Research On Synchronous Control Of Multi-Linear Induction Motors Under Unmatched Disturbance

Linear induction motor plays an important role in magnetic levitation trains and high precision turning and grinding complex machine tools due to its simple structure,high mechanical efficiency and light size,while its edge effect and strong coupling characteristics bring great challenges for effective control strategies.In fields such as rail trains and ejection systems,a single linear induction motor often fails to provide effective drive and two or more motors are required to be controlled in concert.Therefore,the cooperative control of multiple linear induction motors has important theoretical research significance and practical application value.This paper will study and design a synchronous control system for multi-linear induction motors based on the suppression method of unmatched disturbances.The main contents of this paper are as follows:(1)This paper analyses the operating principle and electromagnetic characteristics of linear induction motors.The mathematical model of linear induction motor with edge effect is derived,and the vector control system with secondary magnetic chain orientation is designed,and the speed tracking control of linear induction motor is realized by using traditional proportional-integral controller.The simulation results verify its effectiveness,but the control accuracy needs to be improved.(2)Based on the dynamic model of linear induction motor,an improved sliding mode controller based on the extended disturbance observer is designed in this paper to cope with the disadvantage that the conventional sliding mode control is quite sensitive to the unmatched disturbances.The expansion subsystems and the extended disturbance observers are constructed separately for the two unmatched disturbances in the linear induction motor model,and the observation terms of the disturbance derivatives are filtered by the inverse tangent filter.A new integral sliding surface is designed in the velocity loop and the magnetic chain loop to suppress the effects of the unmatched perturbations on the linear induction motor by the observations of the perturbation derivatives.The simulation results show that the new sliding mode controller developed in this paper has good dynamic and steady-state performance.(3)In the synchronous control system of bilinear induction motor,the conventional deviationcoupled control system continuously compensates the deviation signal,resulting in better synchronization performance but poor dynamic and steady-state performance.To address this shortcoming,an improved deviation-coupled control scheme is designed in this paper.In order to balance the dynamic and steady-state performance,a speed compensator combining the third-order power-average operator and the dead-zone module is developed to deal with the coordination between the tracking and synchronization errors;the strong coupling and nonlinearity brought by this compensator are weakened by the id= 0 control and feedback linearized sliding mode control.The simulation results show that the speed compensator constructed in this paper has better dynamic and steady-state performance than the conventional compensator.(4)When expanding from two motors to multiple motors,the traditional deviation coupling control structure is completed by superimposing synchronization errors.The adaptive compensator designed in this paper is a binary input structure,so it is difficult to complete the expansion in the traditional way.To address this problem,a fuzzy virtual spindle deviation coupling control structure is constructed in this paper.Firstly,a multi-input single-output fuzzy controller is developed and specific language-based fuzzy rules are set in the rule base to generate the virtual synchronization signal;secondly,this fuzzy controller is used as a signal processing module for the improved virtual spindle to accept the speed feedback from the linear induction motors.The generated virtual synchronization signal is used as the another motor speed in the speed compensator so that each linear induction motor completes the control target of synchronizing to this signal.A four-motor synchronous control structure is constructed in the simulation,and the experimental results verify the effectiveness of the control scheme designed in this paper.