Harmonic Analysis of Modified Nine-level Inverter with SHEPWM using Grey Wolf Optimization

This paper presents the nine-level multilevel inverter with reduces switch technique using Grey Wolf optimization (GWO) methods on eliminating the low order harmonics. Using the appropriate switching angles, the low order harmonics can be eliminated completely from the output voltage and current waveform. The switching angles were calculated using the non-linear equations derived from the Fourier series of the output voltage and current waveform. In this paper, GWO algorithm was developed to solve the nonlinear equation and generate the appropriate switching angles specifically for the proposed reduced switch technique topology. The circuit were simulated using PSIM and evaluate based on experimental assessments. The targeted low order harmonic to be eliminated are the 5th, 7th and 11th and two modulation indices will be compared and observed it performance in term of value of total harmonic distortion. The THD results for modulation indexes of 0.7 and 0.82 will be displayed. For modulation index 0.7, simulation yields 7.52% and experimental yields 6.23%. The simulation result for modulation index 0.82 is 5.82% and the experimental result is 4.69%.