Research And Design Of A Novel And High Efficiency LED Driver

LED lighting is a new technology about green lighting industry,widely applied to business,public facilities and family.The development of civil LED lighting industry is rapid and products are divided into two parts including light source and the driver.Some issues are concentrated about the driver,such as low efficiency and ageing topology.It is necessary to develop new and high efficiency driver and make sure that light source works well.Based on the power supply design requirements of medium power civil lighting products and research on the key technology about LED driver,new topology and control technology were chosen in the paper.Researched methods of decreasing capacitance values and raised the energy storage capacitor ripple voltage to reduce capacitance value by the research.In the end,long life thin-film capacitors were used and solved the problem.The Boost-Flyback single-stage PFC correcting circuit was used as main topology.The Boost circuit corrected power factor and flyback circuit adjusted the output voltage,they shared a switch mosfet and reduced the loss and it's easy to control.Zero voltage quasi resonant soft switch circuit was adopted to realize the opening of the switch tube zero voltage and zero voltage turn off,reducing the switching loss.The control circuit was based on the primary side regulation without an auxiliary winding.LED load current was obtained through the secondary side on-time detection circuit and output current estimation circuit.TL494 chip was used and made the current constant based on the technique of PWM control.Designed a 30 watt driver,then calculated parameters indicators and made some model selection according to performance indexes and the circuit design.Made a simulation in Saber and analyzed waveform to prove the feasibility of the system.After analysis and calculation,the design of electrolytic capacitor-less quasi resonant Boost-Flyback single-stage LED driver made a success.The power factor value is greater than 0.9,the efficiency is higher than 90% and the ripple values are less than 2%.