Single-Stage Converter Based on the Charge-Pump and Valley-Fill Concepts to Drive Power LEDs

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.