制冷系统的改进Smith预估补偿和解耦控制

Improved Smith predictive compensation and decoupling in refrigeration system

中文关键词  制冷装置  压缩机  变频器  纯滞后  Smith预估  变负荷  过热度

英文关键词  refrigerating machinery  compressors  frequency converters  pure time-delay  Smith predictor  variable load  superheat

中文摘要

      首先, 本文在实验的基础上对制冷系统进行了模型辨识, 得到并验证了双输入双输出的二阶传递函数矩阵. 其次, 提出了制冷系统的改进Smith预估补偿和解耦控制方法, 并进行了仿真验证. 最后, 提出恒定蒸发温度控制和变最小过热度控制相结合的双闭环控制方案. 此外, 本文给出了最小过热度曲线的实验获取方法. 结果表明, 与常规PID控制相比, 该方法在辨识模型存在强耦合和纯滞后以及模型参数存在一定偏差时仍能保证较好的稳态和动态性能, 满足制冷系统变负荷变最小过热度的控制要求.

英文摘要

      Firstly, a model identification of refrigeration system is carried out on the basis of experiment to obtain a second-order transfer function matrix with dual-input and dual-output, which is then verified. Secondly, an improved Smith predictive compensation and decoupling control are developed for the refrigeration system and simulated. Finally, the dual closed-loop control system consisting the variable minimal superheat-control and constant evaporation temperature-control is proposed. Besides, an experimental method to obtain the minimal superheat curve is developed. Compared with the PID control, this method provides better steady and dynamic performances in strong coupling, delay and inaccuracy in the identification model, and meets with the control requirements in variable load and variable minimal superheat.