A Novel Multilevel Inverter with Reduced DC Sources

Abstract: Multilevel inverters have become more popular in high power and high voltage application. They have a unique structure which makes it possible to reach high voltages with less harmonic content. Harmonic content of the output voltage waveform decreases as the number of output voltage level increases. The main advantages are lower Total Harmonic Distortion (THD), less stress on the power switches and higher efficiency. However, increase in the device count due to increased voltage levels makes the control method complex and hence expensive. This paper presents a nine level inverter with reduced DC sources which is capable of obtaining all additive and subtractive combinations of input DC levels. This topology requires less power switches compared to conventional multilevel inverter and less gate drives. The proposed topology is presented through a nine-level inverter with an appropriate modulation scheme and detailed simulation has been carried out in MATLAB/Simulink. A comparison is made between proposed topology and the conventional multilevel topology on the basis of device count, number of levels in the output voltage and THD.

Keywords: Multilevel Inverter (MLI); Phase Opposition Disposition SPWM; Power Electronics; Total Harmonic Distortion (THD).