A Passive PFC Converter with ZCS

• Main Authors: Chien-Li Tsai, 蔡建利
• Other Authors: 胡國英
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/229sfd

碩士 === 國立臺北科技大學 === 電機工程系研究所 === 96 === The PFC (Power Factor Correction) circuit is widely used in various power supplies so as to reduce the corresponding harmonic distortion and to increase power factor. Up to now, the environment protection and the energy saving are getting more and more attractive in the world. Consequently, improvement in the overall efficiency of the power supply is indispensable, and hence enhancement of the efficiency of the PFC circuit is an important research topic. Consequently, a passive ZCS (Zero Current Switching) PFC circuit topology is presented herein, which is used on the characteristics of the saturable coupling inductor. As the PFC circuit works in the steady state, such an inductor is short-circuited, so as to make the loss in this inductor as minimum as possible. On the other hand, as the power switch of the PFC circuit is switched on, the saturable coupling inductor gets far away from the saturated condition and is represented as an inductor, so as to reduce the reverse recovery current of the boost diode and to absorb the portion of the energy created from this current. By doing so, the boost diode can be switched off under ZCS, and at the same time the switching loss of the main power switch can be reduced. Besides, before the main power switch is turned off and the boost diode is turned on, the ZCS circuit releases this stored energy to the output, so as to further upgrade the efficiency of the PFC circuit.