Single-Stage LED Driver Based on Coupled Inductor Power Factor Correction and LLC Converter

Abstract:
In this paper, a single-stage LED driver using coupled inductors for power factor correction (PFC) is presented. The coupled inductors are utilized to charge and discharge the input inductor in each switching cycle, aiming to achieve an ohmic mains behavior result in a high power factor. The conditions of the ohmic mains behavior are analyzed. The coupled inductors are integrated into a halfbridge resonant LLC converter. The driver is designed so that the bus voltage is limited to the reflected secondary voltage, achieving a high power factor while keeping the bus voltage at an applicable level. Additionally, soft switching is achieved during PFC operation. The accuracy of the analytically determined PFC operation is investigated and approved by the experimental results.