Research And Design Of LED Constant Current Driving Switch Power Supply

LED as a new generation of light source, with the advantages of high efficiency and low energy consumption, safety, energy saving and environmental protection, long service life,widely used in display, backlight, indoor decorative lights, vehicle lighting etc.. With the further development of semiconductor lighting technology, LED lighting will be widely used in the field of general lighting. The influence of the power supply on the life of LED is very high, and the selection and design of the drive power supply scheme are reasonable and directly affect the performance of LED lighting products. Therefore, this thesis has carried on the thorough research to the LED driving power supply plan.On the basis of studying the basic principle of switching power supply and the electrical characteristics of LED, two kinds of LED constant current drive switching power supply are designed respectively. Among them, the power supply design scheme of single stage PFC converter is the key point. The principle and design of EMI filter, filter circuit, clamp protection circuit, PFC circuit and output feedback circuit are studied. In the design, the PFC level and the DC/DC level share a set of control circuit, and the output voltage and current can be adjusted and controlled. This optimized the circuit structure, effectively reducing the number of components,reduce the cost, and can achieve higher power factor and conversion efficiency. In addition,through the optimization of the circuit, the constant current of the current is improved. In this paper, the Saber simulation model is built by LED, and the whole circuit system model is built.By analyzing and calculating the simulation waveforms, the design objective is realized, and the rationality of the whole design is verified.In addition, in order to adapt to the development trend of switching power supply, this paper designs a high precision LED constant current driving power supply with high integration degree of non isolated buck control chip. In this paper, the experimental test platform is set up, and a more comprehensive test of the driving power supply is developed. Test results show that the proposed scheme achieves a wide range of voltage output, constant current outpu; The constant current accuracy is higher than the industry average level, reaching ±3%; The power efficiency ishigher than 88%, the power factor is higher than 0.88 and the current does not overshoot; EMI test is in accordance with international standards. The scheme reached the design requirements.Finally, combining design and application, this paper compares the security, performance,cost volume and the use of the occasion and other aspects of the isolation and non isolation LED driver power supply scheme. This provides help to the choice of the engineer’s design scheme.