conversion in solar power generation, as it requires multiple DC sources. The selection of control strategy for this type of inverter plays a significant role in deciding the inverter output voltage and current profile. In this regard, this paper presents the performance analysis of 5-level CMLI with multicarrier modulation technique with two different types of modulating waves namely, sine and elliptical wave. The performance analysis has carried out with and without load. The output voltage and current profiles are analyzed with respect to rms value and Total Harmonic Distortion (THD) at different modulation indices. The harmonic spectrum of each control strategy has been discussed in detail with help of Fast Fourier Transform (FFT) block of MATLAB/S IMULINK tool. The elliptical modulating wave produces root mean square (RMS) value of the output voltage equal to 184.2V when compared to sine wave equal to 164.2V, at modulation index set to 1; this shows the improved DC bus utilization in elliptical modulating wave.