Design and evaluation of a magnetically coupled piezoelectric energy harvester with parallel connection.

This work proposed a magnetically coupled piezoelectric energy harvester with parallel connections. The rectangular piezoelectric patch in the upper part of the device generates regular vibrations due to the nonlinear forces caused by magnetic coupling. The lower rectangular piezoelectric patch is deformed by contact collision excitation. The parallel connection effectively connects the two sets of piezoelectric patches together and fully exploits the performance of the piezoelectric energy harvester. The intrinsic frequency of the rectangular piezoelectric patch was simulated and verified experimentally. The rectangular piezoelectric patch generates a large vibration amplitude in high-speed operation due to its elasticity property. From the experimental results, it can be seen that the piezoelectric energy harvester can work well in different frequency bands. The parallel piezoelectric energy harvester with a three-contact rotor has a peak-to-peak voltage of 252 V at a speed of 120 r/min and 200 V at a speed of 240 r/min. The maximum voltage achieved by the piezoelectric energy harvester in parallel is 266 V at a speed of 180 r/min with a resistance of 1000 kΩ. The maximum voltage reached by a series-connected piezoelectric energy harvester is 256 V at a speed of 180 r/min and a resistance of 100 kΩ. The peak-to-peak power of the piezoelectric energy harvester connected in parallel is 0.313 W under a resistance of 100 kΩ and a speed of 180 r/min. Besides, the developed piezoelectric energy harvester can light up to 60 light-emitting diodes. Accordingly, the energy can be effectively harvested by the piezoelectric energy harvester and then supplied to the microelectronic device.