Research On The Stator Asymmetric Fault Model And Fault Tolerant Control Of Asynchronous Motor

The stator winding fault is one of the most common and destructive faults in asynchronous motor. Once the fault occurs, it will not only damage the motor itself,but also cause a series of chain reactions, leading to the interruption of the equipment and even the whole production system work. Therefore, as for stator winding fault, it is of great significance to explore an effective fault modeling and analysis methods,and to make timely and effective fault tolerance control to ensure the stable operation of the motor as well as improve the safety and reliability of the system.The main research contents of this paper are as follows:1. For the stator winding resistance and inductance asymmetry fault, the resistance asymmetric rate and the inductance asymmetry rate are defined respectively. On the basis of this definition, a dynamic model of the stator impedance asymmetry fault of induction motor is established. By using the model, the stator winding resistance, inductance and impedance asymmetry fault can be analyzed and studied respectively.2. For studying the motor operating characteristics which is effected by unbalanced faults of three-phase asynchronous motor stator windings, the article establishes the circuit currents and electromagnetic torque function model of the stator and rotor which about the impedance asymmetric rate in steady state. Taking the squirrel cage induction motor as an example, the validity and correctness of the model are verified by simulation and experiment and the operating characteristics of the motor with different impedance asymmetry ratio are analyzed.3. A passivity-based fault tolerant control method of asynchronous motor is proposed for the resistance asymmetric fault in stator winding. The Euler-Lagrange(EL) equation under the fault of asynchronous motor is obtained by modifying the coordinate transformation equation. Then a double closed-loop fault tolerant controller for the stator winding resistance asymmetric fault of asynchronous motor is designed with stator current and rotor flux as state variables to realize the effectivetracking of the torque and speed.