Impact of high frequency conducted voltage disturbances on LED driver circuits

Increasingly, consumer electronic devices utilize power supplies that have switching frequencies up to several tens of kilohertz. Consequently, emission in the frequency range 2 to 150kHz ('supraharmonics') is continuously increasing. Cases of conducted interference in LED lamps using switched mode power supplies, from supraharmonics have been reported over the past three years. This paper presents results from experiments where supraharmonic voltage distortion was applied to commercially available LED driver circuits. Variations of light output were obtained in some cases, along with evidence pointing to reduced converter efficiency and influence of point on wave of the distortion, on the light output. Importantly, it was shown that electromagnetic compatibility is not converter topology dependent, nor influenced by galvanic isolation. The results demonstrate that converters with similar topology can have vastly different behavior and there is a marked dissimilarity in performance among different topologies.