Design and Optimization of an Electromagnetic Vibration Energy Harvester Using Dual Halbach Arrays

In this paper, an electromagnetic vibration energy harvester (EVEH) with dual Halbach arrays is presented based on the Faraday´s law of electromagnetic induction. A Halbach array is a specific arrangement of permanent magnets which could concentrate the magnetic field on one side while reducing the field to almost zero on the opposite side. This array could increase the magnetic field intensity and improve the electromagnetic coupling. The experimental results show that the output performance of the presented harvester is optimal when the height of the coil equals to the sum thickness of two adjacent magnets in the array. An optimal output power density is 1.39 mW/cm³ at a resonant frequency of 11.20 Hz with an acceleration of 0.5 g (with g = 9.8 m/s²) across a 20 mm-high and 1600-turn coil. When other conditions are kept constant, the output power density is proportional to the length of the cantilever. The EVEH based on dual Halbach arrays can increase the output power density and minimize the overall volume, which is beneficial for improving the practical application.