Vibration Energy Harvesting Using Piezoelectric Elements by Multi-switch Circuit with Adaptive Inductance

Mechanical vibration energy harvesting using multi-switch circuit with adaptive inductance is a new method based on impedance matching between electrical circuit and mechanical vibrating system in order to maximize the harvested energy. Considering a vibrating piezoelectric element in parallel with a load resistance, the whole converted energy is not dissipated or flowed into the load resistance and a remarkable portion of this energy is stored on the internal capacitor of the piezoelectric. By connecting the vibrating piezoelectric to a special interface circuit, approximately the whole stored energy portion on the piezoelectric flows into the circuit. The proposed interface circuit contains a set of inductors in series with electronic switches that controlled by a microcontroller which always provides resonance condition in the designed frequency range. In the proposed technique, for a simulated piezoelectric generator with a constant current source in the design frequency range of 100 to 700 Hz, the harvested power of numerical analysis is 2 to 10 times (depending on frequency) more than standard method (simple resistive circuit). Harvested power in the exprimental test for a cantilever piezoelectric plate in the design frequency of 100 to 350 Hz, is 4.5 times more than standard method.