Method and system for avoiding flicker for SSL devices

摘要

The present document relates to illumination systems. In particular, the present document relates to a method and system for avoiding flicker (in particular 100Hz or 120Hz flicker) in solid state lighting devices such as LED or OLED assemblies. A controller (220) for a driver circuit (200) of a solid state lighting, referred to as SSL, device (250) is described. The driver circuit (200) comprises a power converter (230) configured to convert a varying input voltage (402) into a drive voltage for the SSL device (250). The input voltage (402) is derived from a rectified AC mains voltage (401) at a mains frequency. The power converter (230) is used with a maximum voltage step-up conversion ratio. The controller (220) is configured to synchronize to the mains frequency; determine a plurality of pulse intervals (403) repeated at a pulse frequency; wherein the pulse frequency is greater than a perceptual frequency of light intensity variations perceivable by a human eye; wherein the varying input voltage (402) within the plurality of pulse intervals (403) is greater than or equal to a pre-determined minimum input voltage; wherein the minimum input voltage corresponds to an on-voltage of the SSL device (250) divided by the maximum voltage step-up conversion ratio; and control the power converter (230) to generate the drive voltage for the SSL device (250) within the plurality of pulse intervals (403), such that the drive voltage within the plurality of pulse intervals (403) corresponds at least to the on-voltage of the SSL device (250).