Electromagnetic-mechanical coupling analysis and optimization method of electromagnetic vibroseis

Electromagnetic vibroseis is an important seismic wave excitation device. At present, the research of electromagnetic vibroseis mainly focuses on application and prototype design, lacking research on electromagnetic-mechanical coupling. Analyzing the electromagnetic-mechanical coupling and optimizing the air gap magnetic field is of great significance to improve the excitation quality of low-frequency seismic waves. In this paper, the electromagnetic-mechanical coupling is analyzed by studying the parameter force factor, and two novel optimal designs of the air gap magnetic field are proposed. Firstly, the finite element model of the air gap magnetic field is established, and the influence of the force factor distribution curve on the vibration signal is analyzed by using the Gaussian function and parameter spline difference method. Further, an asymmetrical axial dual-magnet design is proposed to enhance the radial magnetic induction intensity ${B_{\text{r}}}$ in the air gap. The design of adding a radial magnet to the outer yoke is proposed to compensate for the nonlinearity of the ${B_{\text{r}}}$ in the air gap. The simulation results show that the asymmetric axial dual-magnet structure increases the ${B_{\text{r}}}$ by 22.2% compared with the axial single-magnet structure. Adding a radial magnet to the outer yoke reduces the amplitude ratio of the third harmonic to the fundamental wave from 23.24% to 4.66%. It is necessary to consider the influence of the height of the driving coils on the maximum displacement, force factor distribution curve, and harmonic distortion.