Single-Stage LED Driver with Dimming and Universal Input Voltage Capability

Abstract

This paper presents a boost bridgeless totem-pole converter operating as power factor correction (PFC) stage integrated with a half-bridge LLC resonant converter as power control (PC) stage. The resultant single-stage converter yields in an effective integration, reducing the number of switches from 4 to 2 (50% reduction). This integrated topology aims decreasing conduction and commutation power losses and, moreover, achieving high power factor (PF), low total harmonic distortion (THD) and good efficiency. The converter is designed to have a fixed bus voltage, which is controlled by changing the half-bridge duty cycle under universal input voltage (UIV). However, since the HB duty cycle also affects the LLC converter due to their integration, a variable inductor is employed to control the LLC impedance and achieve a controlled output current and dimming capability, consequently a constant frequency operation is achieved. Simulation results are presented to verify the theorical analysis, through a 100 W LED luminaire. The results show voltage and current levels in the topology, as well as PF and THD levels in compliance with IEC 61000-3-2. Moreover, it is shown the feasibility of output current control capability through variable inductor even with HB duty cycle variation.