Mitigation Technique for Cascaded H-Bridge Multilevel Inverters Based on Pulse Active Width Modulation

Abstract

This article considers <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${l}$ </tex-math></inline-formula> -level cascaded H-bridge (CHB) inverters and proposes a new modulation method based on pulse active width modulation (PAWM), capable to minimize all harmonics with order <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n&lt; 2l+1$ </tex-math></inline-formula> and to satisfy the European harmonic standards for medium-voltage-level applications EN 50 160 and CIGRE WG 36-05. A mathematical theorem and its proof are presented, stating the features of the procedure, which is an improvement of the selective harmonic elimination (SHE) PAWM proposed by Buccella et al. After a detailed description of the method, simulation and experimental results have been included, showing its capability to reduce low-order harmonics.