单级桥式PFC电路功率变压器偏磁的产生机理分析

The mechanism of magnetic bias exists in power transformerof the single-stage full bridge PFC converter

提出一种单级全桥软开关功率因数校正电路,它采用移相控制方式,能同时实现功率因数校正、软开关、输出电压调节和电气隔离.但由于电路特殊的控制方式和所要实现的功率因数校正功能,该校正电路中的功率变压器除存在普通全桥变换器产生偏磁的原因外,还存在产生偏磁的特殊因素.本文在分析变换器的电路结构和工作原理之后,对偏磁的产生机理进行了分析,指出了该变换器影响偏磁大小的各种因素,并给出一种解决措施,可有效抑制偏磁的产生,最后的仿真和实验证明了理论分析的正确性.

A single-stage full bridge soft-switching power factor correction circuit that adopts phase-shifted control mode is designed, which can realize functions such as power factor correction, soft-switching, output voltage regulation and electrical isolation. However, besides those existing in common full bridge converters, there are new factgors because of the special control model and the required power factor correction functioned. Which lead to magnetic bias occur in the main circuit. Through analysis of the topology of the converter and the mechanism of the magnetic bias, various factors that affect the magnitude of the magnetic bias are pointed out. A solution is then given to restrain the bias effectively and the computer simulation and experimental results prove the validity of the theoretical analysis.