A non-isolated single-stage electronic lighting system with high power factor for driving power LEDs is proposed in this paper. The presented topology is based on the integration of a bridgeless boost rectifier with a non-resonant half-bridge converter. Accurate steady-state analyses of the non-resonant 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 non-resonant 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 VRMS, 50 kHz, 94.2% peak efficiency prototype are presented.

This paper introduces a high-step-up dc-dc converter to provide voltage boosting in low-voltage applications. The circuit contains only a single active switch and is based on the boost-type converter using coupled inductor and voltage multiplier cell. The proposed topology exhibits high efficiency, reduced voltage stress on the semiconductors and requires a low component count. The circuit is intended for applications with rated power in the order of a few hundreds of Watts, which corresponds to the typical level of a single photovoltaic (PV) module. A detailed mathematical description of the circuit operation is carried out, providing the means for the adequate design of the converter. The dynamic analysis is also addressed in the paper, and proper closed-loop operation is demonstrated. A 400 W prototype operating at 90 kHz, with an input voltage range of 24-48 V and output voltage of 400 V was built and tested in laboratory. Experimental results validate the analyses carried out and measurements indicate efficiency levels up to 97.5%, which ratifies the proposed converter as a good solution for typical PV 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.

This paper presents a single-stage converter based on the boost-PFC and charge-pump circuits configured as a current source. The integration between the input and the dc-link stages is performed by an output stage consisting of a full wave rectifier associated to a capacitive filter, an LED array and a resonant series inductor. The charge-pump capacitors operate in order to limit the dc-link voltage and to reduce the crest factor of the current on the output inductor, thus contributing to flicker reduction. The proposed converter exhibits high efficiency and power factor (PF), and total harmonic distortion of the input current (THDi) and flicker satisfying the IEC 61000-3-2 Class C and IEEE Std 1789-2015, respectively. The operation stages and a complete mathematical model in steady state are presented in detail, allowing the converter design and implementation. In this work, a prototype operating with universal input voltage range (90270 V), dimming at 127 V and 220 V, switching frequency in the range of 40200 kHz and a nominal output power of 43 W is built to demonstrate the feasibility of the proposed lighting system.

This article presents the analysis and design of a single-stage charge-pump (CP) bridgeless converter for light-emitting diode (LED) applications. The proposed topology is based on a boost bridgeless converter operating in a discontinuous conduction mode, which is associated with the CP concept. The proposed electronic lighting system employs a reduced component count, and the CP concept is used to reduce the LED current ripple. A high power factor is demonstrated to be an inherent property of the proposed topology, and no input current control is necessary. The operating principle of the proposed converter, which includes two operating modes in a steady state, is presented and analyzed. We also present a prototype operating with a switching frequency of 75 kHz, an input voltage range of 90–160 V _RMS , and an output power of 60 W with a power factor of 0.989, the total harmonic distortion of 14.15%, and the efficiency of up to 95.4%. Additionally, all individual harmonic magnitudes of the input current meet the IEC 61000-3-2 class-C standard limits.

This paper proposes a nonisolated single-stage electronic system for driving power LEDs using the charge-pump and valley-fill concepts. Both concepts are related to the topological configuration based on the integration of a full-wave rectifier at the input stage with a half-bridge inverter at the output, characterizing a single-stage system. The charge-pump configuration is used to reduce the LEDs' current ripple. The valley fill is employed to limit the dc bus voltage at levels below the peak value of the input voltage but maintaining a high-power factor operation. Therefore, it is possible to use bus capacitors with reduced voltage ratings. The operating principle of the proposed converter, which includes three operating modes in steady state, is presented and analyzed. The design methodology and the experimental results are also presented so that the operational characteristics of the proposed system can be verified. A 47-W, 220-Vac input, 67 kHz, 93.5% peak-efficiency prototype is built and tested to validate the carried out analyses.