Modeling and control for an integrated permanent magnet toroidal motor drive with nonlinear electromagnetic parameters

Abstract

This paper presents the modeling, controller design and testing of the integrated permanent magnet toroidal motor drive. As one kind of direct-drive composite motor drive, the integration and configuration for permanent magnet toroidal motor are presented. Based on its special rotor structure, the magnetic flux linkages of the worm stator windings are deduced with its structural and kinematic parameters. The voltage equations and electromagnetic torque in rotary two-phase coordinate are presented. The dynamic machine model for permanent magnet toroidal motor drive is established with nonlinear time-varying electromagnetic parameters, which include inductances and differential information. Then, the dynamic performance with periodic fluctuation is analyzed. Based on the effect analysis for the dynamic response, the electromagnetic torque model of permanent magnet toroidal motor drive is properly simplified. In order to improve the output performance of toroidal motor drive, a terminal sliding surface is introduced in the controller design to accelerate the response speed, and meanwhile, the sliding mode observer is proposed to estimate the angular speed of the rotor in the feedback loop to achieve better tracking performance. The foundation test of inductance was conducted and demonstrates the validity of the machine model. The simulation results show that the proposed control strategy can significantly improve the dynamic behavior and robustness of the permanent magnet toroidal motor drive system.