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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. [ABSTRACT FROM AUTHOR]

A nonisolated single-stage electronic lighting system with a high power factor for driving power light-emitting diodes (LEDs) is proposed in this paper. The presented topology is based on the integration of a bridgeless boost rectifier with a nonresonant half-bridge converter. Accurate steady-state analyses of the nonresonant- and resonant-based circuits are reported, serving as the basis for designing the lighting systems. The LEDs current is adjusted by means of frequency modulation, being the converter switches driven by complementary symmetrical signals. A small-signal analysis is detailed for the proposed nonresonant scheme, providing fundamental information regarding its dynamic behavior. Also, a step-by-step design procedure based on the performed mathematical analysis is elaborated, allowing the adequate design of the proposed lighting system. In order to confirm the validity and the feasibility of the proposed converter, experimental results for a 42-W, 127- \rmV{\rm{rms}}, 50-kHz, 94.2% peak efficiency prototype are presented. [ABSTRACT FROM PUBLISHER]