Design of a two-degree-of-freedom magnetic levitation vibration energy harvester for bridge vibration response analysis

For bridges with high automobile traffic, a large amount of vibration is generated daily due to cars driving over imperfectly level roads, and a vibration energy harvester can convert this energy into electrical energy, thus providing energy for devices such as bridge health sensors. However, the traditional single degree of freedom magnetic levitation vibration energy harvester (SMEH) has the disadvantage of low output power, so this research designs an improved dual degree of freedom magnetic levitation vibration energy harvester (DMEH), and a mathematical model of the energy harvester is built for simulation tests and an optimization model based on NSGA-II algorithm is developed for optimizing the structural parameters of the energy harvester. The experimental results show that the maximum total output power of DMEH and SMEH on CSSBB1, CSSBB2 and CSSBB3 are 48.7 mW, 36.8 mW, 25.4 mW and 27.2 mW, 21.5 mW, 14.9 mW, respectively, and the minimum total magnet volumes of both on CSSBB1, CSSBB2 and CSSBB3 are 268 cm3, 132 cm3, 219 cm3, 214 cm3, 86.2 cm3, 156 cm3. Based on the experimental data, it is found that the maximum output power of the optimal solution of DMEH is larger than that of SMEH for the selected simply supported girder bridge project, and the volume of the former is also larger than that of the latter, but the degree of increase can still be adapted to the application environment. The research results have some reference significance for improving the energy harvesting efficiency of bridge vibration energy harvesters.