Electromagnetic vibration energy harvester with displacement amplification mechanism

Electromagnetic vibration energy harvesters (EVEHs) offer a promising alternative to chemical batteries for powering low-power sensing devices, yet their energy harvesting performance is often constrained by the limited relative motion of conventional spring–mass systems. To address this limitation, a displacement-amplified EVEH is proposed, in which the vertical motion of a main mass is converted into transverse relative motion between two horizontal sliders via a triangular lever mechanism, enabling enhanced magnetic flux variation. The geometric amplification characteristics are analyzed, showing that effective displacement amplification is achieved when the assembly angle exceeds 44.91°. A coupled nonlinear electromechanical model is established based on the Lagrange–Maxwell formulation, and the nonlinear dynamic responses are investigated using the semi-analytical harmonic balance–alternating frequency/time (HB-AFT) method combined with arc-length continuation and Floquet stability analysis. The results indicate that the system exhibits effective two-degree-of-freedom behavior with two resonance peaks under equal slider masses, whereas unequal mass configurations lead to effective three-degree-of-freedom characteristics with an additional resonance and broadened energy harvesting bandwidth. Parametric studies further reveal the influences of mass distribution, damping, and stiffness on the amplitude–frequency responses and nonlinear characteristics. Compared with a conventional harvester without displacement amplification, the proposed system achieves a significant enhancement in output voltage, with improvements on the order of two times. An experimental prototype is developed, and the measured results show good agreement with the theoretical predictions, validating the proposed model and analysis.