An increasing number of multi-motor driving systems (MMDSs) appear in the new energy, transportation and aerospace owing to its high reliability, small weight and size, and other beneficial features. Multiple motors drive the gear assembly in these transmission systems. Uneven load distribution (torque or speed synchronization issues) and motor fault are the most likely problems in their usage. The interaction between the motor and the gear transmission system plays a major role in the synchronization and dynamic characteristics of MMDS, especially when a motor fault occurs. Therefore, the influence of a motor fault on the synchronization and dynamic characteristics of MMDS will be investigated. An electromechanical coupling dynamic model of MMDS is established by using node finite element method. The numerical calculation is used to predict the synchronization and dynamic characteristics of system, and the experiment is performed to validate the model. Results show that the speed synchronization characteristic between the non-fault motors is affected less by the motor fau However, the motor fault has a relatively large influence on the torque synchronization characteristic and the stator current synchronization characteristic between the non-fault motors. In addition, the motor fault has an important influence on the dynamic characteristics of the system; it not only increases the dynamic responses amplitude, but also slightly changes the compositions of the excitation frequency. In the practical engineering, the stator current can be selected as the feedback signal to monitor the output torque and torque synchronization characteristic of motor.
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