斜坡补偿电路在峰值电流控制模式中的应用

介绍了电源驱动电路在峰值电流控制模式下的工作原理,分析了占空比D>50%时驱动电路产生振荡和不稳定的原因,从理论上论述了电感电流的斜率,占空比与系统稳定性之间的关系,运用斜坡补偿的方法实现电源驱动电路在峰值电流控制模式下的稳定,给出了斜坡补偿的基本原理,设计步骤以及补偿电路,最后给出以UC3842为控制芯片的反激式变化器斜坡补偿电路设计实例。仿真与实验结果表明,斜坡补偿电路能够实现峰值电流控制开关电源在占空比D>50%时稳定工作,保证了系统的稳定性和抗干扰能力。

Application of Slope Compensation Circuit in Peak Current Control

The paper introduces the principle of driving circuit of switching power in peak current control mode.When duty-cycle is D>50%,the reasons for instability and oscillation in the system are analyzed,the relationship of the inductor current slope,duty-cycle and system stability is discussed.The way of slope compensation is applied to realizing stability of driving circuit in peak current control mode and the principle of slope compensation and design step and compensation circuit is given.Finally,the paper gives a practical slope compensation circuit of fly-back converter controlled by UC3842.The result of simulation and expe-riment shows that slope compensation circuit can realize switch power stability in peak current control mode when duty-cycle is D>50%,and can ensure stability of system and ability of anti-interference.