GA based hybrid selective harmonic elimination (SHE) technique applied to five-level Nested Neutral Point Clamped (NNPC) Converter

摘要

This paper presents, genetic algorithm based hybrid selective harmonic elimination scheme for recently introduced Nested Neutral Point Clamped (NNPC) Converter. The Selective harmonic elimination (SHE) modulation scheme reduces device stress, switching losses and filter size in high power and high voltage applications. SHE technique aims to solve non-linear and transcendental equations while keeping the objective, to maintain the fundamental harmonic component at its reference value and to eliminate lower order odd harmonics. To solve these nonlinear equations Hybrid algorithm has been adopted in this paper. This algorithm has two stages, during first stage GA has been run for four iterations and in second stage obtained solution from GA is used to initialize newton algorithm, which finally gives the exact converged solution. Thus, proposed algorithm overcomes the drawback of newton algorithm to have strong initial guess. This work also investigates the performance of five-level NNPC inverter by doing spectral analysis of phase and line voltages. The MATLAB/SIMULINK software is used for comprehensive simulation of five-level NNPC inverter.