Tunable Piezoelectric Vibration Energy Harvester With Supercapacitors for WSN in an Industrial Environment

This article presents the design strategy and experimental validation of a battery-free power supply for wireless sensor nodes (WSN) on an industrial study case. The power supply is based on the principle of vibration energy harvesting (VEH). The general architecture of the linear generator with electronic is presented. It is composed of commercially available components as a MIDE PPA 1014 piezoelectric cantilever beam and a LTC3588 circuit to extract and shape the electrical energy. The energy source comes from mechanical vibrations measured on the industrial environment in operation. A tunable mechanism of the resonance frequency is added in order to have a wider range of use than the natural range of a linear harvester. To adapt the VEH according with the source, it resonant frequency range can be tuned with a dedicated tip-mass. Then a fine adjustment within a range of about 20 Hz is set using both a moving clamping device and a temporarily wired electronic device working as a maximum power point finder (MPPF). To achieve a long lifetime, the storage is done using balanced supercapacitors. Two operational demonstrators are shown. The test benches as well as numerous experimental tests are presented. Shaped according to the industrial environment (49.0 Hz @ 2.7 m/s
²
), the VEH is capable of delivering continuously 100mA@3.3V with 200 mA peaks. When the power harvested (
$\approx 2.9$
mW) is upper than the sensor average power, it offers the capability to store 17.5 J at 18.5 V. As a result, from this work, a WSN can successfully operate over a significantly long period of time despite fluctuations in the vibration source.