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ABSTRACT
In this article, a simple dynamic light controller (DLC) is proposed, designed, and fabricated for practical realization of variable correlated color temperature (CCT) but constant light output white light emitting diode (WLED) light source. This WLED light source consists of alternate strings of warm white (WW) and cool white (CW) LEDs. Light control logic of developed DLC is based on Grassman’s color mixing law and hence the range of CCT variation of the test light source lies within the CCT values of the WW and the CW LEDs. A pulse width modulation (PWM) technique is applied to implement the light control logic and embedded in a PIC microcontroller to control the light outputs of two WLED arrays through enhanced PWM mode with dual PWM output. The developed controller is connected with the test light source and controllable by infrared (IR) remote within a distance of 4 m. Thus, the developed DLC is an integrated module consisting of an IR receiver, IR decoder, control signal (PWM) generator, amplifier, and switching device. Performance of the developed DLC is experimentally validated for a set of desired CCT points (2840–5750 K) and constant illuminance (300 lx) measured at a fixed distance. Measured CCT values show maximum deviation of 160 and 194 K for warm white and cool white regions, respectively, compared to desired CCT points. On the other hand, the deviation of measured illuminance values lies within
to
with respect to set illuminance value of 300 lx. Variations of measured CCT lie within the acceptable range. Experimental results establish the satisfactory performance of the developed DLC.
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Notes on contributors
Pradip Kr. Maiti
Pradip Kr. Maiti received an M.E. in illumination engineering from the Electrical Engineering Department of Jadavpur University, India, in 2014 after qualifying for a B.Tech. in electrical engineering from the Future Institute of Engineering and Management, Kolkata, under the West Bengal University of Technology, India, in 2011. Presently he is pursuing research at the Illumination Engineering Laboratory, Electrical Engineering Department, Jadavpur University. His research interests are smart lighting control systems, daylighting, and color specification systems.
Biswanath Roy
Biswanath Roy is Professor of Illumination Engineering at the Electrical Engineering Department of Jadavpur University, India. He received a Ph.D. (Engg.) in daylighting in 1999 from Jadavpur University after received an M.Sc. (Tech.) in optics and optoelectronics in 1993 and B.Sc. (Hons.) in physics in 1989 from the University of Calcutta. He is Life Fellow of the Indian Society of Lighting Engineers (ISLE), Life Member of the Institution of Engineers (India), and Member of IESNA.