标题: 具快速暂态反应及适应性相位控制技术的电流模式直流/直流降压电源转换器
Fast Transient Technique and Adaptive Phase Margin Control for Current Mode DC-DC Buck Converters
作者: 李昱辉
Lee, Yu-Huei
陈科宏
Chen, Ke-Horng
电控工程研究所
关键字: 直流/直流转换器;快速暂态反应控制;适应性相位;极零点补偿相销;稳定度;内嵌式补偿;DC-DC converter;fast transient control;adaptive phase margin;pole-zero cancellation;stability;on-chip compensation
公开日期: 2008
摘要: 在消费性电子产品中,尤以手持式产品的应用上,需求越来越广泛。拥有高效能与小型化的电源转换器日趋重要。为了有效使用有限的电池能量,电源管理系统为晶片系统中非常重要的一环。故本文提出一个运用于切换式电源转换器的技术,以期在此切换式电源转换器的暂态响应和稳态响应,都能够有最好的效能表现。
本论文所提出的内容,则是运用密勒等效电流来充放此误差放大器的输出电容,来达到电容放大的功用,使整合进IC内部的小电容相当于大的系统补偿电容,让整体电路减少一样外部原件进而降低成本和得到较佳的表现水准。因为此电容放大的技术,以致于在稳定系统反应时,可以让系统保持在一个稳定的操作状态。而当系统在负载瞬间改变的暂态阶段,一旦稳压器瞬间遭受到大负载电流的改变而需要快速稳压时,即可将一部分的密勒等效电流用来快速充放误差放大器输出电容上的电荷,等同于是将原本的稳定的密勒补偿大电容还原成本来的小电容,以达到电压快速反应回稳之效果,亦可以避免震荡的发生。而且此额外的密勒等效电流原本即为误差放大器输出电流的一部分,完全没有增加额外的功率消耗。
另外提出动态零点的补偿。当负载瞬间变动进入暂态响应阶段时,用频率的角度来解释,等于是把系统的频宽瞬间拉大,让整个系统的反应快速,以达到电压快速回稳的功效。因此我们用上了负载相关的动态零点补偿,使系统在暂态时零点能够依据当时的负载状况,移到不同的最佳化位置,以确保在加大系统频宽反应速度时,依然保持应有的系统稳定度,来达到整个系统最佳化的情形。另外,在稳态系统响应时,动态负载相关零点补偿也可以确实抵销掉系统的极点,使整个系统近似一单极点系统确实达到大频宽和最佳稳定度的功效。
本论文所提出的方法运用于电流模式直流/直流降压转换器上,并用台湾积体电路公司三五微米制程来实现。实验结果显示本论文的方法在不增加太多额外的功率消耗的前提下,显着的加强了系统的暂态响应和稳定度。
This paper proposes a fast transient (FT) control with adaptive phase margin (APM) to achieve good transient response of current-mode DC-DC buck converters at any load condition. Thus, the overshoot/undershoot voltage and the transient recovery time are effectively reduced. Owing to the load-dependent output pole of the current-mode buck converters, the operation of a load-dependent compensation pole-zero pair is designed to be moved to a higher frequency at transient period and back to an optimum position for pole-zero cancellation in steady state. Therefore, an adaptive phase margin is always maintained at a suitable value in all load conditions for achieving good transient responses. In other words, the compensation pole-zero pair is adapted to the load current to extend the system bandwidth and get the optimum phase margin. Experimental results demonstrate the improved transient performance at transient period and good phase margin in steady state. The overshoot/undershoot voltage is smaller than 60mV and the transient period is shorter than 12μs as the load current suddenly changes from 100mA to 500mA, or vice versa. Compared with the conventional design without any fast transient technique, the performances of undershoot voltage and recovery time are enhanced 45 % and 85 %. With the proposed technique, the performance of the current-mode buck DC-DC converter is improved significantly.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT079612522
http://hdl.handle.net/11536/41839
显示于类别:Thesis