An Improved Multicarrier PWM Technique for Harmonic Reduction in Cascaded H-Bridge Based Solar Photovoltaic System

An improved multicarrier modulation technique is presented for single-source cascaded H bridge based solar multilevel converter (SMLC). Main aim of this article is to improve harmonic profile at converter output voltage. New modulation is introduced, which is summation of pulse and triangular carrier functions to have a new modified level arranged carrier scheme (MLACS). In MLACS, frequency of pulse function is Sf times carrier wave. Comparative Fourier investigation of MLACS and LACS is discussed. It is implemented in closed loop for enhancing power quality of SMLC at grid end. Comparison of new scheme is done with level arranged carrier scheme, phase-shifted carrier scheme (PSCS), and parabolic level arranged carrier scheme in under and over modulation ranges. MLACS efficacy is investigated in terms of weighted total harmonic distortion for five level output. Presented results at laboratory level validate MLACS concept for improved harmonic performance of SMLC.