Design of the Frequency Conversion Velocity Modulation System of Water Pump for Central Air Conditioning Controlled by PLC

This article deals with the operational principle and integral parts of the frequency conversion velocity modulation system of water pump for central air conditioning controlled by PLC,and presents the design procedures and methods of concrete electric circuit,hardware circuit and software.The adoption of modular design structure can meet the operation requirements in the aspects of reliability and precision.The realization of logical functions through software enhances the operation reliability of the system.This system enjoys such merits as sound openness,strong expansion capacity,high reliability,and easy installation.Therefore,it has good prospects for development.