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With the rapid development of wind turbine, the operational reliability of the main drive systems of wind turbine has received extensive attention. The wind turbine drive system is affected not only by random wind loads for a long time but also by the electromagnetic torque of the generator. Exploring the coupling behavior and mechanism is particularly important for optimizing the design of the drive system and improving the operational reliability of the main drive system. This study establishes a mechanical–electrical coupling model, which includes a translational–torsional dynamic model of a gear transmission system that can be used for variable speed and variable‐load conditions, a finite element model of the generator, and voltage vector control. This model takes into account nonlinear factors such as the time‐varying meshing stiffness of the gear system and the magnetic characteristics of the generator. The speed sweep analysis method was used to identify the resonance speed and dangerous components of the system. Under different external excitation conditions, the dynamic characteristics of the system were compared with and without considering electromagnetic characteristics. The generator speed of 1030 r/min and 651 r/min is the potential resonance speed of the system. The gear system and generator system have strong coupling characteristics. In the vibration signal of the gear system, there will be electrical system frequency components dominated by 6kfe and (h − 1)fe. In the current signal, not only appeared the excitation frequency in the gear system, but also the modulation signal with the excitation frequency in the gear system as the carrier frequency and the electric frequency as the fundamental frequency ((6k ± 1) ⋅ fe ± n ⋅fm) appeared. Under the gust wind, the transient response of the system will excite the gear‐generator coupling vibration mode. The electromagnetic characteristic of generator can suppress the vibration of mechanical system.

Dynamic modeling of multistage gearboxes and identification of dangerous resonance paths are necessary to avoid failure induced by resonance. Based on the lumped-parameter/finite element method, an improved dynamic gearbox model that considers the structural flexibility of the shaft and housing and can be used for dynamic analysis of variable speed processes, is proposed. Compared to previous lumpedparameter/finite element models, the proposed model does not divide the speed range into a lot of constant speeds to identify resonance; therefore, it has a higher computational efficiency (the previous model takes approximately 168 h to identify resonance whereas the proposed model takes just 47 h). Based on the proposed model, an analysis method for identifying the dangerous resonance paths of multistage gearbox is proposed. First, the natural frequencies and vibration shapes of the gearbox are calculated. Second, the time-frequency analysis of variable speed processes is used to identify resonance. Finally, the modal energy method is adopted to quantify the resonance energy of each component. Thus, the dangerous resonance paths of the multistage gearbox is determined by using the proposed analysis method. The proposed method provides a basis to reduce noise and vibrations and for fault prediction of gearboxes, and it can also be applied to other mechanical systems.INDEX TERMS Gear, gearbox, dangerous resonance paths, dynamic modeling, an analysis method.

The extensive use of organic dyes in industry has caused serious environmental problems, and photocatalysis is a potential solution to water pollution by organic dyes. The practical application of powdery photocatalysts is usually limited by the rapid recombination of charge carriers and difficulty in recycling. In this study, recyclable carbon cloth-supported ZnO@Ag3PO4 composite with a core–shell structure was successfully prepared by solvothermal treatment and subsequent impregnation–deposition. The as-prepared carbon cloth-supported ZnO@Ag3PO4 composite showed an improved photocatalytic activity and stability for the degradation of rhodamine B (RhB), a model organic dye, under visible light irradiation. The decomposition ratio of RhB reached 87.1% after exposure to visible light for 100 min, corresponding to a reaction rate constant that was 4.8 and 15.9 times that of carbon cloth-supported Ag3PO4 or ZnO alone. The enhanced performance of the composite can be attributed to the effectively inhibited recombination of photoinduced electron–hole pairs by the S-scheme heterojunction. The carbon fibers further promoted the transfer of charges. Moreover, the carbon cloth-supported ZnO@Ag3PO4 can be easily separated from the solution and repeatedly used, demonstrating a fair recyclability and potential in practical applications.