Conversion energy technology like converters and inverters is rapidly upgrading to properly harness one energy into another energy source. Solar, wind and biomass are the popular choices for converting energy sources into electrical output. This output usually can be produced by a multilevel inverter. Multilevel inverters are known for their reliability in producing high power ratings with low harmonic distortions by converting DC sources to AC output power. The inverter also can be cascaded to add more phase output power like the three-phase power. The demand for multiphase inverter systems is also increasing as higher-phase systems produce a more reliable and higher output voltage. Therefore, a five-phase multilevel inverter is introduced in this book. However, harmonic distortions still occur in the system causing many unwanted problems with the power output. The capabilities of the Improved Whale Optimization Algorithm (IWOA) to reduce Total Harmonic Distortion (THD) and eliminate selected lower-order harmonics are clearly shown and compared to Particle Swarm Optimization, Sine-Cosine Algorithm and Whale Optimization Algorithm. The IWOA successfully eliminated the selected lower-order harmonics and obtained the lowest THD outcome. Moreover, the outcome also showed that in RL load circuit simulation, IWOA could produce a good sinusoidal current output waveform. In conclusion, the proposed IWOA is expected to be advantageous in developing a practical high-performance five-phase cascaded multilevel inverter.