An Efficient Soft-Switched LED Driver for Street Lighting Applications With Input Regulation

In this article, an efficient soft-switched light emitting diode (LED) driver with input regulation is proposed. The converter drives multiple lamps, and it is divided into two sections. Lamp-2 and lamp-3 are driven by a full bridge converter (FBC), while lamp-1 is placed in series with the input dc voltage source. Power is delivered to lamp-1 without passing through the FBC, which results in improved efficiency. The main benefits of the presented LED driver are: 1) lower current ratings of the FBC switches; 2) ripple-free lamp currents; 3) zero voltage switching (ZVS); 4) high power efficiency; 5) drives multiple lamps; 6) input regulation for source variation; and 7) lower components per lamp. To reduce the current rating of FBC switches, two identical lamps are powered using interleaved inductors. Owing to this, the lamps experience ripple-free currents. Further, due to this, the ZVS is achieved which results in high efficiency. A closed-loop buck-boost converter will compensate for the variations in input by adjusting the duty cycle. The converter operating modes, steady state, and efficiency analysis are discussed in detail. Moreover, to indicate the performance of the converter, a 130 W prototype is built, and experimental results are presented.