PFC/PWM复合控制芯片ML4824及其应用

PFC and PWM Controller Combo Chip ML4824 and its Application

由于传统两级有源功率因数校正(PFC)有两套控制电路和至少两个开关管,增加了电路的复杂度和成本。采用PFC/PWM复合控制芯片,可改善两级电路的缺陷。在研究复合控制芯片ML4824的基础上,设计完成了一个带PFC的开关电源,其前级采用平均电流控制的Boost型PFC电路,以提高电源的功率因数;后级采用新型不对称半桥(Asymmetrical Half Bridge,简称AHB)拓扑的PWM电路,以提高电源效率。证实了该方法的可行性和实用性。

In the conventional active two-stage power factor correction （PFC） approach, two sets of control circuits and at least two power transistors have greatly influence on its complexity and cost.With the PFC and pulse width modulation （PWM） controller combo chip, the performance of active tow-stage PFC circuit can be improved.Through the analysis based on ML4824,a switching power supply with PFC is developed.The Boost PFC circuit controlled by average current control mode is adopted in AC/DC converter,which is able to improve the power factor.And the converter＇s efficiency can be improved by adopting asymmetrical half bridge（AHB） topology in the DC/DC converter.The experimental results reveal that the technique is feasible.