Application of semi-active inerter in a two-body point absorber via force tracking

摘要

In this paper, a self-reaction point absorber (PA) wave energy converter is studied, where wave energy is collected by the relative motion of the on-board plate and the buoy. The purpose of this study is to increase the relative displacement to obtain the maximum power. A semi-active inerter (SAI) is applied in the system, which is controlled by a force-tracking (FT) strategy. Two parts are required in the FT strategy: a target active control law; and a proper control law to adjust the inertance to track the active force (AF). The target control law is obtained by the full-state feedback of the state-space model of a two-body PA . The control law to adjust the inertance is to saturate the AF between the maximal and minimal semi-active force of an SAI. Both linear time-invariant system and linear time-varying system are studied. Power absorption is improved in both two systems by the application of SAIs. Moreover, the influence of dimensionless parameters on the ratio of power absorption improvement in the considered linear time-varying system is studied. Numerical simulation shows that the ratio of power absorption improvement is most sensitive to the changes of mass ratio of the on-board plate and the buoy.