Analysis and design methodology of a self-oscillating system based on integrated sepic half-bridge for LED lightning applications

This paper presents an analysis and design of an integrated self-oscillating power factor correction (PFC) light emitting diode (LED) driver. The PFC is based on a Single Ended Primary Inductance Converter (SEPIC) operating under Discontinuous Conduction Mode (DCM). This converter was chosen because of its low input current distortion characteristic making possible reducing, or eliminating, the electromagnetic interference (EMI) filter. The LED is supplied by asymmetrical Half-Bridge resonant converter (HB) with isolated LLC filter. It is used the leakage inductance of the transformer and the magnetizing inductance in the LLC filter voltage gain, so as to reduce the volume. The integration of these converters is performed in order to reduce the number of components, drivers and consequently the volume and cost of the circuit. A self-oscillating driver circuit is used avoiding the use of integrated circuits. Design and experimental results are presented to demonstrate the feasibility of the proposed LED driver.