Research On The High-power-factor LED Driver Based On CLL Resonant Converter

With people's attention to energy consumption and environment,the idea of energy saving and emission reduction is becoming more and more important.Lighting electricity has a large proportion in energy consumption,so energy-saving in lighting is urgent.Because of its high efficiency,energy saving,long life and other advantages,LED is used more and more widely.So it's one of the key issues in the field of lighting to design high power factor,high reliability of high-power LED driver.Firstly,this paper analyzes the structure and characteristics of several single-stage LED driver,then introduces the research status of LED driver,including the dimming of LED and power factor correction,multi-channel current balancing technology and so on,and based on it,a novel single-stage topology with PFC and constant current output is proposed.The circuit combines the Boost PFC circuit and the half-bridge CLL resonant converter through the shared switch,it has the advantages of simple circuit and convenient control,which can realizes the high power factor and constant current output.The paper introduces the circuit structure and working principle in detail.And according to the energy coupling between the PFC circuit and the half bridge CLL resonant converter,a relation of the PFC circuit output voltage to AC input voltage and load can be derived,which provides a basis for the parameters design of the resonant converter and the realization of the dimming.For this single-stage LED driver circuit,a multiple output current balancing scheme which combines the series transformer and balancing capacitor is studied,and the balancing principle is analyzed.Based on this circuit,a hybrid dimming control strategy of PFM and PDM is proposed,which realizes a wide range dimming of LED lights.At last,the design process of hardware circuit and software program in single-stage LED driver based on CLL resonant converter are described in detail.And the design method of some of the key parameters in the circuit is given,then the circuit is simulated and tested by Saber simulation software,and the simulation analysis verify the effectiveness of the proposed circuit topology and control strategy.Finally,a 100W LED driving power supply experimental prototype with four outputs current balancing is designed.It using dsPIC micro-controller as the main controller and also can achieve power factor correction and light dimming.The experimental tests has been done,and the results verify that the proposed scheme is feasible.