Dual duty ratio based impedance modulation technique for low frequency adaptive damping and energy recovery in ball screw type regenerative dampers

Regenerative suspension systems have gained enormous attention as an effective approach of energy harvesting from road vibration parallel to riding comfort and vehicle stability. This paper presents a theoretical based control modelling and adaptive damping control with impedance modulation technique for Ball screw based regenerative dampers. The model aims for improving the damping performance with energy recovery; at the same time through a technique claimed as dual duty ratio impedance modulation technique. The dynamics of the Ball screw damper has been analysed by considering the transfer function of each individual block and further cascading the gain of individual mechanical as well as electrical subsystems into account. The proposed model has been further validated after comparing with the previously reported experimental readings, that concludes close agreement with the magnitude of per-phase generated power. The regeneration efficiency with respect to low frequency sinusoidal vibration reaches maximum within a narrow band of 0.4 Hz beyond which the conversion efficiency declines. In contrast, the damping efficiency linearly increases within low frequency excitation frequency. Hence, critical frequency points illustrating the point of equalization of regeneration efficiency with damping efficiency has been graphically identified. This corresponds to low frequency ranging from 301mHz to 390mHz by varying the external load impedance between 2 Ω and 92 Ω. LTspice simulations reveal that, varying load side duty ratio within the operational duty bandwidth of the converter enables almost linear regulation of terminal voltage thereby maintaining stable energy recovery.