SHE Controlled CHB 7-Level Inverter with Unequal DC Sources using MPSO Algorithm

Particularly, the control of multilevel inverters at medium voltage and higher power levels have technical challenges like higher switching losses and high %THD. Control of multilevel inverters at low switching frequency is highly desirable at higher power levels and this can be achieved by Selective Harmonic Elimination (SHE) technique. Solving the non-linear transcendental SHE equations set at various values of modulation index as to attain feasible values of switching angles to control MLI is quite complex which involves a lot of computational effort. In order to interface DC source solar panels using SHE technique is quite complex because the solar panels may give slight variation in the output voltage. To find feasible switching angles as to control the MLI is a challenging task while in particular handling with unequal DC sources. In this paper, Modified Species based PSO algorithm has been used to find the optimum switching angles which are formed in control of three-phase CHB 7-level inverter with unequal dc sources by using selective harmonic elimination technique. MATLAB programming and SIMULINK environment have been used to validate the proposed approach. This research work enlightened, the %THDs obtained at various values of modulation indices are better and complies with IEEE 519-1992 harmonic guidelines too.