A Compact Electromagnetic Vibration Energy Harvester with High Output Voltage

Non-resonant vibration energy harvesters (VEHs) attract much attention for the excellent performance in scavenging ambient low-frequency and broadband vibrations. In this paper, effects of the mild steel sheets, thicknesses of the magnets and coils, wire diameter of coils, and inner dimension of the coils on the outputs of a non-resonant electromagnetic vibration energy harvester (EMVEH) were simulated and the optimized geometries was obtained. Numerical simulations show that the mild steel sheets can enlarge the magnetic flux density about 25.0%, agreeing well with the experimental result that the output voltage increased about 29.3%. Under a base excitation of 0.3 g (where 1g = 9.8 m s(-2)) at 8.3 Hz, the RMS voltage across a 10.4 k Omega resistor of an EMVEH prototype, with the inner volume of 76.26 cm(3), is about 15.53 V. The power density is about 304 mu W cm(-3), about 18.7% higher than the previous device.