Research On LED Lighting Control Strategy Based On The Photo-Electro-Thermo Multi-domain Model

LED is one of the fourth generation lighting sources with energy saving,environmental protection,long life,small size,fast response,etc.Its optical,electric and thermal characteristics are interact with each other.In this paper,based on the Photo-Electro-Thermo theory of LED,Photo-Electro-Thermo multi-domain models of LED are studied,and a new LED control strategy based on the multi-domain model is proposed,which are elaborated as follows.First of all,technology development of LED lighting is introduced in this paper,according to which,the importance of the research on the multi-domain model is analyzed,and the significance of the research on the new control strategy based on the multi-domain model is illustrated.Secondly,based on the classical LED volt-ampere characteristic model,Electro-Thermo multi-domain model is established.According to this model,a new measuring method of LED junction temperature Tj is presented,and a LED Electro-Thermo experiment platform is designed.Through which,the experimental conditions such as variable junction temperature and variable current can be created,so as to further complete the parameter extraction of Electro-Thermo multi-domain model.Research results indicate that,Electro-Thermo multi-domain model is correct and effective,and the new measurement method of LED junction temperature is simple,efficient with low cost.Thirdly,based on the proposed multi-domain model above,in this paper,through analyzing the interaction principle of LED optical,electric and thennal characteristic models are,further put forward,whose variables are forward voltage and forward current of LED.According to LED manual data offered by manufacturer and the LED photoelectric test platform built last section,the relevant parameters of two models can be obtained.The optical experimental results of several well-known LED chips show that the proposed Photo-Electro-Thermo multi-domain models can effectively reflect the change regularity of LED luminous efficiency and luminous flux.Then,based on Photo-Electro-Thermo multi-domain models,a new LED control strategy is presented,which is applied in the LED luminous flux control,and compared with the constant current control strategy and constant power control strategy.The simulation results show that,in the case of temperature variation,the new control strategy based on Photo-Electro-Thermo multi-domain model can achieve more precise control of luminous flux than LED constant current control strategy or constant power control strategy.Finally,according to the new LED control strategy of presented above,the experimental research on a Flyback converter is carried out in order to make a comparison of three control strategies.The results show that the control effect of the new control strategy is better than that of the constant current control and constant power control.This is consistent with the theoretical research and simulation results.