Three-dimensional piezoelectric energy harvester with spring and magnetic coupling

This letter proposes a three-dimensional piezoelectric energy harvester (3D PEH) that enables energy scavenging from vibrations in arbitrary directions. The proposed harvester comprises a spring, a primary beam, an inner beam, and two magnetic masses. The beams capture vibrations along their surface normal directions, and the spring, which acts as a mechanical energy buffer, is used to sense vibrations that occur parallel to the length direction of the inner beam. Magnetic coupling is introduced to perform frequency up-conversion and thus transfer vibration energy from the inner beam to the primary beam. As a benefit of the proposed structure, the 3D PEH can sense and convert all vibration energies occurring within the 3D space. When compared with use of the same beams in a linear configuration, the peak voltage of the proposed configuration is more than 3V, and the bandwidths of voltages exceeding 5V are wider by more than 3 Hz. Simultaneously, the primary beam resonant frequency is reduced by more than 6 Hz. Experimental results indicate that the proposed 3D PEH offers the advantages of higher open-circuit output voltages and wider frequency bandwidths at a lower resonant frequency. Published by AIP Publishing.