Integrated Bridgeless-Boost Nonresonant Half-Bridge Converter Employing Hybrid Modulation Strategy for LED Driver Applications

A single-stage high-power-factor LED driver based on the integration of the bridgeless boost rectifier with the nonresonant half-bridge converter (BLB-HB-NR) employing a hybrid modulation strategy is introduced in this article. A key feature of the proposal is that the system can operate with universal input voltage range and dimming from 100% to 10% of rated output power while keeping the dc-link voltage limited to a safe level. In the proposed hybrid scheme, the LEDs current is regulated by pulse-frequency-modulation (PFM) while the dc-link is controlled using an asymmetrical-pulsewidth-modulation strategy. The system owns important operational and constitutive features, such as reduced component count, high-power factor and soft switching on the main switches, thus a high-efficiency operation is achieved. Steady-state and dynamic analyses are discussed in the article and a complete control strategy is also elaborated. Finally, experimental results for a universal input voltage, 42 W output power prototype demonstrates the feasibility of the proposed lighting system.