Finite Element Simulation for Predicting the Magnetic Flux Density for Electromagnetic Vibration Energy Harvester ^†

The current revolution in the field of electromagnetic vibration energy harvester requires that both wireless sensor nodes and relevant power sources be cost- and size-optimized while ensuring that, during design/fabrication of the sensor’s power sources, the power deliverable to the sensors be maximum. Flux density dependency on the nature of the magnetic coupling material of VEH magnet-coil transducer is well reported while reports on size-optimized but improved performance in the VEH is available. This paper presents on the realization of an approach to ensure an accurate prediction of size-optimized but maximum power output on the electromagnetic transducer of a VEH. The adopted approach justifiably verifies the geometrically determined flux density on a Finite Element Magnetic Method Software (FEMM) on the permanent magnet (NdFeB N52) as a basis for optimization. An empirical formula—which predicts size-optimized flux density and could be used to predict the performance of a miniature energy harvester for wireless sensor nodes application—was formulated. For the geometry presented in this work, where $l_c$ and $N_{c-2}$ are the effective length and turns on the reference coil, the magnetic flux density, coupling coefficients, coil width and transducer thickness were predicted to optimize at 0.4373 T, 0.3978${\mathsf{\mu }}_3{l}_c{N}_{c-2}$ Tmm, 4.00 mm and 18.40 mm, respectively, with all corresponding to instances when the flux density per unit volume on the coil was approximately 0.4373$/\left({\mathsf{\mu }}_3{\overline{v}}_{c-2}\right)$T${\mathrm{mm}}^{-3}$. The above optimized values were measured on magnet-coil geometry with the smallest overall thickness. However, in comparison to other models, the coil thickness in the optimized geometry was not the least.