Design And Research Of Vertical Mixing Mill Decoupling Control System

Vertical mixing mill is an important ultrafine grinding equipment, which is used not only in beneficiation but also in many fields such as power plant and coating mate-rial product. Because of the mill control system’s properties-multivariable, nonlinear, large-delay and close coupling, the output variables become uncertain, and the system becomes hard to control. The vertical mixing mill’s safety, economical efficiency and labor intensity are also badly influenced. In real productive process, the failure rate of vertical mixing mill is much higher than common ball mill, which makes us can not make full use of vertical mixing mill. Based on the technological characteristics of ver-tical mixing mill and common control technology, this paper studies on vertical mixing mill control algorithm and the structure to realize it.The first part analyzes the problems existed in vertical mixing mill, and mean it’s useful to study the decoupling control system. To solve these problems, the develop-ment status of vertical mixing mill control technology is studied.The second part studies vertical mixing mill working principle, and draws a con-clusion that output torque, ore grinding concentration and ore output speed are main factors that influences mill’s working and ore grinding process. To control these factors, we should control the input parameter-ore feeding speed, water feeding speed and stir-ring rotate speed. These input and output parameters have effects on each other., so, the three input and three output variable coupling system is built.The third part studies the coupling relationship between the input and output var-iables. Vertical mixing mill transfer function is obtained, based on least square method and system identification tool in MATLAB software. The feedforward decoupling con-trol principle is adopted to control three input and three output coupling system. Cou-pling system, feedforward decoupling control system and feedforward decoupling-PID control system are simulated on Simulation platform in MATLAB, the simulation re-sult shows that feedforward decoupling control principle works to decouple the cou- pling system.The fourth part describes how the decoupling control principle works in hardware structure and the design of monitoring software. The system consists of upper comput-er with monitoring software and PLC. Firstly, the hardware construction of system is designed, which shows the different places of decoupling control principle, PLC and site plant. Then, it describes the settings of power module, CPU, I/O port and so on. At last, the PLC program is written, which enable to control input and output, convert an-alog variable and realize alarm function. The monitoring software WinCC flexible is chosen to use in the system, which can control on-off and size of the input and output, display the curves of variables, record the output and alarm accidents, and so on. The last project is to define different users permissions, and make simulation for monitoring software.