A high performance primary-side-regulated LED driver based on single-stage SEPIC-flyback converter

Traditional flyback LED driver is limited by its low performance which usually dissatisfy the power factor (PF) and Total Harmonic Distortion (THD) according to Energy Star or IEC61000-3-2. The control loop from secondary-side to the primary-side has low reliability to reduce the working lifetime and employs more components, which reduces the power density of system. In this paper, based on single-stage SEPIC and flyback, a primary-side regulated LED driver is proposed to improve the performance of the system. For the SEPIC circuit, working in DCM, it realizes the PFC naturally. For the flyback converter, the proposed primary-side regulated method improves the power density and assures the accuracy of the output current. Laboratory experiments demonstrate that a high performance LED driver can be achieved. The primary-side regulated validity of a 100W prototype based on SEPIC-flyback is verified by the experimental results.