基于集成三端口变换器的无电解电容LED驱动

An Electrolytic Capacitor-Less LED Driver Based on an Integrated Three-Port Converter

电解电容是影响AC-DC LED驱动电源寿命的主要元件,因此,消除电解电容技术是长寿命LED驱动电源的关键技术。将Flyback变换器与Buck变换器集成,提出一种无电解电容LED驱动电源拓扑结构,其具有较高的拓扑集成度,且控制方式易实现。通过将输入功率pin和输出功率po分为pin>po和pin<po两种情况,避免了整机能量的二次变换,通过第三端口的储能电容充电和放电平衡pin和po之间的低频脉动功率。分析了该拓扑结构的工作原理及开关模态,详述了主电路关键参数的设计思路和要点,并给出了简单易实现的控制电路。最后通过一台原理样机验证了该方案的正确性和可行性。

The electrolytic capacitor is the key component that limits the lifetime of AC-DC light-emitting diode（ LED） driver. Therefore,how to eliminate the electrolytic capacitor in LED drivers is a key problem. In this paper,an electrolytic capacitor-less LED driver which is integrated by Flyback converter and Buck converter was proposed. The driver is highly integrated with simple control. In the proposed circuit, the relationship between input power（ pin） and output power（ po） was divided into two modes： pin poand pin po,in order to avoid double energy conversion. The low-frequency pulse power was balanced by the energy-storage capacitor of the third port which is done by charge and discharge. Parameter design of the main circuit was addressed following the analysis of operating principle and switching-modes,as well as the control circuit. Finally,a prototype was built to verify the correctness and effectiveness of the driver.