Study on Implementation of PWM Dimming in Beam Angle Switched LED Street Light to Achieve Energy Efficient Standard Lighting

To study the effectivity of implementing PWM dimming in conjunction with BAS (Beam Angle Switching) method to a low powered LED street light and the effect of varying PWM (Pulse Width Modulation) duty cycle on the overall Illuminance Uniformity (Uo) of the working plane (here the simulated street under controlled environment) under a low wattage LED street light and to find any co-relation between duty cycle and overall illuminance uniformity and other lighting parameters like CCT, CRI and Illuminance, a decorative experimentation is done in Illumination Engineering Laboratory of Electrical Engineering Department of Jadavpur University. The percentage PWM duty cycle precisely refers to the proportion of time that a digital signal is on over the period of time or an interval. The waveform's frequency is inversely proportional to the period of the signal. Besides, overall Illuminance uniformity is the ratio of minimum illuminance value and average illuminance value found from a particular grid, drawn under the experimental street light. In this study, PWM dimming is successfully implemented with BAS method in a 55-Watt LED Street light. Moreover, study shows that overall Illuminance Uniformity does not change significantly with the change in PWM duty cycle, further indicating that PWM dimming can be easily incorporated with BAS method and it would be beneficial from energy consumption reduction.