| With the rapid development of electronic information industry, power electronics equipments such as switching power supply have been widely applied. At the same time, such conventional switching power supply contaminated electrical network, consequently a novel power supply with power factor correction (PFC) and high efficiency emerges as the times require. With people's more demand for quality of power, the power supply with high efficiency, little bulk and low contamination have became mainstream of research and development. So using advanced chip and designing appropriate external circuit, in order to increase the transforming efficiency of AC/DC and DC/DC Converter. This paper attempts to design a novel switching power supply with high power factor, high efficiency and low cost performance, to providing the power supply to LCD TV of 32 inch. This switching power supply not only can achieved high power factor, improved effecting on electrical network and ensured high efficiency, but also can be easily controlled and had steady performance. Therefore it has great value of application.Firstly, future development of switching power supply, power factor of switching power supply and power factor correcting is described. Next the design project of whole system is set down, which including every technique stander and protect function. Then several common topology of PFC are contrasted with their performance, and Boost circuit elected is analyzed with operating in continuous mode. It use advanced control chip of ML4800, so not only the bulk of inductance was reduced, but also the voltage stress of switching tubes were decreased, and reaches power factor correcting easily and effectively. In the second DC/DC converter system, the system of 12V output and 24V output choose different topology. The system of 12V output takes the Flyback converter with advanced control chip of FSCM0565, which reduce the external elements and simplify the circuit. At the same time, the system of 24V output uses two-switch Forward Converter, in order to decrease the voltage stress of switching tube, and the drive of switching tubes is provided by the chip of ML4800.This paper constructs small-signal models according to each subsystem circuit and analyzes systemic stabilization, which proves stability of them. And using the software of MATLAB forecast the efficiency curve of each subsystem. This paper uses experiment instrument to observe the waves of key parts. The waves from experiment are analyzed and compared with design project, experimental result is satisfying. The switching power supply of high power factor and high output efficiency is realized. The aim and direction of next task has been put forward at the end of this paper.With the development and demand of society, it is undoubted that next generation of power converter will be developing in the direction of high-power, high power factor, high efficiency, low power loss, low contamination and little bulk as well as advanced performance. By theoretic analyzing, designing and simulating of circuit together with experimental researching, the result testified that it is good to meet above performance by adopting of advanced control chips and appropriate external circuit. Therefore, this study has certain significance of academic guidance, besides has been worth spreading application. |
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