Multilevel inverters (MLIs) have become a trend in the field of DC/AC inverters and one of the main requirements in many of the industrial applications. MLIs spread in the academic research field and replaced the conventional inverters due to the several advantages that these topologies presented over the conventional inverters, as follows. (1) Operate with a high number of steps in the output voltage waveform, which helps in reducing the level of harmonics and presents fine and clear waveforms; furthermore, reduce the voltage stress on the switching devices and gives it a long lifetime and more reliability. (2) MLIs have a low rating of the switching devices, which has a noticeable role in reducing the system cost. (3) MLIs can be operated at both higher and lower switching frequencies, which reduces the level of power losses and enhances the overall efficiency. The main problem that faces the researchers in the multilevel inverters field is to design a topology that uses the optimum number of components to ensure the low cost and obtain a high efficiency. This paper presents a description of different topologies of MLIs that were investigated in the last two decades to show the pros and cons of each topology. Also a set of performance parameters that were used to measure the effectiveness of the MLI topologies have been discussed.

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This paper presents a novel hybrid Multilevel Inverter (MLI) system. This hybrid system consisted of a nine-Level MLI unit that is connected back to back with a developed H-Bridge unit. The combination synthesizes only 10 power switches, two diodes, and four DC supplies to generate an output voltage waveform with 19 steps. The high number of steps in the output voltage helps produce a fine output waveform and more close to the sinusoidal shape with a small amount of THD. Also, it reduces the voltage stress across the switches and gives it a long lifetime, which brings more reliability. Moreover, the system synthesizes a reduced number of switches, which reduces the power losses and achieves high efficiency, and ensures small size and low cost for the proposed system. For amplifying the output power level, the paper presents two scenarios for the system expansion; both the scenarios achieve good