Discussing the application of HMI in the VVVF system

In recent years, frequency control technology developing rapidly, PLC and frequency control technology has penetrated into all fields. While saving energy it can also reduce emissions and energy consumption. The application of control technology has greatly reduced the size of the device and improved efficiency, resulting in huge economic benefits. Frequency control system is a control system that its´ various parts operate coordinated. In this article, the system assigns the specified speed curve through human-machine interface (HMI); motor speed is controlled by a frequency transformer. The PLC gets the motor´s actual speed through rotary encoder feedback. Finally, the man-machine interface (HMI) displays motor speed curve in real time to achieve monitoring function. The design of this system requires that frequency transformer is controlled by to achieve step less speed controlling, rotary encoders used for speed measurement, human-machine interface (HMI) and control of the main station through the CC-link connection. The whole system works reliable, easy to debug and maintain.