Research On Variable Frequency Speed Regulation System Of Kneading Machine

The blades'speed regulation is important for the control system of kneading machine, which is the key equipment in the solid propellant production. The speed control precision, mode of speed regulation, and control algorithm directly affect production efficiency and quality of the products. In this paper, based on analysis of the speed regulation system, method of mathematical model establishment, model characteristics and control algorithm were studied.Firstly, the structures and work principles of kneading machine were introduced. Factors affecting revolution fluctuation while running process were studied. Work principles and demands of variable frequency hydraulic speed regulation system were analyzed as well.Secondly, mathematical modeling methods and model characteristics were studied. Models of frequency converter link, motor link and hydraulic loop link were established. Then the stabilities and frequency characteristics of the speed regulation system were analyzed, and influences of the load, impulsion, moments of inertia, and leakage on response characteristics and control precision were discussed as well.Thirdly, practical speed control algorithm was studied. The principle, and meanings and functions of parameters of the general PID algorithm were discussed. The differences between general PID algorithm and two freedom degrees PID algorithm were compared. Simulation research of the two freedom degrees PID algorithm was conducted. Results showed that, two freedom degrees PID algorithm reveals better speed tracking characteristics and disturbance restrain characteristics for the speed regulation system. After that, parameters auto-tuning principle of the PID algorithm was discussed, and 3 main the PID parameters of the algorithm were optimized.Finally, a PLC control program was developed for the speed regulation system and was employed in practical project. In the program a PIDAT instruction based on two freedom degrees PID algorithm was adopted. The instruction can auto-tuning the PID parameters with a start button. The hardware connections and program settings were presented also. Running results showed that the mathematical models established are effective, the control algorithm is useful and practical, programming is simple, and control property is good. The mathematical models have good application prospects for similar control systems.