White-light LED clusters with high color rendering index

Based on light-mixing technology and Chebyshev method of simulating Planckian locus, the relationships between chromaticity coordinate, luminous flux, relative color temperature and duty ratio of three-channel pulse width modulation (PWM) are derived in the paper, and limitation of three channels' PWM dimming is established. On the basis of this method, intelligent light-control system is designed, which can realize dimming and tunable color temperature of white-light LED clusters the warm white/green/ blue (WW/G/B) with high color rendering index (CRI) Ra by mobile client. Experiments show that maximum flux error between the setting value and the test value is 0.74% while the correlated color temperature (CCT) of the LED clusters is 3 600 K and the luminous flux is less than 600 lm. The deviation mean of CCT is less than 1.82% and luminous flux fluctuation is no more than 4% while the luminous flux is 300 lm and the range of CCT is from 3 200 K and 7 600 K. Meantime, CRI is generally more than 90, and the maximum value is 95.3 in the tunable range of the white-light LED clusters.