SEPIC PFC converter fed LED driver

Abstract

This paper presents a single ended primary inductance converter (SEPIC) fed power factor correction (PFC) based light emitting diode (LED) driver. The application is needed for high brightness LED control for projection application. A pulse width modulation (PWM) scheme is used for LED brightness control. In order to control LED with better power quality a SEPIC converter is proposed as a power factor corrector which works in discontinuous output inductor current mode (DICM).The SEPIC PFC converter feeds constant dc voltage to bi-flyback DC-DC converter. The bi-flyback DC-DC converter supplies constant low voltage with isolation required to the forced cooling unit and the synchronous buck based constant current multi-string LED driving unit. The forced cooling unit is introduced to control LED temperature near ambient to increase life of LED and matching color. The synchronous buck based LED driver is used to control LED brightness and fulfills the constant current for LED driving. A prototype of the proposed LED driver is developed and experimentally verified. The power quality parameters of the proposed LED driver are evaluated at rated and light load conditions for universal AC mains (90 V-265 V). The PFC and total harmonic distortion (THD) are found within acceptable ranges of international harmonic standard IEC 61000-3-2.