Study On The Intelligent Vector Control Of An Induction Motor Speed-adjustable System

Induction motor is a system with the characters of high orders, strong complex coupling nonlinearity and multivariable. As a kind of decoupled control approaches, Vector control transforms the AC model by coordination transformation, which improves the industry applications of induction motor. However, the inherent nonlinear character of induction motor and the uncertain parameters variety in practical application induce that conventional control methods cannot obtain satisfactory results. At the other hand, most energy is wasted on the condition of using traditional control methods. Therefore, the paper combines fuzzy control with modern control methods in order to study the intelligent control and optimization in AC speed-adjustable system.Based on analysis conventional control method, a novel hybrid controller, which composed of a self-adjusting fuzzy controller and a PI controller is designed to improve the transient performance of the Vector-controlled system. With the speed sensorless Vector control of induction motor and fuzzy theory, MRFAS is applied to estimate rotation of induction motor in the speed-sensorless system. The paper describes a fuzzy logic based on-line efficiency optimization controller to improve the efficiency of the system. At steady-state light-load condition, a fuzzy controller adaptively settles down the system to minimum input power. If the load torque or speed command changes, the efficiency search algorithm is abandoned and the rated flux is established to get the best transient response.To prove practicability of the control in AC speed-adjustable system, the paper includes detailed simulation process and results. The experiment results show that the control methods adopted in the paper obtain satisfactory results basically.