Hardware-in-the-Loop Implementation of Projectile Target Search Algorithm for Selective Harmonic Elimination in a 3-Phase Multilevel Converter

Multilevel converters (MLCs) are extensively used in medium-and high-power applications. Currently, MLCs are also used in grid integration of renewable sources of energy. In this paper a three-phase 11-level MLC topology is investigated which requires a smaller number of active switches compared to similar existing topologies for the same number of levels. In order to eliminate lower order harmonics, selective harmonic elimination (SHE) pulse width modulation technique is used. A projectile target search (PTS) algorithm is used to solve nonlinear SHE equations to determine the optimum values of switching angles to eliminate 5th, 7th, 11th and 13th harmonics from the converter output voltage. The PTS algorithm finds the best value of switching angles for different modulation indices (M) and these values are used in simulating the converter for eliminating lower order harmonics. Total harmonic distortion (THD) analysis is conducted for PTS optimization techniques at different modulation index. Simulation results are verified by hardware-in-the-loop test of the proposed three-phase converter using a Typhoon HIL-402 emulator.