Design Of LED Driver Based On Current Five-level DC-DC Convert

In recent years,with the rapid development of semiconductor technology,light-emitting diodes(LEDs),as the new generation of green light source,is the leading product in the market due to its advantages of energy saving,environmental protection,safety,reliability and long life.Conventional LED drivers generally use electrolytic capacitors as energy storage components.The relatively short life of electrolytic capacitors is regarded as an important factor limiting the life of LED drivers.Therefore,how to avoid the use of electrolytic capacitors has always been one of the hot spots in the research direction of LED drivers.This paper proposes to use a new type of current five-level DC-DC circuit to build the LED drivers,which not only removes the electrolytic capacitor,but also prolongs the overall life of the LED drivers.It can also realize the high power factor and constant current driving LED load.The main research contents of this paper are as follows:Firstly,a class of non-isolated two-cell current multi-level DC-DC converters is introduced.According to the characteristics of LED driver input and constant current driving LED load,the dual-cell buck converter is selected as the new current five-level DC-DC circuit is used to build the LED drivers,and the inductor is used instead of the electrolytic capacitor to balance the input and output power difference,thereby realizing the long life of the drivers.Then,by analyzing the relationship between the five-level generation mechanism of the main circuit and the switch combination,a multi-level PWM modulation technique suitable for the power supply is presented,which can realize constant current driving LED load and achieve high input power factor.The self-current-flow characteristics of the shunt inductors with intermediate levels are analyzed,and the current-sense closed-loop control strategy is given.Finally,based on the PSIM simulation environment,the system model is built.The simulation results verify the correctness of the above theoretical analysis of the LED drivers.The software and hardware design of the experimental prototype is introduced in detail.Based on the above design,a 50.4W prototype is built to verify the feasibility of the theory.