Optimised active harmonic elimination technique for three-level T-type inverters

This study develops a pulse-width modulation (PWM) method that is referred the optimised active harmonic elimination (AHE) technique to eliminate more harmonics with minimum switching frequency for three-level T-type converter (3 L-T2C) based on the fundamental frequency switching control method. First, Homotopy algorithm is applied to non-linear transcendental equations to eliminate low-order harmonics and to determine switching angle sets for selective harmonic elimination PWM in 3 L-T2C. The characteristics of the multiple solutions in terms of harmonic distribution, and total harmonic distortion (THD) are investigated. Then a detailed analysis of optimised AHE-PWM technique is presented to cancel more harmonics in 3 L-T2C using harmonic compensation strategy. A switching angle solution set that gives the lowest THD for optimised AHE-PWM is derived and the effectiveness of the control method is verified through extensive simulation studies. Finally, selected experimental results are reported to verify and validate the theoretical and simulation findings.