Multiloop Minimum Switching Cycle Control Based on Nonaveraged Current Discrete-Time Model for Buck Converter
Multiloop Minimum Switching Cycle Control Based on Nonaveraged Current Discrete-Time Model for Buck Converter
复制标题
基于非平均电流离散时间模型的Buck变换器多环最小开关周期控制
DOI：
10.1109/tpel.2016.2570304
复制
发表时间：
2017
影响因子：
6.7
通讯作者：
Liu Zhenglin
中科院分区：
文献类型：
--
作者：
Min Run;Zhang Qiao;Tong Qiaoling;Zou Xuecheng;Chen Xiaofei;Liu Zhenglin
buck变换器的高性能控制器很容易受到变换器模型精度的影响，因此具有挑战性。本文提出了一种新颖的非平均电流离散时间（NCD）模型，该模型将导通和关断状态下的电感电流表示为时变方程。在高频范围内，它比传统的平均模型具有更高的精度，因此可以用于优化高速控制器的设计。基于NCD模型，提出了一种由输出反馈（of）、线路前馈（LFF）和参考前馈（RFF）环组成的最小开关周期（MMSC）多环控制策略，并对其进行了调谐。通过特别设计LFF和RFF补偿，考虑并消除了三个回路之间的相互影响，这两个补偿与OF补偿相适应。在考虑采样和计算延迟的情况下，从计算输出电压误差序列中发现暂态开关周期与控制器极点几何中心之间的关系。此外，通过在复杂平面的单位周期内移动中心计算理论最小开关周期，保证了系统的稳定性。此外，负载/线路暂态响应和参考跟踪时间同时优化到最小的切换周期。通过变换器闭环极点/零点图、瞬态响应仿真和实验验证了控制器的有效性。
Exploring high-performance controller for buck converter is challenging since it can be easily affected by converter model accuracy. In this paper, a novel nonaveraged current discrete-time (NCD) model is proposed, in which inductor current is expressed as time-varying equations during switch-on and switch-off states. It achieves higher accuracy than the conventional averaged model at high-frequency range, thus can be used to optimize high-speed controller design. Based on the NCD model, a multiloop minimum switching cycle (MMSC) control strategy, composed of output feedback (OF), line feed forward (LFF), and reference feed forward (RFF) loops, is proposed and tuned for buck converter operating in continuous conduction mode. Mutual influences among three loops are considered and eliminated by specifically designed LFF and RFF compensations, which adapt the OF compensation. With consideration of sampling and calculation delays, relationship between transient switching cycles and geometric center of controller poles is discovered from a calculated output voltage error series. Furthermore, theoretical minimum switching cycles are calculated by moving the center inside the unit cycle of complex plane, which ensures system stability. Moreover, load/line transient response and reference tracking time are simultaneously optimized to the minimum switching cycles. Effectiveness of the controller is proved by converter closed-loop pole/zero plots, transient response simulations, and experiments.