A Research Of Power Driver IC Based On MCU Of Intelligent LED Lights

The LED(light emitting diode)lighting market is broad and has great advatages in energy saving and emission reduction.Especially in the field of street lighting,energy saving effect is more obvious.Intel igent LED street lamps are becoming more and more popular.One kind of time controlled LED intelligent lighting lamp can not only meet the requirements of lighting but also realize the secondary energy saving of the LED street lamp,which has a good application prospect.This article is to study the driving scheme of the time controlled street lamps that adjusts LED brightness according to the season and time.It mainly includes two modules,the power drive and the intelligent control,which are studied and designed respectively for the two.This article first summarizes the recent domestic policies and plans for LED,as well as the market situation and development at home and abroad,and clarifies the significa nce of this research.Secondly,the working mechanism of LED and its requirement for driving power are analyzed,the characteristics of switching power supply and linear power supply are compared,the category of switching power supply is understood,the basic structure of switching power supply is analyzed,and the reason for selecting the half bridge isolation switch circuit to drive the high power rate LED is given,and the basic structure of the high-power LED driver is introduced.The switching power transistor RCIGBT(reverse-conducting IGBT)is also studied,a vertical and a lateral structure are proposed to suppress the Snapback phenomenon.Then the principle of the half-brid ge LLC circuit is analyzed,the steps and methods for the calculation of LLC parameters are introduced,and a 150 W LED constat-voltage driving circuit based on IR21844 is designed,including open-loop and feedback curcuits.These curcuits are verified using Saber software.The actual application cuircuit of IR21844 is also optimized.Finally,the intelligent control module based on 8-bit microcontroller PIC16F84 A is designed,including the software implementation of I2 C bus communication,and the software realization of two control methods based on time,as well its corresponding princip le circuit,in order to adjust the brightness of the LED according to the season and time.The simulation software Multisim and the real object are used for testing the intelligent control module.The simulation and test's final results of the whole research show that:1.The design of 150 W LLC half-bridge open-loop circuit achieves the desired output of 43 V,3.5A,and the switch transitor realizes zero voltage turon-on(ZVS),and the output rectifier diodes also achieve zero current shutdown(ZCS),the purpose of reducing the switching loss is realized;The feedback loop designed can transfer the change of output voltage.2.The I2 C communication program meets the requirement of bus communica t io n and can realize data acceptance and transmission between two devices.The time control module can adjust the output power of the LED drive circuit on time.The corresponding program of the two regulation mode can adjust the output pulse width on time,or adjust the reference voltage of the feedback loop,and then adjust the brightness of the LED.