Search

In order to design a high-efficiency, cost-effective, high-power driver for supplying multiple light-emitting diode (LED) strings in parallel, a novel single-stage bridgeless, soft-switched integrated AC–DC converter is proposed. The proposed converter can be derived by integrating the totem-pole bridgeless boost power factor correction (PFC) circuit and half-bridge LLC resonant converter. Therefore, the number of semiconductors in the line-current path can be significantly minimized, and the power losses in the secondary rectifier diodes and the primary switches can be dramatically reduced. Moreover, the twin-bus concept can be adopted to achieve the quasi-single-stage power conversion of the total LED driver with multiple LED strings load. In addition, this circuit allows removing the bulky electrolytic capacitors with short lifetime by increasing the bus voltage ripple, and thus, the long lifetime is another advantage of the proposed LED driver. The detailed operation principles and design considerations for the proposed converter are analyzed and discussed. The feature of the proposed solution was demonstrated using a 100-W hardware prototype with six LED strings. The experimental results showed the converter achieves full-range ZVS for primary switches and the efficiency of 94.5% under the 120 V input voltage. [ABSTRACT FROM AUTHOR]

In this paper, a single-stage integrated bridgeless AC/DC converter is proposed. As compared to its counterpart that is composed of totem-pole boost power factor correction (PFC) cascade fly-back DC/DC converter, the studied circuit has less components number while overcoming the limits of the totem-pole type. Thus, it is suitable to the low-power LED lighting applications. Furthermore, when both PFC inductors Lb and magmatic inductance Lm of the transformer TR1 operate at discontinuous current mode, the bus voltage vCB can be used to decouple the ac input and constant dc output power. Thus, the approach of increasing bus voltage ripple is employed to eliminate electrolytic capacitors and obtain long operation lifetime. Additionally, it is able to be compatible with our studied twin-bus configuration for increasing the overall efficiency. A 50-W hardware prototype has been designed, fabricated, and tested in the laboratory to verify the proposed converter validity. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]