With Power Factor Correction, High-power Switching Power Supply Design

In recent years, the research in switching power supply has been developing widely not only in theory but also in applications. Switching power supply includes many technology fields such as electronics, electrics and automatic control etc. Power factor correction (PFC), soft-switching conversion and electromagnetic compatibility (EMC) are the important subjects of switching power supply.The traditional DC power supply has big bulk and weight, high ripple coefficient of output voltage, low stability and efficiency. It is hard-switch to transit which makes efficiency falling to about 70%.The major polluting source of electric and electronic system is the harmonic current, so we usually use power factor correction circuit to eliminate the problem at the source. Soft-switching technique is a hotspot of power electric research. It`s the key technique in high frequency converter. The zero-voltage-switching (ZVS) phase-shift full bridge DC/DC converter is an advanced DC/DC converter with soft-switching technology.This paper introduces the circuit principles of linear power supply and switching power supply, analyzes the circuits of power factor correction technology and zero-voltage-switching full-bridge DC/DC converter technology, the frequency selection methods and the EMC design of switching power supply are analyzed. This designed converter is working at the frequency of 100 kHz and its maximum power output is 2.0 kW. So we choose structure of two-stage PFC circuit, the forward stage uses UC3854 as controlling chip while the backward stage uses UC3875 chip. The parameters of key components of the main circuit are designed and calculated, the peripheral circuits of the chips are designed also. Finally, PSpice 9.2 software is applied to simulate the main circuits.