基于模型的制冷系统过热度DMC-PID串级控制

摘要

In order to ensure stable and efficient operation of refrigeration system, a model based DMC — PID control method was proposed for evaporator superheat. Based on evaporator operating data, the evaporator model, with opening of expansion valve as input and thermal as output, was established by using recursive least squares method. And the DMC - PID cascade control algorithm for superheat was proposed based on the evaporator model. The simulation results prove that this algorithm has strong robustness, ahead of predictability, and good resistance. Compared with traditional single - input single — output PID control strategy, this method has a faster response and control accuracy.%为保证制冷系统稳定高效的运行,克服系统存在的大惯性以及时滞等缺点,文中基于模型提出一种蒸发器过热度的DMC-PID串级控制方法.根据蒸发器运行数据,采用递推最小二乘方法建立以膨胀阀开度作为输入,过热度作为输出的蒸发器数学模型并加以验证；基于蒸发器模型,提出了过热度DMC-PID串级控制算法,该算法具有强鲁棒性,超前预测性以及良好的抗干扰性.通过仿真实验与传统单人单出PID算法比较,结果表明该算法具有更快的响应速度以及控制精度.