Regenerative Base Isolation With Multi-Resonant Electromagnetic Shunt Dampers

Electromagnetic (EM) shunt damping has been recently proposed for dual-functional vibration isolation and energy harvesting. This paper proposed two multi-resonant electromagnetic shunt damper configurations, namely in parallel and in series, with application to the building base isolation system. The electromagnetic shunt circuit parameters were optimized based on the H₂ criteria to minimize the RMS relative displacement for the concern of building safety subjected to broad bandwidth ground acceleration excitations. The performance of the proposed multi-resonant electromagnetic shunt dampers was compared with traditional multiple tuned mass dampers (TMDs). It shows that, for multiple TMDs and multi-resonant electromagnetic shunt dampers with 5% total stiffness ratio, the parallel electromagnetic shunt damper can achieve the best vibration isolation performance. Case study of a base-isolated structure was analyzed in both the time and frequency domain to investigate the effectiveness of the multimode electromagnetic shunt resonances. It shows that both multimode shunt circuits outperform the single mode shunt circuit by suppressing the primary and the second vibration modes simultaneously. Comparatively, the parallel shunt damper is more effective in vibration isolation and energy harvesting, and is also more robust in parameter mistuning than the series shunt damper. This paper further experimentally validated the effectiveness of the multi-resonant electromagnetic shunt damper on a scaled-down base-isolated building.