一种单级无桥式高功率因数无电解电容AC-DC LED驱动器

A Single-Stage Bridgeless,Electrolytic Capacitor-Free AC-DC LED Driver with High Power Factor

电解电容用于处理脉动功率差势必限制LED驱动器使用寿命,采用全桥整流结构造成导通损耗加大,引用变频控制产生较高的电磁干扰(EMI)。为此,提出一种基于串联谐振变换器(SRC)的LED驱动电路,用于衰减功率因数校正(PFC)单元传递到LED负载的低频纹波,从而减少储能电容值。采用可控开关电容(SCC)替代固定电容,通过改变等效电容值实现驱动器恒频运行。此外,SCC结构和半桥开关管单元的共享不仅提高了电路功率密度,而且消除了全桥整流二极管。最后,所提LED驱动器的优越性能通过PSIM仿真和搭建的输出功率80W的两路LED样机进行了实验验证。

The bulky electrolytic capacitor used to compensate the difference of pulsating power needs to restrict the driver lifetime.The full bridge rectification structure causes the conduction loss to increase,and the existing drivers adopting Pulse Frequency Modulation(PFM)is bound to arouse heavy electromagnetic interference(EMI).Therefore,the Series Resonant Converter(SRC)based LED driver is proposed for attenuating the low frequency ripple delivered from the Power Factor Correction(PFC)to LEDs,thereby reducing the capacitance for energy storage of off-line LED drivers.The Switching Controlled Capacitor(SCC)is used to replace the fixed capacitor,and the constant frequency operation(CFO)is realized by changing the equivalent capacitance.In addition,the sharing of SCC and half-bridge switching unit not only increases the circuit power density,but also eliminates the full-bridge rectifier diode.Finally,the superior performance of the proposed LED driver is verified by PSIM simulation and a 2-channel LED prototype with an output power of 80W.