Design Of DC24V/50W LED Driver

Along with carrying out the Green Lights Program, Light Emitting Diode(LED) as the representation of the fourth generation light sources, becomes more and more popular in factory , infrastructure and homes. LED has its characters that the longevity, the high reliability, he rich color, the regulation is conventient, the security. So it can satisfy the demands for the lighting installation that it must be green, energy-efficient and environmental. LED will perform better with proper driver, and based-DC LED driver can save energy by combining with solar photovitaic system ane wind power generation system, and decrease the network load. As a result, the research of LED driver base on DC has become a hot spot.In the paper we firstly introduce the"Green Lightings"and the disadvantages of the previous three generation light sources, then illuminate the advantages of LED lighting and develop status. Secondly, we explain the basic principles of LED's light-emitting, analysis the relations during voltage, current, and LED light-emitting efficient. By analyzing several styles of LED driver, propose flyback converter circuit structure. Then after analyzing the work modes, we determine that circuit should work on critical conduction mode, and combin technology of the quasi-resonant(QR) zero-voltage-switching(ZVS), thus reducing the loss. After expounding the principle, merits and drawbacks of the three aiming modes, the paper use the digit dimming mode. We carry out a detailed calculation for the key parameters in the main circuit. A specific design is completed for the transformer.Control circuit is composed by microcontronller and quasi-resonant(QR) switch mode power supply(SMPS) controller which achieve the invariable control of the current. The microcontroller output a signal which can adjust the brightness for the ratio of 1:1024. The microcontroller is also used to realize the self-protection when the drver is short, open, overvoltage, low-voltage, thus improve the stability of the drver. The factors are analyzed which may impact the reliability and generate electronmagenetic disturbance, the paper gives the reliably design to the key component.. The hardware and software is designed to restrain the electromagnetic disturbance.Finally the paper achieves an sample of 50W LED driver based on 24V DC, and the waveforms of key points are collected and analysised. The test result indicate that the LED driver works stably, and reach the designed demand. Sum up the shorts, and made give the direction of improve and study further.