Piezoelectric Energy Harvester with Zigzag Root Section for Self-Powered Transformer Monitoring

A slender piezoelectric cantilever for energy harvesting features high efficiency but a low operational frequency, which cannot meet the requirements for self-powered transformer monitoring. In this research, a piezoelectric vibration energy harvester with a zigzag root section was proposed. The harvester has a vertically arranged zigzag root section, enabling the capability of integrating multiple piezoelectric transducers as well as increasing the resonant frequency and reducing strain. A linear electromechanical coupling model was formulated. The theoretical and experiential base-movement analysis demonstrates that the zigzag root section of the piezoelectric cantilever beam can effectively reduce the equivalent mass of the system and thereby increase the resonant frequency of the slender beam to 100 Hz, the vibration frequency of a transformer. It was also experimentally shown that the harvester can output 13.54 mW of power. An STM32 microcontroller (MCU) based sensor node with a wireless data transmission module was then designed for evaluations. The piezoelectric harvester with a zigzag root section can successfully support a wireless sensor for transformer monitoring.