Research On Internal Model Control Of Electromechanical Toroid Drive System

The electromechanical toroidal drive system is a typical mechatronics system,which integrates the characteristics of permanent magnet synchronous motor and planet worm drive.It has the advantages of compact structure,good heat dissipation and function integration.The system has the function of deceleration,which can achieve low speed and high torque output in a small space.It has broad application prospects in aerospace,electric vehicles and military fields.In this paper,the toroidal drive system is studied from the aspects of structure characteristics,working principle,internal model control and vector control.Based on the spatial structure and working principle of the toroidal drive system,the motion of the planet in revolution and rotation at the same time is analyzed,and the unique structural parameter and motion parameter of the system are obtained.On this basis,the electromagnetic parameters of the system are analyzed,and the mathematical model of the system is established combined with vector coordinate transformation.According to the principle of electromechanical coupling,the speed transfer function of toroidal drive system is derived,and its steady-state performance is analyzed.In order to solve the problems of slow response speed,large steady-state error and large influence of its own periodic fluctuation,a two degree of freedom(2DOF)internal model controller is designed.The simulation results show that the controller can effectively improve the response speed and steady-state accuracy of the system.The disturbance observer is introduced into the 2DOF internal model control.The simulation results show that the disturbance observer can greatly reduce the influence of its periodic fluctuation on the system output.Aiming at the current coupling phenomenon in toroidal drive system,a 2DOF internal model decoupling controller is designed,and the correctness of the controller is verified by complex vector method.Combined with the vector control of i_d=0,the vector control model of toroidal drive system is built in Simulink environment.Compared with PI control,it is found that the system with 2DOF internal model decoupling control can realize current loop decoupling,and has good signal tracking performance,anti-interference ability and robustness under parameter changes.The inductances of AC and DC axes of toroidal drive system are not equal,so in order to further improve the utilization ratio of output torque,the i_d=0 control is replaced by the maximum torque per ampere(MTPA)control.According to the basic equations of the system in dq coordinate system,the MTPA control is analyzed.The relationship between the output torque and the AC/DC axis current is obtained by using the extremum principle and formula method.The simulation results show that the proposed control method can control the output of small stator current under the condition of constant torque,and improve the tracking and anti-interference performance of the system.