Hybrid energy harvester based on piezoelectric and electromagnetic mechanisms

A novel hybrid energy harvester integrated with piezoelectric and electromagnetic energy harvesting mechanisms is investigated. It contains a piezoelectric cantilever of multilayer piezoelectric transducer (PZT) ceramics, permanent magnets, and substrate of two-layer coils. The effect of the relative position of coils and magnets on the PZT cantilever end and the poling direction of magnets on the output voltage of the energy harvester is explored. When the poling direction of magnets is normal to the coils plane, the coils yield the maximum output voltage, i.e., the type I and III devices. The maximum output voltage and power from the PZT cantilever of the type III device are 0.84 V and 176 mu W under the vibrations of 2.5-g acceleration at 310 Hz, respectively. And the maximum output voltage and power from the coils are 0.78 mV and 0.19 mu W under the same conditions, respectively. The power density from the type III device is derived as 790 mu W/cm(3) from piezoelectric components and 0.85 mu W/cm(3) from electromagnetic elements. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3373516]