Design And Research Of Heat Pump Drying Control System Based On PLC

The heat pump drying system can precisely adjust the temperature and humidity of the drying air to achieve material drying.In this paper,the heat pump technology is applied to the drying system,a heat pump drying system with heat recovery is designed,and the host computer configuration monitoring software that can monitor the heat pump drying process in real time is developed,and the heat pump drying temperature and humidity control system is designed.The performance of the control scheme was analyzed.The main contents are as follows:1.Based on the principle of heat pump,a heat pump drying system with heat recovery is designed.Through accurate and reasonable control,it can realize various modes of operation,including fast heating mode,heating dehumidification mode,constant temperature dehumidification mode and cooling dehumidification mode.The temperature,humidity and air volume of the system can be adjusted flexibly and accurately controlled,which can meet the requirements of drying process parameters in different drying stages.2.A heat pump drying control system with Siemens PLC S7-200 SMART as the control core has been designed,the control scheme of the system is determined according to the control requirements,the types of various components included in the control system are selected,and the input and output addresses of Siemens PLC are assigned.Complete the control cabinet design and connect the hardware circuit according to the electrical principle.3.The host computer configuration monitoring software has been developed,which can detect the state changes of the parameters of the heat pump drying equipment,monitor the heat pump drying process in real time,display the change trend of the state parameters through the real-time curve,and also display the alarm information to indicate the failure of the heat pump system.The monitoring system will store the data,and use the functions of real-time report and historical report query,printing,etc.,the operator can check the operation status and data of the entire control system at any time,and control the equipment as needed,so as to monitor the operation of the heat pump drying equipment.Real-time monitoring and protection.4.In the heat pump drying system,the temperature and humidity of the drying air are coupled with each other and cannot be controlled independently.The parameters of the system model are identified based on the test data,the controllers and parameters of different control schemes are determined according to the controlled object model,and the simulation is carried out with the Simulink simulation tool,and the operation results are simulated according to the response curve and dynamic performance index of the control output.analyze.On the whole,the predicted PI control system has small overshoot,small oscillation,good robustness and strong interference suppression ability,and is suitable for the heat pump drying process with large inertia and large lag.