Design Of Multi-channel Constant Current LED Driver Based On LLC Resonant Converter

LED is a new type of lighting source,which has the advantages of high luminous efficiency,long life,energy saving,environmental protection and so on.It is widely used in many places,such as display backlight,indoor lighting and street lighting.In the application of high-power LED,most of the LEDs are connected in the way of hybrid connection.In order to prolong the service life of the LED,it is of great practical significance to study the multi-channel constant current LED Driver with high efficiency,good current sharing effect and high reliability.LLC resonant converter has the advantages of high switching frequency,low switching loss and high efficiency,which has been paid attention to and applied in the high-power LED driver.This paper presents a fuzzy self-tuning PID control algorithm for multichannel constant current LLC resonant LED driver,studies the circuit characteristics of LLC resonant converter and the volt ampere characteristics of LED,analyzes the working principles of series transformer current sharing method and capacitor current sharing method,designs fuzzy reasoning rules on this basis,and realizes PID parameter self-tuning.The algorithm is verified by Simulink simulation Based on LLC resonant converter,a 20 W four channel constant current output LED driving power supply prototype is designed and verified.The LED driver control system designed in this paper has the advantages of simple circuit structure,simple algorithm design and good current sharing effect.It realizes the soft switching of the switch tube and reduces the system loss.Compared with the PID controller with fixed parameters,when the input voltage of the system is disturbed,it has faster recovery speed and smaller current fluctuation amplitude,and has good control performance for the input voltage disturbance.