A Piecewise Linear Piezoelectric Energy Harvester With Controllable Gap Size

Abstract Research in the field of vibration energy harvesting has been increasing over the past decade. Researchers have developed various methods to collect unused or wasted energy from physical systems, such as bridges. This paper presents and tests a piecewise-linear (PWL) piezoelectric energy harvester design. Similar studies have been conducted for an electromagnetic energy harvester and have shown the benefit of implementing a PWL energy harvester for some potential applications. This work investigates the performance of the PWL energy harvester using a piezoelectric cantilever beam as the energy generator, which is more suitable for smaller-scale harvesting applications. The design of the piezoelectric cantilever beam system uses a simple control algorithm to maintain the optimal gap size in the system. This design actively adjusts the resonance frequency to maximize power generation over a larger frequency range to make self-powered sensors more viable. The resonance frequency is optimized by adjusting the gap size between the piezoelectric cantilever beam and an elastic stopper using a combination of linear actuators, circuits and microprocessors. The design shows an increased performance in maintaining an optimized vibrating amplitude in the pre-computed frequency range. An experimental realization of the design is tested and compared with the computational prediction to validate the design’s effectiveness.