Piezoelectric vibration harvesting device with resonance frequency automatic tracking capability
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1218-Z07-09
Piezoelectric vibration harvesting device with resonance frequency automatic tracking capability Maxime Defosseux1, Marcin Marzencki2, Skandar Basrour1 1 TIMA Laboratory (CNRS-Grenoble INP-UJF), 46 avenue Félix Viallet, 38031 Grenoble Cedex, France 2 CiBER Laboratory, Simon Fraser University, Burnaby, BC, Canada ABSTRACT Further development in the area of vibration energy harvesting is limited by the lack of efficient methods to adapt the harvester to its surroundings. To this end, we propose an innovative passive way of automatic passive resonance frequency tracking. We present a new approach employing mechanical non-linear behaviour of the system to track the vibration frequency peak. An analytical model representing these nonlinear harvesting systems has been developed and analysed. Experimental results obtained with custom fabricated MEMS devices show an experimentally verified frequency adaptability of over 36% for a clamped-clamped beam device at 2g (1g=9.81m.s-2) input acceleration. We believe that the proposed solution is perfectly suited for autonomous industrial machinery surveillance systems, where vibrations with high accelerations that are necessary for enabling this solution are abundant. INTRODUCTION Nowadays, there is a huge interest for wireless sensor networks in industrial or natural environments. However, a challenge is still present to see these networks commonly used: replacing batteries with limited energy capacity that are used as energy sources for the nodes which imply costly periodic maintenance. Piezoelectric ambient energy scavengers are a promising solution to this problem [1]. However, as these scavengers are resonant, their resonance frequency has to match the dominant frequency in the surroundings to be efficient. Unfortunately, precision of fabrication and scattering of material properties lead to variations in resonance frequency of the devices. As a consequence, an energy harvesting device with adaptable resonance frequency is needed to make this energy scavenging method more efficient [2]. Two kinds of solutions can be found to tune resonance frequency of vibration energy harvesters: -active methods need an external action that modifies the device mechanically ([3], [4]) or electrically ([2]) in response to changing excitation frequency. Usually, an active frequency tuning method is more efficient than passive methods, but requires a large amount of energy to tune the system. This amount of energy is too important compared to the possible energy harvested, so this system is not suitable for energy harvesters. -passive methods consist of harvesters with bandwidth large enough to accept frequency changes ([5], [6]). They are actually the only tuning devices usable for energy harvesting.
In this work, an innovative passive way of resonance frequency automatic tracking is presented. Nonlinear energy harvesting has already been proposed by Cottone and al [7] with a system based on a bistable oscillator to increase the gain of power harvesting, but not to adapt the syste
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