A novel LED driver is proposed and analyzed in this paper. The main circuit topology is based on a quadratic buck and a buck-boost. They share a switch through cascading, simplifying the topology and control strategy, reducing the cost of the control circuit. Using two-stage cascade structure, the input current dead-time problem of the original quadratic buck topology is eliminate. It improves the power factor and the input current THD. At the same time, the duty cycle of the switch operates in a more reasonable area. Finally, the correctness of the theoretical analysis is verified by experiments.%提出了一种新型的LED驱动电源,分析了其工作原理和工作特性.主电路拓扑基于二次型Buck和Buck -boost变换器,通过级联,共用一个开关管,简化了拓扑结构和控制策略,降低了控制成本.采用两级式级联结构,消除了原二次型Buck拓扑结构的输入电流过零死区问题,进一步提高了功率因数,改善了输入电流的总谐波失真(Total Harmonic Distortion,THD).同时,开关管的占空比工作在更合理的区域.最后通过实验验证了理论分析的正确性.
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