A comparative study of magnetically coupled nonlinear configurations for broadband vibration energy harvesting

Abstract Environmental vibration energy, as a widely available renewable source, presents a promising solution for powering low-consumption electronics like wireless sensor networks and internet of things nodes. While piezoelectric cantilever energy harvesters have been extensively studied, their inherently narrow bandwidth remains a major obstacle to their practicality in random vibration environments. Although introducing magnetic nonlinearity has proven effective for bandwidth broadening, a systematic comparison of the performance and intrinsic mechanisms of different basic magnetic configurations under uniform benchmarks is still lacking. This paper presents a systematic comparative study of four magnetically coupled nonlinear configurations for broadband vibration energy harvesting through integrated theoretical modeling and experimental validation. A distributed-parameter magneto-electro-mechanical coupling model was established, which successfully predicts the output voltage and bandwidth characteristics of each nonlinear configuration. The influences of magnet spacing, excitation level, and frequency sweep direction on system performance were thoroughly investigated via experimental tests and simulation analysis. The results reveal several key findings: first, multistable configurations demonstrate significant advantages in bandwidth broadening. The double-magnet attractive configuration, forming an ideal tristable potential energy distribution at specific parameters, achieves an effective bandwidth of 7.38 Hz and a peak-to-peak voltage of 181.45 V under forward frequency sweep, outperforming the optimal bistable configuration’s bandwidth of 6.72 Hz. Second, the system performance exhibits strong sweep-direction dependence. The double-magnet repulsive configuration under specific parameters in a reverse frequency sweep achieves an ultra-wide effective bandwidth of 10.99 Hz, while maintaining a peak-to-peak voltage of 143.31 V. Furthermore, the study identifies precise optimal ranges for the magnetic parameters, with any deviation leading to significant performance degradation. Through the mutual verification of theoretical prediction, numerical simulation, and experimental measurement, this study provides the first systematic performance comparison of four typical nonlinear magnetic configurations under a unified benchmark. The results clarify the advantages and design principles of multistable nonlinear mechanisms for achieving high-performance broadband energy harvesting, offering critical guidance for optimizing vibration energy harvesters in practical applications.