一种改进的平均电流控制方法的研究

摘要

Buck circuit is analyzed in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) under different duty ratio-output voltage characteristic.Because it is difficult to apply the average current control method to the wide load, a control method of improved current loop's given signal is proposed, which is based on the average value equivalent principle on a switching cycle.It can be obtained by multiplying a pulse signal which is produced by comparing the inductance current with the threshold value (a near zero signal) and the output signal of the voltage loop.Though voltage and current loop of the method are built under CCM, it has higher average inductor current tracking accuracy on steady-state than without correction in DCM, meanwhile it slows circuit's inductive current changes from CCM to DCM, and reduces the system's effect of the output voltage overshoot and improves the dynamic response speed with load or input voltage changed.The proposed method is proved the feasibility and effectiveness by simulation study.%文章主要分析Buck电路在连续导电模式(CCM)和断续导电模式(DCM)下不同的占空比-输出电压特性.针对平均电流控制方法难以适用宽负载的问题,依据在开关周期内平均值等效原则,提出了一种改进电流环给定信号的控制方法.该给定信号由电感电流与接近0的阈值相比较输出脉冲信号,再与电压环的输出相乘得到.所提方法的控制环路尽管是依据CCM而建立,但是较修正前在DCM稳态下具有更高的电感电流平均值跟踪精度;同时减缓了电路从CCM到DCM切换时的电感电流变化,减小输出电压超调和提高投切载的动态响应速度.最后通过仿真研究证明了该方法的有效性和可行性.