Implementation of a Single-Stage Forward-Flyback Driver with High Efficiency and High Power Factor for LED Streetlight

Energy conservation is a big concern issue. Especially, various traditional lighting devices are being replaced by LED lights that offer advantages including low pollution, low energy consumption, and long life. This paper presents a design for street lighting that includes a high-power LED series as a light source. An LED driver was built up by combining a buck-boost converter and a forward-flyback converter. An energy-regenerative snubber was integrated into the driver circuit, which improved the efficiency. A primary-side sensing technique and a quasi-resonance technique were employed to minimize circuit size and switching losses. A Digital Signal Processor (DSP) was used to integrate all related controls for the driver and the dimming circuit with a phase-shifted pulse-width modulation method. Finally, the magnetic parameters of the driver were determined by using Taguchi method to optimize the system efficiency. A prototype was produced and tested in laboratory. The test results are presented, which also verify the feasibility of the system.