多主色LED照明光源的相关色温调控

Abstract

Based on the established photo-electro-thermal(PET)model,a model predictive control method of Correlated Color Temperature(CCT)for a Light Emission Diode(LED)was investigated to realize the CCT control of multi-primary color LEDs.The Guassian distribution hypothesis and the thermal equilibrium variable relationship stability hypothesis were presented.The regression submodels of different model parameters were calculated by least square estimation method successively according to the strategy of soft model.The change trend of spectral sensitive coefficient curves with different CCT curves was analyzed.Then,current control parameter values of 3typical CCTs at3 000,4 500 and 6 500 K were fixed by the gravity line adjusted method.Finally,a set of spectral power distribution curves were obtained by bringing a certainty random variation to the fixed current control parameter values to validate and evaluate the accuracy of the PET model.Experimental resultsindicate that the PET model predicts accurately the heat sink temperature and the Spectral Power Density(SPD)of the LED by control of the currents and environment temperatures,the accuracy of predictive chromatic coordinate value is better than±0.005,and the accuracy of predictive CCT is better than ±150K.The model-based control method has good accuracy for CCT control and can be generalized to the multi-primary color LED illumination with more primary color channels.