Research Of Sliding Mode Variable Structure Techniques On Ac Motor Control System

AC motor driven has a wide range of applications. Vector control is the more mature control scheme for the induction motor driven system in the shaftless driven techniques of printing machine. The accurate flux orientation that decide whether or not the AC motor can steady start and run with load, is the core of the vector control for induction machine driven system. This paper presents the rotor flux observation method applied to the induction motor. It focuses on the design of several practical sliding mode observers. And studying an observer based on fault detection method applying sliding mode observer. The state observer are designed based on the variable structure for AC motor to increase robustness under the condition of internal parameters variations and external disturbances, and to improve dynamic characteristics of AC motor.First, the sliding mode control theory and the shaftless driven technology are discussed. Based on the principle of induction rotor field orientation control. The mathematics model of AC induction motor is summarized, and design the vector controlled motor drives.Because the state variables are necessary in controller, design of state observer is the key to the controller. For the shaftless driven AC motor vector control system, the rotor flux observer based on Luenberger is discussed. And then design the rotor flux observer based on equivalence trending law of the silding mode variable structure control theory. The simulation results show that the method can track the rotor flux effectively.The chattering of sliding mode algorithm can't be avoided completely. In order to reduce chattering, the path of speed is associated with the distance of the sliding surface and trajectory. The sliding mode controller based on the adaptive trending law and the integration trending law are designed on the observer. It verified the validity of the observer through theoretical analysis and experimental design. To the steady-state error of the sliding mode observer. Then a new method is designed which is based on the adaptive and integration trending law. The simulation results show that the observers can reduce chattering effectively and the steady-state error.Finally, in order to keep high sensitivity to the fault signal. Studying a fault detection method applying sliding mode observer based on the sensor fault of motor. The simulation results show that the unknown input disturbance didn't effect the fault detection system.