LED Lamp Flicker Caused by Interharmonics

The current IEC flickermeter standard only considers light flicker of incandescent lamps. Hence, the standard flicker-meter has limitations regarding assessing flicker of lamp types other than the incandescent lamp, particularly in the presence of interharmonics. In this paper, the flicker responses of various lamps (e.g., incandescent, compact fluorescent, and LED (light-emitting-diode) lamps) are investigated using a laboratory interharmonic flicker station and a photo detector. The experimental results demonstrate that LED lamps exhibit flicker response similar to that of compact fluorescent lamps, which are sensitive to high-frequency interharmonics located close to the odd order harmonics. Our analysis indicates that a diode bridge rectifier, which converts AC to DC for both compact fluorescent and LED lamps, is a source of flicker due to high-frequency interharmonics.