Theoretical analysis of a new adjustable broadband PZT beam vibration energy harvester

•It introduces a new adjustable broadband vibration energy harvester.•It develops PZT voltage equation utilizing structure combination theory.•Harvester voltage equation is experimentally verified to be accurate.•A computational algorithm is introduced for adjusting harvester frequency.

This paper proposed a feasible design of an adjustable PZT beam vibration energy harvester. The adjustability of the harvester was achieved via varying the beam׳s support stiffness, off-line for design or on-line for control, which could be accomplished through, for instance, such as magnetic supports. The theoretical approach employed a structure combination technique for the frequency equation, sensitivity matrix and PZT beam voltage output equation. The harvester’s resonance frequencies and voltage outputs at various excitation frequencies were numerically calculated and experimentally verified to be accurate. Adjusting three-support stiffness to precisely tune the harvester׳s first resonance was demonstrated, theoretically. The adjustable frequency range could be up to ±30% and this was significant from a comparison with the existing literature. Simulations of sudden ambient frequency changes of 5%, 10% and 15% were illustrated and an efficient computing algorithm showed that no more than five steps of support adjustment was enough to regain the resonance state and deliver another maximum voltage output. The harvester׳s output voltages through the whole frequency band were calculated as well and it appeared the designed harvester would sustain a high level of voltage output.