The self-powering condition of the active skyhook H-bridge circuit based electromagnetic damper (HB-EMD) as the SDOF isolator

To address the power challenge of conventional active control, the H-bridge circuit-based electromagnetic damper (HB-EMD) was recently proposed. Its self-powering feasibility has been validated in the previous study showing the actively controlled HB-EMD allows bidirectional power exchange between the EMD and the controlled system. However, a lack of quantitative study leads to an insufficient understanding of the self-powering condition (SPC), hindering its potential application. Although the instantaneous power could be either positive or negative, the SPC implies that the accumulated harvested power, which equals the control power minus the resistor dissipation, in the HB-EMD should be positive over an adequately long period. A mathematical model of active skyhook-controlled HB-EMD integrated into the SDOF system under the ground excitation is established, incorporating the mechanical and electrical coupling dynamics. Under the harmonic excitation, both instantaneous and cycle-averaged powers are derived analytically. The SPC depends on the excitation frequency, the structural inherent damping, the active skyhook gain, and the EM damping coefficient. Harvesting energy is challenging when the control power is bounded while the resistor dissipation diverges to infinity as the low frequency approaches zero. Under the band-limited stochastic excitation, the EM force variance and the mean control power determine the SPC. The wider excitation band and higher skyhook damping adversely affect energy harvesting. In comparison with the semi-active regenerative control, the active control meeting SPC could achieve more vibration reduction without energy consumption under both stochastic and harmonic excitations by properly choosing the control and damper parameters.