一种无电解电容的单级复合LED驱动电路

近年来为了提高LED驱动电路转换效率和减小输出纹波,单级复合型电路得到深入研究与应用。针对辅助绕组支路上串联Buck电路的单级反激LED驱动电路,研究了一种输出电流谐波注入方案,以减小输出电容,使得输出电解为高频容所代。首先,介绍单级复合电路的工作原理,推导输出电压纹波与负载电流的关系,分析脉动电流的相位对电容电压纹波的影响,给出负载电流谐波注入方案的设计依据;其次,给出所述方案的实现方式与电路;最后,研制了一台150 W实验样机,验证方案的可行性与有效性。

A Composite Single-stage LED Driver Without Electrolytic Capacitor

In order to improve efficiency of LED driver and reduce output ripple, composite single-stage circuit has been well studied in recent years. In this paper a scheme of output current harmonic injection applied to Flyback converter is studied which the auxiliary winding branch is in series with Buck converter, forthat high frequency capacitors can be adopted instead of electrolytic capacitors. First the function equation between output voltage ripple and load current is deduced , the effect of pulse current's phase to capacitor voltage ripple is analyzed in details,and the design basis of the scheme of output current harmonic injection is given; Then the implementation of the scheme is given; Finally, a 150 W experimental prototype is developed. The experimental results prove the feasibility and the effectiveness of the scheme.