Optimal Coordinated Control Of Coupled Dual Permanent Magnet Synchronous Motor Systems

Large inertia loads,such as cement kiln,paper making,belt conveyor,are usually driven by two or more motors cooperatively,which is helpful to increase the flexibility of the structure of the systems,reduce the motor size and the energy consumption.The safety and reliability of the multiple motor system affect directly the production efficiency and product quality,and even leads to production accidents.Permanent magnet synchronous motors have been widely used in the industry due to their high torque inertia ratio and high efficiency.Therefore,this thesis will consider the coordinated control problem of dual-permanent magnet synchronous motor systems,which is important and significant for both engineering applications and academic research.The main works are summarized as follows:1.The mathematical models of dual permanent magnet synchronous motors with flexible coupling and rigidly coupling are established,respectively.Firstly,for the flexible connected dual-motor systems,the mathematical model is established by describing the flexible coupling relationship by the Hooke's law and using model of model of permanent magnet synchronous motors under the rotating coordinate system dq0.Then,for the rigidly connected dual-motor systems,the mathematical model is established based on the gear transmission characteristics and the model of permanent magnet synchronous motors.2.For the flexibly coupled dual-permanent magnet synchronous motor systems,an optimal coordinated control method is designed for speed synchronization and power balance by using singular perturbation theory.Firstly,according to the characteristics of the system,the cross-coupling coordination control structure is combined with the LQR control to establish an optimal coordinated controller design model.Then,using the singular perturbation and optimal control theory,the composite optimal controller design method and stability analysis method are proposed.Finally,the obtained method is applied to a dual motor driven belt conveyor system.The simulation results show that the method can significantly improve the coordination control effect,ensure the double motor speed synchronization and power balance in the dynamic environment,and can effectively avoid the excessive tension fluctuation of the tape and the motor overload.3.For the rigidly coupled dual permanent magnet synchronous motor systems,an optimal coordinated control method is designed to minimize the speed tracking error and motor torque synchronization error based on singular perturbation theory.Firstly,according to the rigid characteristics of the system,the master-slave coordinated control structure and the LQR control strategy are combined to establish an optimal coordinated controller design model.Then,the singular perturbation theory and optimal control theory are used to propose a composite optimal coordinated controller design method,and the stability of the closed-loop system is proved.Finally,the feasibility and effectiveness of the proposed method are verified by simulation.Compared with the existing methods,the tracking error and torque deviation are considered simultaneously,which can effectively improve the speed tracking accuracy and torque synchronization performance of the rigidly coupled dual permanent magnet synchronous motor systems.