基于箝位电路的新型单级PFC技术

单级桥式功率因数校正变换器由于变压器存在漏感,在电路换流过程中产生较大尖峰电压,增加了开关管的电压应力,降低了系统可靠性.提出一种基于箝位技术的新型单级桥式功率因数校正变换器,利用一级电路同时实现功率因数校正与DC/DC变换;通过在所提出变换器中设置箝位电路,吸收了尖峰电压,解决了开关管电压应力过高的问题,并分析了实现功率因数校正、抑制电压尖峰的原理;针对电路结构以及功率因数校正电路的特点,分析了所提出变换器中高频变压器的偏磁产生机理,并给出了相应的抑制措施.通过对实验系统的测试与分析,表明所提出的变换器具有较高的功率因数和转换效率,并验证了理论分析的正确性.

Single-stage full-bridge PFC technique based on clamp circuit

Because of the leak inductance of transformer,the power switch on-off operation of single-stage full-bridge PFC (Power Factor Corrector) generates high over-voltage, which increases the voltage stress of power switch and lowers the stability of corrector. The PFC based on clamp technique is presented,which realizes the power factor correction and DC /DC conversion with single stage structure. The over-voltage is absorbed by the clamp circuit and the voltage stress is lowered. Its working principle is explained. Based on the structure of PFC,the mechanism of magnetic bias generation in the high frequency transformer is analyzed and the eountermeasures are presented. Experimental results show that,the proposed PFC achieves higher power factor and DC/DC conversion efficiency, which verifies the validity of the theoretical analysis.