Nonisolated Quadratic SEPIC Converter Without Electrolytic Capacitors for LED Driver Applications

This work presents an ac-dc quadratic Single- Ended Primary Inductance Converter (SEPIC) to provide input power factor correction (PFC) for light-emitting diode (LED) driver applications. This structure allows obtaining wide conversion range and operation in either step-up or step- down. Considering that the lifetime of LEDs is much longer than that of electrolytic capacitors, a prominent advantage on the proposed converter lies in the use of only film counterparts. The integration of two SEPIC stages using the graft technique allows independent PFC and power control (PC) while using a single active switch. A detailed mathematical study is presented in terms of a consistent qualitative and quantitative analysis. Experimental results are also discussed to demonstrate the claimed advantages and validate the theoretical assumptions.