High efficiency, wide load bandwidth piezoelectric energy scavenging by a hybrid nonlinear approach

Energy harvesting from ambient energy sources and particularly vibrations have been of significant interest over the last decades for powering consumer electronics. However, vibration energy harvesters that use the piezoelectric effect feature limited output power and load dependency. The purpose of this paper is to present a hybrid technique that consists of combining two nonlinear techniques for enhancing the conversion abilities while providing a relative load independency. Although the proposed scheme relies on the use of two existing approaches, it will be shown that the operation of the overall system is different from the behavior of the two techniques taken separately, allowing four energy extraction cycles per vibration period. Theoretical analysis validated through experimental results indicates that the proposed scheme allows harvesting up to 6 times more energy while having a relative independency from the load connected to the harvester.