PLC对冷凝压力控制的应用研究

冷凝压力是制冷循环的主要参数之一,它直接关系到制冷装置的制冷效果、安全可靠性和能耗水平.针对制冷系统中存在的对影响冷凝压力的主要因素分析不够详尽、对干扰因素的克服方法不够明确与控制精度不高、以及控制流程不够清晰等问题,特别设计了一套控制系统,采用可编程控制器（PLC）作为控制核心,触摸屏TP170A作为监控画面,前馈-反馈控制模型作为理论依据,对冷凝压力的影响因素进行了仿真分析,对经典的反馈控制模型与前馈-反馈控制模型在工程应用中的优、缺点进行了比较,对控制系统的实现过程进行了详尽的阐述.研究结果表明,所设计的控制系统能够实现各种控制模型应用,冷凝压力控制精度显著提高,干扰因素影响得到了抑制,实现了参数监控、故障报警以及人机对话,整个制冷系统可靠平稳运行.

PLC-based application for the control of condensing pressure

The condensing pressure is one of the main parameters of the refrigeration cycle,which has a direct influence on the effect,security reliability and energy consumption level of the refrigeration device.Aiming at such questions as the analysis of the main factors that influence the condensing pressure in refrigeration system not being detailed enough,the method to overcome the interference factor not being explicit,the controlling accuracy not being high,and the control process not being distinct,on the basis of the theory of feedforward-feedback controlling model,a set of control system was designed especially by using the programmable controller （PLC） as the controlling core and taking a touch screen （TP170A） as the monitor screen.Besides,a simulation analysis on the influential factors of condensing pressure was handled,a comparison between their advantages and disadvantages of the classical control model of and feedforward-feedback controlling model in the engineering application was made,and the realization process of controlling system was presented clearly.The results indicate that the designed controlling system can manage the application of every kinds of the controlling model with the great improvement of the condensing pressure control accuracy,the well suppression of the interference factors.Meanwhile,the parameters is managed to be monitored,the faults will be alarmed,and the man-machine dialogue are realized,the whole refrigeration system is to operate stably and reliably.