A Combination of Optimal PWM Techniques for Control Across a Wide Modulation Range in Five Level Voltage-Source

The genetic algorithm (GA) and Newton-Raphson (NR) methods are used in this study to present an effective selective harmonic elimination (SHE) approach for a cascaded five-level inverter with six switching angles (N=6) every quarter cycle. For induction motor drive systems, a mixed PWM technique based on the distribution ratios 5/1, 3/3, and 1/5 is recommended in order to accomplish wide modulation range management. By resolving a series of nonlinear transcendental equations, the optimal switching angles for the three different distribution ratios are calculated while retaining the desired fundamental voltage and successfully removing the low order non-triplen odd harmonics up to the
$17^{th}$
harmonic order
$(THD_{17})$
. Additionally, in order to find the best solution that produces the least total harmonic distortion up to the
$49^{th}$
harmonic order, numerous existing solutions for each value of the modulation indices are assessed and compared. The findings demonstrate that the five non-triplen low order harmonics i.e. the fifth, seventh, eleventh, thirteenth, and seventeenth are successfully removed from the inverter line voltage output, and that the least
$THD_{49}$
is obtained when utilizing the suggested method for a broad modulation range.