mechanicalvibrationsenergyharvestingandpowermanagement-外文文献(编辑修改稿)

mechanicalvibrationsenergyharvestingandpowermanagement-外文文献(编辑修改稿)内容摘要：

to use a triangle structure in term of capacitance density. Furthermore, with this type of structure it is possible to mechanically adjust the gap and then adapt the structure to the vibrations conditions in order to maximize the capacitance variation. To validate the interest of its new geometry, we designed and fabricated a second tungsten prototype. This second prototype, presented on Figure 3, has an inertial mass 10 times smaller than the first one and permit us to have a first analyze the scaling effect. Figure 3. Second tungsten prototype with triangle fingers ( cm3) B. Initial energy production The big limitation in electrostatic transduction pare to other transduction principles is that it requires an initial energy to start. Indeed, if the electrostatic force can be actively driven to maximize the input energy absorption in against part it requires an initial energy source to be applied. If the objective of scavenging energy is to prolong the battery lifespan, that it’s good. But if the objective is to realize a system only based on energy scavenging with some long period without input energy, it can be a problem. To overe this limitation, we propose to bine the electrostatic principle with piezoelectricity by a judicious synchronization between the both phenomena [2]. The idea is that the piezoelectric structure reach its maximum of deformation when the capacitance of the electrostatic structure reach is maximum, enabling a direct transfer from the piezoelectric element to the capacitance. The electrostatic structure is then naturally polarized at the good time without external source. After the starting, the system can e back in an optimizing active mode. 1052 181。 W1884 181。 W Scavenged power Self maintenance power 2936 181。 W 460 181。 W Discharge losses 3396 181。 W 170 181。 W Charge losses X 78 181。 W Transduction losses 1884 181。 W Transduction Mechanical energy 1760 181。 W 1714 181。 W 30Authorized licensed use limited to: GUILIN UNIVERSITY OF ELECTRONIC TECHNOLOGY. Downloaded on January 13, 2020 at 05:55 from IEEE Xplore. Restrictions apply. Our second tungsten prototype is totally dismountable and adjustable and we can exchange a passive beam by a piezoelectric beam (Figure 4). For this structure, the maximum mechanical tension of the beam corresponds to the maximum of capacitance. Figure 4. Second tungstene prototype with exchangeable beam C. Keeping a constant relative displacement amplitude The efficiency is strongly dependent of the vibration amplitude and it is optimal only while the relative displacement amplitude is close to the gap between fingers but the input vibration amplitude is variable. To keep quite constant the relative displacement amplitude we patented a solution based on a geometrical nonlinearity of the beams used as spring and guidance [3]. The idea is to have a very flexible beam for the low displacements amplitudes in order to let free the relative displacement and to have a hard beam when the input displacement bees high in order to limit without dissipation the relative displacement amplitude. Furthermore, if the stiffness increases with the relative displacement amplitude, the equivalent resonant frequency also increases with the amplitude and can follow the input frequency onto one decade. On the Figure 5 is presented the inertial mass displacement response to different input frequencies and accelerations level. For each point, the calculation restart from a zero position but if the input vibration e from a low frequen。