## 5 Conclusions  
This study presents an electromechanical coupling model that combines the equivalent magnetic network model of a DTP-PMSM with the dynamic model of a helical planetary gear train. Using this model, the dynamic response characteristics of the system with or without the self-fault tolerant control strategy are thoroughly investigated. The main findings derived from the integrated analysis of simulation and experimental data are as follows:  
1. During open-phase faults, the self-fault-tolerant control strategy adopted in this study can automatically switch the system at the instant of fault occurrence, ensuring a swift transition to fault-tolerant operation. This approach substantially reduces fault recovery time, enhances the system's sustained operational capability, and improves overall reliability under various conditions. 2. Simulation analysis demonstrates that under self-fault-tolerant control, stator winding reconfiguration leads to an increase in the 3 rd and 5 th harmonic components in the phase current. This current distortion disturbs the air-gap magnetic field in the motor, leading to an amplified 2 nd harmonic component in both motor speed and electromagnetic torque. This specific electromagnetic harmonic disturbance transmits to the gear system through electromechanical coupling, leading to a commensurate  
Figure 18: Dynamic responses of the electromechanical system at light-load conditions before and after self-fault-tolerant control: (**a**) electromagnetic torque, (**b**) electromagnetic torque spectrum, (**c**) planetary gearbox vibration signal spectrum. augmentation of the 2 nd harmonic component in the dynamic response spectrum of the planetary gearbox. Both simulation and experimental data demonstrate that compared to the open-phase faults condition, the self-reconfigurable fault-tolerant control strategy achieves an approximately 40% reduction in the amplitude of the 2 nd harmonic within the planetary gear system. This result confirms that the experimental observation trends of the electromechanical drivetrain's dynamic response under self-fault-tolerant control align with the simulation predictions. This study reveals the influence mechanism whereby specific electromagnetic harmonic excitations, introduced by fault-tolerant control strategies, propagate through electromechanical coupling paths to the mechanical system, exciting and amplifying corresponding-order vibration responses in the gear system. It establishes a crucial theoretical foundation for the fault-tolerant operation design and performance optimization of complex electric drive transmission systems. Subsequent research will focus on investigating the dynamic characteristics of the system under concurrent multiple fault conditions, particularly transmission wear faults. Additionally, the incorporation of a second-harmonic suppressor into the fault-tolerant control strategy will be explored. This measure aims to collaboratively suppress specific electromagnetic harmonic excitations and their induced electromechanical coupling vibrations, thereby enhancing the overall performance of fault-tolerant control. Conceptualization, W.B. ; methodology, W.B. ; software, Y.K. and Z.X. ; validation, Y.K. and Z.X. ; formal analysis, Y.K. ; investigation, Y.K. ; resources, W.B. and Y.W. ; data curation, X.H. ; writing--original draft preparation, Y.K. ; writing--review and editing, W.B. ; visualization, Y.K. and Z.X. ; supervision, W.B. ; project administration, W.B. ; funding acquisition, W.B. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (Grant No. 52105127) and the Natural Science Foundation of Zhejiang Province. (Grant No. LGG22E050025). The data presented in this study are available on request from the corresponding author. The authors gratefully acknowledge [PERSON] for his valuable methodological recommendations during the conceptualization stage of this research.