A low energy dissipation circuit is proposed to achieve more effective energy harvesting, called 'synchronized switch harvesting on inductor (SSHI)'. The proposed circuit only has two diodes, while the original SSHI circuit has four diodes comprising a diode bridge. It thus reduces the voltage drop during the energy-harvesting process, because the actual diodes have forward voltage regarded as equivalent electrical resistance or energy dissipation. Energy-harvesting experiments demonstrated that the proposed circuit increases the harvested energy output to as much as 120% of that for the original SSHI circuit. We confirmed that the storage voltage in the steady state is independent of the storage capacitance through extensive energy-harvesting experiments, and that the settling time of the storage voltage is proportional to the storage capacitance but independent of the harvesting circuit.
An innovative method of hybrid vibration suppression using piezoelectric materials is proposed. It combines bang-bang active vibration suppression and energy-recycling semiactive vibration suppression. The piezoelectric materials are electromechanically coupled and convert mechanical energy into electrical energy and vice versa. With this method, a part of the electrical energy needed for suppressing vibration is obtained from the mechanical energy of the vibrating structures and is efficiently recycled. Furthermore, the actively supplied energy is stored in the transducers and is reused many times for vibration suppression. Therefore, the hybrid method has better performance than the case where the bang-bang active method and the energy-recycling semiactive method are both used, but independently. The hybrid method saves the actively supplied energy and is thus a low-energyconsumption vibration control. Its effectiveness in suppressing vibrations was proven in numerical simulations and experiments using a 10-bay truss structure. Moreover, a novel method to prevent undesired control chattering is proposed to further save energy supplied from the external source. NomenclatureB p = input matrix b p = piezoelectric constant of piezoelectric transducer C p = diagonal constant-elongation capacitance matrix C S p = constant-elongation capacitance of piezoelectric transducer I rms = performance index in simulations; Eq. (28) I 2rms = performance index in experiments; Eq. (42) K = constant-charge stiffness matrix of structure k p = constant-charge stiffness of piezoelectric transducer L = inductance in electric circuit L = diagonal inductance matrix M = mass matrix of structure Q = electric charge given to piezoelectric transducer Q = charge vector Q T = target charge vector obtained from active control q = modal displacement vector R = electric resistance in electric circuit R = diagonal resistance matrix u 1 , u 2 = x-directional displacements at tip and central nodes V a = voltage generated by piezoelectric effect V ext = externally supplied voltage V p = voltage across piezoelectric transducer V p = voltage vector V ref = reference voltage for chattering prevention V 1 , V 2 = noise intensity matrices for Eqs. (33) and (35), respectively W 1 , W 2 = weighting matrices; Eq. (12) w = external force vector x = displacement vector of structure z = state vector; Eq. (10) δ rms = rms of displacements of all truss nodes ζ = modal damping coefficient φ i = eigenvector of ith vibration mode ω i = angular frequency of ith vibration mode Subscripts and Superscript j = jth piezoelectric transducer or electric circuit (for C S p , L, Q, Q T , R, V ext , V p , and V ref ) p = piezoelectric transducer = estimated value based on Kalman filter
This paper presents an extensive investigation on the LR-switching method (also called the energy-recycling semi-active method). Compared with the energy-dissipative R-switching method, the LR-switching method has been shown to have significantly better vibration suppression performance. However, certain essential issues affecting a system employing the LR-switching method remained to be dealt with. In particular, we had to clarify its vibration suppression mechanism from the viewpoint of mechanical and electrical energy exchange. Second, the robustness of the method against model errors and control time delays had to be verified. The experiments and numerical simulations that we conducted on a 10-bay truss structure demonstrate that the LR-switching method outperforms other suppression methods under sinusoidal and random excitations, which are more common in real systems and more difficult to deal with than transient vibrations. This paper provides fundamental insights on the LR-switching method and gives the method a guarantee for actual applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.