Investigation on behavior of the backpressure based piezoelectric energy harvester driven by compressed air.

A piezoelectric energy harvester with backpressure pre-loaded is designed to investigate the performance that can be driven by the compressed air load in the pneumatic system. The power generation principle and microelement mechanics model are established, which can explain the principle that backpressure changes the internal energy of materials. The backpressure affects the internal stress of materials. The electromechanical coupling coefficient can be adjusted by the backpressure. The power generation obviously changes as the electromechanical coupling coefficient is adjusted. An experimental testing system is established, and the experimental results are analyzed to prove the effect of backpressure on the output power. There is a linear relationship between the peak voltage and backpressure. When the backpressure increases every 1 kPa, the voltage increases by 0.667 V. The voltage increment under backpressure is 5.13 times that without backpressure. The optimal output power is 12.3 mW in 30 kPa backpressure pre-load. The output power increases to the original 237% under the backpressure. The prototype can directly supply energy to the temperature sensor, and it can supply power to a magnetic switch with capacitor energy storage.