Study On The Photothermal Characteristic Of LED Light Source And Design Of Network Control System

With the popularity of LED lighting applications,the high junction temperature and light failure phenomenon of the LED light source gain more and more attention.For the light and heat characteristics of LED,the equivalent thermal resistance model of LED is constructed according to the heat transfer method,and the thermal law of PN junction of LED under different conditions is studied and verified by simulation experiment as well.Lastly,the LED light source with low junction temperature,high luminous efficiency and long life,and network control system are put forward and designed.The actual operation results show that the system is effective and feasible.The main work of the paper is as follows:1.The equivalent thermal resistance model of single and multi-LED array are built.Based on the theory of heat conduction,the calculation method of thermal resistance and junction temperature of single LED and LED array is studied,and the factors influencing LED junction temperature are discussed,which provides theoretical support for the photothermal characteristics analysis of LED and LED light source design.2.The simulation of thermal resistance model and the photothermal characteristics of the single LED is studied.The impact of the input power(input current)of LED,the material of pcb and the type of LED chip on the junction temperature of LED is studied,and in order to find out the optimal operating point of photothermal characteristics,the photothermal characteristics of LED are tested and analyzed.3.The simulation of thermal resistance model and photothermal characteristics of LED array is studied.The impact of the input power(input current),the material of pcb and the layout structure of LED array on the junction temperature is studied,the relationship among the LED number,layout and the photothermal and luminous efficiency of LED array is then analyzed to find the optimum designing method of LED array.4.The hardware and software of LED lighting source with low junction temperature,high light efficiency and long life hardware,and network control system are designed.Based on the thermal resistance model and the photothermal characteristics of LED array,the LED array circuit,the controllable constant current driving circuit,the PWM control signal generation and dimming circuit,the power source and power factor correction circuit and detection circuit of the LED lighting source are designed,and apply the uplink communication mode using wifi and Ethernet combination,and apply the downlink communication mode using ZigBee and RS485 combination to achieve the real-time monitoring and network control of LED lighting source.Based on the statistical analysis of the experimental data,the relationship between the photothermal characteristics of the single LED and the LED array is established and verified,the LED lighting and network control system of mine roadway lighting are then developed independently.The running test data shows that this method can not only ensure that the LED junction temperature is lower than the light failure requirement under the illumination conditions,but luminous efficiency and power factor are high,the method provides a demonstration for the long-term energy saving operation of the LED lighting source.