一种单级非隔离型无电解电容LED驱动电路

Single-stage non-isolated LED drive circuit without electrolytic capacitor

针对电解电容影响LED驱动电源寿命和可靠性问题,提出一种单级非隔离型无电解电容LED驱动电路,该拓扑是在反激变换器基础上增加一个辅助功率平衡电路,通过控制辅助储能电容的充放电实现了输入瞬时功率和输出功率之间的平衡,从而降低了输出电流的低频纹波,并且漏感能量也可以得到有效利用。详细分析了该拓扑结构的工作原理及开关模态,针对所提电路拓扑给出了电路关键参数设计,并提出了一种适用于该电路拓扑的控制策略。最后搭建了一台30 W原理样机,实验结果表明,所提的电路方案可以将输出电流的纹波抑制至20%以下,辅助储能电容和输出滤波电容可分别降至6.6μF和8.8μF,从而使用寿命更长的薄膜电容去代替电解电容,提高了LED驱动电源的寿命与可靠性。

Aiming at the problem of electrolytic capacitors affecting the life and reliability of LED driving power supplies, a single-stage non-isolated type without electrolytic capacitor LED driving circuit is proposed. The charging and discharging of the energy storage capacitor achieves the balance between the input instantaneous power and the output power, thereby reducing the low-frequency ripple of the output current, and the leakage inductance energy can also be effectively used. The working principle and switching mode of the topology were analyzed in detail. According to the proposed circuit topology, the key parameters of the circuit were designed and a control strategy suitable for the circuit topology was proposed. Finally, a 30 W principle prototype was built. The experimental results show that the proposed circuit scheme can suppress the ripple of the output current to less than 20%, the auxiliary energy storage capacitor and the output filter capacitor can be reduced to 6.6 μF and 8.8 μF respectively, so that the electrolytic capacitor can be replaced by a film capacitor with a longer life, which improves the life and reliability of LED drive power.