电容钳位型LED均流电路

Capacitor Clamped Current Sharing Circuit for Multi-String LEDs

高亮度发光二极管(LED)自身导通压降的离散性及负温度系数特性使得多个LED串并联时出现各串电流不均衡的现象。提出了一种简洁的电容钳位型LED均流电路,各LED支路串联的开关管轮流交错导通。利用各LED支路间跨接的钳位电容在一个周期内的电荷守恒,实现了多路LED串的均流。对电路的均流原理、参数设计进行了详细的理论分析,在此基础上,进行了三支路均流的实验验证,实验结果表明所提出的电路具有良好的均流效果,控制方式简单,电容、开关管两端电压应力低,无磁性元件,便于集成。

This paper proposes a simple capacitor clamped current sharing circuit for multi-string LEDs to solve the current imbalance problem caused by voltage drop tolerance and the negative temperature coefficient of LED, which employs staggered turn-on switchs and multi-capacitor charge conservation. The operating principle and parameter design of the topology are analyzed in detail. On this basis, three-string current sharing topology validated by experiments and relative experimental waveforms are presented, which show that the proposed circuit has good effect on current sharing while the effect isn＇t affected by the output voltage of each branch, but also has the advantages of low voltage stress, non-magnetic components, ease of integration and .simple control.