A Low-Frequency Resonant Electromagnetic Vibration Energy Harvester Employing the Halbach Arrays for Intelligent Wireless Sensor Networks

In this paper, an electromagnetic (EM) vibration energy harvester (VEH) employing the Halbach arrays magnetic circuits to convert a low-frequency vibration energy into an electrical energy is presented. The VEH is made up of the Halbach arrays magnetic circuits, a coil, and a cantilever beam. The Halbach arrays magnetic circuits can concentrate the magnetic field on one side while canceling out the magnetic field on the other side. An analytical model is developed to analyze the distribution of the magnetic field of the Halbach arrays magnetic circuits. The electric output performances of the VEH have been investigated. Compared with the traditional EM VEH, the proposed VEH can significantly increase output power and power density. When coil diameter d, turns number N, and cantilever length L_c are 20 mm, 1400, and 80 mm, we obtain the optimum output power of 90.35 mW and the power density of 0.55 mW/cm³ at 12.65 Hz under 0.5 g, respectively. Remarkably, the proposed low-frequency resonant EM VEH employing the Halbach arrays has great potential for applying in intelligent wireless sensor networks.