Supraharmonics reduction in LED drivers via random pulse-position modulation

Abstract

ABSTRACTIn power electronics, deterministic pulse width modulation strategies, aimed at reducing the emission of low-frequency harmonics (<2 kHz), resulting in the transfer of these emissions to the switching frequency and its multiples, in the kilohertz range. The impact of these spectral components is the main concern when studying electromagnetic interference from rectifiers with active power factor correction stage, commonly employed in LED lighting. These so-called supraharmonics (emission in the frequency range 2 to 150 kHz) are at the root of numerous problems in today’s smart distribution grids. Consequently, the standardisation organisations are currently reviewing the compatibility limits within this frequency range. Supraharmonics behave differently from (lower frequency) harmonics, as being reported in the literature. Fortunately, as will be proved further, it is possible to greatly reduce their presence, and at low computational cost, when methods like random pulse-width modulation are properly selected from the very beginning, avoiding the later need to use any mitigation technologies.