Design Of 90W LED Driver

As the latest lighting product, LED will have a great development.Its lighting performance andusage life is influenced by drive quality and operating environment. Therefore, it is necessary todevelop LED specific driver of high efficiency and reliability to work with it. The current LEDdriver is characterized by low efficiency, low power factor, low liability and substandardelectromagnetic compatibility, so, carrying out the research of high efficiency and high-performanceLED driver has a high practical value.Based on briefly introducing the working principle, the electric characteristic and the drivesystem of LED, this thesis studies power factor correction circuit, the quasi-resonant flyback circuit,the constant current circuit and the electromagnetic interference of circuit. Besides, this thesisdesigns a 90W LED driver based on the theory analysis. The design of the driver choosesthree-level model circuit. The front-end adopts boost topology power factor correction circuit underthe critical mode, the mid-end is the quasi-resonant flyback circuit topology and the back-endadopts constant current control of dual operational amplifier. The driver would take TEA1751 ofNXP as its control chip, and TEA1751 would combine power factor correction controller andflyback type switching power supply controller together. Its advantage is high integration density,less external components, thus making power supply design low cost and high efficiency. Specificworks completed are summarized as follows: The first section introduces the electric characteristicand the topology of several LED drive circuits. The second section introduces the principle ofpower factor correction circuit under the critical mode and designs the circuit parameter of powerfactor correction circuit. The third section analyzes the working principles of quasi-resonantflyback circuit, introduces several forms of clamping snubber circuit and designs the circuitparameter of quasi-resonant flyback circuit. The fourth section analyzes the principle of dualoperational amplifier feedback circuit and provides the design process of parameters, in which thechip AP4310 is used to make constant current feedback. The fifth section analyzes theelectromagnetic interference of circuit.Based on the said design proposals, this thesis designs a 90W LED driver with wide inputvoltage and the output 36V/2.5A. The output characteristic is stable, the power factor is above 0.9,the overall efficiency could reach 87%, and EMC test completely meets the National CompatibilityStandard by testing the developed driver proto.