Design and experimental characterization of an electromagnetic transducer for large-scale vibratory energy harvesting applications

Abstract

This article reports on the design and experimental characterization of an electromagnetic transducer for energy harvesting from large structures (e.g., multistory buildings and bridges), for which the power levels can be above 100 W and disturbance frequencies below 1 Hz. The transducer consists of a back-driven ballscrew coupled to a permanent-magnet synchronous machine with power harvesting regulated via control of a four-quadrant power electronic drive. Design considerations between various subsystems are illustrated and recommendations in terms of minimal values are made for each design metric. Developing control algorithms to take full advantage of the unique features of this type of transducer requires a mechanical model that can adequately characterize the device’s intrinsic nonlinear behavior. A new model is proposed that can effectively capture this behavior. Comparison with experimental results verifies that the model is accurate over a wide range of operating conditions. As such, the model can be used to assess the viability of the technology and to correctly design controllers to maximize power generation. To demonstrate the device’s energy harvesting capability, impedance matching theory is used to optimize the power generated from a base-excited tuned mass damper. Both theoretical and experimental investigations are compared and the results are shown to match closely.

Output power and efficiency of electromagnetic energy harvesting systems with constrained range of motion

“…In linear electromagnetic energy harvesting systems (henceforth referred to as linear system) such as those studied in [11,[19][20][21] a linear generator is employed. However, in a rotational energy harvesting system (henceforth referred to as rotational system), an intermediate mechanism, such as rack and pinion [7,10,22] or a ball screw [23][24][25][26], is utilized to convert linear motion of the mass to rotational one to drive a rotary generator. The paper is distinguished by three main contributions.…”

“…Note that n  is a characteristic of the transducer, but here the system is designed such that the undamped natural frequency of the device is equal to the frequency of excitation. Considering (26), the efficiency of a constrained linear system for the load resistance corresponding to the maximum output power ( max ,, l linear P i RR  ), can readily be shown to be [27] For weak linear coupled systems, the efficiency is low. By increasing em  the efficiency increases until it reaches a maximum value of 50%, i.e.…”

Nonlinear damping and quasi-linear modelling

“…The scale of such systems can vary from miniaturized devices for low-power wireless sensors [40], to devices designed to harvest power from human motion [41], to large-scale devices powered by ocean waves or large structures [42,43]. If driven at resonance, the harvested power is, in principle, maximized if the electromechanical damping is very small, so that the motion of the inertial mass is very high [44], but the maximum extent of this motion, the maximum throw, is generally limited by practical construction constraints.…”

Wind Induced Vibration Control and Energy Harvesting of Electromagnetic Resonant Shunt Tuned Mass-Damper-Inerter for Building Structures

“…For the TMD with damped primary systems, substantive design methods and tuning criteria have been raised [9], and the TMD applied in nonlinear and distributed primary systems has been studied [10,11]. Meanwhile, energy harvesting from large-amplitude lowfrequency oscillating primary structures has emerged as a promising research area [12,13], especially from TMD [14][15][16][17][18][19]. It depends on replacing the energy-dissipating element of the TMD or supplementing with electromagnetic harvester, for relatively large-scale applications [14][15][16][17][18], or piezoelectric materials, even for relatively small-scale applications [17,19].…”

“…Meanwhile, energy harvesting from large-amplitude lowfrequency oscillating primary structures has emerged as a promising research area [12,13], especially from TMD [14][15][16][17][18][19]. It depends on replacing the energy-dissipating element of the TMD or supplementing with electromagnetic harvester, for relatively large-scale applications [14][15][16][17][18], or piezoelectric materials, even for relatively small-scale applications [17,19]. Under this background, a concept of tuned massdamper/harvester (TMD/H) is presented in [20], in which the basic conversion consists of a linear voice coil motor connected to a resistance emulator consisting of rectification and variable impedance unit.…”