Study And Realization On The High Power Factor Switching Power Supply

Switching Power Supply is an important equipment to achieve power conversion and power delivery. In recent years, Switching Power Supply is widely used in various fields of national economy with the development of power electronics technology, and achieveing remarkable results, because of its high efficiency, good performance and low cost. So designing a kind of Switching Power Supply with steady performance and high reliability has high scientific and commercial values. Therefore an adjustable Switching Power Supply with high power factor is studied and designed, whose output voltage of 4～20V and output current up to 25A. Meanwhile, it also can be designed as a fixed output voltage.To maintain a high power factor, high frequency active power factor correction circuit is used, and active power factor correction topology and control methods are analyzed and studied by MATLAB simulation software. UC3854 chip control boost active power factor correction circuit is used in the specific circuit, in which a Boost circuit and UC3854 control circuit is included, making regulator functions have rectification and correction system. It has been verified by simulation circuit, whose input power factor is 1 and having a stable output voltage.In order to eliminate and restrain the high-speed du/dt and di/dt interferences from power semiconductor switching devices, EMI filter and soft-switching half-bridge DC/DC Converter are designed. At the same time TL494 chip is chosen by DC/DC converter as the output pulse width modulation control module. Negative feedback regulator circuit composed by the error amplifier and TL494 peripheral circuit is used to regulate and stabilize the DC output voltage. Another TL494 error amplifier integrator is used by over-current protection circuit for the over-current protection of system circuit.Finally the feasibility of switching power supply system is verified by MATLAB simulation.