Study On Hybrid Control Algorithm Of Variable Frequency Speed Control On AC Motors

In the last few years, the development of the technique of modern Electric Power and Electronics, Micro-processor, and modern control theory improves the high-performance control of motor very much. At the same time, with the development of the technique of production and the level of modern automation equipment, favorable stable-state and dynamic-state performance for the drive system of motor is wanted. the Vector Control (VC) and the Direct Torque Control (DTC), which belong to high performance variable-frequency adjusting-speed technique in the AC drives,are both researched widely. It is a better method to solve the above questions that a novel DTC theory is founded by synthesizing VC.Through the paper studying the present situation and the development of AC motor, DTC and VC are chosen to be analyzed. Through analyzing the vector control theory and its decoupling, we simulate the slip frequency control of the vector control systems and Fuzzy Controller with the slip frequency control of the vector control system respectively in the environment of MATLAB. From the results of the simulation experiments, we know fuzzy control of the simulation results superior to the traditional PI regulator; it shows the effective and reasonable of the design. At the same time, the paper enter into detail of the direct torque control theory and the control system. And it analyses the effects of six voltage space vector on the stator flux and torque of asynchronous motor.Based on the previous theory and simulation of the Vector Control and the Direct Torque Control, we can get the comparing results. And the papers presents a new hybrid control method of combing the vector control and the direct torque control, etc. the designed system runs into Vector Control method containing fuzzy controller at lower speed and into Direct Torque Control method at higher speed. Meanwhile the paper designs the switch point that is 30% of the rated speed. The new control method is verified in Matlab, and it combines advantages of the two above control methods.