Led Drive Power Research And Design

LED(light-emitting diode),due to its adavangtages such as green,long lifetime,high efficiency, has become more and more popular on indoor lighting.the incandescent lamp has commonly used for conventional lighting,in orde to saving power,often can be dimmed by dimmer.With the incandescent lamp is forbidding,the LED driver with the function of dimming is developing as a result.Finally the LED driver compatability with dimmer is presented in this paper,can achive high PF and dimming function.Based on the working principle of DC/DC converter and power factor correction(PFC),the PFC function is implemented by single stage Quasi-Resonate (QR) Flyback converter based on its isolated,small size,high efficieccy and simple controlled strategy. After the characteristic and high PF achievement of Flyback converter, working in QR mode,is analyzed, a transformer design method,that is suitable for single-stage PFC flyback,is choosed,meanwhile the transformer making skills are also researched.According to the design requirements,one single-stage high PF dimmable LEDs driver is designed and implemented with output power of 50W based on SSL2103.The main circuit of converter,clamp circuit,EMI filter and feedback circuit have been analysed and designed.At dimming part,both conventional dimmer and the failtures of conventional dimmer applied to LED driver are explained,moreover,the solutions are also discussed.By experiment,the circuit work properly, good dimming performance and power factor is over 0.98.The circuit basically eliminates the harmonic and EMI pollution of the grid,the harmonic performance meets the IEC61000-3-2Class C harmonic standard,EMI meets the EN55015 Standard. The prototype has been implemented to verify the experimental measurements with the theoretical predictions,can provide a guideline to design the dimmable LEDs driver.