Acceleration

Electrical engineering

Physics

Cantilever

Electromagnetic coil

Rectification

Structural engineering

Shunt generator

Energy harvesting

Magnetic field

Electric generator

Engineering

Magnet

Voltage

Vibration

Power (physics)

Acoustics

Materials science

Permanent magnet synchronous generator

Power density

Quantum mechanics

Generator (circuit theory)

Resistive touchscreen

Classical mechanics

Journal of Micromechanics and Microengineering

Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes. This paper presents a small (component volume 0.1 cm3, practical volume 0.15 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data. The generator uses four magnets arranged on an etched cantilever with a wound coil located within the moving magnetic field. Magnet size and coil properties were optimized, with the final device producing 46 µW in a resistive load of 4 kΩ from just 0.59 m s−2 acceleration levels at its resonant frequency of 52 Hz. A voltage of 428 mVrms was obtained from the generator with a 2300 turn coil which has proved sufficient for subsequent rectification and voltage step-up circuitry. The generator delivers 30% of the power supplied from the environment to useful electrical power in the load. This generator compares very favourably with other demonstrated examples in the literature, both in terms of normalized power density and efficiency.

A micro electromagnetic generator for vibration energy harvesting