电流平方控制的大功率LED驱动电路

High-power LED drive circuit based on current square control technique

简单介绍了峰值电流控制Buck型LED驱动变换器基本原理,峰值电流控制具有快速响应和高稳定度的特性,但并不能直接控制其平均电流,因此不能精确控制其发光亮度。通过在峰值电流控制的基础上增加一个电流外环,提出了一种新的控制方法——电流平方控制。它利用参考信号和检测信号的差值积分来调节控制信号,从而精确控制平均电流,建立了电流平方控制环节的小信号模型,进而对系统的动态性能进行了分析研究,最后通过仿真对控制性能进行了验证,证明了理论研究的正确性。

The principle of LED drivers based on peak-current mode control technique of Buck converter was introduced in this paper. It could be known from the analysis that peak-current mode control technique featured fast transient response and high stability. But it only controlled the forward peak current of LED, but not the average current. A new control method, current square mode control technique was proposed by adding a new current outer loop. It regulated the control voltage to eliminate the steady error of the average current. Small signal models of the new control technique were obtained to analyze the dynamic performance of the systems. At the same time, the new control technique was verified by time-domain and frequency-domain simulation finally.