亳菊恒温烘干系统双闭环PID控制设计

Control Design with Double Closed Loop PID for Bozhou Chrysanthemum'sConstant Temperature Drying System

在对亳菊进行干燥时,为了保证其有效成分含量最高,同时降低物料烘干的能耗,设计了一种采用双闭环PID控制的恒温控制系统,由供热系统、储热系统、烘干系统和监控系统4部分组成。内环PID目标值和测定值分别进变频器2和4号端子,运算后操作量作用于空气能热泵,实现水箱水温调节;外环PID室内温度设定值和测量值分别进FX3U-3A特殊适配器模拟量通道,PLC运算后输出量控制SSR的通断,驱动烘干室风机运行,实现恒温烘干需求。

In order to ensure the highest content of effective components and reduce the energy consumption in drying process,a constant temperature control system with double closed-loop PID control is designed,which is composed of heating system,heat storage system,drying system and monitoring system.The target value and measured value of inner loop PID are respectively fed into terminal No.2 and terminal No.4 of the frequency converter.After calculation,the operation amount acts on the air energy heat pump to realize water temperature regulation of the water tank.The temperature setting value and measurement value in the outer loop PID room are respectively put into the analog channel of a special adapter FX3U-3A.After PLC calculation,the amount of the output controls the on-off switch of SSR,which drives the fan in the drying room to operate,and realizes the constant temperature drying demand.