Evaluation of a light controller for a LED-based dynamic light source

Abstract

In this paper, the performance of a dynamic light controller (DLC) is experimentally evaluated to achieve a dynamic light source consisting of alternative arrays of warm white and cool white light-emitting diodes (LEDs). The DLC is programmed to drive the light source through both step and continuous variations of correlated colour temperature (CCT) and light output. For step variation, the DLC generates pulse width modulation (PWM) signals to drive the LED arrays to achieve 16 desired set points out of four CCTs (2900–5600 K) and four illuminances (100–300 Lux). The measured set points show deviations within acceptable limits. For continuous variation, the DLC is programmed to make the dynamic light source follow a time-varying pattern of CCT and Illuminance. The variations of measured values are mostly within acceptable limits except at lower CCT and illuminance points. The measured duty cycles of the generated PWM signals from the DLC are almost equal to the corresponding calculated values for both the step and continuous variations indicating good performance. The measured deviations are caused by the differences in lumen output at duty cycles <10% compared to the estimated values.