Investigation on Electrical Output Combination Options in a Piezoelectric Multifrequency Converter Array for Energy Harvesting in Autonomous Sensors

A piezoelectric multifrequency converter array intended for energy harvesting from broadband vibrations to power autonomous sensors and two different configurations of multi-input rectifier circuits are presented. The converter array is composed of multiple bimorph cantilevers with different natural frequencies fabricated by screen-printed PZT films on steel. In the two proposed rectifier circuits, the converters of the array are connected in parallel-like and series-like configurations, respectively. The effect produced on the harvesting performances for the two configurations is analyzed and validated by experimental results on the fabricated array. At parity of mechanical excitation, the series-like configuration can provide a marked increase in the overall output voltage over the parallel-like configuration.