大功率白光LED高效均流并联供电系统

High-Efficiency Current-Sharing Parallel Power Supply System for High-Power White LED Illuminant

为解决可见光通信系统中的白光LED(Light Emitting Devices)光源高效稳定的直流偏置电源问题,设计并研制了一种Buck型双DC/DC(Direst Cunent)并联供电系统。该系统采用ARM7(LPC2148)作为主控制器,利用电压反馈调整两个DC/DC模块的PWM(Pulse Width Modulation)驱动信号的占空比实现稳压,利用两个PMOS(P-channel Metal-Oxide-Semiconductor)电子开关分别控制两个DC/DC支路实现均流。实验结果表明,电源实际输出电压与设定值的误差小于2%,两个支路电流的偏差小于1%,电源供电效率可达75%～80%。在电源开启和关断瞬间的瞬时测试结果显示,驱动电压无尖峰现象,电压从0上升至1.6 V的时间约为20 s,关电降至0的时间约为65 s。两个DC/DC模块交替工作,延长了供电系统的使用寿命。该供电系统在LED照明和可见光通信设备中具有良好的应用前景,为设计多DC/DC模块的高效均流并联供电系统提供了解决方案。

A dual buck-type DC/DC （Direst Cunent） parallel power supply system is designed to provide high-efficiency and stable DC bias for WLEDs （White Light Emitting Devices） used in VLC （Visible Light Communication） links. ARM7 processor （LPC2148） is used as the main controller, and based on the feedback vohage, the duty-cycle of a pair of PWM （ Pulse is adjusted for regulating the output voltage. By switches, the currents of the two DC/DC modules Width Modulation） signals controlling the two DC/DC modules adopting two PMOS （P-channel Metal-Oxide-Semiconductor） are shared. To evaluate this power supply system, experiments are performed by using it to drive a WLED. The error between actual output voltage and expected voltage is less than 2% , the current error between the two DC/DC branches is less than 1%, and the power supply efficiency is within the range of 75% ~ 80%. For the transient response, no overshoot or undershoot is observed during power on and power off processes. The rise time is about 20 s for the output voltage increases from 0 to 1.6 V, and the fall time is about 65 s when it drops from 1.6 V to 0. Besides, the life of this system is extended by using two DC/DC modules working alternately. This introduced proposal can be served as a solution for the multiple DC/DC modules power supply system to get high efficiency, stable output voltage and sharing current.