基于Smith的模糊PID控制器对热泵系统过热度的控制

Fuzzy PID controller based on Smith for heat pump system superheat control

蒸发器过热度系统存在大惯性、纯滞后,与制冷循环其他控制回路相互耦合等特点,简单的PID算法并不适合过热度的控制。探讨将模糊智能算法应用于蒸发器过热度的控制中,将模糊控制器与传统PID控制器以并联方式结合,按照一定方法相互配合,实现两个控制器之间的平滑切换;并引入Smith预估补偿机制,消除时滞环节对控制精度的影响,共同对过热度进行控制。通过Simulink仿真对比传统PID和模糊PID控制,其有响应迅速,超调小等明显优势。

The evaporator superheat system has large inertia, pure lag, and is coupled with other control loops of refrigeration cycle. The simple PID algorithm is not suitable for the control of superheat. The fuzzy intelligent algorithm is applied to the control of evaporator superheat, the fuzzy controller and the traditional PID controller are combined in parallel, and cooperate with each other according to certain methods to realize smooth switching between the two controllers. The Smith prediction compensation mechanism is introduced to eliminate the influence of time lag on the control accuracy and control the superheat together. Compared with the traditional PID and fuzzy PID control by Simulink simulation, it has obvious advantages such as rapid response and small overshoot.