Improved relative coupling control structure for multi‐motor speed synchronous driving system

Abstract

This paper presents an improved relative coupling control structure for multi-motor speed synchronous driving system. Unlike the traditional relative coupling control structure, the proposed structure introduces an additional speed controller so that all the motors in the system can be treated as an entity. It also takes the importance of each motor's speed into consideration in the speed feedback process and the speed synchronous compensation. Meanwhile, the speed synchronisation and tracking performance of the multi-motor system can be decoupled (i.e. independently adjusted) and regulated by changing synchronous coefficient and tracking coefficient, respectively, and the performance of the multi-motor system can be obviously promoted. To evaluate the performance of the system comprehensively, this study proposes an assessment method based on synchronisation and tracking errors of the system, moreover, a comparison between the traditional structure and the proposed structure is analysed. Finally, the simulation and experimental results are carried out under triple-permanent magnet synchronous motor system, which can verify the feasibility and the effectiveness of the proposed method.