Cylindrical halbach magnet array for electromagnetic vibration energy harvesters

Abstract

This paper reports the design, optimization, and test results of a new magnetic structure for kinetic energy harvesters allowing seven-fold increase in power density compared to single-magnet configuration. Electromagnetic energy harvesters with “single cylindrical Halbach array” and “double-concentric Halbach array” magnetic structures composed of NdFeB magnets with 1.4 T residual flux density were fabricated and tested: respectively 5 mW and 15 mW power was measured and generated at low-amplitude (1 mm) low-frequency (<10 Hz) vibrations. These structures yield respectively a maximum power density of 14 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /g <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 26 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /g <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .