Research On Dual Closed-loop LED Drive Control Method Based On Light Intensity And Current Feedback

With the progress of science and technology,the survival of human beings is increasingly dependent on energy consumption.Because the contradiction between energy demand and shortage is becoming increasingly prominent,the use of energy tends to be energy-saving and efficient.Therefore,the development of lighting source is bound to conform to the trend of The Times and towards the development of saving and efficient.Light Emitting Diode（LED）as the new generation lighting source with its high light efficiency,long life,energy conservation and environmental protection is widely used in various fields.The stability of driving power supply is very important for the popularization and use of LED.Therefore,LED drive power supply plays an important role in LED industrialization and mass production.In the traditional LED drive control scheme,the constant current control of the load is realized by changing the voltage and current of the driver by collecting the load signal.However,for LED,the brightness of the light can directly reflect the quality of the working state.Therefore,in this paper,while considering the electrical signal,the optical signal is introduced into the feedback range,so as to improve LED power the driving control precision,adaptability and intelligence.The main contents of this paper are as follows:1.Firstly,analyzing the physical structure of LED is to introduce its luminous principle and factors affecting luminescence.The circuit characteristics and models of LED are be studied in this paper.LED load platform is built.Second order Taylor series is used to obtain the voltage and current equation of LED in practice.2.Analyzing LED driver circuit structure is to select the efficient constant current driving scheme.The DC/DC converter with high conversion efficiency is selected for LED current sensitivity.Both Buck driving circuit parameters and a driving control method based on LED second-order model can be established.3.In order to improve the precision of light intensity control,the light intensity and current double feedback closed loop LED driving circuit control system is designed.Aiming at Buck driving circuit of LED,the driving current transfer function is established and its frequency characteristics are analyzed.The parameters of the current control PI regulator are calculated,and the current closed loop serves as the control link.Open loop transfer function with the light intensity loop is constructed.PI parameters are corrected by MATLAB/Simulink to obtain the parameters of light intensity PI regulator.In order to adapt to the dynamic performance of LED light intensity change,a light intensity control method based on fuzzy adaptive PI regulator is studied.4.The design of LED driving circuit system,and the selection of GY-39 optical intensity sensor module,TMS320F28335 DSP chip controller,and OSRAMOSTARLED load test platform are completed.LED drive circuit control program is designed to complete LED light intensity simulation,light intensity sensor test,LED constant current control test,and LED light intensity tracking test.