Multi-permanent Magnet Synchronous Motor System Improves Coupling Control Strategy

With the continuous development of industry,the control accuracy requirements are getting higher and higher in the application of multiple motors in the mechanical control system.The control performance of the motor in the system is good or bad,and the level of control accuracy directly affects the quality of the product in textile,chemical fiber,printing and other fields.Therefore,to improve the synchronization performance of multi-motor system is so great significance.The traditional multi-motor bias coupling structure uses a PI speed controller with limited bandwidth.And the control structure of the synchronization error compensation link does not compensate for the maximum synchronization error to each motor individually.As a result,the speed tracking error of each motor and the synchronization error among motors are large when the multi motor system under the condition of load mutation or external disturbance.Aiming at this problem,an improved deviation coupling control structure is proposed.In the proposed control structure,converting the PI speed controller in the traditional deviation coupling structure into an integral sliding mode controller.And using ISMC's excellent dynamic adjustment performance to improve the control ability of the speed tracking error for the control structure in the transient state firstly.Secondly,correct the maximum speed synchronization error and the maximum acceleration among t motors to the control circuit of each motor.It is aimed at enhancing the speed synchronization error control ability of the control structure,to achieve the purpose of eliminating the multi-motor system transient synchronization error.The improved control structure is simulated by Matlab/Simulink simulation platform.The simulation results verify the feasibility and rationality of the proposed structure.For a multi-motor system,the traditional cross-coupling control is affected by the saturation of the controller,which has the problem of large starting synchronization error..To solve the controller saturation effect on synchronization error,in this paper,an improved cross-coupled structure is proposed in order to improve the speed synchronization performance of multi-motor system and to further reduce the speed tracking error between the motors.Different from the traditional cross-coupled control structure,the improved structure uses the PI controller to control the synchronization error and the tracking error respectively;and the improved structure controls the sum of the tracking errors of two motors with a proportional controller and feeds them back to the control loops of the respective motors respectively to establish a feedforward compensation mechanism of the speed tracking error so as to enhance the control effect on the tracking error.In order to verify the correctness of the improved strategy proposed in this paper,simulation and experimental analysis are carried out.It was confirmed that the improved structure reduces the synchronization error between the motors during starting and reduces the tracking error under sudden load changes.