Analyse And Application Of LED Driver With Power Factor Control

The LED is a kind of new SSL (Solid-State Lighting) method for the illumination market. And the LED driving technique is the most important part for the LED illumination technique. Based on the researching of LED characteristics and the different LED drive methodes existing, this thesis has designed a new topologie for the dimmable LED drive with power factor control.This thesis first introduced the achievement of LED driver design obtained during the internship in NXP Semiconductors. This early design of the LED driver was based on the BUCK topologie and the circuit is compatible with the phase-cut dimmer. It can also change the intensity and the color of the LEDs at the same time. But the disadvantage is that it hasn't considered the influence of the power factor to the power grid.For the present research finished in NUAA, it studied the different operating principles of the power factor control in the different converters (BOOST and FLYBACK) and under the different conducting modes (CCM, DCM and CRM). The new circuit is based on the FLYBACK topologie and is working in the CRM mode. This new circuit uses an integrated circuit NCL30000 to realize the power factor control, and finds a new method to control the output of the circuit and established the feedback path to have a contant voltage and current to sustain the LED lighting. The circuit is with a 220V/50Hz input and 24V output. In the thesis it offers the simulation result and the oscillographs of the new circuit.The output current of the LED is from 0 to 500mA. Finally in the thesis it made the conclusion of the research and listed the approvement to be finished for the further study.