Research On Bridgeless Valley-filled Electrolytic Capacitor-less LED Driver

LED(light emitting diode)as a new generation of lighting lamps which has the advantages of long service life,high efficiency,energy saving and less environmental pollution.It has been widely used in many fields.A good driver can extand the life of LED.Although energy storage capacitors in some LED drivers are electrolytic-less capacitors,there are still problems such as large voltage ripple of energy storage capacitors and low efficiency.Therefore,it is necessary to develop a new LED driver with good performance.First of all,in view of the problem of large voltage ripple of the storage capacitor in the original single-stage electrolytic capacitor-less LED driver,a valley-filled circuit is proposed to replace the storage capacitor.Then,based on the analysis of the principle of reducing the capacitance value of the storage capacitor,several methods for reducing the capacitance value of the energy storage capacitor are obtained.The valley-filled single-stage electrolytic capacitor-less LED driver has the problem of low efficiency.Based on the topology optimization method,the bridgeless circuit is used to replace the rectifier bridge,and the efficiency comparison and analysis of the traditional PFC Boost circuit and the bridgeless PFC Boost circuit are introduced.The circuit topology,working modalities and electrical characteristics of the bridgeless valley-filled single-stage electrolytic capacitor-less LED driver are analyzed in detail.Secondly,the state-space averaging method is used to model the proposed bridgeless valley-filled single-stage electrolytic capacitor-less LED driver to obtain the output voltage and duty cycle transfer function.The circuit model and the mathematical model are simulated using Matlab to obtain the output voltage comparison waveform.Then,the state space averaging method and the average current control are combined to obtain the open-loop transfer function of the entire system,and the stability of the system is verified by Matlab.Finally,the average current control of the bridgeless valley-filled single-stage electrolytic capacitor-less LED driver is simulated and researched,and the maincomponents of the circuit are selected.The structure of the control circuit's chips is introduced in detail and a 95 W experimental prototype is also designed.Experimental prototypes are used for experimental research.Through experiments,it is proved that the bridgeless valley-filled single-stage electrolytic capacitor-less LED driver can work normally,reducing the voltage ripple of the storage capacitor and improving the efficiency,and has good performance.