State Observation And Control Of Asynchronous Motors When The Load Is Unknown And The Rotor Resistance Changes

This subject combines adaptive backstepping control and sliding mode control to enhance the robustness of the motor control system.Aiming at the unknown load and the disturbance of motor parameters,the sliding mode rotor flux observer,load observer and disturbance observer are designed.At the same time,consider enhancing the operating efficiency of the induction motor under lightweight load,the loss model of the induction motor was constructed,and a smooth switching strategy of the rotor flux based on the speed error is proposed to achieve the efficiency optimization of induction motor.The research work of this subject is as follows:(1)The backdrop of this subject and the present status of induction motor speed controlling systems at home and overseas are described,and the thesis organization and the main substances are introduced;The LINKS-RT AC induction servo rapid prototyping experiment platform is introduced,and the hardware environment and software environment of the platform are described in detail,all experimental verifications of this subject are completed on this platform;The three-phase steady state model of the induction motor,the coordinate transform method,and the steady state model of induction motor in the two-phase dq synchronous rotating coordinate system are given,and the vector control principle of the induction motor based on rotor flux orientation is described.(2)The principles of adaptive backstepping and sliding mode control are explained;For induction motor load unknown and rotor resistance parameter disturbance,the induction motor backstepping sliding mode controller is designed,and an improved exponential reaching law sliding mode rotor flux observer and load observer are proposed to estimate the rotor flux and load torque.The experimental results indicate that this strategy can calculate the rotor flux and load torque honestly and accurately,which makes the motor have good speed regulation performance,and enhances the robustness of the system to the rotor resistance disturbance.(3)The mathematical model of the induction motor considering the disturbance is introduced.According to the model,a backstepping sliding mode control strategy of induction motor based on disturbance observer is proposed,and the Super-twisting rotor flux observer is designed.The experimental results show that the disturbance observer can estimate the lumped disturbance in real time when the unknown load injection,the resistance,inductance and moment of inertia changes suddenly.This strategy makes the motor system have good dynamic performance and static performance,and enhances the robustness of the system to the motor parameters disturbance.(4)The loss model of the induction motor is given,and the rotor flux smooth switching strategy based on the speed error is designed.The experimental results show that the energy loss of the motor can be reduced at light load by the rotor flux smooth switching method,thereby improving the efficiency of the induction motor.In conclusion,firstly,the backstepping sliding mode control algorithm is proposed for unknown load and rotor resistance parameter disturbance of induction motor,and the rotor flux observer and load observer are designed.Secondly,considering the mathematical model of the motor with disturbance,a disturbance observer is designed to enhance the robustness of the motor system.Finally,consider improving the operating efficiency of the induction motor under light load,a smooth switching strategy of the rotor flux is designed to reduce the energy loss of the motor,which has certain application prospects.