Harmonic mitigation technique for multilevel inverters in power systems

A new procedure to mitigate some harmonics is presented for a 5-level cascaded inverter, varying the modulation index. The two switching angles α₁ and α₂ are computed by using a procedure based on graphycal analysis by using Chebyshev polynomials and the Waring´s formulae. The proposed mitigation technique is applied to reduce a pair of harmonics among third, fifth and seventh in inverter output voltage according to standard code requirements. Experimental results are also extracted by the prototype built at the laboratory. The measured results confirm the quality of the presented procedure.