**6. Conclusions**

Many researchers and industries have acquired a multilevel inverter because of the capacities to regulate high- and medium-power applications. Also, the sustainable power source of DC needs to be changed over to AC. We demonstrate three different types of multilevel inverter, such as a cascade H multilevel inverter, a diode-clamp multilevel inverter, and a flying-capacitor multilevel inverter. Although all multilevel inverters are utilized to produce smoothing signals, the two types mentioned above have some drawbacks. For example, the individual DC sources are required for each inverter in CHB-MLI inverter and DC-MLI inverter switching losses are higher. These topologies are modeled in PSCADS SIMULINK. However, a flying-capacitor multilevel inverter has several features to regulate DC link capacitors compared to another multilevel topology using redundant switch configurations. From the MULTISIM simulation analysis and modeling of a flying-capacitor multilevel inverter in three levels, THD was 28.88% while in the five-level topology the THD was 18.56%. Therefore, we can decrease the total harmonic distortion adopting the higher-level topology.

**Author Contributions:** This paper was a collaboration effort among all authors. All authors conceived the methodology, conducted the experiment tests, and wrote the paper. R.A.R. and S.A.P. analyzed, designed and development of the experiment methodologies, A.M. and C.w.L. supported the work to perform in real time and, H.-J.K. verified the overall experiment.

**Funding:** This research was supported by Basic Research Laboratory through the National Research Foundations of Korea funded by the Ministry of Science, ICT and Future Planning (NRF-2015R1A4A1041584).

**Conflicts of Interest:** The authors declare no conflict of interest.
