Study on electromechanical coupling torsional resonance characteristics of gear system driven by PMSM: a case on shearer semi-direct drive cutting transmission system

In this paper, the electromechanical coupling torsional resonance characteristics of the multistage gear transmission system driven by the low-speed and high-power permanent magnet synchronous motor (PMSM) are studied. Considering the PMSM electromagnetic effect and bending-torsional vibration characteristics, the mechanical-electromagnetic coupling dynamic model suitable for the speed change process is established. Then, the PMSM electromagnetic stiffness and damping characteristics are analyzed through theoretical derivation. On the basis of electromagnetic stiffness, the influence law of electromagnetic effect on the gear transmission system natural frequency and vibration characteristics is revealed systematically. By both of Campbell diagram and modal energy distribution, the potential resonance points under the influence of internal and external excitation are initially acquired. Ultimately, the potential resonance points are identified by frequency sweep analysis and time domain simulation, and the energy concentration components at resonance point are further analyzed. The results show that the electromagnetic effect reduces the first-order natural frequency and has little influence on others. Moreover, the semi-direct drive cutting transmission system in this paper has the resonance risk caused by the gear time-varying meshing stiffness when the PMSM speed is close to 330 r/min, which should be paid more attention in actual operation. This study can provide some guidance for the design and speed regulation of the gear drive system driven by high-power PMSM.