Nonlinear Dynamics and Performance Enhancement Strategies for the Magnetic Levitating Bistable Electromagnetic Energy Harvester

PurposeIn order to enhance the output performance of magnetic levitating vibration energy harvesters over a wide frequency range, this paper investigates performance enhancement strategies for the tri-magnet levitating bistable electromagnetic energy harvesters (BEEHs).MethodsThe bistable nonlinear mechanism is achieved by magnetic interaction between the cylindrical and ring magnets, enabling the harvester to resonate over a wide frequency range. However, the gravity-induced asymmetric bistable potential adversely affects the output voltage response. Therefore, the bistable configuration with balanced potential well depth is proposed to improve the output performance.ResultsSimulation results based on the basins of attraction show that the probability of the oscillator eventually stopping at the left and right-side potential wells is approximately the same for different initial conditions. Furthermore, the output voltage response of asymmetric and balanced BEEHs is investigated under different excitation conditions. The results show that the balanced BEEH can achieve the high-energy orbit response over a wider frequency range for the same excitation level. Two coil series connections are provided, and their performance enhancement mechanisms are analyzed. Simulation and experimental results illustrate that the series connection of coils with the same wound direction (Series 1) is more favorable for the BEEH to achieve inter-well oscillation, which is suitable for vibration environments with small excitation levels. The series connection of coils with opposite wound directions (Series 2) improves the peak output voltage but generates large electromagnetic damping forces, making it more suitable for operating conditions with high excitation levels and large load resistance.ConclusionBalancing the potential well depth can facilitate oscillator travel across the potential barrier, and choosing the appropriate series coil solutions can exploit the BEEH advantages fully. These performance enhancement strategies have been proven to be effective in this paper.