Design and control of a self-powered hybrid electromagnetic damper

In this paper, the characteristics of a hybrid regenerative electromagnetic (EM) damper are first determined and experimentally examined. The main idea is to have two modes of operation for the EM damper, namely passive energy harvesting and semi-active modes. In the passive mode, the vibrational energy of an underlying structure is harvested and stored in a rechargeable battery. The harvested energy can then be employed in the semi-active control mode to supply the power demand for the required sensors and microcontroller. This hybrid damper would thus be capable of realizing the characteristics of a self-powered EM damper. A prototype of the damper was designed and tested under different harmonic excitations. The mechanical and electrical characteristics of both passive and semi-active modes were investigated and verified. The average harvested power and current were measured, and the efficiency of the different elements of the damper is determined. Next, for tuning the semi-active mode, a sliding mode control algorithm was proposed which considers the inherent nonlinear parasitic force of the EM damper. The proposed algorithm aims to track the response of an optimally controlled structure, by having knowledge of the bound of the nonlinear parasitic force. Finally, the effects of the proposed damper and sliding mode controller for vibration mitigation of a small-scale structure is demonstrated through a series of shake table tests, under harmonic and random excitations.